Overview and Scope

The Illinois Department of Transportation (IDOT) is completing the Phase I Preliminary Engineering and Environmental Study for the widening of Interstate 64 from west of Green Mount Road to west of Illinois 158,  and improving the Interstate 64 at Green Mount Road interchange (Exit 16).  The total project length is 2.7 miles.  This portion of Interstate 64 passes through the cities of O’Fallon and Shiloh.  Phase II will consist of preparing contract plans and acquiring right-of-way.  The final Phase III of the project will be construction. 

The Interstate 64 Improvement project extends from 2/3 miles west of Green Mount Road to a ½ mile west of Illinois 158. The study limits along Interstate 64 are approximately 2.7 miles in length.

Interstate 64 was originally constructed in 1975 and consisted of 4 – 12 ft. lanes (2 in each direction east and west).  Due to increasing development and traffic in this area:

• The Interstate 64/ Green Mount Road interchange was constructed in 2000
• Interstate 64 from Illinois 157 to Green Mount Road was widened from 4 lanes to 6 lanes
• In 2014, a new interchange was constructed at Interstate 64 and Reider Road to enhance access into Scott Air Force Base. As part of that improvement, Interstate 64 was widened from four to six lanes from west of Illinois 158 to east of Reider Road

• Insufficient Capacity

Development in the area continues, which also increases the traffic in the area. The traffic volumes on Interstate 64 have grown from 42,400 to 59,200 over the past 20 years, an increase of 40 percent.  These volumes are expected to increase to 72,800 by the year 2038, which includes a 14.5 percent truck volume. The current traffic volumes exceed roadway capacity for this four-lane section of Interstate 64 and has also led to delays at the Interstate 64 and Green Mount Road interchange

• Green Mount Road Interchange Delays

The intersections of the Interstate 64 ramps with Green Mount Road cannot support the volume of traffic that goes through them at peak hours as currently designed.  This results in significant backups on the ramps and traffic delays

• Roadway Design Doesn’t Meet Current Standards

This section of Interstate 64 does not meet current freeway standards for vertical clearance under the bridges and shoulder widths 

• Safety

This segment of Interstate 64 has experienced 149 crashes in a 5-year period, that included four fatalities

• Improve traffic capacity, operations, and safety on Interstate 64
• Improve mobility at the Interstate 64 and Green Mount Road interchange
• Assure bridge clearance is sufficient for structures that cross over Interstate 64 within the project limits

• Mainline Interstate 64 from west of Green Mount Road to west of Illinois 158
  • Widen Interstate 64 within the existing grass median to accommodate three lanes in each direction with wider shoulders. This proposed widening will be consistent with the existing Interstate 64 roadway configuration east and west of the project 
  • Construct a concrete median barrier between the eastbound and westbound lanes which will prevent crossover crashes
  • Increase the vertical clearances under the Green Mount Road and Lincoln Avenue bridges to accommodate larger trucks
• Interstate 64 at Green Mount Road Interchange
  • Widen the Interstate 64 eastbound exit ramp to provide two left and two right turn lanes at the intersection with Green Mount Road
  • Widen the Interstate 64 westbound exit ramp to provide two left and two right turn lanes at the intersection with Green Mount Road
  • Widen Green Mount Road to provide:
    • A southbound right turn lane at the Interstate 64 on=ramp
    • A northbound right turn lane at the Interstate 64 on-ramp
    • Two southbound left turn lanes, two southbound through lanes, and two southbound right turn lanes at the intersection of Green Mount Crossing and Central Park Drive
  • Note that due to the current condition of the structure, no work will be performed on the structure carrying Green Mount Road over Interstate 64 with this improvement. This structure will be monitored so that future improvements can be made, once warranted

A minor amount of proposed right-of-way and temporary easements will be required for this project.  Proposed right-of-way impacts are anticipated on the north side of Interstate 64 just east of Lincoln Avenue to construct a drainage ditch. 

Temporary easements may also be required during construction for some proposed features, but this property then returns to the property owner once construction is complete.

While there may be occasional short-term, off-peak temporary lane closures or ramp detours, IDOT’s goal is to keep four lanes of traffic open to the public during all stages of construction. 

This project is included in the Department’s FY 2022-2027 Proposed Highway Improvement Program.