The 950-ton section of a pedestrian bridge’s collapse at Florida International University (FIU) that claimed six lives on March 15 has put stakeholders, design and installation firms under intense scrutiny. After months of preparation, the 174-foot span had been installed on March 10, and investigators and authorities are trying to establish if negligence played a part in the tragedy on SW 8^th Street on FIU’s Modesto A. Maidique Campus.

The bridge was constructed off-site and relocated using Accelerated Bridge Construction (ABC), a popular (and usually successful) industry method that aims to reduce potential risks to workers, commuters and pedestrians and minimize traffic interruptions. According to FIU, the bridge should have been a record-setter; on March 10, the University claimed it was “the largest pedestrian bridge moved via Self-Propelled Modular Transportation in U.S. history.” It was also poised to be the first in the world to be constructed entirely of self-cleaning concrete, which would have ultimately reduced maintenance costs.

Munilla Construction Management (MCM) was the Miami-based construction firm hired by FIU to manage and construct the FIU-Sweetwater UniversityCity Bridge, which jointly worked with design firm FIGG Engineering-Bridge Group. Barnhart Crane and Riggingoperated the Self-Propelled Modular Transporters that placed the bridge on its permanent supports, and engineering firm BDI was subcontracted to conduct monitoring while the bridge was moved into place.

It was expected that the footbridge would be completed and operational in early 2019 and would also have served as a study and gathering space for students. The $14.2 million project was funded by Florida Department of Transportation, FIU and the City of Sweetwater, U.S. Department of Transportation (DOT) TIGER Grant, but the blame shifting has already begun. The Miami Herald reported:

…the project required “an independent, secondary design check,” and the design team, FIGG Bridge Engineers, hired another engineering firm, Louis Berger. That firm “was not FDOT pre-qualified for this service, which is required under FIU’s agreement with the state. FIU’s design build team is responsible for selecting a pre-qualified firm and ensuring this process is followed.”

The main span of the FIU-Sweetwater UniversityCity Bridge was installed in a few hours with limited disruption to traffic over the preceding weekend. FIU stated that on the morning of the collapse that MCM and FIGG met to discuss a crack on the on the structure, but ultimately concluded that “there were no safety concerns and the crack did not compromise the structural integrity of the bridge. This meeting lasted approximately two hours and included FIU and FDOT representatives.”

FIU added an FAQ page to its website in the aftermath of the collapse. It clarifies that FIU did not yet own the bridge “because it was still under construction” and names the key stakeholders, but does not yet reveal what was happening at the time of the collapse “because it still does not yet have the information.” The DOT stated that Secretary Elaine L. Chao dispatched Federal Highway Administration professional staff to the site to support the National Transportation Safety Board’s (NTSB) investigation.

An insightful article published by Wired explains the ABC process and looks at other incidents, noting that in this case the collapse could stem from design flaws and possibly loose cables burdened by the weight of the bridge.