Illinois Route 31 Study

The Illinois Department of Transportation (Department) is currently conducting a preliminary engineering and environmental study (Phase I) for the improvement of IL 31 from IL 176 to IL 120 in McHenry County. Funding for Phase II engineering is included in the Department’s FY 2018-2023 Proposed Highway Improvement Program. The remaining elements of the project will be included in our priorities for future funding consideration among similar improvement needs throughout the region. The general scope of work for this improvement is anticipated to consist of roadway widening and reconstruction to provide two lanes in each direction separated by a median, bicycle and pedestrian accommodations, and intersection and drainage improvements.

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.


Project Update - January 2018
Your comments from the public hearing have become part of the official public hearing record. As many comments concerned similar issues, this newsletter has been prepared to address your concerns as well as provide you with an overview of topics.  Please see the following links for the items referenced in the newsletter.

Updated Traffic Noise Analysis (May 2017)

Preservation and Replacement of Trees Policy

Cross Access FAQs

Cross Access Easement Agreement Example

Public Hearing – February 8, 2017
A public hearing was held on February 8, 2017 from 4:00 to 7:00 p.m. at the McHenry County College Shah Center in the City of McHenry to obtain public input on the preferred alternative and Environmental Assessment.  The following materials were presented at the meeting:

Presentation and Handouts


Presentation (PDF)

Presentation (Video)(Windows Media Player required)

Cross Access FAQs

Cross Access Easement Agreement Example


Project Location Map

IDOT Project Development

Phase I Study Process

Project Purpose & Need

Crash Data

Proposed Typical Sections

Preferred Alternative Benefits

Access Management

Drainage and Water Quality

Environmental Impacts & Mitigation

Cross Access Locations

Land Acquisition

We Want to Hear From You

Existing and Projected Traffic Volumes and Level of Service

Preferred Alternative Aerial - Sheet 1

Preferred Alternative Aerial - Sheet 2

Preferred Alternative Aerial - Sheet 3

Preferred Alternative Aerial - Sheet 4

Preferred Alternative Aerial - Sheet 5

Preferred Alternative Aerial - Sheet 6

Preferred Alternative Aerial - Sheet 7

Preferred Alternative Aerial - Sheet 8

Preferred Alternative Aerial - Sheet 9

Preferred Alternative Aerial - Sheet 10

Preferred Alternative Aerial - Sheet 11

Preferred Alternative Aerial - Sheet 12

Preferred Alternative Aerial - Sheet 13

Preferred Alternative Aerial - Sheet 14

Preferred Alternative Aerial - Sheet 15

Environmental Assessment

Environmental Assessment

Exhibit 1 - Location Map

Exhibit 2 - Local Jurisdiction Map

Exhibit 3 - Wetland Impact Exhibits

Exhibit 4 - Environmental Resource Map

Exhibit 5 - Best Management Practices


Appendix A - Social and Economic Resources

Appendix B - Farmland Impacts

Appendix C - Traffic Noise Analysis

Appendix D - Biological Surveys

Appendix E - Stream Data

Appendix F - Wetland Delineations

Appendix G - NEPA 404 Merger Meeting Materials

Appendix H - Stormwater Performance

Appendix I - Purpose and Need Updates

Appendix J - Traffic Level of Service Map

For project information prior to the public hearing, go to the IL Route 31 website.

If you have any questions or need information, please contact Scott Czaplicki, Project Manager, at (847) 705-4678 or by e-mail at

This section will be updated as the project progresses.

This section will be updated as the project progresses.

Photo Gallery