Article from “Car and Driver”, July 2011
The Minneapolis bridge carrying I-35W over the Mississippi River, which opened to traffic in 1967, was almost 2000 feet long and designed to handle 66,000 cars a day. Over the years, it had been modified, increasing the total weight, or “dead load.” Another construction project concentrated supplies and equipment over a gusset plate that, by an original design error, was inadequate to support so much weight. At 6:05 p.m. on August 1, 2007, under the pressure of the evening commute, the gusset plate suddenly failed, shedding its load onto other gusset plates, which could not handle the burden. The bridge collapsed, killing 13 people and sending 98 to hospitals. It was a spectacular failure. State Departments of Transportation quickly checked out 700 similar bridges and closed a handful.