Although the Federal Highway Administration considers flashing yellow arrows (FYAs) a dramatic improvement over circular green (CG) lights for indicating permitted left-turns at signalized intersection, driver complaints and some high-profile crashes have called into question how well drivers understand them. Time-of-day changes between protective and permissive phasing may be contributing to driver confusion. This research study plans to test driver comprehension of different traffic signal indications and develop guidance on appropriate implementation of FYAs for various conditions.
