Signal Coordination and Timing (SCAT)

Illinois Department of Transportation

OBJECTIVE

Driver delay, air pollution, and traffic noise are all undesirable results of poorly-timed signals. This can often be alleviated by adjusting traffic signal timings and coordination between signalized intersections.

PROJECT DESCRIPTION

HLR’s traffic engineers were contacted by the Illinois Department of Transportation to perform quick, cost-effective reviews of existing intersection efficiency along multiple routes to optimize the flow of traffic on various street systems throughout northern Illinois.

With experience in all current signal platforms used in Illinois (Eagle, Econolite, Traconex, Multisonics), our team developed and implemented revised timing plans and controller settings. Often, a change of a few seconds in signal timings, adjustment of system offsets, or refinements to controller settings can have a big effect on intersection operation and congestion, preventing the immediate need for costly physical improvements such as additional lanes.

Our SCAT projects typically include:

• System Review – Traffic counts; speed & delay studies; review of existing signal timings, coordination data and controller settings; and a field review of operations
• Optimization – Analysis and development of improved timing plans for time-of-day or traffic-responsive operations
• Implementation and Evaluation – Implementation of optimized signal settings (MARC-PC, MARC-NX, ZONE MONITOR, ARIES) followed by field refinements and final evaluation of performance, with quantitative cost/benefit measures (speed/delay, emissions reductions)

Our team’s signal optimization and timing changes greatly reduced delay and congestion, created shorter lines of stopped vehicles, and improved air quality due to the reduced number of stops and starts. 

Examples of recent projects include:

• I-88/Naperville Road/Winfield Road Ramp Detour, Illinois Tollway
• Central Business District Signal System Analysis & Design, City of Elgin
• Illinois Route 64/Illinois Street Downtown System evaluation, City of St. Charles
• Illinois Route 38 System Optimization in Glen Ellyn and Wheaton, Illinois
• IL Route 25 Detour from IL Route 64 to Stearns Road, IDOT
• Hassert Boulevard System Optimization, City of Naperville
• IL Route 21/IL Route 43/Howard Triangle Optimization in Village of Niles
• McCoy Drive & Commons Drive, City of Aurora
• Delany Road System Optimization, Lake County Division of Transportation
• Illinois Route 43 System Optimization in Bridgeview, IDOT
• Lake-Cook Road & IL Route 43 System Optimization, Cook County Department of Transportation and Highways
• New York Street System Optimization, City of Aurora