In 2016, developer Millennium Partners began construction on an ambitious, $398 million mixed-used project, the Four Seasons Private Residences at 706 Mission, to deliver 146 high-end luxury residences. These housing units are in a restored Aronson and a new, adjoining 43-story, high-end condominium tower also housing the city’s long-standing Mexican Museum in its lower levels. This tower, designed by Handel Architects, finished construction in December 2020, and residents moved in soon after, though the Mexican Museum is still building out its space and has yet to take occupancy. (Millennium ultimately sold the project to Westbrook Partners; its subsidiary, 706 Mission Street Co. LLC, is the legal owner of the site.)

Seismic upgrades

To make the whole project work, the Aronson had to be rehabilitated and upgraded to current seismic standards. Seattle-based civil and structural engineering firm Magnusson Klemencic Associates faced two options for improving the historical building’s underlying structure: Use the new tower to brace the existing building or keep the buildings structurally separate.

There were technical benefits to keeping them structurally separate even though they would be linked at each level for circulation purposes. “You’re not mixing a brand-new system with a historic(al) building,” says Peter W. Somers, P.E., S.E. a principal at MKA. Somers managed the structural design of the Aronson renovation and seismic upgrade.

However, there were downsides. Having to add concrete shear walls, steel bracing, or other lateral elements within the interior of the Aaronson to seismically strengthen it would have taken up valuable floor space, he says. And the joint needed between the two buildings to allow each to move independently would have needed to be 2.5 ft to 3 ft at the roof. “It’s very hard to design a joint that’s that wide. It would look messy from the outside as well as (in) its interior layouts and finishes, (and) it’s hard to detail for waterproofing,” Somers says.

So MKA abandoned this approach in favor of structurally connecting the Aronson to the new tower.

The new tower is primarily a post-tensioned concrete structural system supported by perimeter concrete columns and an interior core. The building uses concrete-filled metal decks at the lower museum levels for flexibility. The circulation core provides resistance to seismic and wind forces in east-west and north-south directions.

The Aronson is connected to this tower in the east-west direction at each floor level. “So where the buildings are in alignment, the Aronson forces are 100% resisted by the tower,” Somers says. “So we have structure that drags the Aronson lateral forces from the Aronson Building into the tower floor and into the core walls.”

Meanwhile, he adds, in the north-south direction, a portion of the Aronson has two north-south oriented concrete shear walls that are approximately 24 in. thick and 20 ft long, extending the full height of Aronson. These provide additional lateral resistance to keep the old building from “twisting off” the new one. (These walls take up less space than the shear walls that would have been required if the two buildings were braced separately).

MKA also had to brace and seismically stabilize the Aronson’s exterior walls, composed of non-load-bearing brick — these were at significant risk of falling during an earthquake. MKA used heavy gauge steel studs called strong backs, which are anchored into the walls, to stabilize the exterior.

Because the roof transfers most of the force from the Aronson to the new tower, MKA also rebuilt the entire roof level.

The Aronson has a one-story basement, but the new tower has a three-story basement — this deeper foundation potentially could have undermined the Aronson. To underpin and stabilize the existing Aronson foundation so that the deeper excavation could take place for the new tower, MKA and the building’s contractor, Webcor Builders, used shoring soldier piles and lagging. This involved boring holes and installing long steel beams spaced every 8 ft interspersed with timber lagging beams placed between these steel beams. Those vertical load-carrying piles supported the Aronson footings while the tower excavation was underway and then were integrated into the tower basement walls and foundation for vertical support in its permanent condition.

A lot of planning went into the sequence of connecting the two buildings to make sure the finished condition of the tower structure and floors would align with the existing building floor levels. To maintain compatibility between the tower and the Aronson, most of the new tower was built and allowed to experience its minor initial settlement and deflection before it was connected to the Aronson.

Connecting to the neighborhood

Aesthetically, the tower design takes its cues from the historical buildings of the neighborhood, including the art deco PacBell Building at 140 New Montgomery Street, once the tallest skyscraper in the city. “All the buildings in the Transbay Terminal area, which is about six or seven blocks away, are basically all-glass buildings,” says Glenn Rescalvo, FAIA, the partner in charge of the San Francisco office of Handel. “We really didn’t feel like this area was where (we) wanted to put a full-glass building.” Plus, the developer, Millennium, wanted stone — a material that hadn’t been used in San Francisco to clad a building of this size in years.

The facade of the tower is composed of alternating layers of glass and stone — the latter visually ties back to the masonry of the Aronson.

Replicating original elements

Page & Turnbull was hired by Millennium in 2010 to help guide the mixed-use project through the city’s rigorous entitlements process. This involved completing a historic structure report, an analysis designed to assess the physical condition of older buildings as well as their historical value to their cities.

“A historic structure report is a pretty thorough ‘photograph’ in that it takes a look at everything,” says Elisa Hernández Skaggs, AIA, an associate principal with Page & Turnbull, speaking of the Aronson. “It documents what’s there, what’s in good condition, what’s in poor condition.”

The interior of the building, for instance, had been altered over the years as tenants adapted the spaces to their needs, and much of the historical fabric was already gone. But there were places where the Aronson could be restored, chiefly by replacing the large, non-original aluminum windows inserted into the original wood frames (which range in size but are mostly 9 ft, 6 in. high and 7 ft, 6 in. wide) with operable wood windows that are similar in appearance to the originals.

“Those were a big challenge,” says Hernández Skaggs. They’re very large windows, and so their weight and scale make them really difficult to produce in a way that’s easy for tenants to operate. As it turned out, the first windows Millennium had installed were, in fact, too heavy to operate, so they all had to be replaced again.”

The building’s exterior cladding, except for the ground floor, was relatively intact. The firm was fortunate to work with the original 1903 terra cotta ornament manufacturer, Lincoln, California-based Gladding McBean, which is still in business. The company was able to make molds from existing ornamental terra cotta units to create new units to replace those that were deteriorated and damaged.

A terra cotta band of acanthus leaf ornament, dubbed by the design team as the log and rope course, runs the full length of the two street facades just above the ninth floor and had suffered substantial cracking, creating potential fall hazards. Page & Turnbull used epoxy on the terra cotta and anchored the terra cotta units to the brick with stainless steel rods at “carefully selected locations to avoid damaging the internal structure of the terra cotta units,” says Hernández Skaggs.

The ground floor, on the other hand, had been modernized in the 1960s and again in 1978. In the process, its retail display windows and two primary sandstone entrances were covered with brick. For the current project, the brick was removed, and Hernández Skaggs and her colleagues used a mix of sandstone patching material and cast stone replacement units to restore and reconstruct historical details around the arched entrances, guided by historical photos of the building.

“We’ve been able to walk away from this building knowing that we’ve added value to its historic character,” says Hernández Skaggs.

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The Pennsylvania Turnpike was designated an ASCE landmark in 1988.  Here are five things you didn’t know about the Pennsylvania Turnpike:

1. The turnpike was built primarily along the right-of-way of a never completed railroad venture, the South Pennsylvania Railroad, including seven bored and abandoned tunnels.
2. The Pennsylvania Turnpike appeared in the Russian film Brother 2.
3. On the date it opened, Oct. 1, 1940, at midnight, traffic jams occurred along its length as thousands of people went for pleasure drives.
4. The turnpike had no enforced speed limit when it opened, except for the tunnels.
5. The turnpike has appeared in multiple songs, including George Vaughn Horton’s “Pennsylvania Turnpike, I Love You So,” Billy Joel’s “You’re My Home,” and Why’s? “Probable Cause.”

Members of ASCE’s History and Heritage Committee have been learning fun and interesting facts about HCELs around the world to share in the new “5 Things You Didn’t Know About …” series. As the committee continues to build an inventory of all HCEL projects, members of the committee and other volunteers have been visiting sites to photograph landmarks and ASCE plaques as well as assess their conditions. If interested in volunteering to help the committee record these landmarks, please contact committee chairman David Gilbert ([email protected]).

Learn more about the committee’s work and the ASCE landmark program.

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Born in Detroit and having moved to Chicago as a boy, Avery Brundage enrolled at the University of Illinois and graduated from the civil engineering program with honors in 1909. During college, Brundage played basketball and ran track, contributing to Illinois’ Western Conference championship track team during his senior year. Upon graduation, Brundage accepted a position as a construction superintendent for the Chicago architectural firm Holabird & Roche, where he supervised construction for one out of every 30 buildings that were constructed in Chicago during the time of his three-year tenure.

While he was working as a construction engineer, Brundage continued to run track as an amateur, including the 1912 Stockholm Olympics where he competed in discus and finishedsixth and 16th respectively, in the pentathlon and decathlon. In 1915, he founded the Avery Brundage Co., which was active in the Chicago construction industry until 1947. Among the structures built by his company was the (former) Marshfield Trust and Savings Bank, now known as the Brundage Building, which was completed in 1924 and designated a Chicago landmark in 2008.

During the 1910s, Avery Brundage sustained his track career, as he won the U.S. national all-round title on three occasions (1914, 1916, and 1918). By the 1920s, his penchant for athletics outshone his civil engineering, and in 1928 he became the president of the Amateur Athletic Union and succeeded Douglas MacArthur as president of the American Olympic Committee. Eight years later, July 30, 1936, Brundage was elected to the International Olympic Committee, a position that he held for 36 years, spanning the controversial 1936 Berlin Olympics and ill-fated 1972 Munich Olympics.

In 1952, Avery Brundage was named thefifth president of the International Olympic Committee, a position that he held for 20 years. Although better known for his Olympic leadership, Brundage left his civil engineering legacy in Chicago through his construction of a Ford Motor Co. assembly plant, the 23rd Street Viaduct, high-rise apartment buildings, the landmark Brundage Building, and the modernization of the LaSalle Hotel, which he owned and where he resided for many years. Avery Brundage died May 8, 1975, and is interred in Chicago’s Rosehill Cemetery.

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The Eiffel Tower? The Brooklyn Bridge? The Grand Coulee Dam? All of the above?

ASCE has designated more than 200 projects as Historic Civil Engineering Landmarks.

Civil engineers took to ASCE Collaborate recently to share stories about their favorites. Here are some highlights from that discussion (and be sure to log in and contribute your favorites):

Heidi Wallace, P.E., M.ASCE

Tulsa, Oklahoma

“I didn’t realize ASCE had landmarks until I was in Spain with my dad. We were in Segovia in 2019, looking at the aqueduct, and as we went to walk up the steps I noticed that the plaque said ‘ASCE.’

“I made sure to take a picture of it … . I highly recommend taking the trip if you have the chance. It was incredible to see how precise the construction was with a nearly constant slope considering the terrain changes and the materials being used.”

René Vidales, P.E., M.ASCE

San Diego

“The University Heights Water Tower in San Diego obtained ASCE Local Historic Engineering Landmark status in 2015, with local leaders in attendance. Originally built in 1924, a riveted steel tank raised on 12 steel girders high above San Diego’s early streetcar suburbs, it held more than 1 million gallons of water for a growing city. Now the water tower has become a hallmark for the neighborhood.”

Mitchell Winkler, P.E., M.ASCE

Houston

“Growing up, I spent countless weekends with my father and sometimes mother and siblings exploring the remnants of the Middlesex Canal. The canal, opened in 1803, connected textile mills in Lowell, Massachusetts, to Boston Harbor.

“It operated for about 50 years before being replaced by rail. It’s been recognized by ASCE with this claim to fame: The Middlesex Canal is one of the oldest man-made waterways in the United States. The canal served as a model for the later Erie Canal.

“My father remains active in the Middlesex Canal Association, while my brother has started leading walks along different sections that remain preserved today.”

Join the conversation on ASCE Collaborate.

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Having no formal education after the age of nine, Ellis Chesbrough, at 15, became a surveyor for the city of Baltimore, through his father’s job as a surveyor for the Baltimore and Ohio Railway. By the later 1840s, Chesbrough was in Boston where he engineered much of the city’s water system, including the Cochituate Aqueduct and Brookline reservoir. In 1851 he was the sole commissioner of the Water Works and was named the first city engineer.

The city of Chicago, founded in 1833 with a population of 200, saw rapid growth in its first two decades due to its position as a transportation hub and its economic allure to rural Americans and immigrants from abroad. Twenty years later, with a population greater than 60,000 and flood-prone topography, the circumstances demanded improved sanitary conditions as standing water and a lack of drainage infrastructure contributed to six consecutive years of epidemic outbreaks. The topography, just 4 feet above the elevation of Lake Michigan, not only inhibited natural drainage but limited the ability to install engineered drainage systems. The Chicago Board of Sewage Commissioners selected Ellis Chesbrough to solve Chicago’s public health crisis.

Chesbrough designed and constructed a tunnel extending 2 miles into Lake Michigan, beyond the point where the water had been fouled. Then Chesbrough devised a plan to build a sewer system above ground and fill the grade over the sewers, while raising buildings as much as 10 feet to accommodate them. For the next decade, the first comprehensive sewer system in the United States, the “Chesbrough sewers,” were constructed. During this time, engineers displayed their inventiveness by raising buildings, rows, and blocks of structures as tall as six stories, many of which remained occupied as commerce continued during the lifting.

Ellis Chesbrough served ASCE as president in 1878, and in the following year resigned his position as Chicago’s public works commissioner. Through his civil engineering work, the sanitary and structural ingenuity that he envisioned elevated Chicago, not only physically out of the muck but culturally into a world-class city.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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The Martin Luther King Jr. Memorial Library is located at 901 G St. NW in the heart of Penn Quarter in Washington, D.C. Penn Quarter is only a short walk from the National Mall in a commercial district of federal office buildings, high-end restaurants, shops, and cultural institutions.

The existing library was designed by modernist architect Ludwig Mies van der Rohe, opening in 1972. By the early 2000s, it had fallen into such a state of disrepair that there was a movement to sell or demolish the building. Years of deferred maintenance accelerated the deterioration caused by water infiltration at the unique facade joints. This deterioration led to rust jacking of the glass framework and to distortions and cracks in the glazing. At below-grade levels, this water infiltration led to extensive concrete deterioration. In addition, the original mechanical, electrical, and plumbing systems were beyond their service lives and were beginning to fail.

The original interiors were dark and uninspiring and the brick-clad entrances uninviting. In addition, at most floor levels, rows of bookshelves and storage areas had been installed adjacent to windows, which effectively blocked natural light from reaching the interior spaces, where reading areas and offices were once located. Masonry completely enclosed the building’s four cores, creating cramped and dark stairways that were difficult to find. Oddly, the two front cores adjacent to the main entrance serviced building staff, while library patrons had to use the rear cores to get to the upper floors.

Historical significance
Despite the many design criticisms, historic preservation groups fought to save the Mies-designed library, which, interestingly, was the only library in his vast portfolio. It is also one of Mies’ final projects. Adding to the preservationists’ arguments, the building is one of the first to be dedicated to civil rights icon Martin Luther King Jr. These two historical figures may appear to have very little in common; however, the design architects eloquently noted of Mies: “In his work, transparency and light stand as metaphors for freedom and knowledge, the very principles of Dr. King’s life teachings.”

Fortunately, in 2007, the District of Columbia Historic Preservation Review Board designated the library as a historic landmark, and it was placed on the National Register of Historic Places. This paved the way for the $211 million renovation to begin a decade later.

After an international design competition in 2013, Mecanoo, headquartered in Delft, Netherlands, and Washington, D.C.-based OTJ Architects were selected for the redesign.

Mecanoo, led by celebrated architect Francine Houben, is known internationally for its work on libraries. The firm based its design on its philosophy that a 21st-century library should no longer be solely a repository for books but rather a public facility that welcomes all people and provides spaces for learning, collaboration, exploration, and recreation.

In deference to Mies, Mecanoo clearly differentiated between its new design and the Miesian aspects of the original design. While Mies’ design is distinguished by a disciplined grid of framing emphasizing structure, the new spaces are characterized by rounded forms and accentuated by various colors to create an airy and relaxed atmosphere.

Existing conditions
The building’s form is rectangular with plan dimensions of 180 by 360 ft. Typical column bays are 30 ft in both directions. The exterior of the building is clad in steel and glass with steel mullions spaced 10 ft on center between steel-clad columns every 30 ft.

The original building comprised three levels below-grade and five levels above-grade, including the ground floor and an uninhabitable roof. The foundation consisted of a 6 ft thick mat slab that occupied a portion of the building’s footprint, with the balance supported on piles. The below-grade levels and ground floor were framed with cast-in-place concrete slabs and beams supported by CIP concrete columns and walls. The above-grade superstructure was steel framed with CIP concrete slabs supported by composite steel beams and steel columns.

The existing structure was in good condition except for the exterior steel and glass cladding, which sustained moisture damage from condensation, and the below-grade elements, where waterproofing systems had started to fail.

Facade update
Given the building’s history of facade problems and that facade’s significance as a character-defining feature, a substantial portion of the work for the building involved the rehabilitation of the envelope system. Modern sustainability requirements for thermal performance also mandated an upgrade of the envelope, and the original steel anticorrosion coating needed to be replaced.

Facade consultant Wiss, Janney, Elstner Associates Inc. surveyed the condition of the envelope and tested the existing coatings. The testing informed their plan for preparing the surfaces for the application of new coatings.

Additionally, single-pane glazing was replaced with laminated glazing. The exterior panes have a clear low-emissivity coating that improves thermal performance, while the interior panes are tinted bronze.

Protected elements
Because of the building’s landmark status, there were elements and features that were historically significant, including the first-floor brick masonry as well as the MLK mural and the supporting brick masonry directly behind it. The mural, which depicts events of King’s life and the civil rights movement, was installed in 1986 in celebration of the first MLK holiday adopted by Congress. The 7 by 56 ft mural is centrally located in the Great Hall, and it is immediately visible upon entering the main entrance. The mural spans two structural bays.

Directly in front of the mural, the new design called for an informal performance space with an alcove below the mural for a stepped seating area. This required the demolition of the masonry wall below the mural, which was temporarily relocated during construction. In addition, the upper portion of the wall behind the mural was needle-shored for its protection before the demolition of the lower portion.

To support the wall in its final condition, Silman, the structural engineering firm for the project, designed supports to span between the existing columns and a central intermediate support from above. The support from above would limit deflection of the masonry at the midspan of the horizontal hollow structural steel elements. The existing second-floor beam directly above could not support the central support load, so a V-shaped truss system was designed instead. Two diagonal HSS members diverge from the center of the HSS beam up to the columns on either side of the bay.

Because of the building’s landmark status, there were elements and features that were historically significant, including the first-floor brick masonry as well as the MLK mural and the supporting brick masonry directly behind it. 

Adding to the complexity, the support system needed to be offset to be clear of the masonry wall it was supporting, it needed to fit within the architecture, and it had to limit any disturbance of the remaining masonry wall. To support the offset masonry wall, a continuous plate and HSS tube outrigger system, spaced 2 ft apart on center, were welded to the bottom of the HSS beam. The system was designed to cantilever and support the entire width of the masonry wall.

Lateral system
An initial study was conducted to determine the lateral load-carrying capacity of the existing structure. Based on the existing structural drawings as well as probes that Silman conducted, the engineers determined that lateral resistance was provided by moment-frame action in the structure combined with the resistance of interior infill masonry walls. The existing drawing details of the spandrel beams at the column joints showed top bars in the slab welded to the columns.  These columns had continuous steel fascia plates that were anchored into the concrete encasement of the steel. These details resulted in continuity through the joint, creating moment-frame action.

Other probes were conducted on the detailing at the base of the columns to determine the degree of fixity. Ultimately, the analysis showed that the existing lateral capacity would not meet wind and seismic demands dictated by current codes.

Additional analyses were conducted with new concrete walls placed at all four cores, extending from the foundation to a new roof addition. The dual system of moment frames and concrete shear walls provided adequate resistance and stiffness for the new lateral loads.

Cores and monumental stairs
The mural was not the only historically significant element. Much of the existing brick masonry veneer at the first floor — along with its concrete masonry unit backup — and at the four cores on all levels qualified for preservation. At all levels of all four cores, the architectural programming required a complete reframing of the structure. However, the existing beams directly below the protected walls needed to remain in place. The framing surrounding these protected walls was demolished for the new design. The existing framing that supported these walls was supported by a complex web of new framing.

Two new helical-shaped monumental stairs were designed within the two southern cores to flank the main public entrance at the first floor and provide access between the first below-grade level and the existing roof level. At the new roof, the design team added a skylight to allow natural light to enter the shaft. The stairs are identical and mirrored along the central axis of the building.

The stairs’ widths vary from 5 to 6 ft and allow for the designer’s vision of a “social stair” that provides patrons with a meeting point rather than just circulation. The helical shape shifts at each level to provide unique views of the stairs as well as views of patrons descending and ascending the stairs below.

The stair structure comprises standard rolled-steel shapes supported by new beams within the cores and existing beams located along the perimeter of the cores. The stair landings between floors are supported by HSS posts and exposed plate hangers that are tied to the existing perimeter beams. The hangers are 0.5 by 2 in. plates that have been carefully integrated into the handrail system.

At the second floor and above, some of the existing perimeter beams required reinforcement, which was achieved by welding WT reinforcement to the bottom flange of the existing beam. At the concrete-framed levels, support points were strategically located to avoid reinforcement of the existing concrete beams.

A vibration study was conducted to meet appropriate criteria for comfort.

New spaces
The design team wanted to have high ceilings — such as those found in the great libraries of the past — in the new Great Reading Room. To make that happen, the reading room was placed on the east side of the third floor. This required the demolition of a two-bay section (30 by 60 ft) of the fourth-floor framing directly above to carve a two-story space out of the upper floors.

Demolition was limited to the concrete floor plate and one steel beam along the grid that divided the two bays. The edge of the opening is 2 ft from the grid, resulting in a cantilevered slab. To support this cantilever, the existing slab reinforcement was protected during demolition and was bent to develop the bars in tension. New steel edge angles and headed studs were cast to form the new slab edge and to support floor-to-ceiling glass walls that provide views into the reading room below.

A new 289-seat auditorium is located at the center of the roof between the four cores. It replaces the original one-story below-grade auditorium. It is a double-height space between the fourth floor and the new rooftop addition. The auditorium is designed for performances and lectures and has direct access to the rooftop, adding to the value of the library as a community space.

Construction of the auditorium required the demolition of roughly 60 by 50 ft of roof framing. The auditorium seating is steel framed with seven lines of sloped steel beams supported by posts. The posts bear on the existing 60 ft span composite 30WF steel beams at the fourth floor. The original design of the floor system specified a live load of 150 psf; therefore, reinforcement of the existing beams for the new loads was not required.

The main function of the rooftop addition is to house the new auditorium. There are also flexible event spaces, a kitchen, a cafe, and staff lounges. The rooftop addition is a single floor that is set back from the existing building line due to zoning requirements.

The design also makes room for a full floor addition in the future. To accommodate this, the existing roof structure was designed for a live load of 150 psf and is similar in composition to the floors below. The new rooftop structure consists of concrete on a composite steel deck supported by composite steel beams and steel columns. Careful planning and coordination of the location and size of vegetated and occupied areas enabled the design team to minimize costly reinforcement of the existing roof structure.

The new columns are typically spaced to align with the existing steel columns, with six exceptions. These six columns are transferred by the existing composite girders, which were the only six existing roof beams requiring reinforcement.

The design team incorporated a slide into the program south of the eastern core between the second and first floors. Located within the children’s reading area, the slide is a playful element that enhances the idea that this library is more than just a place to store books but rather one that allows young patrons to engage with the built structure.

The slide is primarily supported by sloped W18 beams that are tied to existing steel at the second floor and supported by steel posts that bear on existing first-floor concrete beams.

The Martin Luther King Jr. Memorial Library has been sensitively restored and adapted by the design team led by Mecanoo and OTJ Architects. Silman addressed the structural challenges through a series of preservation-sensitive interventions, using the original structure to its fullest extent. The renewed midcentury modern building — by one of the masters of the modernist movement — provides a reinvigorated community resource for Penn Quarter.

PROJECT CREDITS
Design architect: Mecanoo, Delft, Netherlands
Architect of record: OTJ Architects (formerly known as Martinez + Johnson Architecture), Washington, D.C.
Landscape architect: Oehme, van Sweden & Associates, Washington, D.C.
General contractor: Joint partnership of Smoot Construction, Washington, D.C., and Gilbane, Arlington, Virginia
Structural engineer: Silman, Washington, D.C., office
Building enclosure consultant: Wiss, Janney, Elstner Associates Inc., Falls Church, Virginia
Mechanical, electrical, plumbing engineer: Collaborative Engineering Group, Houston
Fire protection engineer: Engenium Group, Washington, D.C.
Civil engineer: Wiles Mensch Corp., Reston, Virginia

This article first appeared in the July/August 2021 issue of Civil Engineering as “Reinvented Space.” 

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Nestled at the base of a wooded hill in Keene Township, Ionia County, Michigan, Whites Bridge stood for 144 years until it was destroyed by arson in 2013. Built in 1869 at a cost of $1,700, the span carried Whites Bridge Road across the Flat River. In August 2015, the Whites Bridge Historical Society and the Ionia County Road Commission hired AECOM to design a replica superstructure to be placed atop the remaining abutments. Completed and opened to traffic in June 2020, the new bridge retains as much of the original appearance and structural system as possible while meeting current loading demands.

The structure destroyed in 2013 was the third bridge at the site. The first, a corduroy bridge made of logs, was built in the 1840s by Levi T. White, for whom the bridge and road were named. A second structure of unknown type, built in 1856, was destroyed by an ice jam.

Built by J.N. Walker and Jared N. Brazee, the 1869 covered bridge structure was a 118 ft, 10 in. long single span with a gable roof and wood siding. It sat on cut stone masonry abutments, both of which sustained only minor damage from the fire. The southern abutment is slightly higher than the north, providing a longitudinal slope of 0.79% along the superstructure. A single, 14 ft, 4 in. wide bidirectional lane crossed the bridge; stop signs at each end regulated traffic. The bridge had a 12 ft vertical clearance over a width of 11 ft and a vertical clearance of 10 ft, 9.5 in. at the bottom of the chamfers at the bridge entry opening.

The original structural system consisted of a vertical truss along each side of the travel way with top and bottom sway cross bracing. The trusses were a type patented by Josiah Brown Jr., of Buffalo, New York. Brown’s patent dates to 1857 and included sawn, not hewn, timber, with iron bolts and rods. Each truss was made of a top and bottom chord, crossing X web members, and vertical web members only at the truss ends and midpoint. The top and bottom chords were each made from four plies of an unknown wood species.

The top chord plies were 4 in. by 10 in. and the bottom plies were 4 in. by 12 in. It is assumed the bottom chord plies were spliced at alternating locations with boards that fit into ply notches on each side of a splice point, commonly referred to as a fish splice. This would have created a continuous chord member, similar to other existing Brown-style covered bridges in the area. The top chord plies were spliced with end-to-end, contact-type splices with side wood members between the plies at the splice. The web elements consisted of 6 in. by 8 in. tension members split by 6 in. by 6 in. compression members.

Two other covered bridges in the area have similar Brown truss systems. The Fallasburg and Ada covered bridges are within 11 mi (as the crow flies) of the Whites Bridge site and feature similar truss configurations. Constructed around the same time as the Whites Bridge, the 100 ft long Fallasburg structure was built in 1871 and the 125 ft long Ada span in 1867. The Fallasburg structure was made with Douglas fir. Although it is not known what type of wood was used to make Whites Bridge, it is assumed to have been made from Douglas fir.

The original floor system was made of transverse floor beams and longitudinal stringers supporting transverse floor planks and two sets of longitudinal runners. The floor beams were spaced at 2 ft, 4 in. intervals and were 4 in. by 10 in. in section. The original structure’s approaches contained bituminous wedging ramps adjacent to the bridge’s floor runner locations. The wedging was damaged during the fire, with very little remaining. The original gable roof included trusses, sheathing boards, and, originally, a metal roof, which was replaced with a cedar shingle roof in 1991.

The bridge had been posted for a maximum vehicle live load of 3 tons. The clients requested an increase in live-load capacity for the new structure because a three-axle, 27-ton county maintenance vehicle needed to use it. This vehicle, which has an 18-kip front axle followed by a second and third 18-kip axle spaced respectively at 13.75 ft and 4.25 ft, was used for the design. The design team also reviewed Standard Specifications for Highway Bridges, 17th Edition, from the American Association of State Highway and Transportation Officials, and determined that the live load consisting of a two-axle, 15-ton vehicle or distributed lane loading would not control the design.

Based in Kalamazoo, Michigan, Building Restoration Inc. inspected and rehabilitated the abutments, including repointing them and replacing damaged or missing stones. Completed in summer 2018, this work was conducted under a separate contract, before construction of the new superstructure.

Gathering guidance
Published by the U.S. Federal Highway Administration in 2005, the Covered Bridge Manual (FHWA-HRT-04-098) can be used to provide guidance for the rehabilitation, construction, and design of wooden covered bridges. This manual was used for general guidance during design of the new Whites Bridge.

Covered bridges vary from typical bridges primarily in that they have walls and roofs that are typically gabled, making them susceptible to snow and wind loads in addition to standard dead and live loads. The wind loading described by AASHTO standard specification documents is for standard structures and thus is not calibrated for a covered bridge. Because of these unique loadings, the Covered Bridge Manual discusses using ASCE 7, Minimum Design Loads for Buildings and Other Structures.

Snow and wind loads can be significant, and the engineers determined that because ASCE 7 contains load combinations with wind and snow, this document would be appropriate for the project’s design load combinations. While conducting allowable stress design, the design team followed AASHTO’s Standard Specifications for Highway Bridges and the American Wood Council’s National Design Specification for Wood Construction.

In accordance with these two specifications, allowable stress calculations for wood members must include a load duration factor (C_D) that can vary, depending on the load duration experienced by the member. Unlike concrete or steel, wood can support high forces for short durations rather than sustained loading. The factor used typically ranges from 0.9 for permanent loads to 2.0 for impact loads. The National Design Specification for Wood Construction and the Standard Specifications for Highway Bridges allow a factor equivalent to the shortest-duration load to which a member may be exposed, while the Standard Specifications for Highway Bridges prescribes a value of 1.15 for live-load combinations.

The team determined the load demand for the structure’s main members by using Structural Analysis and Design Software Pro V8i, a general analysis software from Bentley Systems Inc. Because of the relatively complex roof-floor-truss system, accurate load paths from wind, snow, and live load were not easily found. A 3D model of the structure was created in STAAD, Bentley’s 3D structural analysis and design software, to determine the system response. This response involved each truss, sway bracing, and the floor beam and stringer system. 

Although the roof trusses were not included, load distribution from the roof was determined for dead load, snow, snow drifting, and wind loads and applied to the top chord of each truss. Therefore, any secondary bracing effects from the roof were not included in the model.

When the wind blows
At each end, the new bridge has a 14 ft, 4 in. wide threshold opening that is 12 ft, 3 in. tall at its maximum height and 10 ft, 9.5 in. at its minimum. These dimensions match the width and slightly exceed the opening height of the original structure. The upper-corner chamfers are similar in appearance to those of the original structure.

To help stiffen the bridge for lateral loads, the structural system includes steel wind portals that are connected to the top and bottom truss chords at each end of the bridge. Covered bridges experience significant lateral loads, typically without dedicated lateral stiffening elements. The top and bottom sway bracing cause the two trusses to act as a single unit.

However, if the tops of both trusses translate because of wind loading, sway bracing does not impede translations. This is similar to a simple frame having beam-to-column shear connections but no moment connections, resulting in a frame that is unstable for lateral loading. Even though many load paths from the floor and roof systems may contribute to lateral stiffness, preliminary modeling determined that additional means of stiffening the structure for lateral loads would be required.

