Regional Transportation Officials Report Progress on Traffic Signal Coordination

Dec 17, 2003

The Transportation Planning Board (TPB) at the Metropolitan Washington Council of Governments (COG) today announced significant progress in improving traffic signal timing in the Washington region through a process known as Traffic Signal Optimization.

Building on efforts already in place, more than 500 stoplights in the District of Columbia, Suburban Maryland, and Northern Virginia have been retimed since the TPB passed a resolution last year to encourage transportation agencies to synchronize lights at heavily-trafficked intersections. Participating jurisdictions are working together to increase the number of coordinated intersections from 2,086 prior to 2002 to 2,942 by 2005. The region has already reached a level of more than 2,600 signals optimized, well before the deadline of the program, and progress is continuing.  There are more than 4,500 traffic signals in the COG region.

“This comparatively low-cost program improves travel time for drivers, improves safety for both drivers and pedestrians, and helps with air quality issues,” said David Snyder, Falls Church councilmember and chair of the TPB Management Operations and Intelligent Transportation System (MO/ITS) Policy Task Force. “It truly is a success story. The public asked us to do something and we are committed to doing it.”

Optimization activities retime traffic signals on a coordinated basis roughly once every three years, determining the number of seconds a stoplight remains red, yellow, or green for each roadway direction according to traffic patterns. Traffic signals need regular attention, because constantly changing traffic patterns and loads change the “optimum” timing and synchronization. The process is intended to ensure proper equipment function and improve traffic flow, in turn reducing vehicle emissions and making the streets safer for pedestrians through traffic engineering considerations and improved adherence to speed limits.

The TPB adopted an aggressive regionally cooperative traffic signal optimization program in July 2002 as part of an effort to reduce transportation-related air pollution. Officials viewed the optimization program not only as a good way to make air quality contributions, but also to help mitigate traffic congestion in the region. The region is on track to meet or exceed the goal of an additional 856 signals optimized by mid-2005.

The District Department of Transportation has exceeded its commitment to optimize 344 traffic signals, with 400 retimed as of early September 2003 and plans to optimize all remaining signals in 2004. The Maryland Department of Transportation has optimized all signals under its control in the region, including 182 signals not optimized as of June 2002, and is working with Montgomery County to optimize an additional 225 signals under county control. In Northern Virginia, where the Virginia Department of Transportation has actively maintained optimization for all the signals in Fairfax, Loudoun, and Prince William Counties, plans are in place to begin work in local jurisdictions that operate non-VDOT signals once federal FY 2004 funds are distributed.

 
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