I-255 Rehabilitation

Illinois Department of Transportation

Complete closure of the interstate for construction provided savings of more than 3 years and $14 million


The Interstate 255 corridor is a 6 lane interstate highway built in the mid-80s with no significant improvements to the pavement structure since the initial construction.
H&S was contracted by IDOT for the development of a traffic closure report analyzing effects of additional traffic on the ancillary roadway network for the closure of the I-255 from I-64 north to Collinsville Road in St. Clair County. Existing traffic data was gathered for various roadway segments near the I-255 corridor. Using HCS 7, the data was inputted to establish the baseline Level of Service (LOS) for various state and local maintained routes identified from East-West Gateway traffic models. The main detour of the interstate closure utilized the existing interstate highway system. However, it was apparent early in the analysis process multiple routes may be utilized. The model was updated to reflect potential alternate route options for local drivers to navigate the closure. The increased traffic was then analyzed to determine the difference in LOS. The report identified intersections, freeway ramps, and roadway segments in the study area impacted by the corridor closure.
After successfully submitting the closure report H&S was contracted for the development of plans, specifications, and estimates for the resurfacing of the 3.6 miles of I-255 from I-64 north to Collinsville Road in St. Clair County. The project included 3.6 miles of resurfacing, overhead sign structure rehabilitation, repair of two bridges that cross over the interstate, repairs of five mainline bridges, repairs of two ramp bridges, and one mainline bridge that required a deck replacement.
The project included bridge rehab plans for nine structures including the redecking of one structure, which required a TS&L. The re-decked bridge utilized the new standard constant slope parapet and required re-profiling of the existing grade due to settlement of the approaches.
H&S provided a safety inspection, bridge inspections, bridge TS&L, bridge redecking plans, bridge rehabilitation plans, roadway rehabilitation plans, patching, curb and gutter replacement, shoulder and median full depth replacement, drainage improvements, erosion control plans, guardrail plans, profile correction details, resurfacing transition details, and gore transition details. IDOT Phase II plans were prepared in less than nine months to meet the District’s accelerated schedule to rehab this deteriorating section of interstate.


Project Scope



Site Size

3.6 miles


St. Clair County, Illinois

Year Completed


Innovation. Agility.
Reliability. Horner & Shifrin.