The deadly 2007 collapse of the Interstate 35W bridge in downtown Minneapolis was an awful tragedy. But the lost bridge has remained useful for advocates of transportation funding.
For years, the I-35W disaster has served as a seemingly indispensable exhibit, routinely displayed during discussions of the dangerous deterioration in America's aging infrastructure. It's apparently crucial evidence for the case that America and Minnesota need to spend more tax dollars on transportation.
Our bridges, roads, railways, etc., may very well be in a state of decrepitude and disrepair that endangers Americans. But the I-35W bridge collapse is not clear evidence for that particular proposition.
Instead, the way that sad story is often pressed into service is evidence of a different sort of erosion in another essential foundation: It demonstrates a loosening devotion to diligent logic and truth-telling in our public debate and our journalism.
An old saying has it that the press is very accurate — except when it reports on a subject you happen to know something about. I've had something like that experience in the nearly seven years since — as the Star Tribune's politics and government news editor at the time — I supervised coverage of the National Transportation Safety Board's ruling on the cause of the I-35W bridge collapse.
The NTSB, the definitive word on these matters, found that the collapse had nothing to do with excessive age or deterioration. It was caused by an original design error made in the 1960s, when engineers installed gusset plates — steel braces that hold beams together — only half as thick as they should have been. A contributing factor was a heavy concentration of roadway construction materials on the bridge the day it fell.
Among the issues the NTSB explicitly ruled out as causes of the collapse were "corrosion damage" and "pre-existing cracking."
In short, the I-35W tragedy says something about bridge design processes, something about construction oversight, and maybe something about the need to double-check engineering calculations, even on long-standing structures. But it simply was not an example of a worn-out bridge giving way to the ravages of neglect. There may be such examples, but this isn't it.