Cutting in half the number of piers on a toll-funded Interstate bridge made the litany of obstacles beneath it more manageable.Crews are building a pair of nearly mile-long new highway bridges amid a confluence of existing transportation systems in Chicago’s southwest suburbs. There’s the Des Plaines River, the Chicago Sanitary and Ship Canal, the Illinois and Michigan Canal, two sets of major railroad tracks, local roads and a pipeline operated by Buckeye Partners that sends jet fuel to O’Hare airport.

The Mile Long Bridge is a crucial piece of infrastructure on the Central Tri-State (Interstate 294). Its two bridges carry commuters and commerce over all of those existing systems, and the divided highway intersects I-55 in the same area. Midway Airport, another transportation hub, is less than five miles away. There is also a United Parcel Service Distribution Center and a railyard for Burlington Northern Santa Fe Railway.

Originally constructed in 1958 with the rest of the Illinois Tollway, the Central Tri-State’s mile-long bridges were due for replacement. With only four lanes in each direction and more than 150,000 vehicles traveling over them daily, congestion was worsening, and the 22 miles of the Central Tri-State around them also carry the heaviest volumes of freight traffic on the system.

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