I-35 bridge also rated ‘structurally deficient’

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By Phyllis McLaughlin

 The 40-year-old Interstate 35W Bridge over the Mississippi River in Minneapolis, Minn., collapsed into the Mississippi River on Aug. 1, 2007, killing 13 people and injuring more than 100.

In November 2008, the National Transportation Safety Board cited errors in the original design of the gusset plates in the old bridge as the probable cause of the collapse.

Gusset plates are used to connect beams or truss members to load-bearing columns.

Incidentally, according to an August 2007 article in the St. Paul Pioneer Press, that bridge, built in 1967, had been labeled “structurally deficient” since 1990 because of a 4 (poor) overall rating of the superstructure. At that time, it “was given an overall sufficiency rating of 50 percent, meaning it was time to consider replacing it,” the article states.

To give a comparison, the gusset plates on the Milton-Madison Bridge were inspected as part of the main truss of the bridge during the January 2009 Fracture Critical inspection conducted by the Kentucky Transportation Cabinet’s Division of Maintenance.

Josh Rogers, project manager of the Ohio River Bridge Inspection division of the Kentucky Transportation Cabinet in Frankfort, said Tuesday that the overall main truss section of the bridge rated 3, or serious condition. He said the January inspection, which is required by the state every two years, revealed one gusset plate on the bridge that had a hole in it.

Repair of the gusset plate was part of work done this summer by the state, Rogers said, and is no longer an issue at this time. The bridge, he said, is still safe.

“If we felt there was a need to close the bridge [because of unsafe conditions], the cabinet would close it,” he said.