Signal Coordination and Timing for IDOT

SRF has completed traffic signal coordination and timing (SCAT) efforts on multiple highways in Illinois DOT Districts 6, 7, 8, and 9. Our work has included the following routes:

• IL 32/33 in Effingham (six signals in District 7)
• IL 157 in Cahokia (10 signals in District 8)
• IL 3 in Columbia (five signals in District 8)
• West Highway 50 in O’Fallon (seven signals in District 8)
• IL 13 and US 51 in Carbondale (23 signals in District 9)

Each of these corridor projects was initiated with an in-person discussion between Illinois DOT District Engineers and SRF. These meetings were helpful in setting initial project goals and preferences for each District and helped to minimize Illinois DOT review efforts of the project deliverables. For each corridor, SRF completed traffic and base data collection, calibrated the base model to verify undesirable conditions, created a proposed time-of-day model and plan, recommended phasing and equipment improvements, implemented the recommendations, and prepared final project documentation. Other highlights include:

• SRF determined unusual pedestrian overlap phase conflicts on the IL 32/33 corridor in Effingham and recommended a revised phasing plan to the D7 project manager who was receptive to the change and facilitated that change prior to implementation.

• The IL 3 corridor in Columbia experienced high profile crashes prior to the SCAT study and SRF was requested to review safety in addition to the typical SCAT scope. SRF was approved to proceed with a thorough safety review of the corridor that included field-standards review, crash report investigation, geometric and operational contributors to the evident crash patterns, and investigation of potential improvement alternatives through Highway Safety Manual methodologies including the use of Interactive Highway Safety Design Model and economic appraisal techniques.