Signal Timing Efforts in Salt Lake City

Several years ago, a consultant, with a “fresh set of eyes,” was hired to evaluate the City’s traffic signal timing software and philosophy, and make improvements to the timing of the City’s traffic signals. The project goals included: determining how to immediately reduce traffic delays, fuel consumption and greenhouse gas emissions and, over the long term, determine how to improve the capability and efficiency of the signal control system.

Key Findings

Updated traffic signal timing plan:

• Saves users 337,000 gallons of fuel a year
• Reduces traffic delays by 14% during the morning peak, 10% during midday, and 8% during the evening peak

The signal re-timing reduces:

• CO emissions by 50,700 pounds a year
• NOx emissions by 10,000 pounds a year
• VOC emissions by 13,200 pounds a year

While these efforts have had a positive impact on travel times, and pollutant emissions, Salt Lake City’s traffic signal control staff strives to update the timing on a three-year basis. This is necessary because the efficiency of traffic signal timing plans degrade over time as traffic patterns evolve, thus requiring regular updating.

Here is a link to the full signal timing report.