The West Seventh Street bridge in Fort Worth that opened 10 years ago this month notched a lot of firsts.
It was the world’s first precast network arch bridge, according to the Texas Department of Transportation. The bridge’s 12 parallel arches were constructed off-site at a nearby casting yard then moved into place.
That innovative technology meant the city only had to shut down one of its major traffic arteries — West Seventh Street between downtown and the west side — for fewer than 150 days, shaving seven months off the typical time frame for bridge construction, according to Val Lopez, TxDOT public information officer for the Fort Worth district.
“The idea was to turn to our successes in precast technology and mass production –– only, we knew we wanted something more attractive for the West 7th Street bridge,” said TxDOT structural engineer Dean Van Landuyt when the project was announced in 2013. “Aesthetics were paramount. We tried to do something worthy of the great buildings and great architects who have worked in the city.”
The original Seventh Street bridge, also known as the Van Zandt Viaduct, was first completed in 1913 and updated in 1953 when levees were built on the river. The beams, girders and deck from the 1913 bridge were in critical need of replacement at the time the new bridge was built, according to the city of Fort Worth.
Using conventional techniques to remove and replace the nearly 100-year-old bridge would have meant closing the crossing over the Trinity River for a year or more during key events such as the Fort Worth Stock Show and Rodeo, Mayfest and the Main Street Arts Festival, Lopez said.
That sent the designers and contractor to consider the idea of building the arches off-site and transporting them to the location, minimizing construction time, he said. The construction site was located where the Left Bank development is currently, on land donated by Chesapeake Energy Corp.
“We began constructing the columns that supported the arches around the same time we started building the arches themselves,” said John Carlson, senior vice president at Sundt Construction Co., the San Antonio firm that was the contractor for the project. “This alternative phasing helped speed up the work and eliminated road closure during column construction.”
3D modeling key
That precasting of the arches was an obvious innovation on the project, but Carlson said the project also made extensive use of 3D modeling to plan, build and sequence the setting of the arches and critical floor beams.
That was key to the project’s success, Carlson said.
“Modeling the precast stainless-steel girders before construction started on them identified 27 conflicts between the reinforcing steel, stainless steel, lighting, post-tensioned strands and other miscellaneous imbeds,” he said.
Sundt made corrections to the design to eliminate these conflicts.
“Had we not 3D modeled these girders prior to start-up, we would have had to stop until the redesign was completed and it would have delayed the project,” he said.
What the engineers, designers and construction workers didn’t expect was for the bridge to become a signature visual image of the city itself.
“We did not expect this,” said Carlson.
The bridge has become something of the face of Fort Worth, appearing as the backdrop to local morning television programs, used on Visit Fort Worth and for many visual representations in a variety of marketing uses for the city. The bridge is illuminated at night. In 2016, due to electrical design problems, the original lighting on the bridge was replaced with a multicolor LED system that utilized higher grade components.
“Let’s face it, we live in an Instagram era and the Seventh Street bridge preens for a selfie with its undulating design and candy-colored lights,” said Allen Wallach, CEO and president of PAVLOV Advertising.
The bridge has become a boon to the city’s marketing machine, Wallach said.
“That night image against the skyline adds a burst of color and motion, blends modern and classic, and conveys an appealing sense of arrival and impending excitement for what’s to come,” he said. “It doesn’t surprise me it has quickly been woven into the visual fabric of the city.”
TxDOT used the bridge for a documentary citing the bridge’s construction and artistic breakthroughs. TxDOT also uses the bridge to illustrate many of its publications.
“We have been awarded the Build America Award three times in the last 10 years for TxDOT projects and the Seventh Street project was the first,” he said.
The bridge has received some internal praise as well, with a conference room at Sundt’s San Antonio headquarters named for the bridge, Carlson said.
“All of our conference rooms are named after iconic projects we have completed in our 133-year history,” he said.
West Seventh Street Bridge
Contractor: Sundt Construction Co.
Cost: $26 million
Opened: November 2013
Each of the 12 arches is 163.5 feet long and weighs 300 tons. The bridge span is 980 feet.
The bridge is 30 feet wider than the previous bridge and has sidewalks for pedestrians and bicycles on the sides.
The original bridge used reinforcing steel supplied by local Gachman Metals, now known as GAMTEX Industries, a 113-year-old family firm. The contractors cut out a piece of the old rebar, which was square shaped, unlike today’s round rebar, and presented it to the firm.
Bob Francis is business editor for the Fort Worth Report. Contact him at firstname.lastname@example.org. At the Fort Worth Report, news decisions are made independently of our board members and financial supporters. Read more about our editorial independence policy here.