Engineering students see hidden beauty in Fort Worth bridge

Posted Thursday, Feb. 28, 2013  comments  Print Reprints

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Many people have predicted that when the new West Seventh Street bridge opens in November, it will be a beautiful landmark connecting downtown Fort Worth to the city's west side.

For some, that beauty will stem from the structure's recessed lighting, or the shape of its 12 arches spanning the Trinity River.

For others, like David Tatum, the beauty is deeper. Tatum is a civil engineering student, so he is fascinated by factors such as the load-bearing capacity of the concrete or the role of giant wires buried within the arches to create tension that keeps the bridge standing.

"I like how they're keeping the concrete temperature even on the inside and outside, so they don't get cracks," said Tatum, a junior at the University of Texas at Arlington. He was among roughly two dozen engineering students who toured the construction site for the giant concrete arches last week near Montgomery Plaza. "Concrete is good but it's also not reliable in some stages if you don't properly set it up."

For about a year, residents have watched as the arches were built off-site, about a quarter-mile west of the project location. But beginning late next month, the excitement is going to move from that work site to the bridge itself.

In late April, workers will use giant machines to slowly move the prefabricated arches, one at a time, to the site of the original bridge -- a 100-year-old, structurally deficient bridge that is being replaced after years of neglect. There, the 300-ton arches will be carefully set on new columns installed on the outside edges of the old bridge.

Traffic will continue to use the century-old bridge during the arch installations, said Val Lopez, a Texas Department of Transportation spokesman.

Impact on motorists

The real impact on motorists will occur shortly after the conclusion of Mayfest, which runs May 2-5 along the river near downtown Fort Worth. That's when the contractor, Sundt Construction Inc. of San Antonio, will permanently shut down the old West Seventh Street bridge and demolish it.

Traffic will be detoured to West Lancaster Avenue and other entrances to downtown while the bridge is closed, and motorists will endure several months of traffic delays. State officials believe the delays will be minimal.

The contractor will have up to 150 days to build the new West Seventh Street bridge, using the majestic arches as an exoskeleton. Sundt will have an opportunity to earn a bonus of $30,000 per day for up to 30 days, if the firm can manage to get the new bridge open early.

There is also a disincentive for any project delays. Sundt could be subject to a penalty of up to $30,000 a day if the bridge closure lasts more than 150 days.

The goal is to ensure that the new bridge is open before the Christmas shopping season, when business owners say it will be essential that a good connection between downtown, West Seventh and the museum district is re-established.

Since work began last year, the work site along West Seventh Street has resembled that of a shipyard, with giant overhead cranes lifting each bridge arch upright after the concrete has been cured.

The West Seventh Street bridge was among several aging bridges in the Fort Worth area that were thrust into the spotlight in 2007 after the collapse of a highway bridge in Minneapolis killed 13 people and injured 145. Despite that attention, five years later the Star-Telegram reviewed federal bridge records and determined that conditions were arguably worse.

In Tarrant County, 29 of 2,047 bridges in the area scored below 50 on a 100-point scale in their most recent inspections. Those scores were worse than in 2007.

For example, the old West Seventh Street bridge, which carries an estimated 12,000 vehicles a day, had a 38.8 score.

Its superstructure was rated in poor condition, with advanced deterioration and spalling -- the flaking off of concrete. The deck and substructure ranked only slightly higher, in fair condition with minor cracking and loss of material.

State inspectors said in late 2011 that, were it not for the $25.9 million construction of a new West Seventh Street bridge, the old bridge would eventually have to be shut down.

Bright minds

When politicians visit the work site, their attention focuses on when the work will be done.

For people who live or own businesses along the route, the questions often revolve around the impact of construction detours during bridge construction.

But hosting a group of engineering students is a breath of fresh air for those overseeing the work at the construction site. These students are interested in the fine details of the project, including the types of materials used.

"It's good to have a lot of bright minds come out to see an innovative project," said Scott Cooner, bridge mobility coordinator.

Gordon Dickson, 817-390-7796

Twitter: @gdickson

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