The long process of fixing the Plymouth Avenue Bridge will take even longer than was planned when the job was financed last fall. But if all goes according to plan, cars might start using the bridge again in October, two years after it was closed.
And, the price won’t be quite as high as the early estimates.
Jack Yuzna, a public works engineer for the City of Minneapolis, said the project will be going out for bids soon and they expect to begin the repair work in July. He said the middle span of the bridge will be repaired at that time, with completion expected by Oct. 15.
City officials then plan to open the bridge for automobile traffic for the winter; and then “go back next spring and complete repairs to the approaches”—repairs that he says are important but not critical.
Those repairs, he said, can be completed “under traffic, with some restrictions.”
“The critical work that needs to be done is in the middle span,” he said.
“We are just finalizing the review process with MnDOT (the Minnesota Department of Transportation),” he said, and they expect to advertise for bids within a week or two.
The bridge is currently open to pedestrian and bicycle traffic, with bicyclists asked to walk their bicycles across the bridge. When the center-span repair work begins in July, it will be closed to all traffic, Yuzna said.
City engineers closed the bridge Oct. 22, 2010, after finding corrosion in its support system during a routine annual inspection. It was built in the 1980s and was the first of its kind—called post-tension segmental box girder—in Minnesota. City officials brought in Corven Engineering, a Florida consulting firm that specializes in this bridge design, to inspect the bridge and recommend repairs.
Corven’s initial report, issued in late December, 2010, recommended four major repairs:
- Reconfigure the bridge’s drainage system to direct water away from the bridge’s box girders
- Replace five of the bridge’s corroded support tendons
- Add more tendons to improve the bridge’s flexing capability
- Seal the bridge’s wearing surface with a penetrant sealer, or replace the wearing surface.
Later inspections and computer modeling determined that the damage is not as bad as was originally thought, according to a report from the city’s Public Works Department. “Initial repair estimates placed the cost at between $7 million to $10 million. The computer modeling and structural analysis found that the bridge was very robust when built. The later field investigation also found that damage to the four outside spans was not as broad/extensive as initially thought. These findings have resulted in a reduction to the scope of repairs needed to return the bridge to full service and reduced the project cost estimate to $6 million.”