CHICAGO --- Federal investigators announced this week that a design flaw was largely responsible for last summer's fatal collapse of the Interstate 35W bridge in Minneapolis. National Transportation Safety Board Chairman Mark Rosenker said the bridge was built with gusset plates that were too thin to support the bridge with increased traffic and the extra weight of infrastructure improvements, the Los Angeles Times reported. Gusset plates are the steel parts that connect the girders, which support the bridge. The bridge collapse, which occurred Aug. 1, killed 13 people and injured more than 100. The bridge was originally built 40 years ago. The bridge designers were Sverdrup & Parcel, a civil engineering firm in Missouri, the Times reported. Rosenker added that investigators discovered 16 fractured gusset plates from the center section of the steel-deck truss bridge. At the time of the bridge collapse, maintenance crews were using tons of equipment and construction materials on the bridge's deck. A final NTSB report on the bridge collapse is expected by the end of this year.

Originally posted on Fleet Financials