As stated previously, roof loading on the truss top chords was applied to the model, but bracing effects were not included, nor were such effects assumed to contribute to lateral wind resistance. The wind portals were included in the STAAD model; their member loading was determined through analysis. The portals are hidden from view, whether inside or outside the structure, behind the end facade. The portal members were created in compliance with AASHTO’s Standard Specification for Structural Steel for Bridges (M270) and comprise 36 ksi steel that has been galvanized and coated black for extended life and concealment.

The floor system is similar to the original and had to fit the abutment seat height, matching into the existing approaches. Matching the historic floor configuration was important, even though most of it cannot be seen from within the structure. The floor system includes 3⅛ in. by 9⅝ in. glue-laminated transverse floor beams spanning between the truss bottom chords at intervals of 1 ft, 4 in. Glulam, an engineered wood product, was required to meet the loading demand. Longitudinal stringers measuring 4 in. by 6 in. span between the transverse floor beams at intervals of 1 ft, 4.5 in. Along the structure’s length, the stringers are topped with 3 in. by 10 in. transverse floor planks, atop of which 3 in. by 12 in. floor runners form the wheel path.

The truss system had to replicate the original Brown truss structure while providing increased capacity to meet new loading requirements. This meant that the layout had to be similar, with improvements to members and connections where required.

The overall truss height increased by 1 ft over the original, from 14.5 ft to 15.5 ft. Similar to the original, the top and bottom chords each consist of four plies. However, the bottom chord plies are larger — 4 in. by 13 in. compared with 4 in. by 12 in. in the original. The bottom chord plies are also glue laminated. At 4 in. by 12 in., the top chord plies are also slightly larger than the original, 4 in. by 10 in. chord plies.

Steel sisters
The single web members match the original size. However, to meet demands, 1.25 in. diameter steel rods run adjacent and parallel to the tension members for eight members of each truss. Known as sister members, this concept was successfully used to strengthen the Brown trusses on the Ada and Fallasburg bridges. Like the portals, the rods are AASHTO M270 grade 36 ksi steel that are galvanized and coated black for a somewhat masked appearance.

Extending through the top and bottom chords, the rods are attached using a combination of 0.75 in. diameter bolts with shear plates and plates bearing against the chords. To provide additional capacity, the connections for the single web tension members vary from the original, with steel sleeve ends that bear against the top and bottom chords. The sleeves are galvanized, coated black, and open at the end, allowing improved ventilation for moisture resistance. Connections and splices throughout the structure use shear plates and malleable washers at several locations.

The roof system replicates the original with improvements to meet current loading demands. The original roof plans were limited, lacking member sizes and connection details. Historic photographs of the inside of the structure were also limited; none showed such details as the sill plate or the connection of the roof truss to the sill plate.

The new structure has a wooden cedar shake roof, matching the original style. But plans called for two modern, electrified additions: lighting and security cameras. These are meant to help prevent vandalism or arson incidents.

Building it back
The anticipated construction sequence included two possible methods. The first would require constructing the main trusses with transverse floor beams and sway bracing on the northern shore, followed by lifting the entire assembly into position over the river and completing the superstructure roof and siding in place. The second method involved assembling each truss onshore, lifting each onto the abutments, and then completing the structure in place over the river. 

The second method required a temporary support system in the river and a permit for placing the supports in the river. The Michigan Department of Environmental Quality — now known as the Michigan Department of Environment, Great Lakes, and Energy — granted a permit that would allow for temporary supports in the river but excluded the time period of Oct. 1-April 30 to mitigate any disruption to spawning and/or migrating fish.

The contractor, Davis Construct-ion Inc., chose the second method, using temporary steel-pile supports in the river. The construction sequence included fabricating each truss on the approach, in the flat position, then placing each truss on the abutment bearings using a crane. To brace each truss during this sequence, steel H-piles were driven in the river ahead of truss placement. A total of four piles were used for the bridge, with the trusses secured to the piles using chains or cables. The wind frames, transverse sway bracing, and transverse floor beams were then erected, and the piles were then removed.

Once the piles had been removed, the remaining floor system and roof were installed. The roof was partially constructed on the northern shore and lifted onto the superstructure in sections. The siding was placed on all four exterior walls, and then the roof shingles were placed as the last fabrication step. Final construction tasks included installing new approach asphalt for the northern roadway, which had been damaged by crane tracks, and the guardrail.

Completed at a cost of approximately $690,000, the structure was put into service as soon as the power, lighting, and security cameras were installed. Funding for the project came from various sources, including grants from Michigan’s Local Bridge Program and the Michigan Economic Development Corp., private donations, Keene Township, a group known as Rebuild Whites Bridge, and the Whites Bridge Historical Society. The structure has performed well thus far in 2021, and a proper opening ceremony has been proposed for after the COVID-19 crisis has subsided.

Greg Garrett, P.E., M.ASCE, is a senior bridge engineer at AECOM, working in the Grand Rapids, Michigan, office.

PROJECT CREDITS
Owners: Whites Bridge Historical Society, Lowell, Michigan; Ionia County Road Commission (now the Road Department for Ionia County)
Superstructure design: AECOM, Grand Rapids, Michigan, office
Abutment inspection and rehabilitation: Building Restoration Inc., Kalamazoo, Michigan
Shop drawing production: Cogent Civil Engineering LLC, Alto, Michigan
Superstructure construction: Davis Construction Inc., Lansing, Michigan
Power, lighting, and security system: Strain Electric, Wyoming, Michigan
Signs: United Sign Co., Saranac, Michigan

This article first appeared in the July/August 2021 issue of Civil Engineering as “Replaced with a Replica.” 

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Located in southern Africa, Victoria Falls is among the largest in the world — a sheet of water nearly a mile in width and falling twice the height of Niagara Falls. Peter Roberts, in his 2020 book, Sun, Steel and Spray: A History of the Victoria Falls Bridge, quotes writer Mark Strage, who described the challenge of building a bridge there “supported by a single slender span” as “bold, to the point of arrogance.”

The falls area was home for centuries to the Toka-Leya people, who ascribed cultural and religious significance to the churning waters at the foot of the falls. Their name for the falls alternately translates as both “the mist that thunders” and the “place of the rainbow.”

The first European explorer to see the falls was Scottish missionary and explorer David Livingstone, in 1855. “I did not comprehend it until, creeping with awe to the verge, I peered down into a large rent which had been made from bank to bank of the broad (Zambezi),” he wrote in his journal, which was later published in his 1857 book Missionary Travels and Researches in South Africa. He declared it to be “the most wonderful sight I had witnessed in Africa.”

Livingstone traveled 3,000 mi within Africa and published his best-selling book about the trip afterward, while in England. He saw the Zambezi as the route “by which the central regions of Africa would be opened up to Christian values and trade.” 

But the driving force behind the bridge was Cecil John Rhodes, who founded diamond producer de Beers Consolidated Mining Company in 1888. Beginning in 1890, Rhodes served six years as the prime minister of the British Cape Colony (now South Africa). He was, wrote Roberts, “an ardent believer in British colonial imperialism” and saw the potential of a transportation route linking the entire continent north to south. 

Rhodes helped the British Empire seize control of southern Africa, founding the large territory that for decades bore his name, Rhodesia, in 1895. (Rhodesia essentially encompassed what is now Zambia, north of the Zambezi, and Zimbabwe, south of the river.) Rhodes allegedly once told a friend that “to have a bit of country named after one is one of the things a man might be proud of,” according to Roberts, who quotes the historian Robert Rotberg from his book The Founder: Cecil Rhodes and the Pursuit of Power.

The push to establish a transit route from the Cape to Cairo came in the midst of a European land grab in Africa that included moves by the Portuguese and the Germans. Although the full route never materialized, Roberts wrote, “this period saw the rapid spread of an interconnected web of ‘pioneer railways,’ penetrating the subcontinent from the south and east coasts and opening up the interior to development.”

Rhodes never actually saw the falls before he died in 1902, but he had dreamed of and approved the siting of a rail bridge close enough to the falls so that passengers would be able to enjoy “the spray of the water over the carriages.” The men put in charge of realizing Rhodes’ vision were civil engineer George Andrew Hobson and 27-year-old French engineer Georges Camille Imbault. Imbault was appointed chief construction engineer by Cleveland Bridge and Engineering Co., the British firm that manufactured the bridge components.

There was plenty of opposition in Africa and England to constructing the bridge so close to the falls; many were concerned that a piece of infrastructure would forever ruin such a magnificent landscape, and some maintained that an alternate site several miles upstream would have been an easier crossing. But Hobson defended the plan for a bridge near the river, claiming the alternate site would result in an unimpressive structure. The final choice, just downstream from the falls, “was governed by the natural formation of the rock walls of the Batoka Gorge, advantage being taken of the minimum distance to be spanned, combined with the soundest foundations obtainable,” Roberts wrote.

Rhodes’ rail line had reached the town of Bulawayo, about 269 mi southeast of the falls, in 1897. Between 1902 and 1904 the line finally reached the bridge site near the falls, a landscape teeming with antelope, elephants, giraffes, and lions — and passing, Roberts wrote, through “sand veld, well wooded with mopane and teak.”

According to Hobson, the priorities for the design included a handsome appearance, rigidity, economy, and ease of building without scaffolding. “A steel arch of this character was therefore designed to spring from the rock walls of the Zambezi chasm, to be erected cantilever-wise simultaneously from both sides” (“The Victoria Falls Bridge,” Minutes of the Proceedings of the Institution of Civil Engineers, March 19, 1907).

The final design featured a 500 ft long main arch with a rise of 90 ft, anchored by four touch points called feet on the steep banks of the gorge. The design called for two support spans embedded near the top of the gorge  — one with a length of 62.5 ft on the left bank and one with a length of 87.5 ft on the right.

Hobson noted that a three-hinged arch design was considered but ultimately rejected for “want of rigidity under railway-traffic.” He wrote that designers felt “great uneasiness” about the three-hinged option because “excessive longitudinal vibration” might develop “under traffic at even moderate speeds.” He acknowledged that calculating the stresses for a two-hinged design was more challenging, but ultimately the option was both more rigid and more economical.

There was also the matter of preserving the steelwork, given its proximity to the water spray from the falls and the “comparatively slight” wind bracing of the structure. Roberts noted that engineers strove for simplicity in the design of the bridge sections to avoid “enclosed parts or hidden spaces anywhere in the structure” that might lead to corrosion. “There are no cavities for holding water, nor any surfaces where moisture can condense, the air being free to circulate everywhere.”

The bridge components, made of rolled steel, were not fabricated on the remote site but rather in England by Cleveland. The steel sections were built in a factory in Middlesbrough, then shipped 9,500 mi to the Port of Beira in present-day Mozambique. From there, the pieces traveled by train to Bulawayo and then on to the falls.

Before being shipped off, the steel components were cleaned and treated with a red lead primer and linseed oil then painted with three coats of silver-gray paint. “This particular shade was chosen because a patch of rust in it will appear conspicuous by contrast,” wrote Hobson. “It has the further advantage of absorbing little of the heat of the sun. Thus painted, the steelwork, a year and a half after completion, was reported to be in very good condition, and to respond slowly to changes of temperature.” The color was also expected to blend in well with the falls. 

But before construction began, engineers realized they had made a critical error in their initial surveys. According to Hobson, the north bank of the gorge was “an almost perpendicular cliff, but the opposite bank has a shelf about half way up, and the whole region is composed of erupted rock, mostly basalt.” He wrote that the bridge “was designed to fit the profile of the gorge with as little expenditure on excavation as possible” because the rock in the gorge was thought to be very hard. But the rock on the shelf of the south face was actually “covered to a considerable depth with debris” and was unsuitable to build on unless it was cleared. 

At the time of this discovery, progress on manufacturing the steelwork was too far along for anything in the design to be changed. “The difficulty had therefore to be overcome partly by increasing the depth of the concrete foundations, and partly by lowering the level of the entire bridge to the extent of 21 feet,” Hobson wrote.

As work at the site got underway, the bridge’s assistant resident engineer, Charles Beresford Fox, designed a winch system to carry workers across the river on a bosun’s chair. Workers would sit in the chair, which was attached by pulleys to a ⅝ in. wire rope. The rope was supported on each side of the gorge by 2 ft diameter posts that were sunk 7 to 8 ft into the rock.

Rhodes’ dreams of an empire may not have lasted, but the Victoria Falls Bridge certainly has, bringing the falls’ majestic sprays of water closer to millions. 

Fox took the first safe but somewhat harrowing ride, noting that it felt strange to be “relying absolutely on my own calculations for my safety,” according to the website of the Zambezi Book Co. The website also refers to him as the “Flying Fox” and says he was “the first man to cross the gorge; the first man to descend into the gorge from the southern bank — and, subsequently, the first man to be rescued from the gorge.” Ultimately, though, the bosun’s chair saved work crews hours versus having to transport material by ferry.

Eventually, construction material was transported across the gorge by an electric system nicknamed the Blondin, after French tightrope walker Charles Blondin, who famously crossed the gorge at Niagara Falls. The Blondin, Roberts wrote, “travelled along a single cableway over 870 ft in length, fixed to a tower on the north bank and hinged sheer-legs on the south bank.” The system was “designed to counter the weight of the machine as it moved along the cable.” The Blondin could lift loads up to 10 tons at a speed of 20 ft per minute and travel along the cable at a speed of 300 ft per minute.

The keys to the bridge’s design were the four feet, two on each side of the canyon where the main arches joined the canyon side. These feet were hinged by steel pin bearings and mounted to concrete abutments. According to Roberts, the steelwork of the arch was designed to expand and lift a bit under the heat of the sun, “but at the same time retaining its rigidity without buckling or becoming distorted.”

To build the main arches, two mechanical cranes traveled along the cross girders of the half-arches, moving forward to install each of the 20 panels that would form the main arch. “In order to support the cantilevers as they stretched over the gorge, a system of steel wire cables was used, anchored through tunnels cut into the rock on either side of the gorge,” Roberts wrote. “Two bore-holes were sunk back from the edge on each bank 30 ft deep and 30 ft apart, and joined underground by boring a tunnel through the rock. Wire ropes suspending the weight of each half of the bridge were passed down one hole, along the connecting passage, and out through the other hole, so that the weight was sustained by this solid mass of rock.” Five hundred tons of rail was placed on top of the rock for added stability. The tension of the cables could be adjusted, wrote Roberts, to allow “precise control and adjustment of the half-arches as they were erected.”

The arch halves were finally joined on April 1, 1905. “With the lower arch now connected, work progressed to fix the upper chord in place and complete the steelwork structure,” Roberts explained. “As the horizontal chord neared completion two hydraulic jacks were inserted into the small gaps between either arm of the arch, exerting between them a permanent pressure of 500 tons outwards… .” This pressure forced the gap open and allowed the final section to be fitted into place.

Over the years the bridge has received periodic maintenance and refurbishment.

The upper deck was completed in June 1905. Apparently, the first creature to cross the bridge was a leopard. A few months later, on Sept. 12, the bridge officially opened to rail traffic.

Over the years the bridge has received periodic maintenance and refurbishment. The deck was reconstructed and strengthened in 1929 to fix a structural deficiency in the original design. Roberts writes that the original deck consisted of cross girders spaced 12 ft, 6 in. apart, which placed a heavy load midway between the panel points of the bridge. This, in turn, introduced a bending load on the top chord of the arch. In the new deck, the cross girders were spaced further apart to line up with each panel point. This required a much deeper girder, which raised the rail level by 4 ft, 7 in.

In the years after the bridge opened, Victoria Falls slowly became a tourist attraction and place of intrigue. In 1939, on the eve of World War II, a German saboteur was arrested for plotting to destroy the bridge. Engineers found a hole had been drilled into one of the support beams that was large enough to stuff with explosives. 

In later years, Rhodesia would eventually give way to modern Zambia, which achieved independence in 1964, and Zimbabwe, which achieved independence in 1980, the river and falls between the two.

The bridge has periodically been repainted and renovated. It was closed in 2006 for a thorough examination of its structural integrity and was found to be in generally good shape. A $1.7 million rehabilitation strengthened its sustaining load capacity from 46 tons to 56 tons. In 1995 it was named an ASCE Historic Civil Engineering Landmark.

Rhodes’ dreams of an empire may not have lasted, but the Victoria Falls Bridge certainly has, bringing the falls’ majestic sprays of water closer to millions. 

This article first appeared in the July/August 2021 issue of Civil Engineering as “A Poem in Steel: The Victoria Falls Bridge.” 

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But with COVID-related travel restrictions lifting around the world, it’s finally the right time to feature the next installment.

And this year’s list of ASCE beach reads is especially suited for the beach bum with a passion for civil engineering history.

The 2021 ASCE beach reads:

Benjamin Wright: Father of American Civil Engineering

Author Steven M. Pennington details the life of a man who, in 1839, participated in organizational meetings of what would become the American Society of Civil Engineers, the very organization that in 1970 designated him the “Father of American Civil Engineering.”

Learn more.

Hans Albert Einstein: His Life as a Pioneering Engineer

In this biography, authors Robert Ettema and Cornelia Mutel engagingly describe the work of one man’s quest to understand and unravel the complexities of rivers.

Learn more.

Engineering Iron and Stone: Understanding Structural Analysis and Design Methods of the Late 19th Century

Drawing on his career-long fascination with how structural engineers do their work, author Thomas Boothby presents a comprehensive explanation of the empirical, graphical, and analytical design techniques used during the late 1800s in constructing buildings and bridges of wood, stone, brick, and iron.

Learn more.

Washington Roebling’s Father: A Memoir of John A. Roebling

Between 1893 and 1907, Washington Roebling wrote about his father’s life, character, career, and achievements with candor and intimate family details. Part biography, part memoir, Washington Roebling’s Father makes available for the first time the text of this remarkable manuscript, edited by Donald Sayenga, an internationally recognized authority on the history of wire rope.

Learn more.

Karl Terzaghi: The Engineer as Artist

One of the leading civil engineers of the 20th century, Terzaghi is widely known as the father of soil mechanics. This narrative, authored by Richard E. Goodman, shows Terzaghi’s struggle to understand the phenomena observed on many major engineering projects.

Learn more.

Engineering Legends: Great American Civil Engineers

Behind every great American civil engineering accomplishment, there is a great American civil engineer.

Written by Richard G. Weingardt and with a foreword by Henry Petroski, Engineering Legends provides a unique view into the history and progress of 32 great American civil engineers from the 1700s to the present.

Learn more.

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The early 20th century American endeavor to improve roadways and connect communities across the country had its genesis with cyclists, who founded the Good Roads Movement in 1880. By the turn of the century, automobile use eclipsed cycling, and motorists took the lead in the Good Road Movement. By 1912, improved roadway surfaces were still primarily an urban feature as interstate commerce and intercity transportation were dominated by railroads. “Farm to market” and other rural roads were mostly dirt or gravel, subject to muddy and dusty conditions, depending on the weather. Some were maintained by townships and counties, but many were the responsibility of the residents who lived along them.

Among the enthusiasts for roadway improvements was Carl Fisher, an early manufacturer of auto parts and an investor in the Indianapolis Motor Speedway. In September 1912, Fisher started to promote his vision of a continuous east-west highway, running coast-to-coast across the United States. His idea gained support and within a month had pledges for 10% of the estimated $10 million cost. The group chose the name Lincoln Highway, to honor one of Fisher’s heroes.

On July 1, 1913, the Lincoln Highway Association was established with a goal of building a stable highway from Times Square in New York City to Lincoln Park in San Francisco. Less than a month later, the Loyal Order of the Moose dedicated the Mooseheart community in Illinois. They agreed to pave and donate three quarters of a mile of the Lincoln Highway, adjacent to their Children’s Home, the first paved section of the highway. The first section of the Lincoln Highway to be completed and dedicated was Newark to Jersey City, New Jersey, dedicated on Dec. 13, 1913.

The first official length of the Lincoln Highway was 3,389 miles and within a decade, it had been shortened to 3,142 miles. By the 1940s, named routes were replaced by numbered routes and the Lincoln Highway Association faded, but in 1992, it was reactivated for the purpose of promoting the highway and preserving its heritage, which was instrumental in developing today’s American highway transportation system.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Cleveland, Ohio, became a major industrial center at the time of the American Civil War. Like many other cities in the nation that were built on water, Cleveland turned its back on its river, the crooked Cuyahoga. It became a convenient means of disposal for the sewage and industrial waste from steel, oil, chemical, shipbuilding, paint, paper, and other factories that emerged in the 1860s, contributing a toxic mixture into the river. Within a few years, oil slicks and animal carcasses were routine sights on the bubbling river.

Before the end of the Civil War there were 20 refineries in the Cleveland area. As early as 1868, the Cuyahoga River caught fire, an incident that occurred regularly not only in Cleveland, but in other industrialized cities in the United States. In the late 19^th century, the Cuyahoga was described as “so flammable that if steamboat captains shoveled glowing coals overboard, the water erupted in flames.” Notable fires occurred on the Cuyahoga in almost every decade for a century.

In 1912, a spark ignited leaking oil, prompting explosions and a fire that killed five people. In 1936, the river burned for five days, and in 1952, the most substantial Cuyahoga River fire on record occurred, causing $1.3 million in damages. However, it was not until 1969 that the Cuyahoga became a symbol of ecological catastrophe and environmental alarm.

Around noon on June 22, 1969, floating debris was ignited on the river by sparks caused by a passing train. Though reportedly intense, the fire was under control within 30 minutes. The event received little local coverage, and the blaze was contained before photographers arrived. However, the fire received significant negative national media coverage and Cleveland’s image was linked with the calamity, using a photo that was actually from the 1952 fire.

The national media barrage from the Cuyahoga River fire gave a symbolic boost to the ecological movement in the nation. After the 1969 fire, Cleveland’s mayor Carl Stokes worked with his brother, Congressman Louis Stokes, to push for environmental regulation and help shape public perception of it as a turning point. Partially motivated by the 1969 Cuyahoga River fire, Congress passed the National Environmental Policy Act, which was enacted on Jan. 1, 1970.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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The Mauch Chunk and Summit Railroad was a coal-hauling railroad in the mountains of Pennsylvania that operated between 1828 and 1932. Using gravity, the railway would send groups of coal cars down an 18-mile sawtooth course that featured a 2,300-foot-long, 665-foot-high drop at the end. Cars were returned to the top by mules, which were sent down in the special mule cars. The railway became a stirring attraction for tourists who visited by the thousands to ride every year. The railway operated for paying tourists for over a half century after it was abandoned as a freight railroad.

LaMarcus Thompson (1848-1919) was an inventor and businessman who made his fortune by producing specialized machinery for the hosiery industry but left the business due to failing health. It’s said that Thompson was inspired by a trip to the hills in eastern Pennsylvania where he witnessed the Mauch Chunk Switch Back Railway. Thompson developed the idea to capture the essence of Mauch Chunk in a smaller package for amusement.

While not the first to conceive of the idea, Thompson applied his own ideas to an earlier patent for an “Inclined Railway” and developed the first authentic American roller coaster. In 1884, Thompson applied for a patent for his “Roller Coasting Structure,” and was granted patent No. 310,966 the following year.

On June 16, 1884, his “Gravity Pleasure Switchback Railway,” implementing his design, opened at Coney Island and was an immediate success. At five cents per ride, Thompson’s six-miles-per-hour thrill cleared $600 per day in profits. Passengers climbed up stairs and rode a gravity-powered cart down tracks faced outward instead of forward so that they could take in the surrounding scenery. 

Almost immediately, competitors aimed to make rides higher, faster, and steeper. Within months two rival coasters appeared at Coney Island and by the turn of the century, there were hundreds of roller coasters around the country. Although not credited as being the inventor of the roller coaster, LaMarcus Thompson, through his Switchback Railway, introduced the technology to the masses and created the ride that would become the epitome of amusement thrills.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Born in Braintree, Massachusetts, Sylvanus Thayer grew up in Washington, New Hampshire, and entered Dartmouth College in 1803. He was the class valedictorian in 1807 but did not attend his graduation as he was granted an appointment to the U.S. Military Academy and left for West Point before the ceremony. Thayer graduated from West Point one year later.

Thayer was actively engaged during the War of 1812, and following the war, he spent two years in Paris studying at the French École Polytechnique. In 1817, Sylvanus Thayer was appointed to replace Alden Partridge as superintendent of the U.S. Military Academy, but Partridge refused to relinquish his command to a former subordinate. Partridge was court-martialed for insubordination and neglect of duty, and although he was acquitted, Partridge resigned his position. In August 1817, Thayer became the fifth superintendent at West Point.

During his tenure, Thayer’s reforms included setting new standards for admission, establishing minimum levels of proficiency, and creating a system to measure progress. Under Thayer, West Point became the nation’s first college of engineering. Although military subjects dominated the program, Thayer believed that the arts and sciences were important. By 1831 the military engineering course was designated “civil engineering” and had lost most of its military overtones, encompassing the construction of “buildings and arches, canals, bridges, and other public works.” Thayer served as superintendent for 16 years, the longest tenure in West Point’s two century history.

In 1867, six decades after graduating from Dartmouth, Thayer brought engineering to his alma mater, offering $70,000 to create an engineering school and detailing the curriculum: technical studies built on a strong liberal arts foundation. A century and a half later, the Thayer School of Engineering continues the program that he originated.

The “Father of West Point” died Sept. 7, 1872, at his home in Braintree and is interred at the West Point Cemetery on the grounds of the U.S. Military Academy.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

The post Civil Engineering Almanac – Sylvanus Thayer, ‘Father of West Point,’ is born appeared first on Civil Engineering Source.

Several proposals to construct a bridge across River Tay date to at least 1854. Royal assent was given to the North British Railway Tay Bridge Act in July 1870 and a foundation stone was laid one year later. The bridge was designed by engineer Thomas Bouch. During the 1850s and 1860s, Bouch gained experience in Northern England and Scotland designing more than 100 miles of railway, including over 100 bridges.

Bouch was also known for his design of train ferries, ships that were purpose-built to carry railway vehicles. He designed custom-built ferries with railway lines and matching harbor facilities at each end to allow the rolling stock to easily enter and exit the craft. He introduced the first roll-on/roll-off train ferry service in the world.

By the 1870s, Bouch was authorized to design bridges for crossings at both the Firth of Tay and the Firth of Forth. For the Tay, Bouch designed a lattice-grid structure, combining cast and wrought iron. The design was not novel, having been used first in the Crumlin viaduct in South Wales in 1858, following the innovative use of cast iron in The Crystal Palace. The engineering details on the Tay Bridge were considerably simpler, lighter, and cheaper than on the earlier viaducts.

With construction started in July 1871, the Tay Rail Bridge opened for service June 1, 1878. It was among the longest bridges in the world. Queen Victoria crossed the bridge a year later, and Bouch was knighted for his service. However, the acclaim was short-lived. Just 19 months after its opening, the Tay Bridge catastrophically failed on Dec. 28, 1879, taking 75 lives, including Bouch’s son-in-law.

An inquiry concluded that the collapse was a result of defects in design, construction, and maintenance, all of which were attributed to Bouch. His project at the Firth of Forth bridge was canceled and a different design was commissioned. Construction on a new Tay Bridge began in 1883 and was completed in 1887. Sir Thomas Bouch died at the age of 58 on Oct. 30, 1880, less than a year after the Tay Bridge disaster.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

The post Civil Engineering Almanac – Original Tay Bridge opens appeared first on Civil Engineering Source.

The St. Francis Dam failure, which caused the deaths of at least 432 people, is not one of these designated projects but can be considered as instructive as many landmarks. Engineers frequently learn more from failures than from successes. So, with that concept in mind, here are five things you didn’t know about the St. Francis Dam Failure:

1. The St. Francis Dam failure ranks as the worst U.S. man-made disaster of the 20th century. The reservoir, which had a storage capacity of 38,168 acre-feet, was within a few inches of being filled for the first time when the dam failed catastrophically on the night of March 12-13, 1928. The peak flow of the outbreak flood reached about 1.7 million cubic feet per second, emptying the full reservoir in just under an hour.
2. City of Los Angeles Bureau of Waterworks and Supply (now the L.A. Department of Water and Power) constructed the dam from 1924 to 1926 under the direction of longtime Chief Engineer and General Manager William Mulholland. St. Francis Dam was the second concrete dam built by the city and was essentially a duplicate of the Weid Canyon Dam in the Hollywood Hills, which was renamed Mulholland Dam (Hollywood Reservoir) a year before it was completed in March 1925.
3. Mulholland had developed a reputation as a problem solver and for getting projects built on time and within budget. He personally selected the site for St. Francis Dam about five miles up San Francisquito Canyon, based on a nice V-shaped narrows in the canyon. Mulholland’s directive to his engineering staff was to take the basic design for Mulholland Dam and adjust the upstream arch radius to fit the San Francisquito Canyon site.
4. There are no records of geologic or geotechnical investigations at the dam site, except for simple percolation tests of hand-excavated holes and a few exploratory adits extended into both abutments. The dam site was later determined to be a small portion of an enormous prehistoric landslide complex.
5. In the subsequent political furor over the disaster, Mulholland accepted personal responsibility for any shortcomings of the dam’s design. At the coroner’s inquest, he famously said: “Don’t blame anybody else, you can just fasten it on me. If there is an error of human judgement, I was the human.” He resigned from his position a year and a half later and carried the burdens of his misjudgment with him for the rest of his life.

Members of ASCE’s History and Heritage Committee have been learning fun and interesting facts about HCELs around the world to share in the new “5 Things You Didn’t Know About …” series. As the committee continues to build an inventory of all HCEL projects, members of the committee and other volunteers have been visiting sites to photograph landmarks and ASCE plaques as well as assess their conditions. If interested in volunteering to help the committee record these landmarks, please contact committee chairman David Gilbert ([email protected]).

Learn more about the committee’s work and the ASCE landmark program.

The post 5 things you didn’t know about the St. Francis Dam failure appeared first on Civil Engineering Source.

The beaux-arts station, designed by Kenneth Murchison, along with architecture firm McKim, Mead, and White, is still an important connection on the heavily traveled Northeast Corridor between Boston and Washington, D.C. As such, the station remains the eighth-busiest terminal in the United States with more than 3 million passengers a year.

Located in the center of the city, the train station is at the upper end of the central business district, just south of the city’s Station North Arts District and between two of the city’s one-way arteries, North Charles Street and St. Paul Street. The station is composed of the large multistory beaux-arts building with a rectangular footprint that sits on high ground and an enclosed rear concourse that juts out perpendicular to this building and over the train tracks, providing access points that descend to the rail tracks and platforms below. On the opposite side of the tracks is a large parking lot where the new construction will be sited.

Amtrak is planning an ambitious reinvention of the venerable transit hub. Currently, Amtrak trains, including high-speed Acela trains, operate through the station. So do Maryland Area Regional Commuter trains and a light rail line. The new station will include expanded platforms to handle greater train volumes and improved connectivity for buses, cabs, passenger cars, and ride-share vehicles.

Historic rehabilitation

The beaux-arts building that comprises the most visible part of Penn Station is a head house; that is, it contains the ticketing, waiting, and baggage areas of the train station. In Baltimore, this historic structure is a “cherished building,” says Peter Stubb, AIA, a principal and the design director of Gensler’s Baltimore office, which is designing the new addition to the station. “People love this building. But it needs to be modernized. Part of the impulse on Amtrak’s part was to modernize the station but also expand to meet future demands.”

The head house, which is currently mostly vacant, will be rehabilitated and redeveloped with shops, restaurants, and offices. This effort will be overseen by designer Quinn Evans. The work will include a complete exterior and interior restoration, according to James Smith, AIA, an associate with Quinn Evans. “Exterior work will include rehabilitation of all masonry, standing seam metal roofs, windows, doors, marquee canopy, and decorative elements,” he says. “It will also include new exterior lighting. New work will include comprehensive replacement of all electrical, mechanical, and telecom systems throughout the building. New stairs and elevators will be installed. Main public spaces will undergo thorough historic restoration.” 

