Instagram video shows collapse of FIU pedestrian bridge
On the morning before the pedestrian bridge at Florida International University collapsed over a busy Miami road in March 2018, killing six people and injuring eight others, the firm that designed the span assured a meeting of state highway officials, university administrators, contractors and others that the span was safe.
That assurance is revealed in records released Monday by the Florida Department of Transportation. Until now, the National Transportation Safety Board, which has been investigating the cause of the collapse, had ordered that the records be withheld.
The newly released 44-page document contains minutes and slides with detailed engineering calculations from a March 15 meeting of key project officials. The meeting was called to discuss severe cracking that had appeared at the north end of the concrete bridge, which was under construction. In attendance were officials from Tallahassee-based FIGG Bridge Group, which designed the bridge, FIU and FDOT, as well as Munilla Construction Management, the private contractors building the bridge in a joint venture with FIGG.
The summary of the meeting has been regarded by experts and attorneys for the victims as a potentially critical piece of evidence in determining why the bridge collapsed and how the project team went about addressing the cracks. But while it adds some details about team members’ concerns and analysis, it does not answer some key questions and raises others.
The minutes confirm earlier media reports that the project team decided not to close the Tamiami Trail while engineers attempted to repair the cracks and determine what caused them. The assurance that the cracks did not represent a structural risk came from engineers for FIGG, which designed the bridge.
“FIGG assured that there was no concern with safety of the span suspended over the road,” according to the minutes of the meeting, which began at 9 a.m.
The minutes also indicate that FIGG’s engineers did not know what caused the cracks, which were increasing in length daily, but concluded the 950-ton bridge span did not require shoring up from below while temporary repairs proceeded. The document includes numerous photos of a PowerPoint presentation by FIGG with detailed calculations that appear to show the engineers were confident the bridge remained structurally sound and would stand up despite the cracking.
Cracks in concrete are not unusual, and FIGG also said during the meeting that its “analysis predicts diagonal cracking,” according to the minutes. But FIU officials seemed to dispute that. “FIU commented to FIGG that nothing predicted this cracking,” the minutes say.
The notes, however, suggest little sense of urgency among meeting participants. FIU asked engineers for Bolton Perez and Associates, the firm in charge of inspections and project overview, what they thought of FIGG’s analysis. FDOT asked FIGG for a copy of its presentation to send to the agency’s structural engineers. Bolton Perez engineers replied they could not comment but would “expedite” the requests “in 2-3 days.”
Bolton Perez, acting as the construction, engineering and inspection team (CEI), did say it wanted a second opinion on FIGG’s presentation. “CEI requested that it wanted more eyes on this and that the more eyes on this, the better,” the minutes read.
Three hours after the meeting ended, the bridge came apart at the north end and collapsed in a heap of steel and concrete, crushing motorists waiting below it at a stoplight. One crew member working atop the bridge was killed and another critically injured.
The minutes do not clear up a key mystery: Why were the workers on the bridge, and who ordered them out there? The document indicates that FIGG told the group that the crew was sent out to tighten steel rods inside a critical diagonal support strut where cracks had appeared, but there’s no discussion in the minutes of what that was meant to accomplish.
That’s because the decision to send the crew out was made before the meeting convened, the minutes show. But the minutes do not say who made that call.
Independent experts say the tightening is likely what caused the bridge to collapse, but have questioned why that was being done. The experts say the rods inside the diagonal piece in question, known as No. 11, were there only temporarily to provide support while the span, which was built by the side of the road, was lifted into place over the trail. Tightening the rods would not have strengthened the bridge structurally, they say.
The documents show that FIGG engineers did zero in on a critical connection “node” where the No. 11 strut met the bridge deck and the last vertical support piece, No. 12. That’s where independent experts who examined bridge blueprints for the Miami Herald believe the bridge failed. The experts say they believe FIGG’s engineers failed to adequately account for structural stresses that the bridge’s unusual design placed on the node. Consequently, they say, the No. 11 piece and the deck connection were undersized and under-strength.
