Adaptive Signal Control Technology

Adaptive Signal Control Technology (ASCT), in conjunction with well-engineered signal timing, is making traffic signals across the country more efficient and effective, helping drivers to reach their destinations safer and faster. In numerous studies, adaptive traffic signal systems have been proven to:

• Continuously distribute green time for all traffic movements
• Reduce traffic delay and congestion by creating smoother flow
• Improve travel time reliability and decrease travel time variability
• Decrease idling time to reduce wear and tear on roads
• Decrease vehicle emissions
• Prolong the effectiveness of traffic signal timing 

Unlike traditionally timed traffic signals, signals with ASCT are able to react to the changing traffic conditions on the roadway caused by traffic crashes, special events, road construction, and other roadway incidents in real-time. According to the Federal Highway Administration (FHWA), adaptive signal technology can improve a signal’s performance metrics.

How do adaptive signals work?

The goal behind using adaptive signal technology is to provide effective signal timing for fluctuations in the roadway conditions. The technology works by collecting data using strategically placed sensors typically placed through the vehicle detection system, evaluating how the signal is performing with its current settings and then implementing modifications based on the evaluation.

The process is easy. First, sensors collect data and and then evaluate that data to develop signal-timing improvements. Finally, the adaptive signal control technology implements the signal timing updates. This process is repeated every few minutes to ensure the signal timing is responding to real-time conditions on the roadway. In comparison, traditional signal retiming may only be done every three to five years according to the FHWA.

Bell Road Corridor

The Maricopa County Department of Transportation, in coordination with the AZTech Regional Partnership and the Cities of Surprise, Peoria, Glendale, Phoenix and Scottsdale and the Arizona Department of Transportation, is deploying ASCT along the Bell Road corridor, one of the nation’s longest and highest volume arterial corridors.

When complete, the pilot project will extend about 16 miles along the Bell Road corridor stretching from Surprise to Scottsdale. The project has identified 50 signalized intersections broken into four project areas centered along the corridor’s four freeway interchanges. ASCT will be installed at each intersection adding adaptive capabilities to the existing signal system and allow the signal timing to change quickly and frequently based on the changing traffic conditions on Bell Rd in real-time.

More information on the Bell Road Adaptive Signal project progress is available on the MCDOT Project Information Page.