Because the building is located in a 100-year flood plain, Quinn Evans’ renovation will have to meet the city’s flood plain regulations. “We’re wet-floodproofing the cellar and dry-floodproofing the platform/ground floor level to a height of approximately 8 ft,” Smith adds. “All the utilities in the cellar will be relocated to a new (mechanical, electrical, and plumbing) mezzanine raised 4 ft above the platform level with passive flood protection. Site utilities (transformers, generator, cooling tower) also need to be protected from the 8 ft of floodwater.”

New addition

The new low-rise addition to the station will run parallel to the head house on the other side of the tracks, forming an expanded, H-shaped station when it is joined to the existing concourse over the tracks. 

The restoration and expansion of Penn Station is an opportunity to create both a multimodal hub for local and regional travelers but also a community hub connecting the station to surrounding neighborhoods. “One of the benefits of this design is there are more entry points to the station,” says Stubb. 

The design of the new complex attempts to complement the original beaux-arts facade — stoic, classic, with a heavy rhythm of fenestration as well as granite and terra cotta cladding — with a clear, glassy structure that provides both a visual connection to the original and fosters a connection to the theatrical experience of train travel. The design is meant to invoke the “incredible experience of walking over tops of the trains as they’re moving below you,” says Stubb.

The new expansion will be flanked by two outdoor plazas on the east and west sides, joined by the 14,000 sq ft concourse that will run through the building. The concourse will step down as you move through the building to match the changing east-west elevation of the street grid. This topographic quirk will allow the new concourse to evoke the front stone stoops of classic Baltimore row houses, with areas to rest and linger and areas to be used as quick access points.

The station will remain open during construction.

Ultimately, Amtrak and developer Penn Station Partners are planning an additional commercial development just north of this new addition that calls for two buildings and around 250,000 sq ft of office space and 150 residential units. “If you think about the power of having office and residential right there at this location, on the tracks, with easy connections to D.C., Philly, New York — it’s a pretty great idea,” says Stubb.

The post Then and Now: Baltimore’s Penn Station to be restored, expanded appeared first on Civil Engineering Source.

Excavation at Culebra Cut began in 1881 with the French attempt to build a sea level canal between the Atlantic and Pacific Oceans through the isthmus of Panama. A misjudgment of the of the Culebra ridge geology complicated the French operation as large landslides stymied the excavation. By 1886, after years of digging, only a few feet have been removed from the top of Culebra Cut out of the hundreds of feet that would need to be excavated to reach sea level.

By 1888, the French conceded the impact of the unsuitable soil and changed course to build the canal with temporary locks as an interim plan until sea level could be reached. However, a combination of the soils underestimation, disease, labor strife, and financial difficulties led to the collapse of the French effort by the end of the year. In 1894, a second French company was formed for the project, but would not further the canal-building significantly.

The United States took over the project in 1904. At that time, the French had lowered the 210-foot summit by less than 20 feet. The American effort was a lock-based canal, which would require the removal of an additional 150 feet of material, not as deep as the French proposal, but substantially wider. On May 20, 1913, after years of excavating and blasting through the continental divide, steam shovels #222 and #230 met and faced one another on the bottom of the Cut, at 40 feet above sea level.

In total, the French excavated almost 19 million cubic yards of material and the Americans over 100 million cubic yards. It would be another year before the canal was formally opened on Aug. 15, 1914, with the passage of the cargo ship S.S. Ancon. However, the breakthrough at Culebra culminated decades of planning and construction, and it proved a milestone in turning the idea of the Panama Canal into reality.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

The post Civil Engineering Almanac – Panama Canal Culebra Cut milestone appeared first on Civil Engineering Source.

Transforming an ailing street

Sixteenth Street was the historic retail hub of downtown Denver, but by the 1970s, according to the nonprofit preservation group Historic Denver, the street was struggling economically and socially. Downtown generally, and 16th Street particularly, was becoming a place crowded with cars more than people. Plans for a pedestrian mall in Denver had been floated since at least 1963, but they began in earnest in 1976 when city leaders hired one of the most prominent architectural firms of the day, New York City-based I.M. Pei & Partners (now Pei Cobb Freed & Partners), to transform the ailing street.  

According to the 2010 16th Street Urban Design Plan, the mall had three objectives: lessening traffic congestion in downtown, providing more efficient bus service to city and suburban neighborhoods, and creating a new pedestrian environment and place for people in downtown.

The mall was chiefly designed by architect Henry N. Cobb, a partner in Pei’s firm, and also by landscape architect Laurie Olin, founder of the eponymous Olin Studio design firm. Designers divided the 80 ft wide street into three zones, according to the firm: a 22 ft wide central promenade flanked by mature trees, two 10 ft wide bus paths, and a pair of 19 ft wide sidewalks. The central blocks of the mall followed this symmetrical layout; the blocks at the ends of the mall shifted the transitway off center and created a single row of trees to open views to the capitol and Longs Peak on the Front Range.

Signature feature

The signature feature of the mall is its square pavers, laid on the diagonal with individual charcoal gray, light gray, and Colorado red granite pavers combining to create a geometric pattern that is “pronounced at the center and more diffuse at the edges, so as not to detract from colorful facades and window displays,” according to Pei’s site. 

There are several accounts of the symbolism of the patterning. It has been likened to Navajo rug patterns and to the circle and square decorative motifs on the floor of the Pantheon in Rome. “There’s something ancient and thoughtful from the Navajo rugs, with something formal and classical merged together,” says Jason Whitlock, AIA, a principal city planner of urban design with Denver’s Community Planning and Development department.

(The mall pattern has also been likened to a diamondback rattlesnake, but Cobb and Olin purportedly discovered a rattlesnake belt in a shop on the mall only after the design was finished.)

The paver pattern also served, as Historic Denver notes, to “reduce material monotony, which can plague streetscape interventions of this size.” Two tree species, honey locusts and red oaks, were planted “precisely within the field of the paving pattern.” And specially designed lanterns — tripartite stalks capped with acrylic globes — provided a “unified glow along the promenade that was intended to fade and brighten according to the daily rising and falling of the sun.” It was, in typical modernist fashion, an ambitious and holistic attempt to revitalize the heart of the city. Historic Denver cites a 2008 Urban Land Institute study that referred to the mall as a “unified concept and public art of the highest international quality.”

Transit corridor

The 16th Street Mall was more than a pedestrian ramble; it also became downtown’s main transit corridor. The mall’s free shuttle bus service, which is still operational, consolidated hundreds of bus routes running through downtown and reduced bus traffic through the central city by 50%. 

More than 200,000 Coloradans turned out to celebrate the mall’s opening in 1982. Since then, the mall has proved to be one of the most successful pedestrian corridors in the country while also attracting around 50,000 riders a day. More than 200 restaurants and shops line the mall, along with 5,700 residential units and 2,500 hotel rooms. According to the Downtown Denver Partnership, as many as 400,000 people — commuters and pedestrians — traverse the mall each week.

Nevertheless, when it was built, the mall had a projected life span of only around 30 years — which passed in 2012. And by then it was definitely getting run-down. Now, the mall is almost 40 years old, “ and the infrastructure ultimately is failing,” Barton says. “(It) is a long life span for a public infrastructure project. This is the time for us to invest in renovating and taking care of the infrastructure and planning for the next 37 years.”

Renovated design

The deteriorating conditions of the mall were costing the city $1.2 million a year in maintenance. So in 2010, city and community leaders embarked on a decadelong planning effort to renovate the mall. On March 8 of this year, the city council approved a $149 million reconstruction of f the mall.

Among the major moves of the reconstruction is removing the center promenade in favor of a scheme that pushes the buses to the center of the street and opens up much wider sidewalks that will create what Barton describes as more “amenity spaces” including “patio cafes, vendor spaces, (and) play spaces for families and kids.”

Further, the mall’s granite pavers have been deteriorating for years, so all 400,000 of them will be replaced. The original design did not include a subsurface drainage system for the pavers, so “there was no place for (rain) water (and snow melt) to go, resulting in damage from freeze/thaw cycles,” says Travis Bogan, P.E., PMP, the director of special projects for the Denver Department of Transportation and Infrastructure. The pavers also have a low surface profile, so when they get wet with rain or snow, they get slippery. The new pavers will have more surface friction to reduce the potential for slips and falls.

The new pavers will be smaller, which will reduce the surface area buses are coming into contact with, reducing the potential vertical displacement of the pavers, therefore minimizing damage to the mortar that occurs when buses travel over the surface of the pavers, Bogan notes. In addition, Whitlock adds, the new pavement system will feature subsurface drainage to convey moisture away from the subgrade and reduce the frequency of maintenance required on the mall.

The mall’s trees will also get overhauled. According to a DOTI PowerPoint presentation, the original mall had 199 trees. Of those, only 144 remain — 55 were removed due to disease or damage — and 74% of the remaining trees have what the city describes as “fair to poor structure.” In the new plan, 253 new trees, across a wider variety of species, will be planted. While the mall’s original tree planters were large for their time, says Whitlock, they are significantly too small today. The new tree plantings will have larger soil volumes with structural cells supporting the pavers for roots to grow deeper/further and make more connections with other trees, strengthening all of them.

The project will also include new tech infrastructure, including new fiber optic lines, LED lights that can change color, and interactive wayfinding. Lastly, the reconstruction will replace a 140-year-old waterline that runs down 16th Street.

The changes mean that re-creating the exact patterning of the original mall is not possible, though planners note that the color scheme, diagonal layout, and pattern of square and insert circles will remain.

Work begins

Later this year design-build contractor PCL Construction will begin work to relocate utilities in preparation for construction, which will start next summer. PCL is building a 3D building information model of underground infrastructure that Bogan says will “inform potential utility conflicts, so they can confidently design the improvements and construct within the specified constraints, including providing access to businesses and facilities and completing construction by the end of 2024.” (PCL did not respond to requests from Civil Engineering.) 

According to Whitlock, less than 50 pedestrian malls remain in the U.S., and only nine are pedestrian-oriented transit malls. However, Whitlock notes that the 21st-century street is not just about moving people from one place to another: It’s an adaptable, flexible place for people to slow down, live their lives, and join in community building, he says. “In addition to the mall working well as a hallway, it also needs to work better as our city’s living room.”

The post Then and Now: Denver rebuilds historical downtown pedestrian hub appeared first on Civil Engineering Source.

Designated as a National Historic Civil Engineering Landmark by ASCE in 2012, the Huey P. Long Bridge in New Orleans, Louisiana, changed the landscape of the lower Mississippi River.

Here are five things you didn’t know about the Huey P. Long Bridge:

1. Before the opening of the “Huey P” in 1935, trains had to ferry across the Mississippi River near the New Orleans port. Workers uncoupled segments of railcars and loaded them on to specially designed train ferries fitted with rail tracks. Ferries shuttled two to five railcars at a time. Engineers had to wait until the entire length of the train crossed the river, and then workers reassembled it on the opposite bank before proceeding to their next station.

2. The original driving surface was 18 feet wide for two-way traffic, leading one driver to comment, “Because of its extremely narrow lanes, with no shoulders, it is not so popular with those who cross by car. In fact, some say that more prayers have been uttered atop the Huey P. Long Bridge than in all the churches of New Orleans and Jefferson Parish combined.” 

3. The railroad approaches have a 1.25% grade. Engineers from the mountain section of the Southern Pacific rail system had to train local flat-country engineers the intricacies of handling their locomotive and trains on this grade. 

4. The impressive rail bridge, the longest over water in the world at 22,995 feet, had a total construction cost of $9,424,981, more than $3 million under its $13 million budget. 

5. On Sept. 8, 1935, Senator Huey P. Long was shot in the state capitol building in Baton Rouge and died two days later. He did not live to see the completion of his namesake bridge over the Mississippi River. After his death, his widow, Rose, was appointed to fill his seat in the U.S. Senate and later was elected to the position, making her the second woman elected to the Senate — behind Hattie Caraway of Arkansas. 

Members of ASCE’s History and Heritage Committee have been learning fun and interesting facts about HCELs around the world to share in the new “5 Things You Didn’t Know About …” series. As the committee continues to build an inventory of all HCEL projects, members of the committee and other volunteers have been visiting sites to photograph landmarks and ASCE plaques as well as assess their conditions. If interested in volunteering to help the committee record these landmarks, please contact committee chairman David Gilbert ([email protected]).

Learn more about the committee’s work and the ASCE landmark program.

The post 5 things you didn’t know about the Huey P. Long Bridge appeared first on Civil Engineering Source.

Tammany Hall was once notorious for political patronage and corruption, symbolized in editorial cartoons by a sometimes rapacious, sometimes pathetic tiger. But the Tammany Society, the political organization that built the hall in the late 1920s on the northeastern corner of New York City’s Union Square, was actually named more than a century earlier after someone with a far better reputation: the Native American chief Tamanend, a leader of the Lenape people who once lived in the New York area.

The Lenape’s creation story features a turtle rising from the sea, and it was this turtle that inspired a recent reimagining of the Tammany Hall building, an effort that preserved two of the historical brick facades but essentially gutted the interior. Most of the old building — a three-story, neo-Georgian-style steel-framed structure — was then replaced with a new six-story concrete structure crowned by a glass-and-steel grid shell dome designed to resemble a turtle’s shell.

Now known as 44 Union Square, the project added approximately 30,000 sq ft of useable space to the building and features a total of 72,000 sq ft of commercial and retail space.

New York City-based BKSK Architects, which won an invited competition for the project, led the renovation. International engineering firms Thornton Tomasetti and Buro Happold served as the project’s structural engineer and facade engineer, respectively. Although the major structural work was completed last year, the final build-out of the interior spaces awaits a tenant. The building is owned by Reading International Inc., of Culver City, California, and the project was overseen by the owner’s representative, Edifice Real Estate Partners, of New York City. The construction manager was CNY Group, also based in New York City. 

Preserving a landmark
Over its useful life, Tammany Hall featured numerous owners, tenants, and programs. The Tammany Society sold it to the International Ladies Garment Workers Union in the 1940s. By the 1980s, the building, which featured a large auditorium, was being used as an off-Broadway theater. It also housed a film and acting school in the 1990s before being sold to the current owners in the early 2000s. As a result of the building changing hands so often, the interior had been altered considerably, “cut up … into a series of half levels and a warren of spaces,” notes Todd Poisson, AIA, a partner at BKSK Architects. 

The site was designated a landmark building in 2013 by the New York City Landmarks Preservation Commission. So much else about the structure had changed over time, however, that the landmark designation pertained primarily to the northern and western facades, which featured brick and limestone construction with numerous ornamental details. The northern facade, facing East 17th Street, has an arched pediment and a medallion of Chief Tamanend, while the western facade faces Union Square East and features a classical portico with columns and a triangular pediment.

By 2014, the owners proposed converting the site into a modern mixed-use building while preserving the two historical street-front facades and adding the dome as well as a balcony to the roof. Although the landmarks commission rejected that initial design, a new proposal submitted in 2015 won unanimous approval by the commission. The new design replaced the balcony with a reimagined version of the building’s original hipped roof and changed the geometry of the dome “to have a more classical proportion when viewed from the square,” among other alterations, says Poisson.

The eastern and southern facades were not preserved, because they were located adjacent to the walls of other buildings and had not been given landmark status, notes Marco Coco, P.E., S.E., a New York City-based vice president of Thornton Tomasetti. It would also have been more difficult and expensive to brace those walls during the demolition of the interior. 

“We did try to salvage as much of the existing brick as possible and reuse it on the new walls that were built at those locations,” adds John Ivanoff, an associate principal in Buro Happold’s New York City office.

The northern and western facades featured three- and four-wythe deep brickwork and limestone lintels, which were supported during the demolition and construction phases by steel bracing towers designed by the shoring engineer, Howard Shapiro & Associates. The bracing system included steel walers on the exterior and interior of the walls to sandwich the existing facade, says Coco. These horizontal members were supported by the main exterior bracing towers, which were located on the sidewalks surrounding the Tammany Hall site. The towers were not removed until the new interior concrete structure was in place and the original facade walls had been secured to it by a series of steel clip angles and epoxy anchors, Coco notes. 

The original brickwork was monitored for vibration and potential cracking throughout the project. Although some cracking and settling did occur, it was minor, Ivanoff notes. A series of rooftop parapets turned out to be in worse condition than expected and had to be replaced rather than repaired. The new parapets feature sections of both salvaged and new bricks, new balustrades installed with spring-loaded dowels, and new reinforced-concrete masonry units that replaced the original brickwork in some locations.

In addition to demolishing the original interior, the project team also excavated the western side of the site to match the existing basement level on the eastern side, which was about 5 ft deeper, says Poisson. The new interior of the building is founded on new spread footings bearing on rock. The existing foundation wall and footings around the perimeter of the building were retained, “mostly because the existing steel framing was integral with the landmarked facade,” says Coco. “The existing perimeter column spread footings were enlarged to support new loading conditions.”

Because the rock profile at the site slopes from approximately 17 ft below street level along the western side to more than 25 ft below grade on the eastern edge, some of the new footings on the eastern side were changed to micropiles. This was done “so we didn’t have to keep digging and potentially undermine the neighboring buildings,” Coco explains. The project team monitored the adjacent buildings during the construction of the new foundations.

The building’s new interior framing system features reinforced-concrete shear walls, typically 12 in. thick, to resist lateral forces and reinforced-concrete floor slabs typically 11 in. thick. Existing steel columns embedded within the historical facade walls were also encased in concrete to form piers that provide vertical and lateral support and help preserve the integrity of the historical facades, Coco says. The concrete for these piers was placed monolithically with the new slabs, and the piers themselves are supported on new concrete footings that tie into the facade columns’ original footings.

Topping it off
To design the new dome and its support structure, Thornton Tomasetti worked closely with the fabricator and erector, Josef Gartner GmbH, a division of Permasteelisa, from Gundelfingen, Germany. The glazed structure spans 150 ft in a roughly northwest to southeast direction and 75 ft in the northeast to southwest direction. It features a steel tube framing that was welded together at intersecting nodes in the lower portions of the dome and bolted together at the higher portions to accommodate the dome’s geometry. The main steelwork features rectangular steel tubes that measure approximately 6 by 3 in. in cross section. These support more than 800 triangular glass panels that form a surface area of approximately 12,000 sq ft. 

The edge of the dome undulates slightly on the northern and southern sides of the structure, rising like the openings in a turtle shell — especially where it seems to “peak up over the arched pediment on the 17th Street side,” notes Poisson. 

Although most of the new floors within the building feature floor-to-ceiling heights of roughly 12 ft, the dome levels feature heights of 19 ft. The uppermost level, the sixth floor, also resembles an elevated platform at one end, standing on pillars to provide a balconylike space within the dome.

To support the dome, the design team used a reinforced-concrete retaining wall system at the new fourth-floor level, a combination of horizontal restraining and sliding bearings, and a curved reinforced-concrete corbel structure that surrounds the new concrete core, Coco explains.

A thickened floor slab — roughly 16 in. deep — along the northern and western facades and part of the southern facade supports the new retaining wall structure. The concrete wall is designed to support the vertical and lateral loads from the new dome, including the thrust forces imposed by the dome’s free-form geometry.

The final design of the dome steelwork became quite complex in certain locations, especially at critical nodes where multiple steel members came together. In particular, some of the nodal supports were changed from laterally restrained to roller supported in order to reduce the horizontal demand on the supporting structure, says Coco. This was especially necessary where the elevator core walls support the corbel structure.

The original Tammany Hall building had appeared to be topped by a hipped roof made from slate, but this was largely just an aesthetic feature — a false top that concealed a flat roof underneath. To mimic the historical appearance of the original building, however, the design team developed a series of terra-cotta sunshades that were installed along the western facade and a portion of the northern facade. Measuring roughly 1 ft tall and varying from about 18 to 24 in. long, the fixed sunshades are supported on a steel subframe that connects back to the dome’s steel structure. Located above the glazing for the new fourth-floor offices, the sunshades will provide thermal comfort and glare protection.

The dome’s glass is tinted rather than fritted because the proximity of the workspaces to the glazed surface meant that the harsh sunlight would actually be visible between the frits — an effect that the architects learned by studying other glazed domes around the world.

Fitting in
Because of Tammany Hall’s proximity to other buildings and the general traffic congestion of downtown New York City, there was almost no space available for the teams to assemble components on-site, Ivanoff notes. Fortunately, the project relied mostly on prefabricated elements that were assembled off-site and then “fit together like a kit of parts and not stick built,” he explains. This was especially true for the steel elements that were put together in Germany and shipped to the United States in large components that fit inside cargo containers. The glass panels often arrived on the same day they were being installed, minimizing storage requirements.

During the erection of the dome, large steel pieces were assembled in a stepped or ladderlike formation, and strategic locations throughout the dome had to be self-supporting prior to being enclosed. As the steel erection team moved ahead, a second team came behind it, installing the gaskets and glazing. These teams were “literally climbing over this organic shape,” which is not flat anywhere or easy to walk on, Ivanoff adds.

But thanks to these efforts and the work of all the members of the design and construction teams, the former Tammany Hall has been preserved and improved. Its two historical facades still form part of the shell that surrounds the building, while a modern shell now crowns the structure — rising, like the Lenape people’s legendary turtle, toward a new and promising future.

PROJECT CREDITS
Owner: Reading International Inc., Culver City, California
Owner’s Representative: Edifice Real Estate Partners, New York City
Architect: BKSK Architects, New York City STRUCTURAL ENGINEER: Thornton Tomasetti, New York City office
Facade Engineer: Buro Happold, New York City office
Dome steel fabricator and erector: Josef Gartner GmbH, a division of Permasteelisa, Gundelfingen, Germany
Geotechnical engineer: RA Engineering LLP, New York City
Mechanical, electrical, and plumbing engineer: Dagher Engineering, New York City
Construction manager: CNY Group, New York City
Historic preservation consultant: Higgins Quasebarth & Partners, New York City

SIDEBAR
Rebranding Tammany
By Robert L. Reid

Unlike the infamous political organization behind New York City’s Tammany Hall, the group’s namesake — Chief Tamanend — was considered a legendary leader of the Lenape people, notes Todd Poisson, AIA, a partner in the architecture firm BKSK Architects that helped convert Tammany Hall into the modern 44 Union Square mixed-use project. Famed for signing a peaceful coexistence treaty with William Penn in the 1680s, Tamanend also had a reputation of being “someone who’d listen to all voices,” Poisson explains.

Although the design brief for the project competition implied that the owners felt “it was time to move away from the name Tammany,” Poisson says, BKSK’s research into the history of Chief Tamanend and the Lenape people offered “an opportunity to rebrand ‘Tammany’ in a perhaps unexpected way.”

In the Lenape’s creation story, “a giant turtle rose from the seas to create the land,” Poisson explains. That imagery, together with the goal of enlarging the property vertically to create additional space, led to the idea of the shell-like dome. The best design to accomplish that vision involved a free-form grid shell — a structural system that is highly flexible, requires no internal supports, and can be optimized through parametric software “in a way that would be expressive of an organic shape, such as a turtle shell,” Poisson says. At the same time, the dome would appear classically proportioned for its Union Square setting.

Fortuitously, the design team discovered examples of other neo-Georgian-style buildings that were topped by domes, including some that had their domes added long after the original buildings had been constructed. Although such discoveries were helpful in convincing New York City’s Landmarks Preservation Commission to approve the dome scheme, the design team also sought the approval of another critical stakeholder: the Lenape people themselves.

“It was very important to us to be sure we weren’t appropriating cultural imagery inappropriately,” Poisson explains. So, he contacted New York City’s Lenape Center to discuss the project. The Lenape leadership not only approved the project, but two of the organization’s cofounders — Hadrien Coumans and Joe Baker — also came to the newly completed building in October 2020 to perform a traditional blessing ceremony. Designed to acknowledge the past, present, and future inhabitants of the site, the ceremony began outside the building with a prayer of well-being and an honor song and concluded within the new dome.

“We thank the Lenape Center for their guidance and support of the use of Lenape imagery of a rising turtle to inspire Tammany Hall’s new crowning dome,” Poisson said at the event. “We hope Tammany’s new glass dome appears forever frozen at the very moment that the turtle is breaking through the surface of the sea, shedding water from its shell. Because it is at this moment that anything is possible.”

This article first appeared in the May/June 2021 issue of Civil Engineering as “Tammany Rising.”

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In the 1977 Historic American Engineering Record report on the canal, HAER GA-5, historian Robert L. Spude quoted the 1918 book American Negro Slavery, by Ulrich B. Phillips, who described the chaotic scene from about 1827 in Augusta, which was establishing itself as a regional trade center: “The thoroughfares were thronged with groaning wagons, the warehouses were glutted, the open places were stacked, and the steamboats and barges hidden by their loads.” Fueled by their chief commodity, cotton, Augustans believed their city was destined to soon rival Philadelphia.

But Augusta faced competition from other cities — Atlanta, Macon, and Columbus in Georgia and Hamburg, South Carolina, on the other side of the Savannah River — and between 1830 and 1840 the city’s population actually dipped a bit. For years city leaders had been mulling the idea of building a canal along a stretch of the Savannah River that ran through Augusta. Spude noted that small factories had begun to pop up along the creek banks on the outside of town as city leaders speculated about “harnessing the falls of the Savannah, a few miles above the city, and thus providing power sufficient for innumerable mills.”

The goal was to become the South’s version of Lowell, Massachusetts, the center of the American Industrial Revolution. This, too, was an idea that had occurred to rival cities in the South. Throughout the 1830s and ’40s, Spude wrote, “Southern urbanites sought to transform their cities into prosperous centers.” People who dreamed of becoming industrialists set up in towns along the Piedmont, the plateau between the Appalachian Mountains and the Atlantic coastal plain, and those towns “became, or strove to become, manufacturing centers.”

The key figure who drove Augusta’s ambitions was Henry H. Cumming, director of the Georgia Railroad and Banking Co. and member of a prominent Georgia family. In 1844, determined to lead the efforts to build a canal, he hired the chief engineer of the Georgia Railroad, John Edgar Thomson, and local surveyor William Phillips “to determine the fall of the Savannah from Bull Sluice, at the beginning of the falls some six miles from town, to the mouth of Hawks Gully, or Augusta’s western city limit,” Spude wrote. The two concluded that the river fell 52 ft over the course of 6 mi, potentially creating enough power to drive cotton mills.

By 1845, Augusta’s four banks had pledged $4,000 to pay for a more comprehensive survey, which Thomson again oversaw. Thomson, who would later become the chief engineer and the president of the Pennsylvania Railroad, knew his way around canals; his father had overseen work on the Chesapeake and Delaware Canal in Delaware.

According to Patrick M. Malone’s 1976 book, The Lowell Canal System (as relayed in the HAER report), “The ideal way to supply a number of mills with water power is to use a single canal running parallel to a river with a falls. If the canal leaves the river above the falls and reenters at some distance downstream, then the land between the canal and the river becomes an extended island on which mills can be placed in a line. By keeping the level of water in the canal close to that of the river above the falls, there will be a major difference in water level between the canal and the river at every point below the falls.” 

The plan for the Augusta Canal was for it to be built just south of the river and extend into the center of the city. Its configuration, Spude wrote, resembled a “three-pronged fork with an off-center handle and prong tips bent until touching.” The canal ultimately consisted of three levels. A wing dam would channel water from the river at the head of the falls into the first and longest level of the canal to “industries along its eastern bank, then fall through water wheels or turbines and come out at the second level 13 feet lower. From the second level the water again fell 13 feet through mill power machinery to the third level. The third level, actually a widening and connecting of Beaver Dam Creek and Hawks Gully, carried the spent water to the Savannah River.” 

Cumming was aware of the stock company financing of canals that was common in New England as well as the government-subsidized funding common in Europe, and he combined the two ideas in his Augusta Canal proposal. A stock company, the Augusta Canal Co., would supervise construction of the canal; the city of Augusta would buy the stock by transferring $100,000 in city bonds to the canal company. The sale of the bonds would finance the canal’s construction. Additionally, in exchange for a tax on city real estate, citizens would receive a proportionate amount of stock, or “Canal Scrip.” 

“The plan straddled the legal domain of both a private corporation and the city government,” Spude wrote, “but lawyer Cumming judged that all was legally sound.”

The incorporation bill raised eyebrows in the Georgia legislature. One member called the bill “the strangest one he ever saw,” and some merchants and other property owners unsuccessfully contested the financing’s legality in court. But the plan passed in 1845; the city council’s only addendum was that the canal also supply the city with sufficient potable water.

Cumming hired civil engineer C.O. Stanford to oversee construction. Descriptions of canal construction methods were scarce in newspapers of the day. Some reports, Spude wrote, suggested that “explosives were used to cut through rocky sections, that slaves and whites from the hills of north Georgia composed the labor force, and that masons from the North built the culverts, aqueducts, and head gates. In short, construction of the Augusta Canal was slow and primitive.”

Workers came from all over: local white laborers, Georgia Railroad workers, and African American workers, both free and enslaved. According to the Augusta Museum of History, free Black men made up a large portion of the labor force in river towns like Augusta; they typically held jobs as stevedores, boat operators, and sometimes even riverboat captains.

The project crossed the plantation of Judge Benjamin H. Warren. Spude’s history says that the judge had a “force of hands and teams clearing the grade.” His brother-in-law, James L. Coleman, put 70 enslaved people to work on the project. As the New Georgia Encyclopedia notes, the summer heat “decimated the white work crew, and Black labor — slave and free — finished the job.” At least 50 free Black workers were also hired and paid $85 for a year of work — about the same rate as white laborers brought in from Savannah and Charleston, according to Edward J. Cashin’s 2002 history of the canal, The Brightest Arm of the Savannah: The Augusta Canal 1845-2000. 

The museum adds that Black workers, bearing the brunt of that harsh Augusta summer, dug the first level of the canal by hand. By November 1846, about 200 workers had completed the first level of the canal. But it wasn’t until the arrival of entrepreneur Jacobez Smith in 1847 that the financial fortunes of the city began to change. Smith had helped transform Petersburg, Virginia, into an industrial center, and he began to do the same in Augusta, building a pair of mills that eventually became the Augusta Manufacturing Co., one of the largest mills in the South.

Workers continued to flock to the city. In 1848, William Phillips took over as chief engineer on the canal, a position he held for the next 25 years. He completed the second and third levels and enlarged the wing dam. “By 1850, he had crews bolting the finishing timbers atop the cribwork dam,” Spude wrote, “which increased the depth of the first level from 5 feet to 6 feet.” Iron gates were installed downtown to prevent the increased flow of water from flooding the city.

Phillips also enlarged the canal between 1855 and 1857, capping the riverbanks with timber, riprap, and stone. The worm gears of the canal’s head gates were replaced with rack-and-pinion gearing, making it easier to raise and lower the wooden panels. This work was done largely by Irish laborers, making $1 a day, and free Black laborers, making $0.85 a day.

Two old wooden aqueducts, which had begun to lean and collapse, also had to be torn down and replaced. And there were other problems for Phillips, Spude relayed, including “breaks in the canal bank, silt build-up, and users’ complaints of low water.” He also had to deal with at least one lock keeper who had to be fired from his position due to “excessive inebriation.”

The enlarged canal served the city during the Civil War; the Confederacy established a 2 mi long munitions factory, the Confederate Powder Works, along its bank. Other manufacturers joined, including a dye plant, a bakery, and a pistol factory. According to the National Park Service, the Powder Works was the only permanent structure built by the Confederacy; it turned out 2.75 million lb of gunpowder — 7,000 lb a day. It was, according to a video documentary produced by the Augusta Canal National Heritage Area, “the most efficient gunpowder plant in the world.”  

