Combine 101,300 vehicles a day with 200,000-pound beams, spawning fish, plus marsh marigolds and you see why rebuilding the I-90 bridge over the Fox River is not the average project, Illinois tollway engineers said Thursday.
Tollway board directors approved a $75.4 million contract with Northbrook-based Kenny Construction Co. and Edward Kraemer & Sons, a Wisconsin-based contractor that specializes in bridges, to reconstruct and widen the structure on the Jane Addams Tollway.
Work starts in mid-June and finishes in 2016. Planners asked firms to come up with an innovative way to build the structure while keeping three lanes of traffic open in each direction, Chief Engineer Paul Kovacs said.
The conventional tollway approach would involve using a crane to lift beams and other construction materials from trucks, but that would require shutting down some of the six lanes. In a break from tradition, the contractor will set up a gantry system that uses a hoist traveling along an overhead rail to move heavy objects.
"We will have to move lanes around, but the gantry system gives us a lot more room to work with," Kovacs said.
Specifics have yet to be announced, but initial plans indicate work would start on the eastbound side of the bridge, then shift to the westbound side. Traffic will be moved accordingly while the new structure goes up and the old one is demolished.
The new design also will allow the tollway to reduce the number of piers in the water from six to three, which means less disturbance for wildlife, officials said. State regulations prevent the tollway from building during fish spawning season, which runs from April to mid-June.
The bridge is near Fox River Fen Nature Preserve, a rare forested fen, and Trout Park Nature Preserve. The agency is eliminating a storm sewer that discharges water in the area and will redirect stormwater, which could contain road salt, from entering the fen.
"This is a once-in-a-50-year opportunity to get it right," Kovacs said. In addition to the four lanes, the agency will build full shoulders. In the future, "when a car breaks down, you'll have a place to pull off and it won't be as dramatic an impact on traffic," he said.
A pedestrian and bike bridge will also be built that is wider than the existing one.
Once completed, the bridge will consist of four lanes in each direction.