Leave your feedback Share Copy URL https://www.pbs.org/newshour/show/design-flaw-cited-in-investigation-of-minnesota-bridge-collapse Email Facebook Twitter LinkedIn Pinterest Tumblr Share on Facebook Share on Twitter Transcript The National Transportation Safety Board revealed findings Tuesday from its probe of last year's deadly Minnesota bridge collapse, citing a design flaw with steel "gusset plates" used to build the structure. NTSB chief Mark Rosenker details the agency's investigation. Read the Full Transcript JIM LEHRER: Next, what was behind that big bridge collapse in Minnesota? Ray Suarez has that story. RAY SUAREZ: It was the middle of a busy rush hour last August when the Interstate 35 bridge in Minneapolis collapsed into the Mississippi River.Thirteen people were killed, and more than 100 were injured. The eight-lane bridge was also carrying the weight of heavy equipment and materials for a repaving project at the time of the collapse.This video from an Army Corps of Engineers surveillance camera captured how the bridge collapsed while the cars were still on it.Questions about the condition of the steel deck truss bridge and its age — it was 40 years old — quickly led to new inspections of bridges and highways throughout the country.It was one of more than 77,000 aging bridges that had been labeled as "structurally deficient."For months, federal investigators have been looking into the accident. At a news conference today, they confirmed a critical part of the problem was a design flaw with the bridge itself.