Local News

WINONA, Minn. (AP) ― Minnesota transportation officials have cut off traffic at three busy river crossings since March, betting that motorists will put up with the hassle 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 Tuesday, 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.
  
Bridge engineers around the country are paying more attention to gusset plates and original bridge plans than they did before the collapse, but that doesn't seem to be translating into a big increase in bridge closures, said Ken Kobetsky, program director for engineering at the American Association of State Highway and Transportation Officials in Washington.
  
Missouri closed a steel truss bridge near St. Louis for a weekend last August after a regularly scheduled inspection found rust building up behind a splice plate connecting two beams, said state bridge engineer Dennis Heckman. But Heckman said that closure was unrelated to the Minnesota bridge collapse, although it got extra media attention coming just 10 days after the disaster.
  
"It's a more heightened awareness now," he said. "It's not that we're closing more bridges than we used to, at least in Missouri."
  
Transportation officials in Virginia and Pennsylvania haven't closed bridges because of gusset plate concerns, despite stepped-up inspections of steel-truss bridges. But Ken Walus, structure and bridge engineer in Virginia, said he isn't surprised to hear of such closures in Minnesota.
  
"I would assume they're probably being very conservative, and if I were in their position, I would do the same thing," Walus said.
  
A list from the National Transportation Safety Board shows 12,612 truss bridges nationwide as of January. Of those, 466 are steel deck truss bridges like the I-35W span that fell.
  
Two others in Minnesota -- in St. Cloud and Duluth -- have been closed entirely or in part. The Blatnik Bridge connecting Duluth and Superior, Wis., has had lane closures while crews reinforce gusset plates that didn't meet load requirements at eight spots on the bridge.
  
In St. Cloud, state officials opted to replace the Highway 23 bridge over the Mississippi even though one of their engineering consultants advised them that they could probably get by with repairs.
  
Officials immediately closed the bridge and began preparing for the likelihood it would stay shut for good after an inspection team spotted distorted gusset plates. Investigators hired by MnDOT to look into the structural reasons for the Interstate 35W bridge collapse analyzed the St. Cloud river crossing.
  
In a March 31 letter to the top Minnesota bridge engineer, three managers at Wiss Janney Elstner Associates advised that the plates were probably bent at the time the bridge was constructed.
  
"It is also our opinion that the observed distortions have not compromised the abilities of the affected gusset plates to sustain required design loads," the consultants wrote.
  
They went on to say that installing reinforcing elements would "bring the modified plates into full conformance with original design specifications."
  
Even so, the state officials decided to move forward with replacement instead of short-term repairs.
  
They had more money to back up that decision because of a transportation spending package that passed the Legislature over Gov. Tim Pawlenty's objections in February. Before that, the Winona bridge had been scheduled for replacement in 2017. Now, Sorel said those plans are being revised.

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