MINNEAPOLIS (AP) — Old photographs of the Interstate 35W bridge show that two steel connecting plates were visibly bent as early as 2003 — four years before the span collapsed into the Mississippi River, killing 13 people.
Minnesota Department of Transportation officials declined to say when the state first knew about the bending.
Two photographs, part of a report issued earlier this month by the National Transportation Safety Board, reveal slight bends in the two gusset plates, which hold beams together and were in areas thought to be among the first points of failure in the collapse. The board’s Office of Highway Safety confirmed that the bowing was part of the bridge investigation, The Star Tribune newspaper reported Sunday.
Mark V. Rosenker, the chairman of the safety board, did not comment on the photographs, but he has said the original design for the bridge specified steel that was too thin for those and other gusset plates.
A spokesman for the board, Terry Williams, told The Star Tribune that the bowing was among “the many things that we are looking at as part of this investigation.”
The newspaper said inspection records made no mention of repairs to the gusset plates.
Mr. Williams did not immediately respond to a telephone message seeking comment on Sunday. A spokeswoman for the State Transportation Department, Lucy Kender, also did not immediately respond to telephone and e-mail messages.
The two photographs are thought to have been taken by URS Inc., a San Francisco consulting company the state hired to examine the bridge from 2003 to 2007.
“URS and the state have both got a lot of explaining to do,” said James Schwebel, a lawyer representing a group of bridge victims. “How could it possibly have been missed?” he said of the bending in the plates.
No lawsuit has been filed, but Mr. Schwebel said his engineering experts were studying the information.
Since the bridge’s construction in the 1960s, the State Highway Department had increased weight on the bridge by adding a layer of concrete to the deck in 1977 and by installing concrete barriers in 1998. And the National Transportation Safety Board said last week that at the time of the collapse more than 99 tons of sand had been piled on the roadway directly over two of the bridge’s weakest points.