HEBER’S SMART SIGNALS

Signals that communicate with each other and adapt in real time are improving travel time in Heber City.

Called ACS Lite, traffic signals in Heber City are optimized in real time as traffic patterns change. Travel times have improved by 7 percent.

Adaptive traffic signals were installed in Heber City, Utah this summer. While most signals are synchronized by time of day with an internal clock and operated through UDOT’s centralized Traffic Operations Center, the new computerized signals adjust automatically to real-time traffic demand. The sophisticated system is providing a corridor with less delay for road users.

Called ACS Lite, traffic signals on the system are optimized automatically as traffic patterns change. Signals at each intersection communicate with each other electronically to provide more green light time or other adjustments as needed. As the system detects more or less traffic, changes are made gradually so road users can benefit from improved travel time in the peak travel direction.

Before installation, traffic on the corridor was over capacity at peak times with waits of 7 to 10 seconds but those wait times have decreased. “It’s almost surprising” to get this degree of improvement in travel time, explains Jamie Mackey, Assistant Signals Engineer for UDOT.

The corridor was working fairly well before the system was installed – signals were adequately spaced and optimized. But data shows that travel time on Main Street (U.S. 40) “has benefited by about 7 percent in every time period” without drastically hurting the cross streets. “A 7 percent gain is pretty impressive,” says Mackey.

The project received funding from FHWA as part of a program to provide systems that improve signal operation and travel time. UDOT is learning from operating the system to gain experience to possibly use ACS Lite for other appropriate locations.

This is a follow-up to a previous post.

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