The collapse of the Minneapolis bridge, a steel truss structure, is affecting the design for a planned new bridge on Interstate-5 between Oregon and Washington over the Columbia River. The $1-billion project is expected to start construction in 2010. Currently, I-5 traffic travels over the Columbia on a steel truss bridge that was built in 1917.

"We are looking at several designs, but it will probably be a segmentally constructed concrete bridge," says Jugesh Kapur, Washington state bridge engineer. Because of the bridge collapse in Minnesota, "it will definitely not be a steel truss bridge," like the current I-5 structure.

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Stakeholders, which include the transportation departments from both states and the Federal Highway Administration, are reviewing comments from the draft environmental impact statement. Officials hope to be able to choose a preferred alternative by Aug. 1.

Two scenarios are being considered. Either the current bridge will be replaced or it will remain in place and a second bridge will be built to supplement traffic. In either case, the new bridge will be built to the west of the current structure. Alternatives also include options for rapid transit or dedicated bus lanes.

Immediately following the Minnesota bridge collapse, state authorities inspected similar bridges, but no serious flaws were found.

The Oregon Dept. of Transportation (ODOT) did "reinforce its contractual standards for dead-weight loading during construction or repair," says David Thompson, ODOT field operations manager. "Detailed analysis of the Minneapolis bridge collapse hasn't been officially released, but there has been some talk of how much weight was on the bridge from construction materials. We have always included contract language to limit this," says Thompson.

Oregon received $18 million from the $1-billion in additional federal bridge funds that Congress approved late last year. The money will go to improve seven bridges in the state.