Minnesota transportation officials have cut off traffic at three busy river crossings since March, betting that motorists will put up with the hassle of lengthy detours to avoid a repeat of the deadly Minneapolis bridge collapse.
The aggressive approach follows last summer’s failure of the Interstate 35W bridge over the Mississippi River, and in all three cases deals with compromised steel plates connecting bridge beams, identified by investigators as a key factor in the collapse.
But so far, Minnesota seems more willing than other states to throw up barricades even as engineers across the country take a harder look at steel truss bridges with similar designs.
“We’re sort of in a learning process, I’ll have to admit that,” said Minnesota state bridge engineer Dan Dorgan at a news conference on Wednesday. “We haven’t gone through this intense look at gusset plates previously.”
On June 3, state officials closed the Highway 43 bridge over the Mississippi in Winona, the same bridge featured on a new postage stamp commemorating Minnesota’s 150th birthday _ after an inspection found rust and corrosion on several gusset plates on the span’s Wisconsin end. One of the plates showed slight bending, Dorgan said. The latest discovery came eight years after the state repaired a corroded gusset on the bridge.
Transportation Commissioner Tom Sorel said the Winona bridge’s gusset problems are different from the design flaw of too-thin plates identified by federal investigators on the I-35W bridge.
Closing the 67-year-old Winona bridge comes at no small cost to those who use it. Detours to the nearest river crossings take them 50 or more miles out of their way. Sorel wouldn’t predict how long the bridge will stay closed and said there’s no decision yet on whether to repair or replace it. In the meantime, officials are considering ferry service, water taxis and pedestrian access to the bridge.
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