Illinois 171 at Interstate 55 Interchange Improvement

In order to restore 20 bridges and 2 retaining walls to structurally satisfactory condition and to improve Traffic safety and mobility, the Department will be improving approximately 2 miles of IL 171 (1st Avenue) from 47th Street to 55th Street, including the interchange at Interstate 55 in Cook County. The Project traverses the Villages of Summit, Lyons and McCook.

Contract Breakdown

In order to expedite construction operations for this project, the overall project has been separated into seven contracts. Major construction work to rehabilitate 20  bridges and 2 retaining walls will be completed Fall 2016.  Two subsequent contracts will be let in the future for painting of the bridge structures within the limits of the project. 

Note: IDOT projects typically have three distinct phases. Phase I (or the project Study) consists of developing the project scope, environmental studies and preliminary design of a project. Phase II (Design) consists of refining the design to develop contract plans and land acquisition. Phase III (Construction) consists of the actual construction of the project.

UPDATE: March, 2016

Multiple ramps will be closed during construction for the IL 171 over I-55 interchange beginning week of March 28, 2016 and continuing through October 31, 2016.  The detour route will be posted.  The following ramps will be closed during that period with the detour route as noted for each:

Detour Map

Contract #60W75/60W78 Detour Revised

Contract 60W75 & 60W78 will be closing multiple ramps and providing detour routes for the NB IL 171 from 47th St to 55th St including the I-55 interchange beginning March 21, 2016 and continuing through late November 2016.

The following ramps will be closed during that period with the detour route as noted for each:

  • NB I-55 to NB IL 171 Ramp CLOSED (Ramp C)
    • NB I-55 past IL 171, exit Harlem Ave. NB Harlem to WB W. 47th St to IL 171.

  • SB I-55 to NB IL 171 Ramp CLOSED (Ramp B)
    • SB I-55 past IL 171, exit NB LaGrange Rd. NB LaGrange Rd to NE Joliet Rd to NB East Ave to EB 55th St, then NE Joliet Rd to NB Frontage Rd to EB 47th St to IL 171.

  • NB IL 171 to NB I-55 Ramp CLOSED (Ramp D)
    • WB W. Archer Ave (55th St) to NB Harlem Ave to NB I-55 ramp.
    • NB S. Archer Rd to EB W. Archer Ave (55th St) to NB Harlem to NB I-55 ramp.
    • NB Harlem Ave , past W. Archer Ave (55th St), NB I-55 ramp.

  • NB IL 171 to SB I-55 Ramp CLOSED (Ramp A)
    • WB W. Archer Ave to NB Harlem Ave to SB I-55 ramp.
    • NB S. Archer Rd to EB W. Archer Ave (55th St) to NB Harlem to SB I-55 ramp.
    • NB Harlem Ave, past W. Archer Ave (55th St), to SB I-55 ramp.

  • NB IL 171 to Joliet Rd Ramp CLOSED (Ramp J)
    • NB IL 171 past Joliet Rd to EB W. 47th St to SB Lawndale Ave  to Joliet Rd.

    (click on map to enlarge)


    In order to construct all of the work that has been identified, multiple roadway contracts will be let. Careful consideration has been given to which work can take place at the same time with the least impact possible to the motoring public. In general, the major work will take place utilizing stage construction. Several cross-overs will be built. Traffic will use one side of the divided highway (either northbound or southbound) for travel of one lane in each direction while work takes place on the opposite side of the road. Some ramp work may require some closures and use of detours. When possible, work will be constructed on the ramps in stages.

    The only existing surveillance within the project limits consists of traffic signal detector loops located at the signalized intersections of Joliet Road/IL 171 ramps and 47th Street/IL 171 ramps. There are also traffic signal detector loops located just outside the project limits at signalized intersections of IL 171/Archer Avenue and Archer Avenue/Center Avenue. No changes are proposed to the traffic signals or the detector loops. The existing traffic surveillance system on I-55 will not be impacted by this project.

Funding for the improvement of Illinois Route 171 at the I-55 interchange complex is included in the Department's Proposed Improvements for Illinois Highways FY 2015 with funds made available through the 2014 Capital Program.

Replaces and improves major segments of the aging infrastructure.

Will serve the commercial and residential land uses of the developed areas of western Cook County as well as improve the movement of traffic between DuPage County and Cook County.

Air quality will be improved by minimizing travel delays, vehicular emissions and environmental concerns.

Estimated job creation for a total of 1040 workers by the six separate contracts.

As the IL 171 (1st Avenue) @ I-55 Interchange Rehabilitation projects progress, IDOT will periodically update this website to assure that the motorists of Illinois are kept informed of project developments, public involvement opportunities, and construction related activities.

If you have questions about the project, please fill out the feedback form or contact us at:

Illinois Department of Transportation
Office of Communications
201 West Center Court
Schaumburg, IL 60196

Please continue to visit the IL 171 (1st Avenue) @ I-55 Interchange Rehabilitation project website for periodic updates throughout the course of the Project. The Illinois Department of Transportation looks forward to your continued input and support.

Press Releases


11/18/16:  Lanes and Ramps Reopen on IL 171 and the IL 171/I-55 Interchange
12/09/14:  Daily Lane Closures on IL 171 Over I-55

Construction Fast Facts

  • Project Start: Winter 2014
  • Project End: Late Fall 2016
  • Project Cost: TBD
  • Project Municipality: Lyons, McCook & Summit
  • Project County: Cook

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View Project Information

Photo Gallery

Construction Photos - September 2015
Construction Photos - August 2015
Construction Photos - July 2015