Collapse of I-35w Highway Bridge, Minneapolis, Minnesota, August 1, 2007

On Wednesday, August 1, 2007, the eight-lane, 1,907-foot-long I-35W highway bridge over the Mississippi River in Minneapolis, Minnesota, experienced a catastrophic failure in the main span of the deck truss. Major safety issues identified in this investigation include insufficient bridge design firm quality control procedures for designing bridges, and insufficient Federal and State procedures for reviewing and approving bridge design plans and calculations; lack of guidance for bridge owners with regard to the placement of construction loads on bridges during repair or maintenance activities; exclusion of gusset plates in bridge load rating guidance; lack of inspection guidance for conditions of gusset plate distortion; and inadequate use of technologies for accurately assessing the condition of gusset plates on deck truss bridges. As a result of this accident investigation, the Safety Board makes recommendations to the Federal Highway Administration (FHWA) and the American Association of State Highway and Transportation Officials. One safety recommendation resulting from this investigation was issued to the FHWA in January 2008.