Thursday, August 02, 2007

Officials warned in 1990: Bridge was "structurally deficient"

According to the Minneapolis Star Tribune structural deficiencies in the I-35W bridge were so serious that the Minnesota Department of Transportation (MnDOT) last winter considered bolting steel plates to its supports to prevent cracking in the fatigued bridge metal.

"Fears about bridge safety fueled emotional debate within the agency, according to a construction industry source. But on the I-35W bridge, transportation officials opted against making the repairs. Officials were concerned that drilling thousands of tiny bolt holes would weaken the bridge. Instead, MnDOT launched an inspection that was interrupted this summer by unrelated work on the bridge's concrete driving surface.

The Associated Press (AP) also reported that in 1990 Minnesota officials were warned that the bridge was "structurally deficient," yet they relied on patchwork repairs. The federal government also gave the I-35W bridge a rating of "structurally deficient," citing significant corrosion in its bearings.

As recently as 2005 a federal inspection also rated the bridge structurally deficient, giving it a 50 on a scale of 100 for structural stability.

And during the 1990s, inspections found fatigue cracks and corrosion in the steel around the bridge's joints. Those problems were repaired. Starting in 1993, the state said, the bridge was inspected annually instead of every other year.

The collapsed bridge's last full inspection was completed June 15, 2006. The report shows previous inspectors' notations of fatigue cracks in the spans approaching the river, including one 4 feet long that was reinforced with bolted plates. A 1993 entry noted 3,000 feet of cracks in the surface of the bridge; they were later sealed.

Engineers wondered whether heavy traffic might have contributed to the collapse. Studies of the bridge have raised concern about cracks caused by metal fatigue.

White House press secretary Tony Snow said while the inspection didn't indicate the bridge was at risk of failing, "if an inspection report identifies deficiencies, the state is responsible for taking corrective actions."

Gov. Tim Pawlenty responded Thursday by ordering an immediate inspection of all bridges in the state with similar designs, but said the state was never warned that the bridge needed to be closed or immediately repaired.

So whose responsibility was it? It is clear that the bridge was declared "deficient" in 1990 and every year since. The families of the dead, the missing and the injured would like to know.

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