GHA) was selected by IDOT Districts 2-5 (northern Illinois, minus the Chicago area) with multi-year contracts totaling $875,000 dollars since 2013. GHA was assigned multiple coordinated corridors of signalized intersections in several cities.

Most of these corridors had not been optimized for over a decade and were not efficiently handling traffic volumes and patterns.
After performing turning movement counts at each intersection, GHA staff created Synchro models for the corridors. Using these models, GHA staff engineered new traffic signal programming to improve traffic flow, efficiency, and safety. GHA staff then implemented these new signal timings in the field and observed how traffic operated. Along with IDOT staff, GHA adjusted signal timings at the intersections to further improve traffic operations.

GHA staff has years of experience working with many types of corridors, and traffic signal equipment. This experience allowed GHA to optimize the traffic signal programming to best meet the needs of the local traffic, while also being flexible enough to meet the needs of future changes in traffic patterns.

As a final review of the new timings, GHA staff drove the corridor in all applicable time periods, recording speed and acceleration via GPS tracking. By comparing this data before and after implementation, GHA staff estimated overall improvements to driver delay, average stops, and vehicle emissions. All of this information is included in the final report that is submitted to IDOT.