In one of countless bitter ironies, many of the jobs around the Powder Works were performed by enslaved Black workers, including “hauling and chopping wood for the boiler furnaces, burning coal, and moving finished gunpowder down the canal by mule-drawn boats,” according to the Augusta Canal National Heritage Area, which cites the 1974 book Confederate City: Augusta, Georgia, 1860-1865 by Florence Fleming Corley (University of South Carolina Press).

After the war, the federal government confiscated and later sold the land, and a subsequent widening of the canal demolished all but the Powder Works’ smokestack, which was left as a war memorial. The city languished again until Mayor Charles Estes spearheaded a three-year expansion of the canal zone. He hired a former Erie Canal engineer, Charles A. Olmstead, to supervise the work. The construction firm John A. Green & Co., also relocated workers to Augusta. According to Spude, workers used “a steam-powered dredge, vertical steam ‘donkey’ engines, and other updated equipment to dig the canal, quarry stone, and take dam materials across a narrow-gauge track to the Savannah River.”

Once again, a diverse labor force did the work, including African Americans, Irish Americans, Italian Americans, and newly arrived Chinese Americans. Spude noted that Italian American workers completed the “precise stonework” required to renovate an aqueduct at Rae’s Creek, “while the backbreaking menial labor was performed by convict labor crews made up mostly of Blacks, and by (recent) Chinese arrivals in the country.”

Not until 1877, when national money markets began to loosen up and cotton values began to increase, did prosperity return to Augusta. The population doubled between 1870 and 1890, leading to an era of impressive architectural design. One mill, for the John P. King Manufacturing Co., featured a “massive central stair and water tank tower reminiscent of the villa towers of northern Italy,” according to the HAER GA-15 report, written in 1977 by historian Alan J. Steiner. “The tower was covered with ornamental brick-work, which divided and accentuated each of its upper stories. A variety of windows and door openings, ranging from segmental to round-arched to circular, pierced the tower.”

On the remains of the Powder Works, a massive new structure, the Sibley Mill, was built between 1880 and 1882. With its “crenelated facade and corner towers,” it resembled a medieval castle, in the words of the NPS. 

The years that followed were when Augusta truly became the Lowell of the South. It was an era of extremes that saw both the introduction of electrification and the development of “mill villages,” where factory workers, many of them women and children, worked nearly 12-hour days in the textile mills, leading to years of labor unrest.

Between 1880 and 1930, Spude wrote, 12 major industrial complexes used the canal’s water power. But gradually, as the 20th century got underway, the canal declined. Floods in the 1920s and ’30s damaged the canal system. Mills sought cheaper labor or lower costs and departed. In the 1930s the federal Works Progress Administration deployed hundreds of workers to renovate the zone, raising the riverbanks, straightening the canal, and constructing a new spillway, according to the Augusta Canal National Heritage Area and a drawing from the Cashin book. 

During the 1960s and ’70s, the physical form of the canal and the adjacent industries changed greatly. Every industry on the second and third levels, which once ran on water power, stopped using their turbines. Many mills closed and were torn down. The city even considered draining the canal and turning it into a highway.

But preservationists imagined converting the area for recreational use and preserving its stock of industrial structures. The site and its mills were listed on the National Register of Historic Places, and Congress designated the Augusta Canal as a National Historic Landmark. The Georgia state legislature created an oversight body, the Augusta Canal Authority, in 1989 to revitalize the district; Congress designated the canal a National Heritage Area in 1996. Since then, the canal zone has become a popular draw among tourists and recreationists. And ASCE designated the Augusta Canal as a national Historic Civil Engineering Landmark in 2018.

The Sibley Mill produced textiles as recently as 2006 before closing; the building still generates electricity. Developers are looking at converting the Sibley and King mills into mixed-use projects. Another, the Enterprise Mill, has been converted into an office, residential, and museum complex. 

The Augusta Canal still provides the city’s water supply and, as a symbol of an economy dominated by tourism and services, may yet lead a new renaissance in Augusta. 

This article first appeared in the May/June 2021 issue of Civil Engineering as “Powering the South: The Augusta Canal.”

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With the advent of automobiles during the early 20th century, the Good Roads Movement advocated and fostered the growth of roads and highways as critical to economic and social development and inextricably linked to prosperity. By the 1920s, concepts were proposed for a link between the United States and Canada over the Saint Lawrence River, east of Lake Ontario. Connecting central New York state with greater Ottawa, the Thousand Islands Bridge would be, at the time of its construction, the only land crossing between New York and Ontario east of Niagara Falls and the only border crossing of the St. Lawrence west of Montreal.

Early proponents of the bridge struggled to garner government approval and funding for the project. During the early planning years, many described the bridge as going “from nowhere to nowhere.” By 1928, a motion was presented in the New York legislature to form a bridge corporation but without a Canadian partner, a similar bill in Canada failed. Despite considerable local support, the Canadian government did not consider bridge construction a public-works project. With the 1931 formation of the Thousand Islands Bridge Company, private financing was secured, and engineering of the bridge began in 1933. Construction commenced with a groundbreaking ceremony held on April 30, 1937. The bridge opened 16 months later, Aug. 13, 1938, dedicated by President Franklin D. Roosevelt and Prime Minister Mackenzie King.

The 8.5-mile Thousand Islands International Bridge system is actually a series of five bridges spanning the Saint Lawrence from south to north: United States mainland to Wellesley Island (main span); Wellesley Island to Hill Island (international crossing); Hill Island to Constance Island; Constance Island to Georgina Island; and Georgina Island to the Canadian mainland. The bridges’ southern end connects with Interstate 81, and the northern end connects with Highway 401. Upon opening, annual traffic was approximately 150,000 vehicles. Today, annual crossings exceed 2 million vehicles.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Ever since London’s 1851 Crystal Palace Exhibition, cities have hosted World Expositions at recurring intervals, typically every two to three years. These extravaganzas have served to provide cultural exchange, showcase technical achievements of nations, and offer ideas and visions for a global future. Seattle’s Century 21 Exposition, known colloquially as the 1962 Seattle World’s Fair, was no exception. The Seattle World’s Fair’s theme, “Man in the Space Age,” established a mindset of innovation, and structural engineering contributed to the futuristic sentiment with bold, radical, pioneering designs.

The ubiquitous legacy of the Seattle World’s Fair is the 605-foot-tall Space Needle, once the tallest structure west of the Mississippi River. The slender futuristic tower required a 30-foot-deep and 120-foot-wide foundation, the largest continuous concrete pour ever attempted in the West. Once the foundation was completed, it weighed as much as the Space Needle itself, establishing the center of gravity just 5 feet above ground. The Space Needle officially opened on April 21, 1962, the first day of the World’s Fair, and has since become the icon of the city.

Access to the fair from downtown Seattle was made convenient by the construction of the nation’s first full-scale commercial monorail system. The mile-long monorail consists of two lines of pre-stressed concrete hollow box girders 35 and 1/2 inches wide and 59 inches deep. Requiring extensive curving and elevation changes of the beams, with unique bends and asymmetrical sections, precise geometry was critical to match the dimensions of the two 250-capacity passenger trains, which were manufactured in Germany.

Washington State Coliseum was designed as a 130,000-square-foot clear span pavilion to house exhibits. The hyperbolic paraboloid, with no interior roof columns, was supported by four colossal concrete abutments, 11 stories tall. In 2019 renovation of the arena began, involving demolition of the entire structure except the 44-million-pound roof, which was suspended in mid-air as redevelopment proceeded beneath. Reopening of the structure, now Climate Pledge Arena, is scheduled for June 2021.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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As the Virginia colony was settled and grew from the early 1600s, maritime transportation was the primary mode of passage between the mainland and the Delmarva peninsula, respectively the western and eastern shores of Chesapeake Bay. In 1954, the Virginia General Assembly created the Chesapeake Bay Ferry Commission with a charge to improve ferry service between the mainland and the eastern shore. Two years later the Assembly authorized the commission to perform a study for a fixed crossing.

Studies concluded that a vehicle crossing was feasible. The selected route at the mouth of Chesapeake Bay crosses two major Atlantic shipping channels. High-level bridges were initially considered for spanning the channels but were objected to by the U.S. Navy and the state of Maryland. Officials expressed concerns that a bridge collapse could isolate critical maritime infrastructure from the Atlantic Ocean. Engineers proposed a solution in a series of bridges and tunnels, similar to the 3.5-mile Hampton Roads Bridge-Tunnel that was completed in 1957, just 10 miles west where the James River meets Chesapeake Bay.

Five times longer than the neighboring Hampton Roads Bridge-Tunnel, the Chesapeake Bay Bridge-Tunnel began construction in October 1960. The tunnels were constructed by excavating a large trench for each tunnel and lowering prefabricated tunnel sections from barges. The sections were then aligned and bolted together by divers, the water pumped out, and each section covered with earth. The bridges consist of a series of low-level trestles and two high level bridges. The tunnels are connected to the bridges at four engineered islands, each approximately 5.25 acres in size.

ASCE recognized the Chesapeake Bay Bridge-Tunnel in 1965 as one of the “Seven Engineering Wonders of the Modern World,” and as an “Outstanding Engineering Achievement.”

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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After America’s entry into World War I, Lewis B. Combs, a 1916 civil engineering graduate of Rensselaer Polytechnic Institute in Troy, New York, received an appointment as an assistant civil engineer in the Navy on Dec. 27, 1917. Seven weeks later he reported to the Washington Navy Yard for duty as assistant civil engineer in charge of field construction, an assignment that he served for the duration of the war. During peacetime between World Wars, Combs’ assignments included developing construction programs in Haiti and experimenting with concrete construction in sea water in Portsmouth, New Hampshire.

In 1938, Combs became assistant chief at Bureau of Yards and Docks and by the time that the United States entered World War II, Adm. Combs had spent four years under Adm. Ben Moreell conceiving, planning, and laying the groundwork for a mobile quick-response construction force, capable of performing under enemy fire. The United States Naval Construction Battalions were envisioned as combat-zone military replacements for civilian construction companies. Better known as the Navy Seabees (from the initials “C B” in Construction Battalion) the battalions were flexible and adaptable and could be used in every theater of operations. For nearly 80 years, Seabees have been the Navy’s construction force, building bases and airfields, conducting underwater construction, and building roads, bridges, and other support facilities, today with 7,000 active personnel and a similar number of reservists.

Following World War II, Combs served as a technical advisor on two John Wayne movies: The Fighting Seabees and Sands of Iwo Jima. After retiring from the military, Combs returned to RPI as head of the civil engineering department until stepping down in 1962. Combs died in 1996 at 101 in Red Hook, New York, where he is interred in the Saint Paul’s Lutheran Cemetery.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Designated a National Historic Civil Engineering Landmark by ASCE in 2011, the Tacoma Narrows Bridge in Tacoma, Washington, is the rare landmark that is considered a qualified failure for its collapse in 1940.

Here are five things you didn’t know about the Tacoma Narrows Bridge (known as “Galloping Gertie”):

1. Washington State Department of Transportation Chief Bridge Engineer Clark Eldridge originally designed the deck as a deep, open truss structure. He was overridden by famous suspension bridge consultant Leon Mossief, who convinced the department to opt for a more aesthetically pleasing shallow, solid girder structure. The shallower design led to its extreme instability in the windy Narrows Channel. The collapse ruined Mossief’s reputation and vindicated Eldridge.

2. The only fatality in the collapse was a dog named Tubby, abandoned by his owner – news reporter Leonard Coatsworth – in a car, which fell into the water when the bridge collapsed (see film link below).  The Washington State Toll Bridge Authority reimbursed Coatsworth $450 for the loss of his car and $364.40 for the loss of his car’s “contents.”

3. In 1998, the Library of Congress selected the Tacoma Narrows Bridge Collapse film for preservation in the United States National Film Registry by as being culturally, historically, or aesthetically significant.

4. Several museums in the Tacoma area display recovered pieces of the bridge, including the Washington State History Museum and Pacific Seas Aquarium at Point Defiance Zoo and Aquarium.

5. The failure led to intense research resulting in a better understanding of the behavior of structures under extreme wind conditions. Its failure was a contributing factor in its approval as an ASCE National Civil Engineering Landmark in 2011, as then-History and Heritage Committee Chairman Henry Petroski (author of To Engineer Is Human) commented that engineers learn valuable lessons from failures.

Members of ASCE’s History and Heritage Committee have been learning fun and interesting facts about HCELs around the world to share in the new “5 Things You Didn’t Know About …” series. As the committee continues to build an inventory of all HCEL projects, members of the committee and other volunteers have been visiting sites to photograph landmarks and ASCE plaques as well as assess their conditions. Email Tonja Koob Marking if you’d like to assist.

Learn more about the committee’s work and the ASCE landmark program.

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The province of New York was established in 1664. From the outset, New York, like other British colonies in the new world, looked to the west, but was hindered by the Appalachian Mountains that separated the coast from the wilderness beyond. In 1724, physician and natural scientist Cadwallader Colden, who was later a lieutenant governor and acting governor for the province of New York, proposed a canal to connect Lake Erie and the Hudson River. The canal would provide a direct waterway link from the Atlantic Ocean to the Great Lakes.

In the years following American independence, canals became the thoroughfares of the Industrial Revolution and initiatives were reinvigorated for a grand canal scheme across upstate New York. After a decade of studies, proposals, and defeated bills, the New York State Legislature passed “an act for establishing and opening lock navigation within the state” on March 30, 1792. That act set in motion a quarter century of politicking and planning that led to the 1817 groundbreaking for constructing the Erie Canal.

The Erie Canal was the first canal project undertaken as a public good to be financed at public risk through issuing bonds. After it was completed in 1825, New York City became the principal gateway to the west and the financial center of the nation, fulfilling the prediction by upstate New York flour merchant Jesse Hawley who foretold that a canal linking Lake Erie to the Hudson would be such a boon to the city of New York that “in a century its island would be covered with the buildings and population of its city.”

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Baltimore’s Francis Scott Key Bridge (not to be confused with the 1923 bridge of the same name in Washington, D.C.) is the outermost of three major Patapsco River crossings at Baltimore Harbor. Paralleling the earlier (1957) Baltimore Tunnel and later (1985) Fort McHenry Tunnel, the crossing was originally conceived as a tunnel between Hawkins Point and Sollers Point in the outer harbor. The design was changed to a bridge when tunnel construction bids proved too costly in 1970. Benefits offered by a bridge as compared with a tunnel, were the opportunity for additional travel lanes, lower operational and maintenance costs, and to provide an alternate route for vehicles containing hazardous materials, which are prohibited in the tunnels.

Construction began in 1972 and the bridge was opened to traffic on March 23, 1977. Including its connecting approaches, the total project length encompassed a 10.9-mile corridor. The bridge itself, with a total length of 8,636 feet, is a steel arch-shaped continuous-through-truss bridge structure that combines the behaviors of an arch, truss, and cantilever. With a main span of 1,200 feet, it was the second longest continuous-truss bridge span in the world when constructed and remains the second longest in the United States and third in the world.

Originally known as the Outer Harbor Crossing, the bridge was renamed after Francis Scott Key, author of “The Star-Spangled Banner.” Historians believe that the bridge passes within 200 feet of the location in the harbor where Key was detained on a cartel boat when, during the bombardment of Fort McHenry, he was inspired to write the words of the song that became the U.S. national anthem.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Civil Engineering: Could I get a quick elevator pitch of the book and its findings?

ML: The book is an attempt to give an international picture on the development of road pavement since the beginning of time to the current day, and then predict the future a bit. We took an international view because we’ve worked in most of the countries of the world and we found that most of what other people had written on the topic was fairly localized. We thought that pavements give an interesting view of society as a whole, so the book emphasizes not just the technology but why it happened and who did it and the politics of it. Even back in the past you can see that over time, the patterns in the history of how pavements were developed are not dissimilar.

What did the earliest manufactured roads look like when it came to form, function, and materials?

The first manufactured road to exist was part of the manufacture of one of the pyramids in Egypt. They had to bring in limestone blocks of about a meter to 2 meters in size from about a hundred kilometers away from the pyramid. And they did it by making a road from the quarry to the Nile and floating the blocks down. And they built another road from the wharf to the pyramids. And that road still exists as the oldest road we have in existence, from about 2,500 B.C. The limestone blocks required a lot of work to move; they probably rolled them on logs.

After that, there were roads built in Mesopotamia in the Fertile Crescent, places like Babylon and Baghdad. And those roads were mainly built for processional reasons, to serve the temples and make the emperor more impressive, rather than for day-to-day use as a pavement. And some of those still exist. A few of them were destroyed in the recent crises in that area, but several of them still exist. And Nebuchadnezzar, whose name is often quoted in the Bible, he is quoted as saying his father built one of the roads that would exist forever.

We have seen that over a long historical period, from 1100 B.C., where they mortared together these big blocks of limestone or bricks made from sand and straw or clay. And in that area there was, and still is, petroleum. So there is also bitumen, the heavy byproduct of petroleum. The bitumen seeped from underground, and they heated the bitumen to use as a mortar to create a coherent surface.

What’s the biggest difference, would you say, between those early roads and our modern roads?

Modern roads also have a coherent surface. Everything is together in a single surface, whereas between the early Mesopotamian roads and now, most of the roads were cobblestones or loose stones, which were very easily disturbed. But for the last hundred years or so we’ve been producing coherent surfaces on the roads.

Why do you think there was that huge period of time where there weren’t coherent roads?

It was very expensive to make block roads. The Romans made coherent roads similar to horizontal walls, but they had lots of masons and slaves who could do it. Otherwise, it was too expensive. A road had to be fairly cheap and use local materials, such as boulders and pebbles from the riverbeds.

What does the evolution process to modern roads look like? And what were the most important elements that got us as a globe and as an industry from there to here?

When the Industrial Revolution began, all of the sudden in Europe in particular and to a lesser extent in America, roads were needed to transport goods and materials. So that’s when people started being serious about road making. And people — a Frenchman called Pierre-Marie-Jérôme Trésaguet and two Scotsmen called John Loudon McAdam and Thomas Telford — developed relatively modern road making methods involving drainage and the use of stone masons.

It wasn’t until steam engines were invented  that we began to be able to crush stone into broken stone that is compacted together to form a pavement. But even then, there was big controversy because the tradition was to use river pebbles, but McAdam said in about 1810 that broken stones make better roads. It took about 100 years before everyone believed that what McAdam said was true. And his name was used to describe the type of road — a macadam road. And when they put the pebbles together with tar it was called tar macadam, which became ‘tarmac,’ a term still used in some places.

And then in the middle of the 20th century, oil refining started, and a byproduct of oil — a waste product really — is bitumen, also known as asphaltic cement. When that became readily available, it became possible to make roads economically. Of course, you can also make roads out of concrete. Concrete roads and asphalt roads are competitive, but by and large asphalt roads are cheaper than concrete roads.

What was the American contribution to the development of modern road making?

America industrialized road making in a way that no one had done before. One of the big American contributions was to produce the machinery that allowed stones to be crushed and asphalt to be mixed and placed.

This industrialization of road making happened in America after the steam engine was developed, which led to the German development of internal combustion engines. After that, in America, Henry Ford got into the act. People started making trucks powered by internal combustion, and initially those trucks were not used too frequently. But in the First World War, the trucks started to be a major facility and part of the war, and America supplied the trucks to the Allies even before America entered the First World War. And those trucks had to be taken from the factories to the seaboard ports. The result was that all the prewar roads from factory to port were quickly destroyed and had to be rebuilt.

The other big American contribution was in the 1930s, when the California Division of Highways (a forerunner to the California Department of Transportation) developed a method called the California Bearing Ratio, CBR, to decide how thick pavements should be. A very simple method based on tests they’d done. And it was so effective that people still use it all around the world. And its use had a big boost in the Second World War, when it was used by the U.S. Army Corps of Engineers to design airfields in the Pacific.

The CBR is determined with a stamping machine that you just press into the site where you are going to put a road to see how far into the exposed soil it goes. And that’s a measure of the bearing strength of the road, which determines how thick the pavement should be. And in a primitive way it works exceedingly well. You just need this machine.

It’s still used around the world for making simple roads. You wouldn’t use it for a freeway, but for an ordinary conventional country road or city street, you’d use it.

What countries saw the growth of roads the fastest? Was it really densely populated countries like you see in Europe? Or was it in the U.S., where you have lots of space?

First, it was density because you have to have a market to pay for the roads. In low-density areas it’s harder to get the funds for the roadways. As the tracks opened up in the west in America, they were very primitive by modern standards. It wasn’t until the 1930s and later that they were upgraded. In fact, a big problem in much of America at that time was the enormous problems with dust produced from those surface roads. If you looked in American magazines in the 1930s, you’d find dust prevention was one of the great issues at the time.  There were complaints from local communities, farmers, and small towns, and there were a number of proprietary products marketed to put the dust down — but they only lasted until the next rainstorm.

What was the biggest surprise or the most significant finding that you came across in your research and writing?

I think the biggest issue we found was how people didn’t think about how they had to maintain their roads after they were built. It was a message that was very slowly learnt. And then there is the economic issue — the engineering is simple compared to the economics of how you are going to fund the construction and maintenance of a road. And that’s a problem all around the world. Some communities are very good at it, and others are very bad at it.

What was the biggest takeaway you wanted to leave your readers with?

The biggest takeaway is that there is more to roads than just their surface. There is quite a complex technology underneath. And in a technical sense, the engineering is difficult because the materials are quite primitive and we must depend on local materials. And, unlike building a bridge, we can’t predict the elasticity or the slant very accurately, so there’s a lot more intuition rather than science in it.

And roads just don’t last very long at all. Roads need to be maintained almost annually and need to be remade almost every 10 years. They start wearing out from the first truck that goes over them.

What does the future of roads look like? The biggest challenges, the biggest opportunities?

The opportunities have to be in the tax and the economics of managing the road. We can now make the roads well, but some of the materials we use are energy intensive. We have to learn how to recycle the road better, although America is already very good at that. Someone said that American roads are America’s biggest quarry these days because once you dig up a road you can recycle it — break up the bits and reuse them. For the most part, we don’t need more length of road or width of road. It’s really managing the roads we’ve got, which is going to be very important through recycling.

In your opinion, where do we as a globe, as an industry, and as an engineering profession go from here?

I think for the future, the road technology is fairly OK. However, although recyling will help, we still lack an alternatives to bitumen, asphalt, and cementitious concrete for use in road construction. Bitumen relies on petroleum, so its availability depends on the reliance on fuel supplies for vehicles. Because bitumen is a byproduct of oil, refining it may become scarcer, more expensive, and less acceptable environmentally in the future.

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On March 13, 1903, the Department of Interior announced five federal projects under the Newlands Reclamation Act of 1902. Salt River Dam #1 was among the projects to be completed under the program. The first stone block of the dam, a six-ton cornerstone that lies 32 feet below the river’s normal bed, was placed on Sept. 20, 1906.

Also in 1906, Congress authorized the Reclamation Service to develop and sell hydroelectric power at the Salt River Project – the beginning of federal production of electric power. The Salt River Project, including the dam, was the first major public works project in the American West to demonstrate that large-scale reclamation of arid land was both possible and practical.

The final stone of the dam was placed on Feb. 5, 1911. At 280 feet tall and 723 feet long, it was the largest masonry dam in the world at the time. A month later on March 18, Theodore Roosevelt, who had signed the authorization for the project when president, dedicated the dam that was renamed in his honor.

The Salt River Project ultimately led to the irrigation of more than 250,000 acres surrounding metropolitan Phoenix. ASCE designated the Theodore Roosevelt Dam and Salt River Project as an ASCE National Historic Civil Engineering Landmark in 1970.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Owing to military threats to the West Coast shortly after the United States entry into World War ll, construction of the Alaska Highway was hastened after two decades of planning and international cooperation between the United States and Canada. Congress and President Franklin Roosevelt authorized the construction in February 1942 and within a month the U.S. Army Corps of Engineers began arriving to build the highway.

The first group of soldiers and equipment arrived in Dawson Creek on March 9, and six other regiments followed at strategic locations along the 1,500-mile route from Dawson Creek to Delta Junction, Alaska. Building in both directions from various locations, each regiment would work toward other groups until meeting. Scouts and surveyors stayed approximately 10 miles ahead of the construction teams. Surveyors were followed by teams of bulldozers who would clear the mapped route and then by a team of graders who would level the surface of the roadway.

By June, 10,000 soldiers had been deployed for the undertaking. Construction was completed in October, and the highway was opened to the military in November 1942. The road was originally built as a supply route, although the road ultimately served little of that purpose as most supplies to Alaska during the war were sent by sea. The road was opened to the public in 1948.

During the project, significant experiences were gained in Arctic engineering and construction, particularly in permafrost. The Alaska Highway was recognized by ASCE as an International Historic Civil Engineering Landmark in 1995.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Sixteen years earlier, in 1852, following the rise and trend of professional organizations in the mid-19th century, the American Society of Civil Engineers and Architects had been founded with a gathering of 12 civil engineers at the Croton Aqueduct office in Manhattan.

Membership was restricted to “civil, geological, mining, and mechanical engineers, architects, and other persons who, by profession, are interested in the advancement of science.” The Society functioned for a few years, but by 1855 had ceased holding meetings. After a period of dormancy, the Society rejuvenated in 1867 under the leadership of President James Pugh Kirkwood, whose address in 1867 was the first publication of the Society.

By 1867, prominent architects in New York City had formed the New York Society of Architects (later American Institute of Architects). The American Society of Civil Engineers and Architects then voted on March 4, 1868, by a count of 17-4, to formally change the organization’s name and remove the reference to architects, establishing what is known today as the American Society of Civil Engineers.

Reuben Hull, P.E., PMP, M.ASCE, is civil regional manager for LaBella Associates in Albany, New York, and a self-made historian who has penned numerous articles on civil engineering history. An active ASCE member, Hull is a corresponding member and former chair of the History and Heritage Committee, serves as vice president of the Mohawk-Hudson Section, served as president of the New Hampshire Section, 1999-2000, and was named New Hampshire Young Engineer of the Year in 1997.

Follow his daily Civil Engineering Almanac series on Twitter: @ThisDayInCEHist.

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Plans for a national network of roads had been under consideration since just after World War I, but America’s modern interstate system began with the passage of the 1956 Federal Aid Highway Act, which authorized construction of a 40,000 mi network — now officially known as the Dwight D. Eisenhower National System of Interstate and Defense Highways — that would link the United States and be paid for almost entirely by the federal government. (Read “Special Report: The Interstate Highway System at 50,” Civil Engineering, June 2006, pages 36-43, 78.)

Initial plans for I-70 called for it to run west from Baltimore to Denver but not to extend into the Rocky Mountains. Colorado leaders quickly pressed for a route through the mountains, however, and military officials wanted a route that would connect the central United States with Southern California. Eventually I-70 was aligned to connect with I-15 in central Utah rather than in northern Utah at Salt Lake City, terminating at Ft. Cove.This meant builders would be faced with plotting a course directly through one of the most beautiful and challenging stretches of the Colorado Rockies. 

According to CDOT, the finished project cost $490 million in 1992 dollars; adjusted for inflation, that would be $925.5 million today.

The route turned out to be less of a single road than a “network of viaducts, bridges, and tunnels constructed through an extraordinarily narrow, environmentally sensitive gorge” (“Glenwood Canyon 12 Years Later,” by Karen Stufflebeam Row, Eva LaDow, and Steve Moler, Public Roads, Federal Highway Administration, March/April 2004).

Carved by the mighty Colorado River over the course of 70 million years, the rock walls of the narrow Glenwood Canyon reach as high as 2,000 ft. It had long been seen as an impassable route, even by the area’s indigenous Utes. But during Colorado’s 19th-century silver boom, speculators and developers recognized the canyon was the most direct link between the Western Slope and Denver. So the Denver and Rio Grande Railroad built a railroad through the canyon in 1887. A “primitive dirt road” followed in the early 1900s, according to the Public Roads article. That road was “upgraded to a two-lane paved highway, designated U.S. 6, in the 1930s.” In 1940, U.S. 6 was extended across Vail Pass and through the canyon.

The two-lane highway worked well for the next several decades, but its narrow shoulders and lack of auxiliary infrastructure meant any kind of recreation — walking, cycling, or accessing the river itself — was extremely difficult. “Motorists turned off the highway at the many informal pullouts to fish, picnic, or camp, leaving garbage, ash-filled fire rings, and other debris within just a few feet of the river,” according to the Public Roads article. 

Meanwhile, the interstate system was expanding through Denver and the Rockies. Planning for I-70 through the mountains began in 1960, and some early work began in the canyon. In 1965 two tunnels were driven through Horseshoe Bend, roughly 1 mi east of Glenwood Springs, just beyond the canyon’s western end, to prevent drivers from having to negotiate the sharp and hazardous curve.

The construction of the road through the canyon might have progressed faster but for the passage of the monumental 1969 National Environmental Policy Act. NEPA, according to a 2019 Historic Context report prepared for the Colorado Department of Transportation by the engineering and design firm Mead & Hunt, required a multidisciplinary approach to federal construction projects that drew on the “natural and social sciences and the environmental design arts” to deal with environmental impacts. NEPA also required public hearings. The result, wrote engineer John Haley in his history of the project, was that projects that might have gotten started within, say, one to three years could now take a decade or longer, with a commensurate rise in costs (Wooing a Harsh Mistress: Glenwood Canyon’s Highway Odyssey,Greeley, Colorado: Canyon Communications, 1994).

Prior to the 1960s, the Mead & Hunt report noted, the federal Bureau of Public Roads (a precursor to the FHWA) and state transportation departments “gave little consideration to the environmental and scenic impact of highway locations and designs.” Engineers developed their plans, calculated their costs, and expected to be met by a grateful public. Moving forward, transportation planning would no longer solely be the work of engineers and bureaucrats but ordinary citizens as well. As Haley archly noted, “Engineers became acquainted with environmentalists. Many were shocked by the experience.”

For years opinion was divided on whether to build through Glenwood Canyon at all — but among the many who supported the project, few argued against protecting the sublime landscapes. According to Haley, a 1971 film produced by the Glenwood Springs Chamber of Commerce (now the Glenwood Springs Chamber Resort Association) called I-70: Where and How? argued that standard cut-and-fill construction methods “could not adequately preserve and protect the rugged beauty of the canyon.” In the film, Haley wrote, “Various shots of unsightly cuts created by I-70 construction in the Glenwood Springs area seemed to prove this point.”

Instead the film argued for a technique used in Italy, where mountain roads were built on concrete spans well off the canyon floor to create an ecologically sustainable zone for vegetation, wildlife, and recreation seekers. 

The film was well received and the method garnered public support, but there were still questions. Alternate routes were proposed. For years stakeholders debated whether the canyon road should be two lanes and 48 ft wide (the preferred option of most environmentalists), four lanes and 56 ft wide (the initial recommendation), or four lanes and 68 ft wide (the option ultimately selected by the planners).

State officials had requested federal approval of the route through Glenwood Canyon after dismissing two alternate bypasses as too rugged or expensive. But the federal government was not ready to sign off. The FHWA instructed the state to consider alternate routes more thoroughly and to create a citizens’ advisory committee to help guide the planning of the highway.

One member of that committee, local businessman Mark A. Skrotzki, emerged as a longstanding critic of the road. “It is impossible to put such a highway through this canyon without permanently scarring the several million year old unique geologic formations and further disrupting the Colorado River headwaters,” he wrote in a petition to Richard Lamm, governor of Colorado from 1975 to 1987.

Skrotzki would eventually enlist celebrity John ­Denver and former Secretary of the Interior Stewart Udall in a fierce and long-lasting public bid to curtail the project. According to the Mead & Hunt report, Denver once staged a media event pressing for a two-lane roadway “where he threw a rock across the canyon waters to demonstrate its narrowness.” But it took him six throws to hit the other side. 

Most residents of the Western Slope concluded that the project was going to happen one way or another, and it was best to work with planners to ensure that the highway preserved the beauty of the canyon. 

