Interstate 35W Bridge Failure

At 1805 CDT this evening the Interstate 35W bridge over the Mississippi River in Minneapolis collapsed into the river. While it’s too early to know the cause, what’s visible on television newscasts paints a remarkable picture of at least one, if not many, catastrophic failures in the forty-year old structure.

It’s not clear where the collapse began, but the central span over the river appears to be more-or-less directly below where it used to be, some sixty feet above. At least two spans at the southern end, I believe it is, looks to have twisted, and collapsed laterally to the east, while the northern end experienced a very disturbing series of failures, including decking collapsing away from the middle of the bridge, pulling one series of steel supports off their concrete pillar.

Now, as of 10pm local, the news media are reporting that remaining southern parts of the bridge – which was several thousand feet long, in numerous spans of varying support types – are beginning to “experience downward movement”, possibly as they are beginning to topple northward.

The Mississippi River is now completely obstructed immediately downriver of Lock and Dam Number Two, by the bridge debris, completely severing access upriver. A span of the bridge has also landed on several railroad tracks (and a couple of grain cars), creating a further transportation nightmare for the region.

How this could have happened, I don’t know. I suspect the final verdict will be age- and fatigue-induced structural failure, but I have to wonder if the design – or construction – were fatally flawed. Either way, time will tell…

Published in: General | on August 1st, 2007| Comments Off on Interstate 35W Bridge Failure

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