Project Overview
Traffic in the Chicagoland area is often heavy, with scores of commuters traversing the city’s roadways each day. Such is the case approximately 20 miles southwest of downtown Chicago, where the Mile Long Bridge, a part of the Central Tri-State Tollway on Interstate 294, supports 150,000 vehicles each day. The Illinois State Toll Highway Authority, in partnership with contractor FH Paschen of Chicago and County Materials Corporation of Janesville, Wisc., reconstructed two aging bridges in the corridor to accommodate increasing traffic demands, minimize maintenance, and improve safety. The project was made possible through the fabrication and installation of 523 colossal precast and prestressed concrete bridge beams.
Massive Scale, Massive Results
Project leaders were challenged with replacing the four-lane northbound and southbound bridges in the area with larger structures to accommodate five lanes of traffic and a flex lane in each direction. Further complicating matters was everything beneath the bridge, including two major railroads, three water sources, local roads, and a series of commercial properties. Given these conditions, unique approaches to design and construction were required. To reduce disturbance to the aquatic ecosystem near the project site and meet the project’s lofty goals, LHQ Tri-State Partners/H.W. Lochner Engineering of Chicago developed a solution that reduced the number of piers from 53 for each of the original bridges to 26 each for the replacement structures. This approach helped minimize the project’s impact on the transportation and commercial activities taking place below the jobsite.
Precast and prestressed concrete bridge beams offered the only solution that would support the goals of the project, which included not only minimal disturbance to the area but also reduced maintenance and extended service life for the replacement bridges. For the work, County Materials Corporation manufactured forty-four 187-ft-long girders and 479 girders ranging in length from 127 to 170 feet. The 187-foot-long precast concrete beams are the largest prestressed concrete bridge girders produced in the region to date. Getting the girders to the project site was a challenge. The massive beams were hauled to the area on specialized trailers, with each load requiring four personal escort vehicles and two state patrol cars. Once precast concrete girders were on site, contractors used an innovative gantry system in lieu of traditional cranes to install them near the waterways. This technique helped allow four lanes of traffic in each direction to remain open throughout construction, mitigating potential headaches for commuters.
Thanks to the use of precast concrete, the Mile Long Bridge project offers myriad benefits to all parties involved. The durable and resilient replacement structures provide exceptional taxpayer value as they have an expected service life of 100 years, need less maintenance, and create additional lanes for traffic moving through the area each day.
Mason Nichols is a Grand Rapids, Mich.-based writer and editor who has covered the precast concrete industry since 2013. |