Florida International University pedestrian bridge collapse

The Florida International University pedestrian bridge collapse occurred on March 15, 2018, when a 175-foot-long (53 m) section of the FIU-Sweetwater UniversityCity Pedestrian Bridge collapsed while under construction. The collapse resulted in six deaths (one worker and five motorists), ten injuries (six serious and four minor), and eight vehicles being crushed underneath. Of the serious injuries, one employee was permanently disabled. At the time of the collapse, six lanes of road beneath the bridge were open to traffic.

The pedestrian bridge was designed to connect the town of Sweetwater to the campus of Florida International University (FIU) in University Park, a suburb west of Miami, Florida, United States. The two were separated by a busy eight-lane highway, which the bridge was designed to span.

The engineering design error that directly led to the collapse was identified by the National Transportation Safety Board (NTSB) as a miscalculation of resistance to sliding of the connection between the walkway surface, and the truss that held it up. The walkway surface was poured concrete, which was allowed to harden before the truss braces were poured above it. These truss members were connected to the deck by steel reinforcing rods embedded in the deck and in the concrete of the truss. In order to hold up the bridge these connections had to prevent the truss from sliding along the walkway surface. The resistance to sliding was miscalculated, and thus was not enough to prevent the connection from sliding causing cracks in the truss concrete. As the cracking enlarged, it ultimately caused the complete disconnection of one of the truss-to-walkway connections, leading to the collapse.