South Tri-State Tollway Reconstruction
Award of Merit: Transportation
The widening and reconstruction of about 3.6 mi of the South Tri-State Tollway extended between Illinois 394 to the Markham Railroad Yard.
Reconstruction included portions of two major interchanges and one mine interchange and the widening of the mainline from three lanes to four lanes in each and, in some locations, a fifth lane. The section contained 13 bridges.
The goals included improving the capacity and traffic operations through the corridor; maintaining traffic movement through the corridor during construction and completing the budget within budget and on schedule.
Tough Work Environment
A high volume of traffic, shallow bedrock and tight rights-of-way created a difficult work environment.
On the east, poor soil and sensitive environmental conditions were prevalent. Looking west, the highway crosses Thorn Creek, and west of it is the Lincoln Oasis where wetlands were discovered.
Moreover, the highway cuts through long stretches of shallow bedrock and the active Thornton Quarry, crossing it with a large precipice on either side.
A number of techniques and tools were used to accommodate the challenging project.
For instance, close-circuit TV and dynamic message signs monitored construction traffic, managed incidents and conveyed information to motorists.
Visualization techniques were used to model the pavement surface through super-elevation transition areas and ensure positive pavement surface drainage.
A computer application—Roadside Safety Analysis Program—developed for the American Association of State Highway and Transportation Officials was used. It computes hazard types, probability of hitting a hazard, whether a barrier protecting the hazard is necessary and other things. The software helped to identify flaws in the project.
Design standards used in mountainous regions were incorporated in the project because the Illinois Tollway’s design criteria did not apply to rocky environments.
Counter-flow lanes were incorporated into the traffic plan so six lanes could be maintained throughout construction.
The mainline was lowered for vertical clearance, rather than raising and replacing existing over-crossing bridges. The decision saved millions of dollars in bridge replacement and reduced the amount of diverted freight and traveler lost-time.
The $136 million project was delivered on scheduled, while traffic was maintained and minimizing delays.
“It’s only the first step in the reconstruction of the Tri-State, but it is needed. The use of the new software was unique. Traffic was maintained as best as possible.”
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