Improve Left-Turn Safety with Flashing Yellow Arrows


This graphic illustrates the flashing yellow arrow signal operation. Graphic courtesy of Indiana Department of Transportation

Most people can relate to the frustration of making left-hand turns in heavy traffic—especially that moment when the light turns yellow and you have to decide if the oncoming car is going to stop and let you turn left and clear the intersection. Some drivers assume a yellow light means they are free to turn, and this common misperception has resulted in many crashes.

The National Highway Traffic Safety Administration (NHTSA) estimates that approximately 22 percent of crashes that occur in intersections are associated with left turning movements. As a result, improving safety conditions for left turns has become an important issue to address both intersection design and traffic operations.

Because this issue is so prevalent, studies have been conducted to examine which signal option is the most understandable to drivers. A National Cooperative Highway Research Program study demonstrated that drivers found flashing yellow left-turn arrows more understandable than traditional yield-on-green indications.

With flashing yellow arrows, drivers were able to correctly time left turns and prevent crashes. FHWA has permitted nationwide use of the flashing yellow arrow since 2010. As communities evaluate traffic safety and invest in new signals, be aware of this emerging method to improve left-turn safety.

Please comment or contact LJB if we can help you evaluate this option for your community.


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