More on Minneapolis Bridge Collapse

The reports issued in 2005 and 2006 by the Minnesota Department of Transportation are not currently available. However, some tidbits about the bridge's condition can be gleaned from the MnDOT's press releases about repairs to 35W bridge, which collapsed about six hours ago.

From a September 2, 2004 release:

The left three lanes in both directions will be closed throughout the night until 5 a.m. Friday morning. The closures are needed so workers can repair a bridge panel in the northbound lanes and conduct the annual fall inspection of the I-35W bridge anti-icing system.

The anti-icing system was installed in 1999--32 years after the bridge was erected-- and according to a press release issued on June 30, 2005, was credited with reducing crashes on the structure by two-thirds. The statement also points out, "The bridge's location above the river near the St. Anthony Falls and nearby power plants made the bridge susceptible to icy conditions and resulting crashes."

This bridge went through numerous freeze-thaw cycles every year (just like thousands of bridges in cold weather climates all over the world): Week-long periods of sub-zero temperatures, big snowfalls that can melt within days, dripping salt water down those steel girders that now sit like a mangled pile of green spaghetti in the middle of the muddy river. That's not to suggest that the load-supporting girders are the primary suspects--no one six hours after this tragedy can fix the blame on any one structural element. Leave that to the engineers from the National Transportation Safety Board who will arrive on the scene tomorrow to start inspecting the rubble and sifting through the MnDOT inspection reports in an effort to root out the cause of what will probably go down as one of the most significant bridge disasters of modern times. But it's worth noting at the end of this blisteringly hot August day that this bridge had to survive 40 brutal Minnesota winters before it succumbed.

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