Last year’s Interstate-35W highway bridge collapse in Minneapolis, the worst such accident in 25 years, was caused by an engineering flaw and the load on its deck, Bloomberg reported, citing U.S. safety investigators.
The bridge’s gusset plates — pieces of steel used to connect its beams — and the weight on the deck as it underwent repairs were central to the collapse, Bloomberg said, citing Bruce Magladry, director of the National Transportation Safety Board’s highway safety office.
The gusset plates, which were cited earlier this year by the NTSB as a contributor to the collapse, had a serious design error, according to Mark Bagnard, NTSB’s investigator in charge of the bridge probe, Bloomberg reported.
The bridge fell into the Mississippi River during evening rush hour on Aug. 1, 2007, killing 13 people and injuring 145. Federal officials later checked dozens of other bridges, and the board staff reiterated its recommendation for inspections on the 465 other U.S. bridges of similar design, Bloomberg reported.
The eight-lane bridge had had more than 577,000 pounds of construction materials and vehicles near a section where the failure occurred, according to a board report issued in March.
