Aiming For Traffic Light Synchronization

Transit agencies have the green light to take lessons learned synchronizing time intervals with traffic signals in Walnut Creek and speed them out to other cities.

A program to synchronize lights better with 339 signals in seven Bay Area counties showed marked gains in shorter travel times, reduced tailpipe emissions, and improved safety for pedestrians and bicyclists, according to a Metropolitan Transportation Commission news release. The PASS project (Program for Arterial System Synchronization) fine-tuned the timing on 87 lights in Walnut Creek.

"The Walnut Creek project was by far the largest in the first round of PASS initiatives and yielded benefits that exceed costs by a ratio of 93 to 1," said Orinda City Council member Amy Worth, vice chairwoman of the MTC board. "I expect the next cycle of PASS projects to deliver the same bang for the buck."

Rafat Raie, traffic engineer for the Public Services Department of Walnut Creek, noted the MTC chart that showed project costs of $293,050 balanced against lifetime projected savings — in travel time, fuel consumption and emissions reductions — of $27.1 million (see PDF that accompanies this article). Raie said the lifetime savings was based on an average traffic light life of five years. The synchronization yielded more efficiencies in adjusting duration of yellow and red lights at many intersections at different times of the day, Raie said.

The MTC news release stated: "PASS projects' safety benefits for bicyclists come from increasing the minimum 'green times' in each direction. Pedestrian safety is enhanced by re-timing walk signals to accommodate pedestrians traveling at a walking speed of 3.5 feet per second rather than the previous standard of 4 feet per second. To improve safety for children and seniors, the PASS program allows for implementation of even greater pedestrian clearance times at intersections near schools or senior centers."

The synchronization of 13 projects and 339 traffic signals resulted in an 18 percent travel time savings for autos, and auto fuel consumption saving of 14 percent — more than 9.8 million gallons, MTC estimated.

The next round of PASS investments is due to be $1.25 million with 21 projects around the Bay Area, including Danville, Oakland, San Leandro and San Ramon.

Do you have a traffic light down the street that is wonky in its timing? Tell us where in the comments.