A story of great resonance in Seattle because of the condition of the Alaskan Way Viaduct and the storm-battered SR-520 floating bridge was the 2007 collapse of a highway bridge in Minnesota. That disaster sent a warning to politicians everywhere that a nasty surprise might be lurking in aging infrastructure near — or under — you. The operating assumption was that America's neglect of roads and bridges was the cause of the collapse.
Governors, like Washington's Christine Gregoire, were quick to wave the bloody shirt of the Minnesota mess to bolster arguments to embark and new megaprojects. We don't want a Minnesota disaster here, they'd warn Chambers of Commerce with a tone of foreboding.
But now we have the National Transportation Safety Board's final conclusion about what caused the collapse: turns out it was a design flaw exacerbated by putting too much weight on the bridge while crews worked on maintaining it (a preliminary finding suggested this last spring). In other words, it didn't collapse because it wasn't being care for, it fell down because it was being maintained. And it likely wouldn't have collapsed at all if it had been designed properly in the first place.
What the NTSB did discover is still serious: a flaw in how bridge design is reviewed. There may well be others around the country that are also poorly engineered. The main culprits in Minnesota were undersized gusset plates in the center of the span.The "gusset gap" is now symbolic of a hole in the review and inspection process that now looms as a greater priority than simply tearing down and replacing stuff because it's old. In other words, build stuff right the first time and rare incidents like the one in Minnesota won't occur.