The U.S. DOT granted final approval in 1979; construction began in 1980. To that point, the key figure on the project had been Colorado Department of Highways district engineer Richard A. “Dick” Prosence, P.E., who had helped survey the route in the 1960s and had been involved in the planning of the highway. CDOH project manager Ralph J. Trapani, P.E., M.ASCE, oversaw construction of the roadway. (The CDOH became the CDOT in 1991.) 

Even before construction began, engineers realized the I-70 project would require a host of new approaches. The very act of surveying would be difficult in the tight, twisty canyon. As Haley wrote, “the party chief could not see the rodmen unless he set up the survey instrument on the south side of the river to sight targets on the north side of the canyon wall.” Conventional survey equipment was too slow and inefficient, he continued, so engineers turned to a new technology: Hewlett Packard’s Total Stations. These “highly sophisticated, battery-powered electronic instruments with no reflective targets” used “light beams to measure horizontal and vertical angles” and displayed the results digitally.

Haley’s book recounted many other challenges, starting with the geology of the canyon itself. Planners assumed bedrock was much closer to the surface of the canyon floor than it turned out to be — in some places it was 125 ft below ground. “At the east end of the canyon, deep, 60-foot-thick layers of highly compressible clays were found under the proposed roadway,” Haley wrote. Unstable talus slopes “ruled out normal piling foundations. The number of boulders embedded in talus, and the damage that heavy pile-drivers could do to the environment, also foreclosed this option.”

In the Mead & Hunt report, Trapani likens the underlying layer of earth at the east end of Glenwood Canyon to a tube of toothpaste — material began to squeeze out as soon as weight was added. 

“Spread footings offered the only reasonable foundation alternative in most talus deposits,” Haley wrote, “but they required stabilizing and strengthening the loose, porous … unreliable material below the footings.” Workers tried to pump thousands of gallons of cement grout into one “void-­riddled talus (deposit),” but the grout just disappeared. 

The solution was an emerging technique offered by foundation specialist Hayward Baker called compaction grouting, by which, as Haley described it, workers bored holes “around the perimeter of the proposed footing. Then they pumped them full of a stiff (cement) grout at low pressure, which formed a cemented curtain wall. Inside this wall they drilled another series of holes on four-foot centers, into which they pumped a zero-slump (cement) grout at pressures so high the ground surface would heave, confirming that they had filled the voids within the perimeter wall.”

The interstate project, Haley wrote, was also one of the first projects to use posttensioned concrete pavement slabs — common in buildings and bridges — on a roadway.The slabs were to be placed on “variable foundations of compacted earth, rock, gravel, Styrofoam, tunnel muck, construction debris, and sometimes even bedrock,” he explained, and many of them would be cantilevered, with only one edge connected to retaining walls. “Normal concrete-paving designs with conventional reinforcement were just not adequate under these foundation conditions,” he wrote. “Posttensioned concrete slabs support the loads irrespective of the underlying foundation materials.” 

Before placing each 200 ft long section, crews laid the cables “in conduits crisscrossed at 45-degree angles, to be tensioned after the concrete had attained its required strength,” Haley wrote. “The cables were tensioned to specified loads, then grouted with epoxy resin. This placed the entire slab in uniform compression and distributed the loads evenly without cracks.” 

The unprecedented use of posttensioned tendons in the retaining walls and roadway slabs gave the composite structure an operational life expected to extend for decades — or even centuries, according to the FHWA at the time.

To put the slabs in place, engineers used a 105 ft tall, 350 ft long erection gantry brought over from France. The self-propelled gantry was able to “move from pier to pier, pivot(ing) around curving canyon walls and tall trees while assembling the segmental deck from the top of the piers,” wrote Haley.

At the same time the CDOH developed 26 fences with flexible posts to protect workers and drivers from rockfalls. “By grouting bundles of wire strands into steel casings, fence posts are created that are rigid enough to support the fence mesh,” Haley wrote, “but will flex as a system under repeated rockfall impacts and then rebound to their original position.”

The project employed two chief design teams. One was led by Gruen Associates (in partnership with Nelson, Haley, Patterson & Quirk, the engineering firm at which Haley was a partner). Gruen was tasked with surveying and creating the preliminary designs for the east end of the canyon; its project lead was the talented ­Italian-born architect-engineer Edgardo Contini. The second design team, which handled the canyon’s western half, was led by Daniel, Mann, Johnson & Mendenhall; DMJM’s project lead, Joseph Passonneau, P.E., was also an architect and engineer.

The unprecedented use of posttensioned tendons in the retaining walls and roadway slabs gave the composite structure an operational life expected to extend for decades — or even centuries, according to the FHWA at the time.

Both men were instrumental in marrying the roadway’s technical bravura with careful attention to aesthetics. The Mead & Hunt report noted that Contini devised the plan to use elevated roadways to protect vegetation (and presumably wildlife). Meanwhile, “Passonneau created the terraced alignment that enabled the highway to fit into the narrow canyon and the overhang design atop retaining walls that softened the appearance of the concrete wall with shadows and created the illusion of a shorter wall.”

Additionally, the report continued, designers used tall, single-column piers, mostly 10 ft wide, that “minimized visual effects to the natural landscape and enabled wildlife to cross underneath the highway. Piers were rusticated with deep grooves spaced in random patterns to reflect the patterns on rock joints within the canyon and had a warm tan or light brown color.”

The final centerpiece of the work was a 4,000 ft long pair of tunnels at the trailhead to Hanging Lake, which preserved the ambiance of one of the most scenic stretches of the canyon (another Contini idea). Each of the parallel tunnels was drilled from four faces — one face at each end and two faces from an open cut in the center. The open cut was then backfilled and landscaped, essentially causing it to vanish into the landscape. 

Workers drilled holes and packed them with dynamite in a staggered pattern along prominent joints to create “portals that appeared to be naturally occurring cuts in the rock,” according to the Mead & Hunt report. Additionally, the tunnel portals were designed with parabolic curves “that created distinct shadow lines to highlight and complement the jagged geologic formations within the canyon.”

Because the rock near the site at Cinnamon Creek was good — free from geological faults and groundwater, Haley wrote — the tunnels there could be designed with a lightweight system of “grouted rock dowels, limited applications of (shotcrete), and a thin, cast-in-place concrete liner. This first-of-its-kind design reduced heavy construction costs by 20 percent.”

Between the eastbound and westbound tunnels, is the traffic control center. The facility, which also houses a plant with equipment to ventilate the tunnels, was designed to monitor vehicles and respond to crashes with a fleet of emergency vehicles and tow trucks. Since the highway was upgraded to meet interstate standards, incidents have decreased by 40 percent, according to the Public Roads article.

According to CDOT, the finished project cost $490 million in 1992 dollars; adjusted for inflation, that would be $925.5 million today. It included the three tunnels, 15 mi of retaining walls, and 40 bridges and viaducts and required 30 million lb of structural steel, 30 million lb of reinforcing steel, and 400,000 cu yd of concrete. 

The planners and engineers never forgot their commitment to the natural environment along the way. Haley wrote, “Horticulturists created the state’s largest nursery just to provide the 150,000 trees, shrubs, bushes, flowers and other perennial plants needed in the canyon for post-­construction landscaping.” (Landscaping was overseen by De Leuw, Cather & Company.)

According to the FHWA, the Glenwood Canyon project won more than 30 awards. Among those were ASCE’s 1993 Outstanding Civil Engineering Achievement Award.

Haley boldly claimed that the Interstate Highway System was the “largest, most ambitious and most successful public works project of all time.” If that’s the case, then Glenwood Canyon proves its ultimate merit: a project that could meet the nation’s demands for economic and technological progress while protecting its rich natural landscape. 

This article first appeared in the March/April 2021 issue of Civil Engineering as “The Last Miles Were the Hardest: The Completion of Interstate 70.”

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Arup was responsible for the acoustical design of a major renovation to the Bijloke concert hall that was completed late last year. ABT Belgium, based in Antwerp, Belgium, was the structural engineer for the project, which was designed by London-based DRDH Architects.

The structure measures 55 m long by 15 m wide, which created a venue with less-than-ideal proportions for a concert space, says Crowe. The hall was “particularly long in comparison to its width,” he explains, especially because “the orchestra platform was right up against the upstage wall and the seating went right to the back at the other end — that was the geometric issue.”

Other concerns involved the side walls of the hall, which over the centuries had begun to lean outward because of the forces imposed by the roof, says Charlotte Franck, an engineer and architect at ABT. Although the walls of the hall were not in danger of collapsing, the outward lean did negatively affect the acoustics. “We want the audience to feel completely surrounded by the sound, immersed in the sound,” Crowe says. “And a good way to achieve that is to have strong reflections from the side walls” of the concert space. But when the sound from the orchestra hit the sloping side walls in the Bijloke hall, “instead of reflecting back to the audience, the sound just got sent upward, so the audience got no benefit from those side reflections,” explains Crowe. As a result, the sound seemed to come only from in front, rather than enveloping the audience, Crowe says.

Sound ideas

The natural reverberance of the site was also inadequate, Crowe says. Reverberance refers to the depth and resonance of the sound, which is controlled by the volume of the space and the amount of sound-absorbing material. In the Bijloke hall, the natural reverberance was “acoustically rather dry,” Crowe says, and the large surface area of the roof timbers was full of cracks and fissures that captured sound. Plus, there were various sound-absorbing finishes throughout the space, including the drapes, the carpeting, the chairs, and other materials. To enhance the reverberation, the music center’s staff had previously installed an electro-acoustic system of microphones and loudspeakers, but that system was getting old and in need of replacement, Crowe adds.

To address these various challenges, the architects and engineers made a number of changes to the site, some subtle, some much more dramatic. The most significant alteration involved lowering the floor of the hall by 1.2 m in order to increase the overall volume of the space, says Crowe. This was accomplished by removing the seats, balcony, and stage of the interior and demolishing the original floor and the plenum space beneath it. During this work, a series of concrete piles were installed to reinforce the existing brick foundation, says Franck. Because of the site’s historical significance, an archeologist supervised the excavation work, Franck adds, and a drainage system was installed to accommodate the site’s high water table.

‘Timber boat’

After a new concrete floor was placed, concrete columns were installed above the floor to support a series of brick walls, clad with wood, that now line the interior of the concert hall. Forming “a sort of timber boat” within the existing structure, the roughly 2.5 m tall walls provide the sound reflection for an immersive audial experience that the tilting masonry walls could not, Crowe says. Under the historical preservation rules that governed the project, the new walls could not be connected to the original masonry walls. But the masonry walls, which turned out to be hollow, could be locally filled in with concrete and mortar to help support the new steel structure that was installed within the hall’s timber roof, explains Franck.

The steel structure supports new lighting and other equipment as well as an array of sound-reflecting timber panels that help the various sections of the orchestra hear each other, says Crowe. A new steel system was necessary because the historical roof structure — which reaches its apex 22 m above the floor — could not support additional loads. The system features a series of steel bowstring trusses and more than 200 steel cables that are painted black and essentially follow the shape of the wooden elements in the roof, making the new steelwork practically invisible, Franck says.

A new concrete-framed stage, topped by a wooden floor, creates an improved acoustical mass. The new stage is also low enough that large musical equipment can more easily be brought on and off without the use of a lift, as had previously been required, Crowe says. The stage was also moved forward into the hall by about 5 m, which improves the concert experience for those in the farthest back seats and also creates space for new choir seating behind the stage. The choir seating involves wooden benches with removable cushions rather than individual chairs; when a choir is not present, the sound-absorbing cushions can also be removed so that the benches help reflect sound.

Elsewhere in the hall, the sound-absorbing drapes and carpeting were removed, and the new audience chairs were designed with wooden backs and armrests. The only soft material is on the seat itself for improved acoustical performance, Crowe notes. Overall, the number of seats in front of the stage was reduced from 975 in the original hall to 720, plus seating behind the stage for another 110 choir or additional audience members.

Acoustical analysis

The process of an acoustical renovation generally begins with a careful examination of the site that includes listening to a musical performance, taking detailed sound measurements, generating a digital acoustical model of the existing hall, and then tweaking and calibrating those efforts as the design develops, Crowe explains. This process is normally repeated after the work has been completed to ensure that the new acoustics are an improvement. But the travel and performance restrictions caused by the COVID-19 pandemic has made such follow-up work nearly impossible.

The Bijloke music center opened last year for rehearsals and a few performances with limited audiences, but more recently the site has offered only livestreamed concerts. Arup’s team held some online discussions with the client and the orchestra members, and the feedback was positive, Crowe says, but the team looks forward to someday revisiting the site in person to confirm the new acoustics.

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Designated as a National Historic Civil and Concrete Engineering Landmark by ASCE and the American Concrete Institute in 1977, the Ward House in Rye Brook, New York, is a landmark that many people have never heard about.

Here are five things you didn’t know about the Ward House:

1. The Ward House is the oldest extant, reinforced concrete structure in the United States. The entire structure was constructed using concrete and iron rods – only the doors, window frames, and paneling were built with wood.

2. It’s believed that owner William Ward’s mother suffered from pyrophobia (fear of fire), and he wanted to build her a house that was fireproof.

3. When it was erected from 1873 to 1876, neighbors called it “Ward’s Folly” because of their lack of confidence in the new building material, but today it’s locally known as “Ward’s Castle.”

4. Although the building currently serves as a private residence, it used to be a popular tourist attraction when it housed the Museum of Cartoon Art from 1977 to 1992.

5. The landmark lies within yards of a state border. The house is located in Rye Brook, New York, but most of its surrounding property is located in Greenwich, Connecticut.

Members of ASCE’s History and Heritage Committee have been learning fun and interesting facts about HCELs around the world to share in the new “5 thing you didn’t know about …” series. As the committee continues to build an inventory of all HCEL projects, members of the committee and other volunteers have been visiting sites to photograph landmarks and ASCE plaques as well as assess their conditions.

Learn more about the committee’s work and the ASCE landmark program.

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Robert Moses, who reigned for many decades as New York’s imperial planning czar in the 20th century, had long wanted a park in the middle of Queens; for years the center of the borough had served as a dumping ground for ash. In 1925, F. Scott Fitzgerald described the site of the future park in The Great Gatsby as a wastelandlike “valley of ashes” — emblematic of the divide the novel depicts between rich and poor.  

When Moses became parks commissioner in 1934, he hired Gilmore D. Clarke, one of the greatest landscape architects of the 20th century, and his partner, Michael Rapuano, to design the 1939 World’s Fair, the first step in transforming the ash heap into a magnificent green space. Clarke and Rapuano created a Beaux Arts site plan, inspired by St. Peter’s Square in Rome, featuring plazas and boulevards and fountains that radiated out from the fair’s signature element, a modernist spire-and-sphere duo called the Trylon and Perisphere. After the fair, these original fountains were removed, and grass was planted in their place. 


Moses hired the pair again to plan the 1964 World’s Fair, and Clarke recommended to his boss that they follow the general outline of the 1939 Fair as a matter of expediency. The Trylon and Perisphere was replaced by the Unisphere along with a series of new fountains radiating east of this monumental structure. Collectively dubbed the Fountain of the Fairs, these included a large 50 ft wide by 310 ft long stepped reflecting pool consisting of five sections connected by 9 in. tall weirs that acted as spill walls, two additional rectangular fountains, and a large fountain at the eastern edge of the park.    

The fair debuted such marvels as the first video phone and the original Ford Mustang but was not a financial success. “It did not generate the revenue that Moses hoped it would, but it was very popular,” says Janice Melnick, the administrator for Flushing Meadows Corona Park at NYC Parks.

The 1964 fair marked the beginning of the end for Moses’ decadeslong grip over the city, but he did get his wish: the 898-acre green space was formally designated Flushing Meadows Corona Park in 1967. Still, the fountains fell into disrepair as early as the 1970s. The pumps on the easternmost fountainswere rehabbed in the early 2000s, but the new pumps burned out a few years later and have not been replaced since. The fountains became a site for soccer rather than water.

A fog is rising


But after the Fountain of the Fairs had sat in disrepair for so long, NYC Parks recently completed the first phase of a $6.8 million renovation and adaptive reuse — transforming the reflecting pool into a new interactive fog garden.


“There are World’s Fair enthusiasts out there that absolutely loved the World’s Fair and remembered it so fondly,” says Melnick. “That was one of the reasons we wanted to renovate and adaptively reuse but keep the footprint.”

In meetings with the public, Melnick says, “It became very clear to us that while they understood it didn’t make sense to just restore the fountains, it was very important to keep the feeling of them and the footprint of them.”

But the still-working Unisphere fountain had become a problem: People were frolicking near its powerful and potentially dangerous fountain jets. “The Unisphere fountain was designed to be an ornamental fountain; it was not designed to be a spray shower or a fountain for children to play in,” Melnick says. NYC Parks placed barricades around them to discourage people from getting too close. 


The agency was “trying figure out a way to get people out of the fountain and give them an access to water so they could cool off in the summer,” says Maria Riley, a project manager with landscape architecture firm Quennell Rothschild & Partners.

In 2016 NYC Parks selected QRP to devise a master plan to breathe new life into the reflecting pools. The city had established new rules to limit the amount of water used in fountains, so designers considered options that would be more water efficient. 
 

“We came up with the idea that we originally labeled a mist garden,” says Riley. Gradually the concept evolved into a fog garden (fog is made up of smaller droplets than is mist). In the old fountain, water in the pool would flow over stepped weirs. Today, you can walk right down the middle of the pool. “It’s like being in the clouds,” says Riley. “You’re in fog, as (if) you’re walking on a really foggy day. Sometimes you can’t see from one end of the fountain to the other.”

The firm left the original outside coping but installed a new field of decorative pavers with an art deco pattern that reflects the previous location of the weirs. Then they fitted 504 fog nozzles. 
      

The fog is even programmable. According to Delta Fountains, which fabricated the nozzle assembly and housing, the fog garden uses less than 15 gallons per minute if all the nozzles are working — yet can cool off thousands of people per day.

Preventing settlement

The challenge for the project’s civil engineers, McLaren Engineering Group, was preventing settling of the new fountain with the installation of the new concrete slab, pavers, pipes, and concrete masonry unit walls. “We were adding extensive weight to the existing pool,” says McLaren President Jeremy Billig, P.E. “We didn’t know if the existing foundation for the pool could support it without differential settlement, so we had to be creative in how we designed the structure, so it would act as one big monolithic mass so it did not settle unevenly. It would do so globally to not cause issues.”

Flexible joints on the fountain’s waterlines could provide a bit of forgiveness if the fountain settled a few inches. Anymore, says McLaren associate Brendan Kelly, P.E., “and you’ll start to have pressure on those lines. You can’t have them crack or snap.” You could also have cracking at the surface, he added, which would create a tripping hazard.
  

McLaren designed the new floor framing and walls so they were integrated into the existing pool structure and would act as one “extremely rigid homogenous structure,” according to Billig.
          

The new fountain is supported by 40 transverse CMU block walls and two longitudinal walls that varied in height from 1 ft, 3 in. to 2 ft, 3 in., depending on their locations along the pool. The surface of the fountain consists of pavers over a 6 in. thick concrete slab. Everything below is filled in with gravel. In all, the new fountain includes 1.8 mi of water pipes up to 8 in. in diameter.      

 Another challenge was to make sure the water could drain at the lowest level of the fountain, according to Kelly. “We can’t have any water sitting down there,” he says.

Those CMU block walls have weep holes along the bottom to reduce the possibility of water collecting at the bottom of the pool. The original base of the fountain still slopes to the center, and at the center — running the length — is a perforated pipe to drain excess water. McLaren also added some extra grading to improve the slope a bit more. (The pool slopes lengthwise from the west to east as it steps down, with the east end approximately 3 ft, 7 in. lower than the west.)       

The reflecting pool opened for a brief photo op last fall before being closed for the winter. It is scheduled to reopen this spring. QRP has done very preliminary conceptual designs on the reflecting pool’s neighbor fountains to the east, but a full renovation still awaits funding.
           

For now, visitors to the park can look forward to a safe and fun way to keep cool in the summer. “The communities around it love this park, and it’s packed in the warmer months,” says Riley.

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Demolished masterpiece

The 486,000 sq ft space creates a new “grand entrance” for rail passengers arriving in New York, more than 50 years after the demolition of the original Penn Station, notes Brian A. Falconer, P.E., S.E., SECB, M.ASCE, a principal of Severud Associates Consulting Engineers P.C.

Severud has been the structural engineer for the Moynihan Train Hall project for more than 17 years. Skidmore, Owings & Merrill completed the architectural design of the new hall, while schlaich bergermann partner engineered a series of giant gridshell skylights that now top the space.

The original Penn Station was a “skylit, beaux-arts masterpiece” designed by the architecture firm McKim, Mead & White in 1910. The same firm designed the Farley Building across the street in 1913, which “echoed” some of the aesthetics of the original Penn Station, according to a Dec. 30, 2020, press release about the Moynihan Train Hall from SOM.

After the original Penn Station was demolished during the mid-1960s, only its underground platforms and concourses remained. The loss of Penn Station, however, served as “a major catalyst” in the creation of the landmarks and preservation movement to preserve historic buildings in New York City and across the country, says Falconer.

The Farley Building was designated a New York City landmark in 1966, though by the 1970s the facility had become 95 percent vacant when the post office moved most of its operations elsewhere.

Expansion plans

Plans to expand Penn Station into the Farley Building started in the early 1990s, championed by Daniel Patrick Moynihan, New York’s longtime U.S. Senator who died in 2003. By 2004, Severud’s engineers started working to make themselves familiar with the Farley Building’s existing structure, reviewing old documents and drawings, performing thousands of hours of visual surveys, and studying the results of extensive material testing.

Eventually, a three-phase redevelopment project was launched. The first phase opened in June 2017 and involved the construction of a new underground concourse, called the West End Concourse, to link what remained of Penn Station to the planned Moynihan Train Hall. The second phase included the hall itself, which was designated for the Farley Building’s long-dormant mail sorting room. A third phase, which will likely be completed in late 2021, will redevelop the remaining portions of the Farley Building. New York Gov. Andrew Cuomo also recently proposed a plan to connect the city’s High Line elevated park to a site adjacent to the train hall.

Measuring 150 ft wide by 200 ft long, the mail sorting room’s size and central location “made it a natural candidate for repurposing as a new train hall,” says Falconer.

The existing floor of the mail sorting room was located one level higher than the planned concourse level, so the existing framing was removed to increase the height of the train hall by 20 ft, taking it to a lofty 92 ft, Falconer says. This also reduced the gravity loads on the existing framing of the concourse level, which acts as a transfer system to span over the train tracks below.

This reduction of load allowed half of the hall’s transfer girders to be cut and reframed to create openings for escalators to extend down to the belowground platforms without the need to install significant girder, column, or footing reinforcement within the train shed. Twelve new escalators now extend from the train hall floor to seven platforms providing access to 14 tracks, Falconer notes.

Trio of trusses

The design of the train hall’s new roof went through multiple iterations. Ultimately, the design team decided to reuse three original 150 ft long steel trusses that featured latticed members reminiscent of the original Penn Station, Falconer says.

Although these trusses had sufficient capacity to carry a new roof, the design called for the installation of four pillowy skylights, each 50 ft by 150 ft, on top of the trusses. As a result, all framing between the trusses had to be removed, making the gabled top chords unbraced for their full span. To rectify this, the design added a 36 in. wide by 24 in. deep steel box beam along the top chord of each truss to restore lateral support and provide seats for the skylights, Falconer explains.

The gridshell design of the skylights features larger panels toward the center of the shells to enable more light to enter the space below. The depths of the steel members decrease toward the middle “to efficiently carry the loads and increase the sense of lightness as you progress into the space,” according to a schlaich bergermann partner website on the project. Diagonal cables within the plane of the roof surface brace the steel gridshell structure, explains schlaich bergermann partner, while the barrels of the shells are braced by a series of diagonal spider cables.

A skylight was also installed above a passageway between two ceiling murals at the Farley Building’s entrances from 31st and 33rd streets.

The redevelopment of the Farley Building created a 21st-century transportation hub that features the expansive new train hall, more than 1 million sq ft of commercial space, state-of-the-art wayfinding, and other amenities designed to improve each visitor’s experience, Falconer concludes.

Project credits:

Client: Empire State Development in a public-private partnership with Vornado Realty Trust, The Related Companies, Skanska, the Metropolitan Transit Authority, Amtrak, and the Port Authority of New York and New Jersey 

Architect: Skidmore, Owings & Merrill

Structural engineering: Severud Associates Consulting Engineers P.C.

Skylight structural engineering: schlaich bergermann partner

Civil/geotechnical engineering: Langan Engineering & Environmental Services Inc. 

Historic building restoration: Building Conservation Associates Inc.

Rail engineering: Systra Consulting Inc.

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But after years of inaction, the federal government will finally put its best foot forward — retiring the longstanding U.S. survey foot in favor of the international foot. “It’s like an anti-standard,” says Michael Dennis, Ph.D., PE, M.ASCE, a geodesist with the National Geodetic Survey. Dennis has been spearheading the drive to retire the old standard — and making the case to skeptical surveyors. “We have these two things out there and these two versions of the foot, which creates nothing but problems. The difference is small, which is why it’s so insidious.”

Indeed, the international foot is shorter than the U.S. survey foot by a vanishing 2 parts per million (or 0.01 ft every mile) — it would be like extending the east-west length of the United States by just 30 ft.

But the difference matters. As the National Oceanic and Atmospheric Administration puts it on its webpage explaining why the U.S. survey foot needs to be retired, “accidentally confusing the two types of feet can severely impact the precise coordinates and measurements used in engineering, surveying, mapping, agriculture, and other industries that depend on accurate positions.”

The change is a collaborative effort between the National Institute of Standards and Technology and the NGS, which is part of NOAA. The change will take place at the beginning of 2023, when the National Spatial Reference System is modernized, although Dennis notes the full transition may end up taking a few years longer.

The questions, of course, are: How did two standards develop and why did they persist? In a public webinar he created on the history of the two standards, Dennis explains that the need for standardized measurement dates back to the Constitution itself, which authorizes Congress to “fix the Standard of Weights and Measures” for the new country. George Washington and Thomas Jefferson were surveyors — Jefferson proposed a decimal system in 1790. Starting in 1815, the U.S. used an object called the Troughton bar, which was an exact copy of the British Imperial Yard. (The physical Imperial Yard was damaged beyond repair when Parliament burned in 1834; the replacement bar — Bronze Yard No. 11 — was 0.022 mm shorter than the Troughton bar.)

Meanwhile, the metric system, Dennis explains, had been developed in France and was gaining support. In 1866, Congress legalized use of the metric system for commerce in the U.S., and in 1893, Thomas Mendenhall, superintendent of the U.S. Coast and Geodetic Survey (the forerunner to the NGS), issued the Mendenhall Order, which based the length of the foot off the meter, where 1 ft equaled 1,200/3,937 m. So, as it turns out, the U.S. really is a metric country; it just doesn’t know it.

A more exacting definition of the foot was adopted in 1933 by the predecessor of the American National Standards Institute, the American Standards Association, to aid industry: 1 ft now equaled 0.3048 m exactly, according to Dennis. Eventually, the predecessor of NASA, the National Advisory Committee for Aeronautics, adopted this new foot standard in 1952, and in 1959, the U.S. government decided that the new foot, now called the international foot, would be, well, the foot. A giant step forward, right? Except for this: According to NIST, the 1959 redefinition of the foot still allowed geodetic surveyors to continue using the older foot standard, renamed the U.S. survey foot. The ruling mandated that the international foot replace the U.S. survey foot “upon readjustment of the geodetic control networks of the United States,” according to NIST’s website about the dueling feet.

The geodetic readjustment was completed in 1986, but reluctance among surveyors to convert to a new standard led to the federal government dragging its feet for several more decades. “The logic at the time was, ‘Well, it’s no big deal,’” says Dennis. “As long as you keep track of which version of the foot, you have no problem. Well, people don’t do that. So it turned into a big problem.”

Most states use the survey foot, though six states use the international foot, and a handful of states do not officially define a system of measurement. Further, in some states you might see one standard used by surveyors and another standard used on military bases or airports. As NIST explains on its dedicated website, the ambiguity of the two systems can result in “professional liability by the inadvertent violation of state law, the introduction of systematic errors in surveying and engineering projects, misreported position and location, land sale and project delays, boundary disputes, (and) additional costs associated with correcting unit mistakes” — to say nothing of the “inefficiency of managing two types of feet.”

Dennis notes that the difference in the two standards once resulted in a building in Arizona near an airport being accidentally positioned slightly within the Federal Aviation Administration’s glide path — the building had to be built with one less floor to resolve the issue.

Judging by the response from webinar presentations that Dennis has given to stakeholders, professional surveyors have bought into the changes and the deprecation will include a template for states to update their statutes to help them move off the survey foot, he says.

“We all know these kinds of processes take time,” says Elizabeth J. Benham, metric coordinator with NIST. “This is a very ingrained process in the survey industry. We wanted to do that to give people a full two years to work on it.”

After that? Maybe the country will be ready to abandon its feet for good. “I liked to see that there are a lot of people (who) were like, ‘Why don’t you just go metric?’” says Benham. “Why are we just eliminating this? Why don’t we eliminate both feet?”

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Not surprisingly, mosquito-borne yellow fever struck the city often; in the summer and autumn of 1793, it killed about 5,000 Philadelphians, or roughly 10 percent of the population. “Close to half the citizenry, including President George Washington (Philadelphia was then the national capital), literally ran for their lives, fleeing the death-haunted metropolis for the surrounding countryside,” wrote historian Carl Smith (City Water, City Life: Water and the Infrastructure of Ideas in Urbanizing Philadelphia, Boston, and Chicago. Chicago and London: The University of Chicago Press, 2013.)

The disease returned over four of the next five summers, Smith wrote, killing roughly as many people in 1798 as in 1793. The ongoing epidemic led city leaders to seriously plan for a coordinated water system, one that proved to be, as Smith put it, “the first truly comprehensive waterworks system in a major American city.”

There had been other water systems in America before Philadelphia’s — Bethlehem, about 70 mi north of Philadelphia, had installed a rudimentary water supply system some 50 years prior. But Philadelphia’s was the first at a large (for that time), municipal scale. And Philadelphians themselves had strong opinions about the need for such a system. According to Smith, favorite son Benjamin Franklin, before he died in 1790, “recommended that Philadelphia construct a gravity-driven aqueduct from the Wissahickon Creek, which flowed into the Schuylkill River a few miles northwest of the city.”

But it took the yellow fever outbreaks for the city to create the Joint Committee on Bringing Water to the City, which issued a report in 1798 calling for a new water supply to mitigate the risk of illness. To oversee the system, the city turned to English-born American architect-engineer Benjamin Henry Latrobe, who was in Philadelphia building the Bank of Pennsylvania, the earliest work of neoclassical architecture in the United States.

According to Smith, Latrobe knew the city’s water was poor; he remarked in his journal in 1798 that water in the city was “not to be drank (sic), and it is worst in the most crouded (sic) neighbourhoods,” where it tasted “as if it contained putrid matter.” His solution? Not Wissahickon Creek, as Franklin had suggested, but the Schuylkill River itself.

Today the Schuylkill forms the western boundary of what is known as Center City, the central business district of Philadelphia, but 200 years ago that river was part of a remote wilderness; the city’s development focused more on the larger Delaware River on the city’s eastern side. According to a 1978 Historic American Engineering Record report on the Fairmount Waterworks written by Jane Mork Gibson, a historian of Philadelphia industry and technology, Latrobe reported that the Schuylkill was the best source of water in the area, but that water was useless unless it could be “raised to an elevated level. To do this, in sufficient quantity, very powerful machinery will be required; and I am very certain that human ingenuity has not hitherto invented anything capable of producing the proposed effect with constancy, certainty, and adequate force, excepting the steam engine.”

