Williamson County - Herrin Road over I-57 Interchange Improvements

The Illinois Department of Transportation is proposing improvements to the Herrin Road interchange at Interstate 57 in Johnston City.

The project includes replacing the existing bridge over I-57, reconstructing the interchange, adding roundabouts at each interchange ramp intersection, and improving pedestrian and bicycle accommodations.

The proposed improvements are intended to improve safety, enhance traffic operations, extend the service life of the interchange and provide safer, more convenient travel for motorists, pedestrians and cyclists.

Highlights:

• Replace the Herrin Road bridge over I-57
• Add a shared-use path and pedestrian improvements
• Construct four single-lane roundabouts
• Reconstruct the interchange ramps
• Improve safety and traffic flow

• Improve intersection design and safety.
• Improve roadway geometry and traffic operations.
• Replace the aging bridge over I-57.
• Improve pedestrian and bicycle accommodations.
• Extend the long-term reliability of the interchange.

• Improve safety for all road users.
• Improve traffic flow through the interchange.
• Reduce vehicle conflict points.
• Replace an aging bridge.
• Improve pedestrian and bicycle connectivity.
• Support future traffic demands.
• Extend the service life of the transportation system.

Herrin Road currently carries approximately 6,500 vehicles per day through the project area and serves residential, commercial and regional traffic. The existing interchange consists of a traditional diamond configuration with stop-controlled ramp intersections. The interchange currently has limited pedestrian accommodations and no dedicated shared-use path.

The existing bridge over I-57 was constructed in 1961 and is nearing the end of its service life.

Road

• Reconstruct Herrin Road through the interchange.
• Improve deficient existing ramp geometry to ease merging onto I-57.
• Add a raised median through portions of the project.
• Construct new pavement throughout the project area.
• Upgrade existing lighting through interchange.

Interchange

• Replace the existing stop-controlled ramp intersections with two single-lane roundabouts.
• Reconstruct both entry ramps to I-57.
• Improve traffic flow entering and exiting I-57.

Bridge 

• Replace the existing Herrin Road bridge over I-57.
• Construct a wider bridge to better accommodate vehicles, pedestrians and cyclists.
• Include decorative bridge features with an outdoor theme.

Pedestrian and Bicycle 

• Construct a shared-use path through the interchange and on the north side of the proposed structure.
• Add pedestrian crossings on the east and west sides of the interchange.
• Improve connectivity for pedestrians and cyclists.

The project is located on Herrin Road from approximately 250 feet east of Meadows Lane to Prosperity Avenue in Johnston City. Improvements also include the I-57 interchange ramps. 

Project Phases

IDOT projects typically have three distinct phases.

The Herrin Road over I-57 interchange improvements project is currently in Phase I: Preliminary Engineering and Environmental Studies. This phase includes data collection, identification of transportation issues and concerns, development of range of alternatives, and identification of the preferred alternative and its refinement. Phase I concludes with the approval of an environmental and engineering report that summarizes the study.

IDOT Project Phases • Phase 1-Preliminary engineering and environmental studies, develop project scop • Phase 2-Contract plan preparation, local agency agreements, land acquistion • Phase 3-Construction 

schedule

IDOT is following the Context Sensitive Solutions process for this study. CSS is an interdisciplinary approach that seeks effective, multimodal transportation solutions by working with stakeholders to develop, build and maintain cost-effective transportation facilities that fit into and reflect the project’s surroundings: its “context.” 

Your input and feedback are critical to the success of this project, and your participation in the process is welcomed.  Here are some ways you can participate and stay informed and engaged:

• Attend public meetings and open houses
• Sign up to receive our project newsletter
• Take our online surveys
• Provide feedback and submit comments
• Share information with your neighbors and friends

A stakeholder involvement plan has been developed to outline the opportunities and timeline for outreach activities. A copy of this plan is available upon request.

IDOT encourages the public to review the proposed improvements and provide feedback.

Virtual public meeting

Available: Aug. 24-Sept. 4, 2026

Public comment period

Comments will be accepted from Aug. 24 through Sept. 4, 2026. Comments submitted during the public comment period will become part of the project's official public record.

Project exhibits (Coming soon)

• Brochure
• Presentation
• Roll Plot
• Comment form

Q. Why is the bridge being replaced?
A. The existing bridge was built in 1961 and is nearing the end of its service life. Replacing the bridge will improve safety and reliability while supporting future transportation needs.

Q. Why are roundabouts proposed?
A.Roundabouts at the ramp terminals don’t require a left turn lane, which in turn allows the proposed bridge width to be used for the multi-use path. This keeps the structure width down while saving costs vs. building a wider structure.

Roundabouts are designed to improve safety and traffic flow by reducing vehicle speeds and eliminating many of the conflict points found at traditional intersections. Learn more by visiting IDOT's Roundabout Information page.

Q. Will traffic be maintained during construction?
A. Construction staging and traffic control plans will be developed to help maintain access during construction. Additional information will be provided before construction begins.

Q. How can I submit comments?
A. Comments may be submitted through the virtual public meeting website or by contacting the project team during the public comment period.

Q. How can I stay informed?
A. Project updates, meeting materials and future announcements will be posted to this project webpage.

For additional information about the project, contact Sean Greenlee at 618-351-5310 or Sean.Greenlee@illinois.gov. Comments may also be mailed to 2801 Murphysboro Road, Carbondale, IL 62901, Attn: Sean Greenlee.

For IDOT District 9 updates, follow us on the social media platform X at @IDOTDistrict9.