Researchers at Oak Ridge National Laboratory estimate that poor signal timing causes 296 million vehicle hours of delay. Appropriate timing of traffic signals can decrease congestion, improve air quality, reduce fuel consumption, and minimize aggressive driving behavior. Optimizing signal timing produces average benefit-to-cost ratios that approach 40 to 1. Across the nation, traffic signal retiming programs have resulted in travel time and delay reductions of 5 to 20 percent and fuel savings of 10 to 15 percent.

The benefits of improved signal timing have been demonstrated in Oakland County, Michigan and Syracuse, New York. In Oakland County, Michigan, retiming 640 traffic signals during a two-phase project resulted in Carbon monoxide reductions of 1.7 and 2.5 percent, Nitrogen oxide reductions of 1.9 and 3.5 percent, and hydrocarbon reductions of 2.7 and 4.2 percent. The benefit-to-cost ratios for the two phases of this project were 55:1 to 175:1.

In Syracuse, New York, benefits were realized when signal timing was optimized for 145 intersections. Signal retiming decreased the number of stops by 15.7 percent, reduced travel time by 16.7 percent, lowered delay by 18.8 percent, caused a 13.8 percent decline in fuel consumption, and resulted in a 13 percent reduction in vehicle emissions and noise pollution.

Notes

See also: Syracuse Signal Interconnect Project: Before and After Analysis Final Report. Prepared by DMJM Harris for the New York State Department of Transportation. September 2003.