The National Transportation Safety Board said earlier this month that undersized gusset plates in the Interstate 35-W bridge in Minneapolis were “the critical factor” in the bridge collapse of August 1, 2007, that killed 13 people and injured 100. Chairman Mark Rosenker said the plates, which connected steel beams, were roughly half (1/2 inch rather and 1 inch) the thickness they should have been because of a design error. Investigators found 16 fractured gusset plates from the bridge’s center span, he said.
The NTSB’s final report is expected this fall. This past Sunday marked the 180 day deadline for filing … Read the rest