Reports: Problems with Minnesota bridge noted twice since 2001

[Flabbergasted]

MINNEAPOLIS, Minnesota (CNN) -- Two reports published since 2001 pointed to structural problems with the Interstate 35W bridge that collapsed Wednesday into the Mississippi River, but both reports determined the bridge was safe despite deficiencies.

"The bridge's deck truss system has not experienced fatigue cracking, but it has many poor fatigue details on the main truss and the floor truss system," said a report conducted for the Minnesota Department of Transportation in 2001.

Trusses are support mechanisms, and floor trusses often act as the "primary load-carrying members in a bridge superstructure," according to the American Society of Civil Engineers.

The executive summary of the report -- undertaken by the University of Minnesota's Department of Civil Engineering -- also points to fatigue problems with the bridge's approach span, the segments that connect the main span of the bridge to land. It attributed the fatigue problems primarily to "unanticipated out-of-plane distortions in the girders."

However, the report also said, "Fatigue cracking is not expected during the remaining useful life of the bridge." Watch the bridge collapse »

In another report two years ago, the U.S. Department of Transportation's National Bridge Inventory database concluded the bridge was "structurally deficient."

http://www.cnn.com/2007/US/08/02/bridge.structure/