Latrobe’s innovative plan actually called for two steam engines, located in two separate pumping stations. Steam engines had never been used before to power a water system; up to this point they had mainly been used in the mining industry in England. The first of the two engines Latrobe proposed, on the east bank of the Schuylkill at Chestnut Street, would raise water from the river, according to Smith. This water would travel through an underground pipe to Centre Square, at what is now the corner of Broad and Market streets — the site of the city’s current city hall and the geographic center of town. “The second engine,” Smith wrote, “located in the square, would lift the water to storage tanks forty feet above the ground, and then gravity would drive it through bored-out pine logs to every part of the city.” 

The city raised money for the project by selling shares of the water itself, an early form of user fees. But public hydrants that people could use for free were also installed. Wooden pipes made from the trunks of white oak, yellow pine, and spruce trees were used to convey the water. Levine noted that “each log was bored through its center with an auger either 3, 4.5, or 6 inches in diameter. The bored logs were joined into pipelines with iron couplings and straps.”

The new system was, in the words of environmental engineer C. Drew Brown, the manager of public education for the Philadelphia Water Department, transformative. “One of the things we were successful in was taking forward the basic outline of a water system,” he says. “That is, pumping from a water supply to an elevated storage facility, then supplying by gravity from the elevated storage to the service area.”

Latrobe bequeathed to the city not only the technical achievement of the system but an architectural marvel. The Centre Square pumping station, three stories high and clad in white marble, was admired for its neoclassical beauty. The building concealed both the steam engine and two storage tanks above it. “It featured Doric columns and a domed roof with an opening at the top, recalling the oculus of the Pantheon in Rome, whose purpose was to allow smoke from the engine to escape,” wrote Smith. (Philadelphians nicknamed the building “the Pepper Pot.”)

In 1802, the committee stated that the system was delivering about 400,000 gal. per day. Yellow fever outbreaks diminished, and the system was useful in putting out fires. But despite this — and despite the beauty of its design — the flaws of the pumping station became apparent very quickly. 

The steam engines were unreliable and in need of constant repair. “Since the engines were arranged in series, if either one stopped, whether for planned maintenance or by accident, Philadelphians faced the inconvenience of having no running water, not to mention the peril of being without protection against fire,” Smith wrote. And the engines were not safe: “In April 1801 two men who entered the large boiler in Centre Square in order to repair it were suffocated to death, and it had to be torn apart to retrieve their bodies.”

And while the system could deliver a lot of water, the two pumping stations only stored about 17,000 gal. Even with a small number of customers (around 64 homes, according to Brown), that amount of water could be used up in 20 minutes. “They didn’t have the data to know how much water Philadelphians would use,” says Brown. Additionally, Philadelphians also used the water to wash the streets and sometimes left the hydrants running, which further depleted capacity.

By the fall of 1811, the city had invested more than $500,000 in its water system, and it was money down the drain. “The annual income of the works was $12,163, while the expenditures were $29,702,” Smith wrote. “All of the 28-plus miles of wooden pipe that had been laid would have to be replaced, and there were only 2,127 paying customers in this city of well over 50,000 people.”

Years before the city was ready to fund a newer, better system, Latrobe had already moved on (he later worked on the design of the U.S. Capitol). John Davis had taken over as head of the city’s water system; when he left in 1805, Frederick Graff stepped in. Latrobe had hired Graff as a draftsman in the 1790s; he later served as an assistant engineer on the Centre Square project. Many of the lasting elements of the city’s municipal water system came under Graff’s leadership, and he remained chief engineer of the water system until his death in 1847.

Graff turned to a site just a mile from Centre Square — a significant hill with a flat top, Faire Mount (later condensed to Fairmount, its current name). Towering 100 ft over the Schuylkill, the site had space for a reservoir of at least 1 million gal., says Brown.

As before, Graff’s plan called for two steam engines — but this time they were designed to run independently of each other. Additionally, the engines featured different designs. One used a Boulton and Watt steam engine, the same kind as the earlier waterworks. But the second, designed by inventor Oliver Evans, was unique. It was, according to Gibson, the “largest non-condensing high-pressure Columbian steam engine built up to that time” and produced about 100 hp. It also represented, Brown says, a “tremendous leap in technology.” While the Boulton and Watt engine operated at 2 psi in its main cylinder, Evans’ engine operated at 200 psi.

But the steam engines again proved to be problematic, and Graff and city leaders knew it was time to move on from what Gibson described as a “noble experiment.” For one, they remained dangerous: two explosions at Fairmount, in 1818 and 1821, killed several people, according to Levine. And cost and efficiency remained overriding issues. The steam engines used wood-fired boilers, and as trees around the growing city became scarcer, the cost of firewood grew. Brown says the practice of burning coal in a boiler came into use around this time, but by then plans for a water-powered system were well underway. By 1822, the steam engines had been replaced by three waterwheels. 

According to Levine’s history, the massive waterworks at Fairmount featured “an earth-filled masonry wall (that) doubled as the wall of the lock at the entry to the canal on the western side of the river,” a 1,200 ft long spillway built across the river to mitigate floods, and the “hollow masonry structure of the millhouse itself, 238 feet long, which housed the waterwheels.” Behind this was a 419 ft long millrace, which brought water to the millhouse and the three waterwheels. The Fairmount Waterworks greatly increased the city’s water capacity; its reservoir contained more than 3 million gal. in 1815 and added another 0.5 million gal. capacity a few years later.

According to an 1824 report Smith cited, the 16 ft diameter waterwheels proved far more efficient than the steam engines: “While previously it had cost $206 to raise 3,375,000 gal. of water a day, this could now be done for $4, a saving of over 98 percent. By adding more waterwheels, the capacity could be increased to 10 million gal. per day, and daily operating costs would be only $10, which was more than $500 less than it would cost to pump the equivalent volume with steam engines.”

Meanwhile, the initial wooden pipe system had grown to more than 32 mi by 1817, and “leakage had been somewhat lessened from the earlier experience by using short ­sections of iron pipe called ‘connectors’ to join the logs,” wrote Gibson, “but it was soon evident that it was not possible to utilize the new system to its fullest unless better distribution could be made.”

Additionally, frequent right angles in the pipes produced friction, which reduced water pressure as water traveled farther through the system. In 1818, the committee authorized the use of larger iron pipes to replace the old wooden mains. “Over the next three decades new cast iron pipes were laid and old wooden ones replaced until, by 1858, the last wooden pipes were taken out of service,” Levine wrote. “The cast iron pipes had less friction, leaked less readily, and lasted far longer than the wooden pipes, in many cases a hundred years or more.” Indeed, cast-iron pipelines from 1824 were still in use in 1947 when the city became an early member of the Ductile Iron Pipe Research Association’s Cast Iron Pipe Century Club. (The Centre Square Water Works was demolished in 1829, and the Schuylkill Water Works was demolished in 1838.)

Like Latrobe’s original plans, Fairmount was more than a utilitarian piece of hydraulic engineering. According to Smith, “The project also included the building of the first few of what would be a group of elegant structures along the river, to enclose the machinery, afford workspace for the system’s managers and employees, and provide shaded viewpoints for visitors.” These structures were built in the neoclassical style and became significant tourist attractions in their own right. 

When the steam engines were finally removed from Fairmount, the engine house that enclosed them fell into disrepair but was refurbished in 1833 and turned into a restaurant. Graff, in what Brown describes as his “first foray into architecture,” had designed and built the engine house in a “Georgian or Federal style whose exterior resembled the nearby summer mansions of wealthy Philadelphians, mansions that were arrayed along the high ground above the east bank of the Schuylkill River, upstream of Fairmount Water Works.”

According to Brown, many of the neoclassical elements that have made the Fairmount Waterworks a tourist attraction to this day were added in stages. The Waterworks’ final ornamental structure, a 20 ft tall pavilion with a pediment, wasn’t added until 1872. 

Fairmount remained in service for years, growing with the city. The reservoir impounded 10 million gal. by the 1840s, and by 1843, Fairmount’s millhouse used eight waterwheels. According to Gibson, the building, open to the public, featured a gallery that ran the length of the building, allowing visitors to view all the wheels at once. The Fairmount Waterworks operated continuously from 1815 to 1909, and since then it has served as an aquarium, children’s theater, and, currently, an environmental education center. The Philadelphia Municipal Water Supply was dedicated by ASCE as a Historic Civil Engineering Landmark in 1975.

For Brown, the legacy of Latrobe and Graff was in their innovative melding of architecture and engineering. “These engineers went out of their way to learn some architecture and then apply that to these structures,” says Brown. “We don’t do that today.” 

This article first appeared in the January/February 2021 issue of Civil Engineering as “First of Its Kind: The Philadelphia Municipal Water Supply.”

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The historic Fenix warehouse, located on the city’s Katendrecht peninsula along the river Maas, is becoming the museum’s home. Built in 1923, the warehouse was once the largest in the world. It was damaged during World War II and underwent a series of repairs in the following decades.

The Fenix warehouse was chosen as the site for the museum to highlight the millions of Europeans who migrated from the banks of the Maas, many of whom were traveling to Ellis Island in New York Harbor, according to the museum’s website.

The Chinese architectural agency MAD Architects is designing the new project’s stairway and observation deck. The work was commissioned by the Rotterdam-based Droom en Daad Foundation, which is dedicated to funding art and cultural projects within the city. MAD was chosen to honor the peninsula’s forgotten history as one of the oldest Chinatowns in Europe, according to the museum.

The warehouse’s iconic green steel windows will be renovated and retained, but its existing facade and roof are being removed and replaced with glass curtain walls and ceilings. The museum’s extensive glazing will create multiple ways to view its stairway centerpiece, dubbed the Tornado.

“From a distance, the platform and staircase look like a single entity, but when it’s in front of you, it stands as a sculptural work that invites you to explore,” says Ma Yansong, the founder of MAD. “It both signifies the Fenix’s witnessing of Europe’s history of migration from the port and symbolizes the future of the city.” The steel and wood that will be used for the staircase are intended to evoke the experience of boarding a ship via a gangplank.

Two structural systems were investigated for the Tornado, according to the architects, who sent written responses to questions posed by Civil Engineering. The structural systems considered included a steel space frame with rigid connections that would be covered with cladding or the use of a monocoque, or unibody, system with a structural skin. The space frame option “was chosen because of the high demand and complexity of the surface: the space frame system allows the handrails to work as trusses, and below the deck that (system) provides torsional stiffness,” the architects say. “Then a stainless steel cladding wraps around the space frame, creating the continuity of the staircase.”

The stairways will be structurally independent of the existing warehouse building. The design team considered coupling the stairways with the existing warehouse but decided against it. “Strengthening the building to be able to transfer the wind forces (from the observation deck and stairways) would have (had) a very large impact, which was not in line with the idea of conservation and respect of the existing building,” the architects explained.

“The main design challenge was to keep the slender and weightless appearance of the Tornado, ensuring the necessary space and dimensions for the structural frame and giving the idea of a floating, intertwined element without any evident intermediate support,” the architects say. The design calls for the stairs’ new structural steel frame to be placed beside and in the same grid alignment as the existing concrete columns in what will become the museum’s central lobby. In addition, a new elevator core is being built within the center of the Tornado. This core will also offer some support and anchor points as the stairways wrap around it, according to the architects.

At the point where the stairways transition from interior to exterior, the design team created a curved glass roof transition that resembles a wave, according to the architects. The glass wave will also act as the ceiling for a portion of the lobby, “creating a visual connection to the outside and blurring the boundary between interior and exterior,” the architects say. The steel frame will support this glass roof with relatively small supports and arches that have been integrated into the design such that they are barely visible, according to the architects.

The museum is expected to be complete in 2024.

Project Credits:

Client: Droom en Daad Foundation Executive architect: EGM Stairway architect: MAD Architects Monumental architecture renovation: Bureau Polderman Construction adviser: IMd Raadgevende Ingenieurs Steel constructor: CSM Steelstructures Cladding constructor: Central Industry Group Lighting consultant: Beersnielsen lichtontwerpers Installation design: Bosman Bedrijven Installation adviser: DWA Building physics adviser: LBP Sight

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The restaurant industry is one of the more visible economic sectors being devastated by the pandemic. Many well-known establishments — often locally owned institutions — are closing their doors for good as a combination of dine-in restrictions and tightened budgets have people eating out less, cooking at home more, and leaning on grocery stores more than ever.

Ironic, then, that this rapid-fire attrition follows a much slower, but still damaging, winnowing of local grocery store options for many Americans over a period of decades, resulting in the much-discussed “food deserts” and compounding many other problems for the poor (while options and variety exploded for others). The Problem with Feeding Cities, by University of Connecticut sociology professor Andrew Deener, takes a long, hard look at the powerful and varied forces that brought about this dichotomy.

The city of Philadelphia, where Deener began his research a decade ago and first realized the much larger national and global forces at work, is the author’s touchstone for illustration purposes as he explores the history over the last century-plus. He traces the most obvious “food-centric” development — the stepwise shift from corner store to local chains to the rise of the supermarket — as well as the effects of the shift from rail to truck transport, the decentralization that accompanied the rise of suburbs, and later, food’s importance as a key component of the gentrification movement that fueled urban redevelopment and exacerbated urban inequality. He also touches on many other, less obvious drivers like the dramatic technological impact of bar codes.

Changes in food infrastructure are, of course, shaped by capitalism and the pursuit of greater efficiency and profit margins. But Deener makes a key point: The specific way the system evolved was neither inevitable nor nefarious.

Deeply researched and scholarly, The Problem with Feeding Cities isn’t likely to be seen as an accessible, popular science bestseller. But it is a major addition to the literature on food infrastructure history and analysis.

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In April 1957, the U.S. Army activated the first nuclear power reactor in the United States that provided electricity to the commercial power grid for an extended period. Based at Fort Belvoir in Fairfax County, Virginia, just outside Washington, D.C., the SM-1 reactor was a prototype of a small nuclear power plant primarily intended as a training facility for reactor operations personnel from the Army, Navy, and Air Force. But its roughly 10 MWt capacity was connected to the local power grid in Northern Virginia and preceded the nation’s first strictly commercial nuclear power plant, which was constructed in Shippingport, Pennsylvania, in 1958. 

The SM-1 was part of the Army Nuclear Power Program, a joint effort between the U.S. Army Corps of Engineers and the Atomic Energy Commission to develop “small, rugged, and transportable nuclear plants that could provide both heat and electricity at remote military installations,” according to the Corps’ online history of the program. Following its success with the SM-1, the Army Nuclear Power Program designed, built, and operated another seven reactors in the United States and at sites around the world. These included the 20.2 MWt SM-1A at Fort Greely, Alaska, in 1962, and the 45 MWt MH-1A in 1967, which was constructed inside the Sturgis, a former World War II Liberty-class cargo ship that was converted into a floating nuclear power barge to help fulfill the program’s goal of producing mobile reactors.

In the 1970s, when they ceased to be necessary, three of these reactors — Fort Belvoir’s SM-1, Fort Greely’s SM-1A, and the Sturgis’  MH-1A — were deactivated and all their uranium nuclear fuel and control rods were removed as the first step toward decommissioning and dismantling the facilities, says Brenda M. Barber, P.E., a program manager with the Environmental and Munitions Design Center in the Corps’ Baltimore District. At that point, control of the three reactors switched to the Army Deactivated Nuclear Power Plant Program.

The process of decommissioning and dismantling a nuclear reactor is not simple — and it certainly is not quick. After the removal of the fuel and control rods, as well as any liquid waste at the sites, each of the three deactivated reactors was then essentially mothballed — put into what the Corps refers to as SAFSTOR, for safe storage, Barber says. That SAFSTOR period lasted roughly 40 years so that the radioactivity of the various remaining reactor components could decay, eventually enabling the decommissioning crews to “safely perform the work without (exposure to) any significant doses of radiation,” she explains.

The Army’s reactor program is self-regulated, Barber adds, but follows the guidelines of the Nuclear Regulatory Commission, which set a 60-year time frame for how long it can take between when a reactor is taken offline and the date by which it must be dismantled and its site made safe for reuse or other activities. The Sturgis reactor was the first to be completely dismantled, beginning in 2015 and ending last year when the ship itself was broken up for scrap. Fort Belvoir’s reactor is scheduled for dismantling next, the work expected to begin early in 2021 and take roughly five years to complete. Work on Fort Greely’s reactor could begin in 2022 but might take as long as eight years to complete due to the remoteness of the site — about 100 mi southeast of Fairbanks, Alaska — the potential for harsh weather conditions, and various other complications, Barber says. The difficulty of accessing Fort Greely was one reason the site was chosen for a reactor in the first place, Barber notes, because it was sometimes problematic to keep the base supplied with regular shipments of conventional fuels. 

At all three sites, the remaining low-level radioactivity comes from the metals used in what remains of the reactor systems. The two major radioactive elements of concern are Nickel-63 and Cobalt-60. Cobalt-60 is a gamma-emitting isotope with a decay half-life of about five years while Nickel-63 is a low-­emitting beta isotope with a decay half-life of 100 years, making it a long-term concern for disposal, Barber notes. More than 99 percent of the Cobalt-60’s radioactivity had decayed during the time in SAFSTOR, which makes the decommissioning safer for the teams from an occupational and radiological safety perspective, Barber explains.

The Corps had dismantled at least two small research reactors before the start of the current program, Barber says, and it has relied on the expertise of private contractors from the commercial nuclear reactor sector as well as other branches of the military and other government agencies with similar experience. Most importantly, perhaps, “we learned a lot of very hard but good lessons” during the Sturgis dismantling that will help improve the processes at Fort Belvoir and Fort Greely, she explains.

Before becoming a nuclear power plant barge, the Sturgis had been a 14,000-ton World War II cargo ship named the S.S. Charles H. Cugle. Measuring more than 441 ft long, the ship was converted to a floating nuclear barge by the removal of a 212 ft long section in the middle of the vessel, a section that included its engine and propulsion systems; as the Sturgis, it had to be towed wherever it was taken, hence its designation as a barge. A new, wider midsection was then installed and structurally joined with the watertight bulkheads of the original ship’s bow and stern sections. The nuclear reactor was located in the center of the vessel to protect it from “potentially catastrophic impacts, such as might occur with a severe grounding of the vessel or a broadside collision with another large vessel, and consequential sinking of the vessel,” according to a July 2019 historical mitigation report, Deactivated MH-1A Nuclear Power Reactor and Barge STURGIS. The report was prepared by Horizon Environmental Services Inc. and Gray & Pape Inc. to document the project for the Corps and the prime contractor, APTIM Federal Services LLC. 

Additional protection for the reactor included a lead-lined sphere that housed the reactor components surrounded by steel-reinforced concrete walls. The concrete walls made the new midsection 8 ft wider than the original beam of the vessel, requiring the fore and aft sections to be tapered to accommodate the new width, according to the mitigation report. A new inner hull section was also created and filled with compartments for saltwater, freshwater, and other liquid ballast to provide 7 ft of separation between the reactor deck and the hull.

The Sturgis spent most of its useful life in the Panama Canal Zone, providing power for military and civilian purposes. After being towed to Fort Belvoir — on Gunston Cove, off the Potomac River — for the initial removal of the nuclear fuel, control rods, and radioactive wastes, the Sturgis was towed to the James River Reserve Fleet at Joint Base Langley-Eustis, near Newport News, Virginia, for long-term storage and monitoring. By April 2015, quarterly monitoring by the Corps indicated that the radiation levels within the Sturgis had decayed sufficiently to begin dismantling. At this point, APTIM (then known as Chicago Bridge and Iron, or CB&I Capital Services) conducted a laser scan to collect point-cloud data that was used to create 3D images and models of the inside of the reactor access compartment and the reactor containment vessel areas, which is where the components of the former reactor were located.

“The modeling allowed us to simulate a task without needing to have personnel go into the radiological areas until we had confidence in our approach and we had verified potential doses,” says Barber. “While we had reports and other information to help us paint a picture of the inside, we did not have access, and this imagery was invaluable in planning for the decommissioning and dismantling by giving us firsthand knowledge of the size, location, and dimensions of components we would be handling. This was accomplished without needing to breach the containment structure or have personnel spend extended time within the containment structure, which was home to the vast majority of the Sturgis’ radioactivity.”

The Sturgis was then towed on a roughly three-week journey to the Malin International shipyard at the Port of Galveston in Texas, where the dismantling work would take place. To prepare the site, Malin hired additional employees, including security guards, and APTIM installed security fencing and electrical services for the barge, among other work. “Out of an abundance of caution,” Barber adds, “we reinforced the dock in Galveston” to accommodate the heaviest materials that would be removed from the Sturgis. The barge’s onboard cranes were refurbished, new boarding ramps were acquired to access the barge from the dock, and a ventilation system was established including high-efficiency particulate air filtration to ensure that “all radiological work” would be performed “under negative pressure during decommissioning efforts,” according to a Corps website that was used to provide updated information to the Galveston community and other stakeholders throughout the Sturgis decommissioning process. Due to the extreme heat in the Galveston area, an air-conditioning system was also installed for the primary work areas on the Sturgis.

Along with the potential for radiation exposure, the work crews faced exposure to lead (including lead-based paint), asbestos, polychlorinated biphenyls, and other hazardous materials used in the wall, floor, and ceiling tiles and various other systems and components found throughout the Sturgis. It was these more traditional environmental concerns, not radiological safety issues, that required workers to wear protective clothing and respirators, Barber adds. The project team also trained with local emergency responders, including the police department, fire department, and other agencies, and maintained regular communications with these groups to ensure the safety of the work site and the community.

One of the first things the work crews did was design and engineer new openings in the deck of the Sturgis to provide access to the reactor and its components. These large penetrations had to be closable and weather tight to accommodate the potential for severe weather in the Galveston area, Barber notes. Moreover, the project team developed a hurricane plan that included securing the vessel itself and all openings; tightening the mooring lines, which were designed to withstand Category 5 storm winds; and removing any loose equipment, including the access ramps. The plan also involved close coordination with the Port of Galveston and the U.S. Coast Guard. Such preparations proved their worth in late August 2017 — while the deconstruction work was well underway — when Hurricane Harvey approached the Texas coast, shutting down the Sturgis project until early September. But everything worked out well. “The site remained secure and did not suffer damage during the storm,” Barber notes, with “no evidence of releases of radioactive material (or) lead or increased radiation exposure.”

The new openings in the deck provided access to the upper refueling room from which the work crews began to dismantle and remove items and material that were then packaged in polypropylene bulk bags — commonly called supersacks — to meet U.S. Department of Transportation protocols for shipping contaminated material. The supersacks were lifted by cranes out of the Sturgis and loaded into special containers to be trucked to the designated waste disposal site operated by Waste Control Specialists in Andrews, Texas. 

Various components — including a steam generator, coolant pumps, ductwork, valves, and piping — were removed first to provide access to the larger pieces of the reactor. Certain components were cut apart with diamond saws or other robust cutting tools. For example, there was a lead canopy atop the reactor containment vessel that had served as a safety barrier to protect personnel when the reactor was in use. The canopy was constructed in multiple layers and included an inner and outer layer of lead, plus interior materials consisting of asbestos sheeting and insulation, Barber says. “The team had to engineer a process to secure the multiple layers so that when we cut through the material and lifted the sections, the canopy would stay intact,” she explains. The canopy sections were lifted one-by-one out of the Sturgis by crane over a period of several months. The individual sections were scanned for radiological contamination and then double-bagged for storage on the deck of the Sturgis until it could be determined how much of the material might safely be recycled. 

The primary shield tank was a ringlike system more than 9 ft tall that surrounded much of the reactor pressure vessel, its outer wall featuring an 8.5 in. thick annulus filled with lead shot. The tank was cut apart in three separate phases of work to minimize potential exposure to the crews, Barber says. The inner wall alone was cut into six sections and packaged in three separate bags.

When the initial work to cut apart the shield tank resulted in higher than anticipated radiological exposure for the cutting team, cameras and video monitors were set up inside the radiological zone to enable the cutting team to observe the cutting operations and minimize the employees’ exposure, Barber says. The system worked well enough that similar approaches will be used during the dismantling of the Fort Belvoir and Fort Greely reactors, she adds.

Other components from the Sturgis reactor remained mostly intact because of the potential for increased radiological exposure if they had been cut apart. These intact items could be quite large — for example, the spent fuel storage tank measured 27 ft tall and 8 ft in diameter and weighed more than 27 tons. The reactor pressure vessel — which once held the nuclear fuel and thus accounted for most of the radiological contamination remaining in the Sturgis — measured 13 ft tall and weighed roughly 81 tons. While still within the Sturgis, the reactor pressure vessel was secured inside a custom-fabricated shielded shipping container that measured more than 16 ft long and 10 ft wide. The shielded container was designed by EnergySolutions Inc., later acquired by Atkins, which is now part of SNC-Lavalin. After being carefully lifted out of the ­Sturgis, the shielded container was moved to the disposal site on a specially designed transporter constructed and operated by Perkins Specialized Transportation Contracting. 

When the time comes, the reactor pressure vessels from the Fort Belvoir and Fort Greely reactors will also be secured within customized shielded containers — the design of each container dependent on the specific levels of radioactivity present in the components, Barber notes.

Once all the Sturgis reactor components had been removed, the remaining bulk of the barge was towed to International Shipbreaking Limited in Brownsville, Texas, where the former cargo ship/nuclear power plant vessel was cut apart for recycling and reuse. Over the years of the Sturgis reactor decommissioning project, more than 2.5 million lb of liquid and solid waste were safely removed and shipped to the disposal site, including more than 1.5 million lb of radioactive waste. More than 300 tons of lead and 5,000 tons of steel were safely recycled.

Through its work on the Sturgis, the Corps gained valuable insights into how to safely dismantle a nuclear reactor. For example, although the original estimated cost of the Sturgis project was $34.6 million, “the complexity of the project and a variety of unknowns encountered” during the work nearly doubled the final cost, which exceeded $65 million, Barber says. The engineering costs, in particular, were triple what the contractor had originally anticipated, she says, because of several factors, including:

• Not checking the engineering assumptions until implementation, which caused significant rework and project delays.
• Not ensuring that all engineering drawings were accurate and/or that the assumptions made about planning an activity were validated before starting the work.
• Learning that all engineering should not and cannot be done upfront for such complex efforts, as each phase may impact the next phase and could change the engineering approach.
• Not having an engineer on-site at all times to provide adequate support as new challenges arose.

The project also experienced problems because the team initially tried to perform the environmental abatement — of asbestos, lead, and other contaminants — on a piecemeal basis “as we worked our way to the reactor components,” Barber notes. But that approach raised too many safety and health issues. So for Fort Belvoir and Fort Greely, the contractors will be asked to fully remediate such potential hazards upfront. 

The other two projects should also benefit from lessons involving relations with stakeholders, government officials, and the community. For example, the team intends to be even more proactive in engaging local government officials earlier in the planning process to ensure they understand the work planned for their communities. “Oftentimes, a great deal of coordination for projects may be done at the state level, with state-level coordinating agencies,” Barber says. “But with the Sturgis, it was the more local coordination with the elected officials and other stakeholders that helped build awareness and understanding of the project.”

Another key lesson was that such large, complex projects require close collaboration between the contractor and the government. “Daily interaction and cooperative team approaches to all work is a necessity,” Barber notes, adding that communication among members of the team “is paramount to success.”

A lack of proactive communication with the local stakeholders on the Sturgis project turned out to be a key challenge, Barber says, especially because the mobility of the barge meant that there were multiple locations at which the work could take place. “When we actually awarded the contract and selected our final spot, we did have some communication challenges and some public relations issues that we learned some hard lessons from,” she adds. “So we are being very transparent and outgoing with respect to our communications for the other two projects. We’ve taken (the lessons from Sturgis) to heart.”

As for implementation, “we did have a lot of engineering challenges” during the Sturgis work, involving “how we approached the work, how we’d take things apart, what the best approach was to removing the components,” Barber says. “So we’ve taken those lessons learned and implemented some of that work for the next two reactors.”

Because the laser scanning and 3D modeling of the Sturgis work sites proved invaluable, a similar approach has already been completed for the Fort Belvoir project by the decommissioning planning team, a joint venture between AECOM and Tidewater, a Virginia-based firm that specializes in radiological cleanup, Barber says. The joint venture is helping develop a decommissioning plan, apply for the necessary permits, and perform other services. The actual dismantling and disposal work at Fort Belvoir will be conducted by a joint venture between AECOM and APTIM.

Because the Fort Greely reactor is partially encased in concrete — for protection against radiation because the site is a multifunctional facility, combining the power plant with a heating plant and other utilities — the laser scanning option is not available there. As a result, the work crews will need to use “other techniques for dose assessment and work planning,” Barber notes. The decommissioning team for Fort Greely has not yet been selected.

Fort Belvoir’s location along Gunston Cove meant that an intake and discharge system was used to pull in and discharge coolant water and to discharge effluent from the reactor operations. That system will be properly remediated and removed, Barber says, after which “we’ll survey the water and sediments to make sure there’s no contamination.” At Fort Greely, a similar system that relied on the nearby Jarvis Creek was removed in 1999 when the base was expected to be closed. The base remained opened, however, and so the early removal of the discharge line for the long-deactivated reactor “is one less thing for us to do when we actually decommission the site,” Barber notes.

At Fort Belvoir, the entire standalone structure housing the reactor will eventually be demolished, any contaminated soils will be removed, and new soil will be brought in as well as new vegetation, Barber notes. Because the Fort Greely site will continue to function as the base’s overall heating plant, only the reactor portion of that facility will be demolished. The site will be cleaned up, and the Corps will then restore the site and any necessary buildings required to support the base’s overall utilities. 

In the future, Barber adds, the Army is considering the installation of new nuclear reactors at other remote locations. If that program moves ahead, one reason will be that the work on the Sturgis and at Fort Belvoir and Fort Greely proved the feasibility of removing such power systems at the end of their useful lives. “We successfully demonstrated that the reactors can be fully decommissioned,” Barber says. “We have the costs associated with that, and they have a full life-cycle picture of what it would take.” CE

PROJECT CREDITS Owner Army Deactivated Nuclear Power Plant Program Project management U.S. Army Corps of Engineers, Baltimore District Sturgis decommissioning planning IEM, now part of Plexus-NSD, Columbia, Maryland Stur­gis decommissioning contractor CB&I Capital Services, now part of APTIM Federal Services LLC, Alexandria, Virginia ­Sturgis reactor pressure vessel shielded container Energy­Solutions Inc., now part of SNC-Lavalin, Montreal Sturgis reactor pressure vessel shielded container transporter Perkins Specialized Transportation Contracting, Northfield, Minnesota Sturgis reactor dismantling site Malin International shipyard, Galveston, Texas Sturgis waste disposal Waste Control Specialists, Andrews, Texas Sturgis shipbreaking site International Shipbreaking Limited, Brownsville, Texas Fort Belvoir decommissioning planning AECOM-Tidewater Joint Venture, Alexandria, Virginia Fort Belvoir decommissioning contractor APTIM AECOM Decommissioning LLC, Alexandria, ­Virginia

This article first appeared in the December 2020 issue of Civil Engineering as “Nuclear Deconstruction.”

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Telegraphs use dedicated wires to send pulses of electric current, which can be received and decoded to deliver messages. “The first functioning telegraph was set up by Francis Ronalds, a distinguished amateur scientist, in his Hammersmith (England) garden in 1816,” wrote historian Gillian Cookson (The Cable: Wire to the New World, Cheltenham, England: The History Press, 2012). But the 8 mi underground line was slow, and Cookson noted that Ronalds could find no takers for his invention.

In subsequent years, however, a variety of entrepreneurs and inventors began to offer glimmers of the world-changing capacity the telegraph offered. These included British brothers John Watkins Brett and Jacob Brett, who laid a 25 mi cable between Dover, England, and Calais, France, in 1850, and American inventor Samuel Morse, who laid a cable across New York City’s East River in 1842. (Morse developed his eponymous code communication system around 1837.) 

