As a result of those findings, NTSB recommended the U.S. Dept. of Transportation direct states to include effects on gusset plates as they do their bridge load calculations, and DOT quickly issued a technical advisory.
During its wreckage recovery, the on-site NTSB investigative team found 16 fractured gusset plates at eight nodes, or joints, in the bridge’s main center span. Rosenker said the damage patterns and fracture features uncovered in the investigation “suggest that the collapse of the deck-truss portion of the bridge was related to the fractured gusset plates and, in particular, may have originated with the failure of the gusset plates at one of those eight nodes.” A construction crew performing modifications on the bridge was working near one of the nodes where there were two fractured gusset plates.