Two years after a horrific pedestrian bridge collapse at Florida International University (FIU) in Miami that left six dead, the Florida Department of Transportation (FDOT) announced it would build a new crossing.
The March 15 collapse was caught on camera as the 174-foot-long, 950-ton span, which was completed only five days prior and crossed eight lanes of traffic, fell onto the road below and crushed eight cars, seven of which were occupied. At the time, it was speculated that the bridge’s novel construction method—assembling the span next to the road, and then craning it into place to avoid disrupting traffic—somehow played a part in the structure’s catastrophic failure. However, the National Transportation Safety Board (NTSB) wrapped up its investigation at the end of 2019 and found a number of factors influenced the collapse. The bridge, designed by FIGG Bridge Engineers, for one, failed to account for the structure’s weight once it would need to self-support; reads the report:
This comparison found that the demand for the node was nearly twice what the design team had calculated. The investigative report discusses how this error was made. Second, the design team also overestimated the capacity of the node to resist shear (horizontal force) where the nodal region (11/12) was connected to the bridge deck. This overestimation was the result of the designer using incorrect loads and load factors in its calculations.
Additionally, the NTSB claimed that FIGG’s independent peer review from consultant Louis Berger failed to catch those mistakes. The report also noted that action to address the bridge’s cracking should have been taken earlier, and greater redundancy should have been baked into the design. FIGG has refuted those claims.
For the FIU bridge’s replacement, the FDOT will be handling every aspect of the project and will integrate the NTSB’s recommendations.
“FDOT has learned valuable lessons since the tragic events surrounding the FIU bridge collapse two years ago. The Department has worked closely with the NTSB and local partners to ensure proactive safety measures are included in the plans for this much-needed bridge,” said Florida Department of Transportation secretary Kevin J. Thibault, in the announcement. “The Department will ensure all safety measures are in place and are followed so we may provide a safe option for pedestrians in this high-traffic area.”
Design of the bridge will be undertaken in tandem with FIU and is expected to begin early next year and last for two years, with construction taking another two years.