Alternatives to Protected-Only Left-Turn Phasing

The Virginia Department of Transportation (VDOT) released a new left-turn phase selection policy and guidance in 2015 and has been installing significantly more flashing-yellow arrow (FYA) left-turn signal faces statewide. The flashing-yellow arrow is VDOT’s preferred signal head for permissive and/or protected/permissive mode left turns when a separate left-turn lane is present. FYAs allow traffic-signal controllers to operate left-turn movements in protected, protected/permissive, and/or permissive modes, varying, for example, by time of day and day of the week. This project will evaluate and document the safety and operational impacts of the variable time-of-day configuration by reviewing national FYA practices and evaluating VDOT’s FYA installations. The findings will support development of FYA-specific, left-turn phase selection guidelines and help VDOT make more informed phase-selection decisions for improved signal safety and operations.