WASHINGTON — Federal investigators have identified a design flaw as the cause of last year's Interstate 35W Minneapolis bridge collapse that killed 13 people, a congressional official said Tuesday.
The official, who was briefed by the National Transportation Safety Board, said that investigators found a design flaw in the bridge's gusset plates, which are the steel plates that tie steel beams together. The official spoke on the condition of anonymity so as not to pre-empt an update being provided later Tuesday by the NTSB chairman, Mark V. Rosenker.
The findings are consistent with what the NTSB said about a week after the Aug. 1 collapse, in which the bridge plunged into the Mississippi River. At the time, the NTSB said it had found issues with the collapsed bridge's gusset plates, but expected a full investigation to take more than a year.
At the time, Transportation Secretary Mary Peters advised states to consider the additional stress placed on bridges during construction projects. An 18-person crew was working on the bridge when it collapsed.
Nearly three months later, she told a gathering in Washington of a "working theory" of a poorly designed gusset plate and a heavy load of construction materials.
Meanwhile, state lawmakers announced plans last month to spend up to $500,000 to hire legal counsel to aid in a legislative inquiry into the collapse.
The bridge was deemed "structurally deficient" by the federal government as far back as 1990.
Late last year, President Bush signed a massive spending bill which included $195 million to help replace the bridge. That came on top of the $178.5 million the federal government has already given Minnesota for the project.
