Optimizing traffic signal timing is considered a low-cost, high-benefit approach to reducing congestion. Signal timing strategies include the minimization of stops, delays, fuel consumption and air pollution emissions and the maximization of the traffic progression through the system.

The article, "The Benefits of Retiming Traffic Signals", presented in the ITE Journal is an interim product of the ITE Traffic Engineering Council's project TENC-101-02. This article describes the who, what, when, why, and how of traffic signal retiming. The presentation "Benefits of Retiming Traffic Signals: A Reference for Practitioners and Decision Makers About the Benefits of Traffic Signal Retiming"¹ was presented at the 2005 Annual ITE meeting and provides similar information.

Signal retiming provides significant direct benefits for the traveling public. One of these benefits is the reduced delay experienced by motorists. Delay savings are more apparent for motorists traveling along coordinated signalized arterials. Improved signal timing also has indirect benefits. Better coordination along major arterials minimizes the diversion of traffic to local and residential streets, improving safety and traffic conditions. It also leads to reduced fuel consumption, reduced emissions, and improved air quality.

¹ Harris, J., Benefits of Retiming Traffic Signals: A Reference for Practitioners and Decision Makers About the Benefits of Traffic Signal Retiming. Presentation at ITE 2005 Annual Meeting and Exhibit, 7-10 August 2005. URL: http://www.ite.org/meetcon/2005AM/Harris_Tues.pdf.

RESULTS

A synthesis of various traffic signal retiming projects across the U.S. and Canada revealed that:

• Delays can decrease by 13 to 94 percent.
• Travel time can fall by 7 to 25 percent.

Below are a few examples of signal retiming projects that benefited from reduced delay and lower travel times:

• The Traffic Light Synchronization Program in Texas reduced delay by 24.6 percent and lowered travel time by 14 percent.
• Traffic signal retiming at 11 intersections on U.S. Route 1 in St. Augustine, Florida reduced delay by 36 percent, and lowered travel time by 10 percent.
• A retiming project for eight intersections on State Route 26 in Gainesville, Florida decreased average delay by 94 percent.
• In Burlington, Canada, signal retiming at 62 intersections lowered travel time by 7 percent.
• In Montgomery County, MD traffic signal retiming reduced delay by 13 percent.
• The Fuel Efficient Traffic Signal Management (FETSIM) Program in California demonstrated a reduction in delay of 15 percent.