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Traffic Light Synchronization is a Cost-Effective Method for Reducing Travel Times

Baruch Feigenbaum
November 21, 2011, 1:27pm

With tight budgets and growing traffic congestion, intelligent transportation systems can often improve traffic flow at a fraction of the cost of road construction. The most basic “intelligent” system is synchronized traffic lights, which increases vehicle speed, the volume of vehicles in the corridor and decreases vehicle hours of delay. The Washington State Department of Transportation estimates that the benefit-cost relationship of traffic synchronization as 40:1, while the benefit-cost relationship of adding one new lane of travel in each direction is 10:1. According to the United States Department of Transportation Research and Innovative Technology Administration (RITA) synchronized traffic signals reduce typical travel delays by 25% and gasoline usage by 5%. Efforts are now underway to introduce such synchronization to 20 miles of Georgia State Road 9.

Alpharetta, Roswell and Sandy Springs, three metro Atlanta, GA governments are joining to improve traffic flow on State Road 9. The expected cost of this is $3.5 million, which compares favorably with the cost of adding another lane to the roadway, which would cost approximately $40 million. Traffic light synchronization could achieve 50% of the congestion reduction of adding another lane.

According to Hatcher Hurd of the News and Review, the project will take sixteen months to complete.

It's called the State Route 9 Advanced Transportation Management System (ATMS), and it involves bringing 21st technology to traffic control.

Miles of fiber optic cable, TV cameras and computers will monitor the flow of traffic to manage the traffic light sequencing in real time. And it ultimately won't cost the cities of Alpharetta, Roswell and Sandy Springs anything.

The project got started in 2003 when Fulton County was still involved (Sandy Springs cityhood ended that). The project is really a pilot for the U.S. Department of Transportation, which is why it is subsidized by the feds.

"The project will not only allow us to monitor traffic on closed circuit TV, with the fiber optic connectivity, we will be able to react to shifting traffic patterns as well as quickly identify accidents," said Pet Sewczwicz, Alpharetta director of Engineering and Public Works.

The lights react to the flow of traffic for the entire corridor, he said. The information is fed into each city's traffic control center. If there are any problems, the center can send a response.

The TV monitor feed will also be online and available for commuters to view.

"With our When you get up in the morning, you can check the traffic flow yourself," Sewczwicz said. 

The three cities working with one plan in mind hired a consultant in 2008 to assess the Ga. 9 corridor as one system. A concept report resulted from that study came up with a plan for a seamless transition for drivers from one city to the next. 

Sewczwicz said the over all goal of the project is to "create a smart corridor that uses the latest advances in technology to improve the driver's experience and minimize the effect of regional congestion."

U.S. municipalities need to begin investing in more cost-effective projects. While traffic signal synchronization will not provide the full traffic relief of widening the road, good synchronization can significantly improve traffic flow. Congratulations to the three North Fulton cities for working together on this cost-effective improvement.


Baruch Feigenbaum is Transportation Policy Analyst


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