The credit for the initial idea for a trans-atlantic line usually goes to English electrician Frederic N. Gisborne. According to writer Thomas A. Dames, Gisborne, who lived in Canada, petitioned the Canadian government around 1850 to build a telegraph that would cross Newfoundland and then travel underwater to the North American mainland at Nova Scotia (“The Transatlantic Cable,” The Military Engineer, November-December 1965, Vol. 57, No. 380, pages 401-403). This was the first step in a larger idea to cross the Atlantic Ocean.

The search for an investor would lead Gisborne to paper magnate Cyrus West Field, one of New York’s richest men. Field, an Anglophile, saw the Atlantic cable as not only a great business opportunity but as “a means of deepening international understanding and harmony, especially between the two countries he loved, the United States and Britain,” according to Cookson. Field would ultimately sideline Gisborne and remove him from the project; Field himself would see the work through to the end. But the end proved a lot harder to reach than he anticipated.

The difficulties of crossing Newfoundland, Canada, from St. John’s to Cape Ray hinted at the challenges that would lay ahead when Field attempted to cross the ocean. The Canadian terrain was, as Cookson described it, 300 mi of “unmapped and inhospitable wilderness impenetrable even on horseback. The forest was dense, the terrain marked with rocks and marshes, the climate foggy. Local fauna included bears and wolves.”

The work was expected to last a few months; instead it took two and half years. 

As recounted by Cookson, Field later wrote he had underestimated the job: “It was a very pretty plan on paper. … Not one of us had seen the country or had any idea of the obstacles to be overcome. ”

Field’s efforts soon attracted investors from both sides of the Atlantic and key scientists and engineers, including Morse, project engineer Charles T. Bright, and one of the greatest physicists of the 19th century, William Thomson — later known as Lord Kelvin.

By 1856, according to Cookson, there were dozens of submarine telegraph lines connecting the British Isles, including Ireland, with London. But the distances were short. No one had attempted anything on the scale of the Atlantic crossing. Morse had laid out four questions: 

• Could an electric signal be sent across such a great distance?
• What was the nature of the ocean bed?
• Could a cable be manufactured to work at the depth required?
• How much was all this going to cost? 

Little of the Atlantic had been surveyed; this was an era when, according to Cookson, to measure ocean depths “a cannon ball was dropped on the end of a long line.” But a survey conducted by U.S. Navy Lt. Matthew Fontaine Maury, head of the Naval Observatory in Washington, D.C., focused on the closest route to bridge the ocean — a 1,600 nautical mi stretch between Ireland and Newfoundland.

Between the two was a “beautiful plateau,” wrote Maury (as detailed by Cookson), about 2 mi deep, a sort of Goldilocks zone that was “neither too deep nor too shallow; yet it is so deep that the wires, but once landed, will remain forever beyond the reach of vessels’ anchors, icebergs, and drifts of any kind, and so shallow that the wires may be readily lodged upon the bottom.”

To build a line that could span that length, Field required the expertise (and the capital) of the British, who were well versed in building submarine cables, though at much shorter distances. In 1856, Field and British investors started the Atlantic Telegraph Co., in London. The U.S. Congress also pitched in a multiyear subsidy reaching as high as $70,000 per year, as well as ships. It was a moment of optimism. Cookson cited an editorial in London’s The Times that claimed the challenges of the transatlantic cable would be solved. The cable would prove another showcase for “the certainties of the scientific age, the unceasing march of technological progress, and the might of Victorian Britain.”

The first challenge was developing a cable capable of transmitting a signal across the ocean. Field recruited Edward Orange Wildman Whitehouse, a British surgeon who dabbled in the field of electricity, as chief electrician. According to Cookson, Whitehouse devised a cable comprising “seven copper strands … insulated with a (triple) layer of gutta-percha, so that it measured three-eighths of an inch in diameter. The core, surrounded by jute yarn saturated with tar, pitch, boiled oil, and common beeswax, would be made by the Gutta Percha Co.”

Gutta-percha was the “wonder material” of the age — a natural latex derived from the gutta trees in Malaysia. It was virtually imperishable, could insulate the line while submerged, and, Cookson wrote, could be shaped while hot but remain flexible as it cooled. From there, the line would be “armored” with seven wires of charcoal iron bright wire to protect the line as it was being “paid out” and to prevent “accidental harm by anchors or fishing lines or rocks once it was laid,” she added.

Designers had to get the weight of the cable just right. It could not be too heavy, Cookson wrote, “for when laying started there would be a length of up to 5 or 6 miles of cable between the ships, a huge mass not immediately supported by the ocean bottom.” On the other hand, she continued, “the cable must not be too insubstantial, for it had to sink to the bottom under its own weight. … A line that was too light would reach the bottom, but it would not be laid straight, as currents would move it from its direct route and introduce damaging kinks.” The final weight of the line was 1 ton per mile.

But even when insulation was properly constructed, Cookson wrote, and the cables well made, “undersea cables simply did not function as expected. Messages would not pass down the line at anything like an acceptable speed without breaking down into a chaotic jumble. This electrical phenomenon came to (be) called ‘retardation of the signals,’ sometimes known as ‘induction.’ Retardation was at the root of problems with long cables, and until it could be understood and its effects overcome, the Atlantic cable could never work.”

Another problem was the capacitance effect, which occurred because the cables could not only transmit an electrical signal, but also store it, which over time interfered with the signal itself. Further, Thomson had developed the law of squares, which indicated that the decay in signal quality “increased with the square of the distance traveled,” wrote David Lindley (Degrees Kelvin: A Tale of Genius, Invention, and Tragedy, Washington, D.C.: Joseph Henry Press, 2004). Further, he added, Thomson concluded that if “the diameter of both the conductor and the insulation of a cable were increased in proportion to its total length, then the signal delay (quality) and what Thomson, groping for technical language to describe the clarity of the signal, quaintly called the ‘distinctness of the utterance,’ would remain the same.”

While Thomson and others worked toward a solution to the challenges of ensuring an adequate signal, Field had more immediate concerns. The first laying of the cable was planned for summer 1857. Because one ship was not large enough to carry all the cable, two ships were used — an American steam-powered frigate, the Niagara, and a Royal Navy steamship, the Agamemnon. 

The Agamemnon was fitted with 10 anchors, which were designed, Cookson wrote, to “stop any motion while the ‘ponderous coils’ were transferred into the hold.” To even reach the ship, the cable was carried “across supports fixed on 10 barges between factory and ship” and wound into a single coil measuring 12 ft in height and 45 ft in diameter.

The ships set sail from Valentia, an island off the west coast of Ireland, on Aug. 6, 1857. Engineers decided that it would be best to string the cable in one direction, east to west, so they could always maintain a connection with land. The Niagara went first, and the Agamemnon followed when the Niagara had paid out all its cable. 

The cable had to be laid at a speed consistent with the speed of the ship. But at one point the cable began moving about 50 percent faster than the ship. “To stop the overrun of the cable the duty engineer set the brakes on the paying-­out machine,” wrote Dames. “At that instant the Niagara was in a wave trough, and when she rose on the next crest the cable was broken by the sudden increase of weight caused by its pull from the ship.”

The second cable-laying attempt took place the following summer, in 1858. William Everett, the Niagara’s former chief engineer, redesigned the brake on the paying-out machine to be smaller and lighter and feature a self-­regulating function “which could release quickly to prevent the cable from snapping,” wrote Cookson.

This time the line was laid from the middle of the ocean — one advantage, Cookson wrote, was that the vessels could communicate with each other. But the Atlantic proved too much. A June 10 storm almost destroyed the Agamemnon, and from there the cable suffered a series of electrical and mechanical setbacks and eventually snapped. Field was at wit’s end. Cookson recounted Field’s brother Henry writing, “The strain on the man was more than the strain on the cable, and we were in fear that both would break together.”

Nevertheless, Field and his investors and engineers persevered. The ships set out on July 17, 1858, for a third — and successful — attempt. The Niagara reached Newfoundland on Aug. 5. The Agamemnon reached Valentia on the same day. The connection was finally made on Aug. 16. In all, according to Dames, the Niagara laid 1,030 nautical mi of cable and the Agamemnon laid 1,020 nautical mi.

“Europe and America are united by telegraphic communication. Glory to God in the highest, on earth peace, goodwill towards men,” was the first message sent from the board of directors in London to associates in the United States. Queen Victoria then sent a 98-word note of congratulations to President James Buchanan; the message took 16 hours to transmit, according to Cookson. “Once the White House had convinced itself this was not a hoax,” she added, “the president penned a reply of 149 words, sent in 10 hours.”

But the success of the cable was short-lived; by Oct. 20 the line was dead. When it was examined, numerous problems were discovered. Whitehouse had used too much current for the insulation to handle. The cable had been made in 1857, Cookson noted, and sat for a year between its manufacturing and laying. It was stored out in the sun, damaging the gutta-­percha. Field, lauded as a hero earlier in the year, was now derided.

What’s more, Field was out of funds. The Atlantic Telegraph Co. had spent ₤465,000 (roughly equivalent to U.S. $69 million today) and had nothing to show for it. Still, there was a growing sense that the solutions were close — and worth the financial push. Over the next several years, according to Dames, other cables were laid, including a 1,535 mi line from Malta to Alexandria, Egypt, and a 1,400 mi cable across the Persian Gulf. The United States completed a transcontinental telegraph line in 1861. 

Meanwhile, Thomson, working with telegraph engineer Fleeming Jenkin, developed an automatic sending device and, along with telegraph engineer Cromwell Fleetwood Varley, developed a method to allow two-way communications along a telegraph. “The problem of ‘retardation of the signals’ was effectively solved,” wrote Cookson.

Thomson also developed a mirror galvanometer that “used a tiny magnet fixed to a mirror, both suspended by a silk thread, to enhance weak incoming signals by light and reflection,” Cookson wrote. This revolutionized “long-distance signaling and electrical testing on board ship,” she wrote. 

By 1865, there was finally new British financing for Field to press ahead with another expedition. He just needed a new cable and a new ship. The former, according to Dames, was a 1.1 in. diameter purer copper wire that was “covered by gutta-percha and hemp-encased steel wires. . . . The new cable could support 11 mi of its own weight in the water and was 2 1/2 times as strong as the previous one.”

As for the latter, Field purchased a vessel called the Great Eastern, which, at 692 ft long, was nearly twice as long as and five times larger (by tonnage) than any other vessel in the world. The Great Eastern was big enough to stow the entire transatlantic cable onboard. The vessel — designed by engineering legend Isambard Kingdom Brunel, along with John Scott Russell — set sail in 1865 and laid two-thirds of the cable before the line failed again. This time, a fault was found in the cable, and the ship — during attempts to retrieve it — passed over it and damaged it.

A year later, at last, the cable was successfully relaid, and more importantly, it worked. Ships required a week or two in the mid-1800s to cross the Atlantic, according to the website transportgeography.org. According to the International Cable Protection Committee, messages could be transmitted at a then-astonishing speed of eight words per minute. 

Field was vindicated for his ability to hold the project together, and the boom in global communication was on. According to historian Simone Müller, in 1866, the first lasting Atlantic telegraph cable — and thus the first long-distance cable — had been laid, and its success set in motion a true submarine cable fever. Cable after cable was run, and by the 1870s, telegraphic lines linked Europe to most of the globe, including India and the rest of Asia, Australia, and South Africa (“The Transatlantic Telegraphs and the ‘Class of 1866’ — the Formative Years of Transnational Networks in Telegraphic Space, 1858-1884/89,” Historical Social Research, January 2010, Vol. 35, No. 1). Many modern, fiber-optic cables spanning the Atlantic still connect between Ireland and Newfoundland. 

And Field is now venerated as much for his multidisciplinary project leadership as his tenacity. Cookson says, “Field’s essential gift, apart from his persistence, was an ability to find the very best, the most useful, talent on offer. The network he built embraced engineers and scientists, financiers and merchants, naval officers and politicians, British and American. The result was the extraordinary story of the Atlantic cable, a feat outside its time.”

This article first appeared in the December 2020 issue of Civil Engineering.

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The age and tightness of SLU’s existing public and private underground utility conditions complicated the project. SLU is the oldest university west of the Mississippi, and its main campus is located in St. Louis’ historic Midtown neighborhood, explains Mike Hartwig, the McCarthy Building Cos. project manager responsible for the utility system project. The Midtown Historic District of St. Louis was placed on the National Register of Historic Places in 1979. 

To ensure that the project could be completed on time and on budget, McCarthy developed 2D and 3D models of the existing underground infrastructure.

The amount of work that had been completed on campus over the last 150 years meant that the existing utility record drawings were unreliable. “Buried utility lines and other underground hazards generally pose a significant risk to construction projects, particularly on dense urban sites where utility line records may be incomplete or inaccurate,” Hartwig says. “Waiting to discover underground hazards until construction is underway can result in unplanned schedule delays as well as expensive cost increases.” 

To ensure that the project could be completed on time and on budget, McCarthy developed 2D and 3D models of the existing underground infrastructure. This included using geophysical locating technologies such as electromagnetic locators, acoustic pipe locators, ground-­penetrating radar, closed-circuit television cameras, and push cameras that were fed through the underground system. All were used to inventory, locate, and depict the existing utility systems. This enabled McCarthy to design, model, and coordinate the proposed routing and identify in advance of breaking ground where subsurface conflicts, design challenges, and constructability issues might be. 

After this design coordination, “a key element of this project was McCarthy’s virtual design and construction capabilities,” explains Hartwig. “VDC involves the alignment and execution of people, process, and technology to drive client-focused value downstream.” VDC goes beyond what building information modeling makes possible. “Whereas BIM involves the 3D modeling and data input of physical objects, VDC is the process of using BIM technology to plan and coordinate the design and construction processes from beginning to end. And it focuses on project stakeholder value by aligning the client’s goals from the beginning to meet the end user’s needs,” says Hartwig.

“As a fast-paced, design-build project, 3D deliverables were a differentiator,” Hartwig says. “As work was being rapidly designed, coordinated, signed off, and approved for field installation, the live linking of all project models (through the cloud) ensured a ‘single source of truth’ for the most current design models.” 

The team used a seven-step signoff process that included twice-weekly meetings for its model coordination and layouts. Mapping, civil, piping, and electrical subcontractors all attended. “Everyone was fully aware of field changes in real time, and adjustments were immediately pushed up to the cloud as work either changed or was installed to ensure all field operations personnel were in the loop,” Hartwig says. “In addition to having a positive effect on the schedule and budget, it instilled a mindset of collaboration among all team members.”

The coordinated process also included strict protocols that relied on designated specialists to provide oversight, including walking alongside mapping surveyors to ensure accurate data collection and meeting with drafters to ensure accurate data depiction.

The mapping process and coordination work implemented by McCarthy was so successful that redesigns for planned utility routing were not required, Hartwig says. In addition, “the two- and three-­dimensional deliverables will also be used by the university in its ongoing facilities management operations,” he says.

The mapping process was completed by McCarthy’s specialized mapping team, which worked alongside its virtual design and construction, preconstruction, and construction teams on the project. A number of partners worked on the project, including Ameren, an electric utility company and Spire, a gas utility company. Primary subcontractors were Sachs (electrical), Corrigan (mechanical), and Castle Contracting. McCarthy’s civil division installed the utility work in the field. 

Planning the project using VDC and the detailed utility map reduced the uncertainty of subsurface unknowns and mitigated risk for SLU, according to Mike Pranger, the vice president of operations for Castle. As a result, “Castle crews were fully informed before starting work in the field,” Pranger says. This meant that Castle could employ “a directional boring rig — a trenchless method — to put in place this extensive network on the active SLU campus versus traditional cut-and-cover methods,” he explains. “This enhanced safety for pedestrians and vehicles, minimized the construction footprint, and allowed the team to be nimble in small spaces and efficient in their sequencing.”

Ameren installed a new two-unit power substation and distribution facilities so that the new SLU electricity distribution system that was being installed could be fully separated from Ameren’s, according to Russ Robertson, P.E., a supervising engineering in the Archview Division of Ameren Missouri. This portion of the project included laying all new underground hardware so that the affected buildings could be cut over from the Ameren system to the new SLU system. Depending on how complicated the systems were, the cut-overs were accomplished in as little as a few minutes to as long as three to four hours, according to Robertson. 

“We could not have asked for better coordination with the level of complication around trying to coordinate four or five different departments working together on the same day in sequence,” Robertson explains. This was, he says, due to the excellent job McCarthy did as the coordination consultant.

This article first appeared in the December 2020 issue of Civil Engineering as “Mapping, Coordination Streamline University’s Utility System Upgrade.”

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Amid growing concern regarding lead levels in drinking water in various areas throughout the United States, the Louisville Water Co., in Louisville, Kentucky, recently achieved a notable goal. After 50 years and a $50 million investment, the company removed its last known public lead service lines in March, a milestone reached by only a few other U.S. utilities.

Louisville Water started as Kentucky’s first public water provider in 1860. Situated along the banks of the Ohio River, the utility began with an ornate pumping station and water tower, a small reservoir, 512 customers, and 26 mi of water main. Today, it delivers an average of 119 mgd of drinking water to nearly 1 million people in the Louisville region by way of its 4,272 mi of water main.

Louisville Water has a rich history of engineering and innovation. The original facilities are National Historic Landmarks, and the Louisville Water Tower is a Historic Civil Engineering Landmark. In 1896, George Warren Fuller conducted his groundbreaking experiments in filtration in Louisville, and today the two water treatment plants rank in the top 18 in North America for outstanding water quality, according to the Partnership for Safe Water. Louisville Water was also the first utility to combine collector wells and a tunnel as a source for drinking water. In 2011, this initiative, known as the Riverbank Filtration project, received ASCE’s Outstanding Civil Engineering Achievement award. 

When Louisville Water began, it was common to install a lead service line to connect to a customer’s property. Between 1860 and 1936, the company installed an estimated 74,000 public lead service lines before switching to copper service lines. (Lead was also used briefly during World War II in the 1940s when copper was required for the war effort.)

Lead has been a well-documented public health concern for decades. In the 1970s, the U.S. Environmental Protection Agency increased its focus on the health implications of lead in the environment, primarily from automobile exhaust. This examination triggered a closer look at the use of lead in various applications, including lead service lines. Recognizing early on the deleterious health effects of lead, Louisville Water took a leading role in addressing the problem, much as it had in the case of filtration. As a result, the utility began replacing its public lead service lines at this time. 

Louisville Water has worked to ensure that its drinking water is safe and in full compliance with the EPA’s 1991 Lead and Copper Rule, which minimizes lead and copper in drinking water by reducing water corrosivity and exposure — usually from lead pipes, lead solder, and brass or bronze faucets and fixtures — to these elements.

Removing the lead service lines, educating the public, and optimizing water treatment make up Louisville Water’s three-prong strategy. Proper treatment is essential in producing water that will not corrode metal pipes or plumbing components that may contain lead. Educating members of the public on how to maintain high standards of water quality in their homes, facilities, and businesses is also essential. 

Minimizing the risk of lead in drinking water begins at Louisville Water’s two treatment plants. A thorough daily evaluation is conducted on the source water, throughout the entire treatment process, and on the final finished product. Along with monitoring water quality at the treatment plants, Louisville Water monitors water quality throughout its distribution system. In recent decades, the utility has implemented many voluntary programs to conduct extensive monitoring and provide valuable data that have afforded a clearer picture of water quality in the distribution system. 

For decades, Louisville Water scientists have researched and carried out methods to optimize treatment specifically to minimize heavy metals in drinking water. This research has helped control pH and alkalinity to prevent corrosion by establishing water quality goals and improving chemical feed selection. Because the noncorrosive water that leaves the utility’s treatment plants is rich in calcium, it forms a calcium precipitate that provides a protective scale layer on the interior of pipes and plumbing fixtures. 

Although corrosion control is paramount to minimizing the risks associated with lead in drinking water, removing the lead service lines truly eliminates it. Dissimilar metallic materials often accelerate corrosion through a process known as galvanic corrosion, which can release even higher amounts of metals. At times, Louisville Water has installed dielectric couplings — 2 ft long plastic pipes — as a transition between a public-side copper line and a private-side lead service line to inhibit galvanic corrosion. 

A typical service line consists of a public section and a private section. Owned by the water utility, the public section extends from the connecting water main, past the water meter, and to the private property line. The private section, which is owned by the property owner, extends from the property line to the home. This section may be made of lead, galvanized steel, copper, or even possibly plastic material. 

The length of the public section varies, depending on the location of the water main. If the water main is installed along the same side of the roadway as the house, the service line could be about 5 to 10 ft long. If the water main is on the opposite side of the roadway from the house and the service line crosses multiple lanes of traffic, the length could exceed 80 ft. Louisville Water installs 0.75 in. diameter copper service lines for typical residential homes, providing a capacity of 20 to 50 gal./min. 

In the early 1970s, when the push to replace lead service lines began, the work often was prompted by requests from customers who had leaking service lines or as part of water main replacement projects. For example, any time a crew was dispatched to repair a leaking or broken lead service line, the team replaced the line with a copper version instead of repairing it. 

A 1991 field and records survey determined that approximately 36,000 public lead service lines remained in service. To complete the switch to copper service lines, the company created the Main Replacement and Rehabilitation Program. One of the results of this program was the development of a model for replacing water mains. This model is based on a formula that evaluated the age of the pipe, pipe material, and the number of breaks and leaks. This model compiled multiyear information on main breaks and used main break frequency as a measurement of system performance. The target is to have fewer than 15 breaks per 100 mi of water main per year, or a main break frequency of less than 15. By 1994, 1,900 of Louisville Water’s lead service lines were being replaced annually.

By 2002, with its replacement program well underway, Louisville Water started the Lead Block Replacement Program. The goal is to remove all known lead service lines. Instead of waiting to find the lead service lines as part of the Main Replacement and Rehabilitation Program, utility engineers developed replacement programs starting with neighborhoods known to have high concentrations of lead service lines. With annual budgets ranging from $500,000 to $5 million, these service line renewal projects were run by dedicated project engineers.

Using field records and historical information, staff created a Microsoft Access database to map the location of lead service lines. This database was updated regularly as additional information was gathered by field inspectors checking vaults and by staff reviewing old project files. The database included service lines that were known to be lead or had an unknown material type but were installed before 1937. Anytime contractors or field personnel who were working to replace a lead service line found another lead line in a vault on an adjacent property, that service line was also replaced. 

As part of the Lead Block Replacement Program, Louisville Water’s engineering department created and managed projects to replace from 100 to 400 service lines at a time. Each project included a pipeline study map for specific neighborhoods; this provided detailed water facility information, including the location and size of the water main and the locations of valves and service lines as well as project specifications, including addresses, size of service, and an engineer’s cost estimate. Although Louisville Water crews did some of the work, a large percentage was contracted to outside parties under the utility’s supervision because of the amount of work needed to complete the program and the limited capacity of its internal crews. 

Projects were prioritized based on city paving schedules, and work was rotated among neighborhoods so that no one area was overly burdened with construction activity. Before construction began, customers were notified and road closure permits were acquired. 

If lead was found on the customer side of the service line, the customer was given the opportunity to replace the line, with Louisville Water agreeing to cover 50 percent of the cost of replacement. If the customer declined, a dielectric coupling was installed at the property connection. Additionally, Louisville Water provided water filter pitchers to customers who had private lead service lines. Following the service line replacement, customers were asked to flush their water lines each morning for five minutes for 30 days to clear out stagnant water that may have picked up residual lead overnight. The company gave credits to customers for the water used in flushing. 

By 2015, the known lead service lines were not as concentrated geographically but instead were spread out. As a result, the costs associated with replacing these increased. By 2018, the average cost of replacement had risen to $4,500. Several factors caused the prices to increase. When the replacement work is concentrated in one neighborhood, the cost of mobilization is reduced. Although competitive bidding lowered the replacement price, changes in government requirements led to higher paving and yard restoration costs. To control those, projects were grouped together to attract larger bidding pools. 

In most cases, replacing a lead service line became routine: a three- to five-person crew would pull out the old service line and pull through the new one. If landscaping was not involved, a small bulldozer was used to dig a hole at the water main and at the property connection. Then a small directional pneumatic boring tool was used to pull the new service line into position. Hand excavation was also used on the customer side to make the final tie-in. The line was then flushed for 60 minutes and returned to service, and streets and yards were restored.

Obstacles occasionally arose. For example, a crew sometimes had to contend with inadequate soil cover above a water main, increasing the risk associated with installing a new service line in such close proximity to the main. In other cases, crews uncovered trolley tracks or other unexpected utility lines. In each of these situations, the utility paused to confirm the clearances between the existing underground infrastructure and the planned location of the new service line. In some cases, the location of the new service line was moved. 

Many beautiful lawns and gardens required hand-digging or vacuum excavations to preserve landscaping or avoid damaging retaining walls. Most customers preferred the use of vacuum extraction for digging holes on their property because of its less intrusive, smaller construction footprint. Some customers have a small retaining wall that adds a unique feature to their property. In such a situation, vacuum excavation enabled the utility to make a smaller hole right at the retaining wall. In this way, a crew could make the service connection while reducing the chance of damaging the wall. 

If a retaining wall is damaged, it is very difficult to match the original construction. Therefore, crews were careful to avoid damage in these unique situations. The more difficult replacements included brick roads and floodwalls. On one project involving a water main in a brick street, the brick was removed and reinstalled using a qualified brick pavement installer. On another project, portions of service lines that were to be replaced passed beneath a floodwall that extended more than 500 ft down the middle of a street. The 10 ft tall reinforced-concrete floodwall had been built to protect against flooding from the Ohio River. Rather than constructing the new service lines beneath the structure, the utility added a new water main on the other side of the floodwall. The old service lines were sealed off and abandoned in place. 

Along with replacing its lead service lines, Louisville Water created a proactive, voluntary monitoring program within school facilities to establish higher health standards for children. Since the late 1980s, Louisville Water scientists have worked with public school districts and private schools within the utility’s tricounty service area. Schools are provided sampling materials, and personnel are trained on how to collect these samples to test the drinking water. 

Louisville Water’s certified laboratory analyzes the samples using EPA method 200.8 (Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma-Mass Spectrometry), which has a detection limit of 0.0010 mg/L for lead. If lead is detected at any individual outlet, school officials are encouraged to carry out several tasks, including conducting an inspection, looking for components that contain lead, performing maintenance, or removing or replacing the fixture or fountain in question. If any work is performed by school facilities, Louisville Water offers free resampling of those outlets to verify that the work successfully reduced lead levels. 

The utility has also expanded this free monitoring program to day care centers. Providing instruction and guidance and developing these partnerships have led to a greater awareness of the potential water quality issues that such facilities may face. 

As mentioned above, Louisville Water’s responsibility ends at the property line where its service line connects to the customer’s service line. The customer is responsible for maintaining the line that extends from the property line to the home. 

Even though Louisville Water had to replace 74,000 publicly owned lead service lines, there are nowhere near as many privately owned lead service lines needing replacement.

Because of its commitment to public health, the company started the Private Lead Service Line Replacement Program in 2017 to assist customers with the removal of their private-side lead service lines. Even though Louisville Water had to replace 74,000 publicly owned lead service lines, there are nowhere near as many privately owned lead service lines needing replacement. In fact, approximately 2 percent of the utility’s 252,000 residential accounts have private lead service lines. The effort to help customers intensified after Louisville Water completed the removal of its public lead lines because it was able to dedicate resources to focus on notifying and working with customers who have private-side lead service lines. 

Utility staff within the engineering, communications, and water quality departments have disseminated information and alerts to customers who may have a private lead service line and offered them financial assistance. Letters and postcards were mailed to customers explaining the process to get financial assistance. Additionally, customer service employees are trained to answer questions about the program. If they are asked technical questions, the reps transfer the calls to the lead program engineer for additional assistance. Dedicated phone lines and email addresses have been set up for customers to contact the utility. Information is also on Louisville Water’s website. Customers can also request to have their water tested for lead as part of a free service offered by the utility. 

Because replacing a private-side service line can be expensive, Louisville Water will pay 50 percent of the cost, up to $1,500. To obtain this funding, customers first must get quotes from two licensed plumbers willing to perform the work, a measure that helps ensure competitive pricing. Customers then send the quotes to Louisville Water for its approval, and the utility chooses one of the plumbers. 

After the new private service line is installed, an inspector from Louisville Water flushes the line for 60 minutes. The inspector also sends information about the new private service line to the utility’s geographic information systems department, which then updates the records. For customers who cannot afford this upgrade and meet eligibility requirements, a grant program administered by the Louisville Water Foundation — the charitable arm of the utility — may pay the remaining replacement cost. 

Private galvanized lines, which can hold lead particles that enter them, have now been added to the program if records indicate that they were once connected to lead service lines. Even though a lead line has been removed, lead particles inside a galvanized line can leach lead into water. Removing galvanized lines also reduces the likelihood of galvanic corrosion.

Louisville Water began with 800 customers whose utility records indicated they had a private lead service line. In the first few months, this effort has had limited success, with fewer than 10 customers participating in the program. Economic hardship resulting from the COVID-19 pandemic and the lack of interest on the part of some homeowners in replacing their service lines are the most common obstacles. The utility has found social media to be a good way to get information to the general public. Plans are in motion to reevaluate how the utility communicates this program to customers. 

It is important to communicate the science and research behind maintaining excellent water quality at the treatment plant as well as what customers can do to maintain this quality within their homes and businesses. Stagnant water can degrade water quality, so maintaining high-quality water requires making sure water is regularly used or implementing proper flushing practices. Louisville Water’s website contains a “Lead Awareness” page that offers information related to lead in drinking water, instructional videos, and resource links for additional information. 

In the 1990s, Louisville Water created an internal “lead team” that met regularly to document line locations, work procedures, treatment optimizations, water quality monitoring, customer questions and issues, and communication tactics. Members of the team now include staff from the treatment plants, distribution water quality, water quality compliance and research, customer service, distribution operations, geographic information systems, communications, and engineering. The water quality staff members assist with water quality issues surrounding sampling and results, while engineering staffers help customers with replacement cost estimates, contractor selection, and construction issues. The team’s work has led to a companywide understanding of the Lead Block Replacement Program and built on the history of advancing public health. Today, the team continues to meet and is focused on the private-side program, with the end goal of assisting and encouraging customers to remove all their known lead and galvanized lines. 

Although Louisville Water invests substantial effort communicating directly with customers known to have private lead or galvanized service lines, a significant number of customers have unknown or unidentified service line materials. The website and social media platforms provide information to a broader audience and will help identify customers with unknown materials. Information is still mailed to customers. 

Although Louisville Water invests substantial effort communicating directly with customers known to have private lead or galvanized service lines, a significant number of customers have unknown or unidentified service line materials.

Beyond the customers, Louisville Water focuses its outreach efforts on a long list of stakeholders, including elected leaders, the Louisville Metro Public Health Department, social service agencies, plumbing contractors, and the Kentucky Division of Water. The outreach extends to conversations with the local health department and medical community, elected officials, and leaders of local schools and child care centers. 

Until the lead crisis in Flint, Michigan, emerged, the communications strategy focused on the customer, employees, and those key stakeholders mentioned above. Reporters might have raised the issue, but the utility was not proactively — or publicly — addressing the topic of lead. This approach changed in 2016, when Louisville Water launched a public-facing campaign with media events, stories about the lead service line replacement program, the private-side assistance, and the overall quality of Louisville’s drinking water. Although the ongoing pandemic has prevented a large-scale media event to announce the completion of the work to remove its known lead lines, a video created to tell the story quickly reached more than a million people in just a few hours. 