The NTSB, in a brief report issued in November, said design flaws led to the cracking, but stopped short of blaming those for the collapse. The NTSB investigative update bolstered conclusions reached by independent bridge engineering experts consulted by the Miami Herald and others posting in online professional forums. The agency said Monday it expects to publish a full report on its investigation in the fall.
The NTSB said it lifted restrictions on the release of documents because its investigation has progressed sufficiently that it no longer requires they be sealed from public view.
“The NTSB received requests from several of the parties to our investigation for relief from the restrictions our ongoing investigation placed on the release of documents and information we collected,” said agency spokesman Christopher O’Neill in an email. “Given the nature of the requests, and that the NTSB’s investigators have completed all the group factual reports and the technical review of those reports, the NTSB believes it is at a point where some of the restrictions can be removed.”
Stuart Grossman, an attorney for survivors Kevin Hanson and Richard Humble, said the lifting of the NTSB restriction would make it easier to pursue civil cases that have been filed against the companies that built and designed the bridge.
“We had access to these materials in a limited capacity,” Grossman said. “Now, the gloves are off. We can really go forward.”
He said he expects the newly released materials will continue to demonstrate the project dangerously lacked oversight.
“This was a debacle from its design through its failure,” he said. “No one took the time to understand the implications for the public and the public paid the price.”
The discussion summarized in the minutes suggests that the tightening taking place when the bridge fell may have been part of a temporary repair scheme to lessen the stress on that node by placing steel clamps on an adjacent structural support piece, said Dave Beck, a New England engineer who has closely analyzed the project and who examined the minutes and PowerPoint images on Monday.
Beck said he believes the team did not spend enough time focusing on the cracks and the possible causes. He and other engineers say the cracks, which reportedly first appeared when the bridge was lifted into place over two pylons five days before the meeting, were severe enough to have justified stopping work while a diagnosis was made.
But Beck said that, judging from the PowerPoint images included in the document, the team spent most of its time at the meeting discussing a “diaphragm” — a triangular concrete piece that goes between the bridge deck and a support pylon at the north end — and the placement of temporary wedges between them to provide extra support.
Beck said he believes that did nothing to address the causes of the cracking, likely the result of the under-designed No. 11 strut shearing away from the deck.
“The engineers here, they look more concerned about the diaphragm than they were about Number 11, which is where the cracks were,” Beck said. “They go through a lot of numbers, but did not take into consideration the actual cracking conditions.
“Being a professional reading this, it’s sad,” he said.
The document also appears to lend support to contentions by Beck and other independent experts who say the catastrophe might have been averted had the bridge’s second, shorter “back span” — a piece connecting the main deck across a canal to the town of Sweetwater — already been in place or under construction. The back span would have tied into the main span structurally and would likely have provided enough additional strength to prevent the bridge collapse, experts say.
But the plan called for constructing the back span only after the main span was in place. The minutes show that FIGG told meeting attendees that repairs to the span could start once that back span was in place because that would relieve the forces on the No. 11 piece. MCM then said it would “expedite” construction of the back span.
Until then, FIGG recommended only temporary measures to stabilize the critical node, but no repairs of the cracks.
FIGG and MCM had no response when asked whether there would be a crack monitoring plan, according to the minutes.
A spokesperson for FIGG did not immediately respond to a request for comment. MCM declined to comment due to an ongoing investigation by the National Transportation Safety Board.
But NBC-6 has reported that FIGG has contested the accuracy of the minutes, taken by someone with Bolton Perez, in court hearings in suits filed by survivors and families of victims. FIGG has submitted alternative notes, but those have not been released.
A bridge worker first noticed cracks in the bridge on March 10 — the day the prefabricated span had been raised over a pylon at each end — and passed photos of the cracks up the chain of command, according to his attorneys. The bridge’s unusual variation on a traditional “truss” design meant it needed support only at either end, leaving the roadway clear of columns.
Three days later, the project’s chief engineer reported the cracks to the state’s transportation department, although the engineer said he and his team were “not concerned about it.”
MCM said it filed for bankruptcy on March 1 — a steep reversal in fortunes for a company that had been a top builder of local government projects. The company has reached a deal with its insurers to pay up to $42 million to victims and their families.