Repairs on the sagging Leo Frigo Bridge on Interstate 43 in Green Bay, Wis., are expected to be completed in mid-January after workers add 20 drilled shafts at the bases of five piers.
Zenith Tech of Waukesha, Wis., won the $7.7-million repair contract and will run two crews on 12-hour shifts, seven days a week, until the work is completed, according to the Wisconsin Dept. of Transportation. Work started in mid-November.
The 20- to 24-person crews will add 60-in. concrete shafts with coated steel rebar, about 120 ft long, at the bases of Pier 21 to Pier 25. Then, the Pier 22 deck will be jacked up to its original height, and added concrete supports, reinforced with epoxy-coated steel, will be installed, WisDOT said.
The repairs will use more than 388 tons of steel and more than 1,300 cu yd of concrete.
Pier 22 sank 2.5 ft in late September, creating a sag in a 400-ft span and shutting down the 8,000-ft-long bridge.
Investigation revealed corrosion in the 100-ft-deep pier-support H-piles caused them to buckle. The probe found additional corrosion in the other piers, according to Tom Buchholz, WisDOT investigation team leader.
WisDOT blamed the corrosion on the area's soil composition and the water table's varying levels.
Before starting repairs, WisDOT hired Lunda Construction Co., Black River Falls, Wis., to erect two pairs of steel-truss support towers on each side of Pier 22. That $1.5-million job, nearly complete, will allow WisDOT crews to review the bridge deck.
The permanent repair contract puts the total cost estimate at about $15 million, instead of the $50 million initially thought. Federal funding is expected to cover most of the cost, WisDOT has said.
The bridge, built in 1980, typically carries 40,000 vehicles daily and is especially thick with traffic when the Green Bay Packers play a home game.