Much of Louisville Water’s success in achieving its milestone comes from the collaboration and commitment that have evolved over decades. Today, employees frequently work with other water utilities to develop treatment and monitoring strategies, replacement programs, customer communications, and public outreach. Scientists at the utility continue their research, even working on patented technologies to reduce levels of lead in drinking water fountains. Because schools and child care facilities often lack funding to address problems pertaining to lead in drinking water, identifying cost-effective solutions for these customers while reducing children’s potential exposure to lead is a win-win. 

The organization’s three-pronged strategy for addressing lead by optimizing water quality and treatment, replacing lead and galvanized service lines, and educating the public has improved public health. In October, Louisville Water marked its 160th anniversary of delivering water. Along with this milestone, customers of the utility can take pride in the quality, innovation, and value that go into every glass of drinking water. 

This article first appeared in the December 2020 issue of Civil Engineering as “Lead-Free in Louisville.”

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The city of Jingdezhen, China, has been producing pottery for 1,700 years. Dubbed the Porcelain Capital, this area is known to have exported huge amounts of Ming and Qing dynasty pottery to Europe. This year saw the opening of a new museum honoring that history. With a design inspired by the area’s Imperial Kiln ruins, the museum also pays homage to the construction methods and craftspeople who have been responsible for the kilns through the generations.

The Imperial Kiln Museum is located on a restricted historical area that is adjacent to the Imperial Kiln ruins. It includes just less than a dozen brick vaults — some interconnected — that have been shaped in the traditional form of a kiln and nestled together in rows. Each of these new vaults is formed with a slightly different curvature, length, and size, according to Studio Zhu-Pei, the design’s architects along with the Architectural Design and Research Institute of Tsinghua University. The project’s chief designer was Zhu Pei, Hon. FAIA, the founder and principal designer of Studio Zhu-Pei.

Traditionally, craftspeople built the thin and light brick kilns with a minimum of materials and a maximum of space — all without scaffolding. The arched structures of the kilns are made up of two thin layers of masonry brick walls that sandwich a thin layer of concrete, according to the architects.

The vaults each extend below street level, forming two stories of visitor spaces that offer a variety of interior-yet-open-ended, open-air, and enclosed spaces that overlook five sunken courtyards. Each of these courtyards has a dedicated theme — water, soil, wood, fire, and gold — that reflects traditional Chinese thinking about the earth. Each also has a role in the creation of porcelain, according to Studio Zhu-Pei.

Recycled kiln bricks were used in the structures, which were built with a mixture of old and new brick. The use of recycled kiln bricks is literally embedded in the fabric of the city: Brick kilns are demolished every two to three years to maintain a certain thermal performance within the kilns, according to Studio Zhu-Pei. As such, the use of recycled kiln bricks to build homes and other buildings is an age-old tradition within the city.

This mixture of brick interweaves the past and the present together, according to Studio Zhu-Pei. This strategy was used to excite visitors’ curiosity and interest, evoke memories, and generate new questions. “The past cannot be erased but can be rewritten by recounting a new awareness and maturity, a sort of contemporary archeology,” says material released by the architects.

The 10,370 sq m museum also houses an auditorium, bookstore, and a tearoom.

Project credits:

Client: Jingdezhen Municipal Bureau of Culture Radio Television Press Publication and Tourism, Jingdezhen Ceramic Culture Tourism Group

Architects: Studio Zhu-Pei and the Architectural Design and Research Institute of Tsinghua University

Structural; mechanical, engineering, and plumbing; and green building: Architectural Design and Research Institute of Tsinghua University

Facade: Shenzhen Dadi Facade Technology Co. LTD

Lighting: Ning Field Lighting Design Co. LTD

Acoustic: Building Science & Technology Institute, Zhejiang University 

Main contractor: China Construction First Group Corp. LTD, Huajiang Construction Co. LTD of China Construction First Group

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But in the world of civil engineering, you’ll find a much less cynical spin.

“Know your history, so that you can successfully repeat it!”

Steve Pennington, P.E., L.S., M.ASCE, a senior manager for Geo-Instruments Inc. in Washington, D.C., is a an advocate for the value in understanding the history of the civil engineering profession.

A longtime member of the ASCE National Capital Section’s History and Heritage Committee, Pennington has a new book out this month, published by ASCE, detailing the history of Benjamin Wright, the man designated as the “father of American civil engineering.”

Pennington talked recently with ASCE News about Benjamin Wright’s career and why every professional civil engineer should make it a point to learn their profession’s history.

ASCE News: So, what earned Benjamin Wright the “father of American civil engineering” title?

Pennington: The father of the profession, traditionally, is considered John Smeaton, from England.

In the late 1960s, the mandate for ASCE was to find someone we could consider the father of the profession in America. So, the search went out, and it led to the declaration of Benjamin Wright as the father of the profession in the United States.

The formal resolution has about eight or nine “whereas”es as to why he’s considered the father. And the three most important ones are that:

• First, he was the chief engineer on America’s first great public works project, the Erie Canal.

• Second, he was a mentor to many young civil engineers who went on to have careers of note – John Jervis with the Croton Aqueduct, Charles Ellet with the Wheeling Suspension Bridge; Horatio Allen with his development of railroads; and others.

• And third, Wright was active in the effort to establish a professional society, as the chairman of the committee to draft a constitution for the proposed society. The story goes that the constitution was not ratified and the effort did not take, and it was only in 1852 that the effort was rekindled and they were able to get the organization (ASCE) established.

ASCE News: Obviously, the Erie Canal transformed the country. What most impresses you about that project or Wright’s work in general?

Pennington: At that time, nothing in America had been undertaken of that size. Any project that had been done that you’d call an engineering effort was very small in terms of concept. You might have a breakwater in a harbor. You might have a short canal. But the Erie Canal was the first effort on a large scale. It was unprecedented.

There’s an argument, if you really get into the history of transportation in this country, that the relative magnitude of the Erie Canal and its importance to American society was not replicated until the interstate highway system began in the 1950s.

The Erie Canal is what made New York City what it is. New York City would not be the great political and economic center had it not been for the Erie Canal. For Wright and his engineering group, everything was a challenge with all they had to overcome. Excavation was done by hand, so steps had to be taken to create new ways to speed up the process and improve production. They came up with ways to bring down trees quickly, they devised winches to remove stumps, they improved the horse drawn plow to decrease time spent in excavation, and most importantly they discovered sources of hydraulic cement to allow cost effective completion of the numerous masonry structures throughout the canal. Everything done was new. They had nothing to go on.

It was an enormous undertaking from an engineering standpoint to get that completed, and Wright was able to manage it and get it done.

ASCE News: Why do you think it’s important for civil engineers, especially younger professionals, to be aware of who he is and that history?

Pennington: I’m not the only one who has said this – civil engineering is a profession, not a trade.

And as a professional, if you’re going to be a civil engineer and call yourself a professional, you have to have a basic fundamental understanding of your history and how it relates to society.

You don’t have to have an academic understanding, but just a basic understanding of your history – the great projects, the great engineers. Because it’s from the experiences of those men and women who came before us that lessons are learned today.

This is not a new concept. There have been many papers delivered and presentations made on the idea that as a professional it’s important that he or she knows their history.

As part of that history, it’s important to know the beginning point here in America. Where did it all begin and why? It’s almost a genealogy. As you trace back the projects you can almost develop a family tree of sorts.

And that beginning point would be with Benjamin Wright.

Preorder your copy of “Benjamin Wright: Father of American Civil Engineering” by Steven M. Pennington.

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A Great Progressive Step

Civil Engineering, it is intended, will deserve and, I am certain, will have the unqualified general approval of the membership.

With a freer style than was suitable for Proceedings, it will take over from that publication the portion susceptible of a treatment characterized by brevity and vivacity. It will be the medium of communication with the membership on Society activities: technical, professional, and administrative. It will deal with those interests of the civil engineer that become vibrant as a consequence of the new Functional Expansion Program.

Such a transfer to a publication with a more facile style, with attractive type, with non-transparent paper, and with clearer illustrations, will offer marked advantages. Few members have realized the difficulties which the Society has overcome in producing its Proceedings in the quality and quantity of content which it has been its effort to maintain. Proceedings has constituted a contribution to the highest of technical literature amounting to 1,300,000 words a year, contained in a publication of which approximately 15,000 copies have been distributed free to members, to universities, to libraries all over the world, and in exchange with other societies. It will be continued as the Society’s fundamental technical publication, meriting and receiving study and analysis.

With the recent adoption of the Functional Expansion Program, the Society accepted the obligations incident to the improvement of the profession along lines other than technical. The plan devised sets up administrative units whose influence, as time goes on, will be felt far and wide. For the furtherance of that program, if for no other reason, the new publication would be almost an essential.

Civil Engineering will carry advertising matter. These advertising pages should be as interesting and informative as those of the text.

Civil Engineering is to be the work of its contributors, primarily members of the Society, and as such will be just what the membership makes of it. Details, here or there, it cannot be expected, will be entirely satisfactory to each of the Society’s 14,000 and more members, but in its conception and general endeavor it certainly must appeal.

I bespeak for Civil Engineering your loyal support, your constructive criticism, your contributions to its pages. I hail Civil Engineering as a great progressive step which has been taken by the American Society of Civil Engineers.

J. F. Coleman
President, 1930

90 Years Later, Still Progressing

In his letter introducing Civil Engineering to ASCE’s membership in its debut issue in October 1930, then-president of the American Society of Civil Engineers J.F. Coleman implies that the magazine is a bold step — an experiment for the improvement of the profession. Spun off from a publication called Proceedings that was a compendium of highly technical papers, the magazine was to provide articles that were “more facile” in style than those articles, with “attractive type” and “clearer illustrations.”

Over the decades, as ASCE has grown from serving roughly 14,000 members in 1930 to more than 150,000 members today, that dedication to marrying sophisticated graphics with expertly reported, written, and edited articles that balance just the right level of technical detail with a shorter, easier-to-read style has continued to be the hallmark of our Society’s flagship magazine.

It is fascinating to note how the challenges facing the civil engineering profession in 1930 remain, though altered in form, 90 years later. Coleman writes that Civil Engineering was meant to present both technical information and articles on topics relating to “the improvement of the profession along lines other than technical.” Today, we would call these professional skills, and they would include everything from delivering effective client presentations to managing project schedules, juggling work and home life, and ensuring the diversity and equity of teams. Each issue of Civil Engineering still strives to balance the technical with the nontechnical, the brief with the in-depth, and the many topics of interest to our diverse membership.

Coleman acknowledged that contributions from the membership would make the magazine what it is. This is still the case, and ASCE genuinely appreciates the time and effort it takes civil engineers to write or serve as sources for the wide array of informative articles presented in the magazine for the benefit of the entire profession. We honor our members’ points of view and respect their constructive feedback.

As we look toward 2021, we expect many changes in Civil Engineering — in content, format, and reach. Yet one thing that will not change is the magazine’s dedication to presenting the latest developments, trends, research, and news to help further the practice of the critical civil engineering profession and the success of you, the members of ASCE.

Kancheepuram N. Gunalan, Ph.D., P.E., D.GE, F.ASCE
President, 2020

This article first appeared in the October 2020 issue of Civil Engineering.

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The Morandi Bridge, built in the mid-1960s, spanned the Polcevera, a river that runs through the center of the city of Genoa, Italy. A landmark of the city and an essential connection for goods and people, the bridge was an important artery that connected the districts across the Polcevera Valley, and it was a major link connecting the A10 motorway toward France and the A7 to Milan. It was also the main route to the Port of Genoa, a major Italian seaport on the Mediterranean Sea. As well as traversing the river, the bridge crossed two main railway lines, passing over homes and large industrial areas. 

Designed by Riccardo Morandi, the original bridge was 1,182 m long and 45 m high at road level, with three hybrid prestressed cable-stayed spans and a series of other minor spans. Each of the three major cable-stayed spans was supported by a reinforced-concrete pier and a 90 m tall pylon. A-frame towers with V-shaped supports below the bridge deck created a stiff arrangement. When a 210 m section of the bridge collapsed in August 2018 during a torrential rainstorm, the city was suddenly divided in two. An investigation is underway to determine the official cause of the collapse; unofficially, the likely causes are areas of corrosion, fatigue phenomena, high volume, and load cycling during the life of the bridge. What is certain is that the bridge experienced much heavier use than was anticipated in the original design. 

A landmark of the city and an essential connection for goods and people, the bridge was an important artery that connected the districts across the Polcevera Valley …

The bridge’s collapse left Italy in a state of emergency. Officials responded quickly by appointing a special commissioner, who was given authority to speed up the replacement project allocation and start-up process. A joint venture led by Omini (with Fagioli SpA and IPE progetti) and Pergenova ScpA (a joint venture between Webuild — formerly Salini Impregilo — and Fincantieri Infrastructure) was the main contractor for the new bridge. RINA, an international firm that specializes in management services, was awarded three contracts by the special commissioner to provide demolition project management, construction management, and coordination of safety and quality assurance services. 

The top priority was to quickly and safely replace the bridge to restore this vital transport artery. The complication for the teams was how to carry out the demolition of the existing structure and construction of the new bridge simultaneously, with restricted urban and industrial space in which to work and under tight time constraints.

The original Morandi Bridge was situated in the middle of the town, with four roads connecting higher parts of the town to the city center. If all four roads had been closed, residents would have been isolated, and the social impact would have been huge. One of the first challenges for the project team, therefore, was to plan the demolition of the bridge while keeping at least two of the four roads open at any one time. 

The bridge spanned residential buildings on its east side and commercial buildings to the west. It was not possible to keep these buildings safe and secure while the bridge was being taken down, and space was needed to establish a work site for the project. So people were immediately relocated, and these buildings were demolished. For the deconstruction of the bridge, two methods were used. The first was mechanical, using cranes and strand jacks to lower large bridge sections. Smaller sections were cut into three slices and slowly lowered using chains. The large piers were lowered by crane.

The second method was explosives, and this occurred mainly on the east side of the bridge. Explosives were used because the team determined it would take too long to use mechanical methods. There was also a chance of further uncontrolled collapse of this section, which would place personnel at unacceptable levels of risk. Another factor the team had to consider before razing the bridge was asbestos. If it was present in the structure, then explosives would aerosolize it. Extensive testing was carried out before commencing the explosion, and the results showed that the asbestos levels were insignificant or absent. On the day of the explosion, a 400 m perimeter was set up around this section of the bridge.

RINA carefully managed the explosion, addressing all possible outcomes before starting the work. It also monitored the area after the explosion for any potential impact on the environment and nearby structures. After just a few hours, there was no trace of powder in the area. Residents were able to return to their homes that evening, making this stage of the project a huge success. Authorities kept parts of the exploded bridge to aid in their investigation. 

The demolition phase of the project also involved close cooperation with utility companies to ensure utility pipes that ran beneath the bridge remained structurally sound. The explosion required the utilities to be temporarily shut off, but careful review after the work showed there was no damage to these services and they quickly resumed.

At a cost of 19 million euros (approximately $22.3 million), demolition was completed in September 2019.

Construction of the new bridge before the complete demolition of the existing one required strategic planning, precise project management, and exceptional attention to safety. The design followed the alignment of the existing bridge, except at the west side where a new line was taken to move the bridge an additional 20 m away from an industrial building that had been just 10 cm from the existing bridge. This direct alignment was required to connect with the existing Coronata tunnels on the west side and junctions toward the A7 motorway on the east side.

The new bridge was designed free of charge by leading Italian architect Renzo Piano. Its design, inspired by Genoa’s maritime history, resembles a ship’s bow. Bright steel reflects the sunlight, and its pale gray-blue color blends with the skyline, resulting in a gentler visual impact on the valley than its predecessor. The bridge comprises 18 elliptically shaped, reinforced-concrete piers that are 50 m tall, 9.5 m wide, and 4 m thick (at their widest). There are 19 spans, 16 of which are 50 m long. There are three middle spans, two of which are 100 m long and one that is 40.9 m long. The longer spans were required to cross the river and the rail lines, and the third was added for symmetry. The bridge’s continuous deck comprises steel and concrete and is 1,067 m long. 

The central body of the bridge has two sides (wings), and each section has a passage inside for maintenance activities. The bridge has six lanes: two travel lanes in each direction and an additional lane on either side for emergency traffic and for carrying out maintenance work without having to close traffic lanes. The structure, substructures, and foundations were optimized using support devices to separate the deck from the piers, so that the bridge can naturally expand and contract without compromising stability or strength.

All design documents, including more than 10,000 technical design documents, and safety procedures were reviewed by RINA. Furthermore, RINA produced more than 3,000 technical review documents; conducted approximately 600 technical, quality, and safety audits; and performed nearly 2,500 material and structural element inspections. 

Elements of the bridge were built in factories throughout Italy and shipped to Genoa, arriving by port, and taken to the site by convoys during the night to minimize disruption. The parts were assembled on the ground and lifted into place by either one or two cranes, depending upon the part’s size and position. As with the deconstruction, the larger sections were raised into place using strand jacks.

Noise and dust levels were monitored throughout the project, and mitigation steps were implemented to minimize environmental and social impacts. Work crews wet the roads to reduce dust, and careful consideration was given to the time of day for construction activities to occur. PM10 and PM2.5 levels were monitored before and after operations.

Infrastructure needs monitoring and maintenance, and asset management is now an accepted part of ensuring ongoing safety and reliability. As a result, the new bridge is equipped with a digital monitoring system, robots to carry out some maintenance tasks, and a dehumidification system to help prevent corrosion. Photovoltaic panels power the bridge, controlling the lighting, sensors, and other systems. 

The project faced extraordinary challenges, including one of the worst winters in recent times and a global pandemic. However, despite these challenges, work on the project was continual, stopping only one day: Dec. 25, 2019. When the pandemic began, the RINA safety and project management team immediately took action. Safety measures were implemented before the end of February and before lockdowns in Europe. Checks were systematically made on personnel, including temperature checks upon entering and exiting the site as well as determining whether they had come from locations termed “red areas,” which had high numbers of cases. Workers wore gloves and masks on-site, and they had to keep diaries noting anyone they had been in contact with for more than 15 minutes and within proximities of 1 m during their shifts. In many ways, this was one of the first track-and-trace systems used in Europe to manage the impact of the pandemic.

Teams were organized into smaller groups; they were kept separate from other teams to enable easier isolation if a case of the virus occurred; and workflows were reviewed to maximize social distancing. Throughout the project, there was only one case of COVID-19 on-site. This individual and his 23-person team were immediately placed into quarantine. Fortunately, the worker fully recovered, and no other member of the team contracted the virus. 

One of the biggest challenges RINA faced was obtaining sufficient personal protective equipment for the approximately 450 people at the site daily. A large amount of PPE was needed, and there was no readily available source. RINA worked promptly to source PPE, but the only equipment available did not meet the required certification levels. In response, the RINA team engaged several laboratories to certify the equipment to higher safety standards. During the pandemic, authorities visited and assessed the work site on many occasions. RINA received praise for how the site was managed and was subsequently able to share its experiences with the government to help cope with the wider pandemic in Italy. 

What makes this bridge unique is not its design and construction but the teams that worked and continue to work on it. The expert management, parallel deconstruction and construction, and the can-do attitude of a highly motivated team have been termed “the Genoa approach.” The lessons learned about what can be achieved have created a model for other infrastructure projects and industries in Italy and throughout the world. 

Many proposals estimated that the job would take two-and-a-half to three years. However, in just 14 months the old bridge was demolished and a new one was in place, reopening on Aug. 3. Never has such a complex infrastructure been built within such a tight schedule. A project that started from tragedy has achieved something to make the people of Genoa and the whole Italian nation proud. 

Morandi Bridge Demolition Project Credits 
Demolition project management RINA, Genoa, Italy 

Genoa-Saint George Bridge Construction Project Credits
Special commissioner Marco Bucci, Genoa Design architect Renzo Piano, Genoa Technical project Italferr, Rome General contractor Omini (a joint venture with Fagioli SpA, Sant’Ilario d’Enza, Italy, and IPE progetti, Torino, Italy) and Pergenova ScpA (a joint venture between Webuild, Milan, and Fincantieri Infrastructure, Verona, Italy) Construction management RINA Safety and quality assurance services RINA

This article first appeared in the November 2020 issue of Civil Engineering as “The Genoa Approach.”

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Explosion Event and Magnitude
On Aug. 4, 2020, just after 6 p.m., an intense fire broke out at Hangar 12 in the Port of Beirut. Unbeknownst to the nearly 100,000 people who lived within 1.6 km of the warehouse, Hangar 12 was storing everything needed to make a bomb. The fire started a chain reaction, beginning with the activation of fireworks and finishing with the detonation of ammonium nitrate. According to researchers, approximately 2,750 tons of ammonium nitrate were stored in Hangar 12. Based on eyewitness videos and estimated shock wave velocity, researchers and experts have estimated that approximately 1,500 tons of ammonium nitrate contributed to the explosion. In practice, explosions are defined based on their equivalence to a TNT charge to better match historical experimental data and use industry standard relationships between the TNT charge weight and the pressure/impulse measures that are used for analysis purposes.

The explosion resulted in a form of blast wave that, although not unexpected, was considerably different in duration from smaller explosive events. To put the Beirut explosion into perspective, Table 1 compares the TNT equivalent with other historical explosion events. For the purposes of this article, the authors use a TNT equivalent of 630 tons, although current estimates vary from 300 to 960 tons.

Industry Standard Methodology
It is important to understand how industry standard calculation methods compare to the damage witnessed throughout Beirut. The U.S. Department of Defense Explosives Safety Board and the United Kingdom Ministry of Defence publish standards on proper siting for explosive safety. The siting requirements include minimum distances between the stored explosives (Hangar 12 for this event) and inhabited buildings, public traffic routes, electrical systems, and other explosive storage locations. The resulting distances are based on the quantity of stored explosives and construction of the storage buildings (i.e., earth-covered bunker versus light-gauge warehouse). In general, the goal of explosive safety siting is twofold: life safety for the public and mitigating the propagation of explosives between storage locations. The critical parameter most applicable to Beirut is the inhabited building distance. The IBD is the minimum permissible distance allowed between a quantity of explosives and any building inhabited by the public or where people are accustomed to assembling. This minimum distance provides a high degree of protection against structural damage based on blast or shock wave effects to frame or masonry buildings. It does not provide protection against glass breakage. Personal injury from flying glass is possible even when in compliance with government regulations due to its high failure potential under low blast pressure. The IBD for the assumed 630 tons of TNT equivalent explosion is a distance of 1,700 m (according to U.S. standards) and 1,900 m (according to U.K. standards), which results in a peak pressure of 6 kPa and 5 kPa, respectively. The expected pressure at the IBD is sufficient to shatter typical residential and commercial glazing, which is considered allowable damage.

Structural response to explosive events has been studied in extensive detail since World War II.  The Jarrett damage criteria for buildings, published as Derivation of the British Explosives Safety Distances in the Annals of the New York Academy of Sciences in 1968, are common references when considering explosion effects. These damage criteria can be further developed into pressure-impulse or iso-damage curves, as shown in Figure 1. PI curves allow an estimate of building damage based on the peak side-on overpressure versus impulse from an explosive event. Examination of these iso-damage curves shows that as the peak pressure load and impulse increase, the corresponding level of damage also increases. However, these iso-damage curves also indicate that there are different regions of loading response: impulsive, quasi-static, and dynamic, also known as pressure-time. In the impulsive region, the structural response is controlled by the overall energy of the blast wave above a threshold peak-pressure level. In the quasi-static region, the structural response is governed by the peak pressure almost regardless of the impulse. In between, the dynamic region response is dependent on both the peak pressure and the impulse.

A key characteristic of the pressure wave from an explosion is the relationship between the peak pressure and impulse with range. As the pressure wave from an explosion expands, the resultant pressure wave peak decays rapidly and the duration of the blast wave increases. Explosions in the impulsive region tend to occur from smaller explosions, close to the target, whereas explosions in the quasi-static region tend to be the result of extremely large explosive events. Figure 2 shows the Jarrett PI curve with a range-charge weight overlay of three charge weights (630 tons TNT, 500 kg TNT, 1,000 kg TNT) clearly showing the different response regions.

Damage Assessment
It is also important to quantify the damage throughout Beirut to compare it with the explosive safety and blast-loading methodology. It is difficult to personally investigate the entirety of damage in the city, so the damage was quantified and compared using various methods as shown in Figure 3. Initially, the Earth Observatory of Singapore, in collaboration with the Advanced Rapid Imaging and Analysis team at NASA’s Jet Propulsion Laboratory and the California Institute of Technology, provided a high-level survey of damage using satellite imagery before and after the explosion. This damage map overlay uses differences between the satellite imagery to identify locations where damage is expected to be heavy (red) to moderate (yellow), with the absence of color signifying minimal damage. IBD curves corresponding to the range of TNT equivalent estimates are also plotted in Figure 3 for direct comparison to the industry-accepted explosive safety standards.

Subsequently, researchers and engineers from the American University of Beirut personally inspected and assessed individual structures throughout the city to quantify damage. The damage levels were broken down into similar categories as the satellite imagery, from destructive damage (red) to nondestructive damage (green). However, unlike the satellite imagery, the AUB team was able to differentiate between structural and nonstructural damage on a case-by-case basis. The individual buildings assessed by the AUB team are shown in Figure 3 using appropriately colored circles.

Beirut features a variety of ancient religious buildings as well as historic, heritage, and newly developed buildings and high-rises. Most of these buildings were affected by the blast waves, which caused significant or partial damage. The level of damage is mainly dependent on the type, age, and location of these buildings. The damage assessment for these buildings is being performed to inform the public about the extent of damage that occurred and to assist in the engineering decision of either repairing or demolishing the affected buildings. Also, these assessments help provide the cost estimations for buildings that need to be repaired.

For residents, Beirut now looks like a war zone, with broken glass, destroyed facade systems, and collapsed buildings at every turn. But the city is also now a treasure trove of data for engineers who study the effects of explosions on structures and infrastructure. To help the city’s recovery efforts, researchers and engineers at AUB set up a hotline for residents or building owners to schedule structural damage assessments. The initial observations from these assessments show that damage can be classified, and the buildings tagged, using three main categories: destructive (red), partially destructive (yellow), and nondestructive
(green).

Table 2 details a subset of the buildings that the group surveyed, the range from the explosive event, and the peak side-on overpressure and impulses based on a 630-ton TNT equivalent blast that the authors calculated using the Kingery and Bulmash equations described in the U.S. Army Ballistic Research Laboratory’s Airblast Parameters from TNT Spherical Air Burst and Hemispherical Surface Burst, Technical Report 02555, published in April 1984.

The buildings exhibiting destructive damage collapsed, as did the unreinforced masonry bearing wall of the building. This building is located about 1 km away from the explosion, and it is classified as a historical masonry building that consists of unreinforced masonry blocks from natural stones with wooden roof trusses. This type of building is designed to resist gravity and wind loads only; it cannot resist lateral loads (that is, earthquake or blast loading). This is due to the absence of seismic structural systems and horizontal diaphragms that can help in resisting the shock waves due to explosion. A reinforced-concrete building located near the collapsed historical building withstood the blast load without any severe structural damage recorded. It is assumed that the gravity reinforced-concrete building frame provided adequate stiffness capable of resisting the blast shock waves.

The buildings identified as having partially destructive damage are not totally collapsed but were still severely affected by the explosion. These buildings need careful damage analysis and assessment to assist in the engineering decision to rehabilitate or demolish each structure. The image below shows a building identified as having partially destructive severe damage. The building is classified as a historical building that consists of natural stone masonry bearing walls with wooden roof trusses. This building is located about 1.2 km away from the explosion. The top timber roof truss failed and is sitting on the floor below. This is because the timber roof trusses, as constructed, cannot act as diaphragms to resist any lateral load. The third floor of the exterior wall of this building also experienced severe damage.

The buildings with nondestructive damage resisted the blast load with nonstructural component damage only. Those buildings were typically reinforced-concrete buildings located less than 1 km from the explosion. The damage was limited to window glazing, facades, external tiling, false ceilings, and water pipes and other utilities. Theses building were designed to resist earthquakes using reinforced-concrete shear wall systems that provide the building with very high stiffness in both directions, which was able to resist the blast-induced lateral loads. While this damage may seem minor with respect to the structural damage experienced by other types of buildings, it can severely impact a community’s ability to recover and occupy buildings damaged in this manner.

Mitigation of Future Events
For engineers, the obvious question is: What’s next? What can the building industry do to prepare for events such as this? The Port of Beirut explosion unintentionally resulted in a substantial amount of experimental data to be used in comparing expected and actual performance of buildings under an extreme blast event. The assessment and comparison methods discussed throughout this article only scratch the surface. However, four important findings were developed from this study.

First, explosive safety standards adopted by the United States and the United Kingdom were compared to actual damage witnessed from satellite imagery and field observations. In general, the existing minimum distances specified in government standards for the location of inhabited buildings are quite conservative, as non­destructive damage was routinely found within this limit. The IBD is typically applied to military bases or rural settings where sufficient space is provided throughout the site. Explosive safety standards are rarely applied to urban environments like that of Beirut.

Second, it is clear that there was an overall lack of structural damage in Beirut. Several old buildings, designed and constructed prior to modern seismic guidelines, did collapse. However, most buildings experienced substantial nonstructural facade damage. The failure of the facades helped dissipate the blast energy and kept the load from transferring to the structural load-bearing elements. Had this not occurred, the energy from the explosion could have caused substantial structural damage. It is important to note that lack of structural damage does not guarantee an adequate level of life safety. Broken glass, failed facades, damaged false ceilings, and inoperable elevators can and will present substantial dangers to building occupants. In fact, the Explosives Safety Board states in its Defense Explosives Safety Regulation 6055.09 that “it is evident that, even at IBD, conventional structures may not provide complete protection from the blast. Generally, the weakest portions of any conventional structure are the windows.”

Third, the damage in Beirut fits within the explosive safety framework commonly used throughout the world to protect people and infrastructure from extreme explosive events. Viewing the explosion and aftermath within an explosive safety framework highlights the wide variation of building response found throughout the city. While facade and nonstructural damage were found within the IBD, no structural damage was found outside of it. This means that a vast majority of the buildings in Beirut south of the Charles Helou highway survived the explosion with little to no structural damage, regardless of their proximity to Hangar 12. Had they not, the casualties would have been substantially higher and recovery for the city would take much longer. It is important to note that the buildings north of the Charles Helou highway, located at or directly adjacent to the Port of Beirut, were inaccessible to the AUB team. Observation of published photographs shows that this area was mostly destroyed.

Finally, the field observations and structural assessments are extremely important in helping provide engineering solutions for the damaged buildings in Beirut, especially for the ancient religious, historical, and heritage buildings. The structural design (i.e., seismic resistance) and construction quality vary throughout the infrastructure in Beirut, which has a major influence on buildings’ responses during explosions. Upgrading critical infrastructure and culturally important buildings susceptible to dynamic loading (seismic or blast) would help mitigate risk in future events.

Kevin Mueller, Ph.D., P.E., M.ASCE, is a senior project engineer in the Chicago office of Thornton Tomasetti. Elie Hantouche, Ph.D., A.M.ASCE, is an associate professor of structural engineering at the American University of Beirut. Nicolas Misselbrook, CEng, C.Phys, is a principal in the Dalgety Bay, Scotland, United Kingdom, office of Thornton Tomasetti Defence Ltd.

The authors would like to thank the AUB post-disaster building structure safety team, including the structural engineering faculty and staff and the university’s ASCE student chapter, for participating in the data collection.

This article first appeared in the November 2020 issue of Civil Engineering as “Lessons Learned.”

Errata: The print version of this feature incorrectly noted in the text that Figure 2 included a charge weight of 100 kg TNT. That number, as identified in Figure 2, is 1,000 kg. The print version of table 1 incorrectly listed Chernobyl as being in Russia; this version corrects the location to Ukraine. We regret the errors.

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