Innovative Gantry System in Place for Mile Long Bridge

Wed January 05, 2022
Illinois Tollway

As part of the construction of a new southbound Mile Long Bridge on the Central Tri-State Tollway (I-294), the Illinois Tollway will begin using an innovative gantry system to move and install bridge beams behind barrier wall in the work zone, without disrupting traffic.

Construction of the new bridge as part of the Tollway's $500-million Mile Long Bridge Project is anticipated to continue through 2022. The massive gantry system will be used in place of traditional construction cranes to install beams in the area over the Chicago Sanitary and Ship Canal.

The innovative gantry system includes three main gantry frames each approximately 28 ft. tall and 145 ft. long. The gantries extend from the existing southbound bridge structure across to the newly constructed northbound bridge structure. In addition, a rail system was installed on both existing bridge structures to allow the gantries to move from north to south during beam placement.

Each of the gantries is equipped with overhead movable hoists and cranes. Each hoist moves east and west across the gantry and can lift up to 30 tons using a crane that drops down to pick up beams from the delivery truck below and then lift the beams into position on the bridge piers.

During beam placement, each gantry is controlled by a crane operator. Gantries are positioned on each end of the beam as they are hoisted into place, and the third gantry can be used to hold the beams in place while the other two gantries move to deliver the next beam segment into place.

The gantry system allows four lanes of traffic to remain open in both directions on the bridges currently carrying northbound and southbound traffic as 30 steel beams are installed in the area over the Chicago Sanitary and Ship Canal.

Beam installation for the new southbound Mile Long Bridge began in August. Beam deliveries will continue into early 2022, and altogether 250 concrete beams and 165 steel beam segments will be delivered to the site for the new southbound Mile Long Bridge Project. Steel beams, measuring up to 10 ft. tall and range in length from 57 ft. to 134 ft. long, are transported from a manufacturing plant in Indiana and concrete beams, measuring nearly 8 ft. tall and are up to 187 ft. long, are transported from a plant in Wisconsin.

As part of the $4 billion Central Tri-State Tollway Project, the Illinois Tollway is reconstructing the Mile Long Bridge that carries up to 150,000 vehicles daily over two major railroads, the Des Plaines River, the Chicago Sanitary and Ship Canal and the Illinois and Michigan Canal and local roads, and over several major distribution centers. Construction of the new northbound structure was completed in 2020 and construction of the new southbound structure is scheduled to be complete in 2022.

A $184.6 million contract to build the new northbound bridge structure began in summer 2019 and was completed in November 2020. Work began on a second $182.6 million contract in 2020 to remove the old northbound structure and deliver the new southbound Mile Long Bridge to drivers by the end of 2022. The entire Mile Long Bridge Project is scheduled to be complete by the end of 2023.

The Mile Long Bridge Project includes building two new side-by-side 4,800-ft.-long bridge structures designed to last 100 years and increasing capacity to five lanes in each direction. The original bridge structures were built in 1958.

Both of the new bridges feature 27 spans supported by 26 piers, compared to the previous structures with 53 piers, reducing the impact on waterways, roadway and rail operations below. In addition, the bridges' inside shoulders in both directions will be built to serve as Flex Lanes for transit, for emergency vehicles and as an alternate lane when warranted.

The Illinois Tollway is coordinating work on the Mile Long Bridge Project with the Village of Hodgkins, Village of Countryside, Village of Willow Springs, Village of Justice, Cook County, Forest Preserve District of Cook County, Metropolitan Water Reclamation District, Burlington Northern Santa Fe Railway, Illinois Department of Transportation, Illinois Environmental Protection Agency, U.S. Army Corps of Engineers, U.S. Department of Fish and Wildlife, U.S. Coast Guard, Illinois Department of Natural Resources (IDNR), IDNR Office of Water Resources and the Illinois Nature Preserve Commission, as well as numerous businesses located near the Mile Long Bridge.

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