Construction on the pedestrian bridge that collapsed and killed six people in the Miami area was behind schedule and millions of dollars over budget — partly because of a key change in the design and placement of one of its support towers.
Documents obtained by the Associated Press show that the Florida Department of Transportation in October 2016 ordered Florida International University and its contractors to move one of the bridge’s main support structures 11 feet north to the edge of a canal, which widened the gap between the crossing’s end sports and required some new structural design.
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The bridge’s signature 109-foot-tall pylon was to be built atop a base at the northern end of the span. In addition to basic support, its design would also contribute to the aesthetics of the bridge, which was touted as an architectural marvel. The bridge would have spanned a busy road and canal to connect the quickly-growing university to the nearby community of Sweetwater.
Designers wrote in their 2015 proposal that it provided “spectacular views” for both pedestrians and drivers passing beneath it.
But videos of the collapse show the the concrete, prefabricated segment of the bridge started crumbling on the same end of the bridge where the tower redesign occurred, two days after an engineer on the project reported cracks in the same location. The segment that failed had been placed atop the pylon’s footing.
Though it’s still unclear if the design change played a role in the failure, the Associated Press reports that emails between the school, contractors, Sweetwater officials and permitting agencies show a project that ended up behind schedule, which had officials worried that further delays could jeopardize millions in federal Department of Transportation funds.
The project was already running $2.6 million over its $9.4 million budget, and the finish date had been pushed back to January 2019 from July 2018.
Multiple engineers who reviewed the documents obtained by the AP said moving the tower after the bridge’s initial design invited errors.
Henry Petroski, a professor of civil engineering at Duke University and a leading authority on engineering failures, said even seemingly minor changes in a bridge’s design can lead to failures.
“Once a design is completed, subsequent modifications tend to be suggested and approved without the full care that went into the original design. This has happened time and again in bridges and other engineering structures,” he said.
Officials previously said they knew of the crack in the bridge but believed it was not a safety concern.
According to a FIU statement, FIGG’s engineer “concluded there were no safety concerns and the crack did not compromise the structural integrity of the bridge.”
Six people died and another 10 were injured when the bridge collapsed.
Among the people killed was Alexa Duran, who was driving her car at the time of the collapse. Friend Richie Humble, who was in the passenger’s seat, narrowly escaped the vehicle after is collapsed and killed Duran.
“I looked up, and in an instant, the bridge was collapsing on us completely. It was too quick to do anything about it,” Humble told the AP.
