This paper describes how it is common practice for operations engineers to program traffic signal controllers to serve the pedestrian movement at the same time that the parallel vehicular through movement is served. This requires drivers completing a permissive left-turn movement to yield to both opposing vehicles and pedestrians prior to selecting an appropriate gap. To minimize this potential safety problem, it is critical that both drivers and pedestrians have a clear understanding of the permissive left-turn signal indications. The recently completed National Cooperative Highway Research Program (NCHRP) Report 493 identified that a flashing yellow arrow (FYA) permissive indication provided a preferred alternative to the existing circular green (CG) permissive indication and recommended that the FYA permissive indication be included in the MUTCD. This paper presents the research findings of a follow up study that targeted the FYA impact on pedestrians, including both driver comprehension of the need to yield to pedestrians as well as pedestrians recognition of appropriate crossing opportunities. Both driver and pedestrian comprehension of the FYA indication was evaluated at or near the pedestrian crosswalks using a series of dynamic driving simulator evaluations and computer-based static evaluations. In total, 139 drivers and 100 pedestrians evaluated over 5,930 experimental scenarios. The findings indicate that the FYA permissive indication can be safely and effectively used at intersections with pedestrian activities. Given the high level of comprehension to yield requirements, the FYA is a recommended indication at "T" intersections where pedestrian crossings are prevalent. From a pedestrian perspective, less than half of the pedestrians understood correct crossing procedures when pedestrian signal heads were not present, and pedestrian comprehension of the walking requirements under a flashing DON"T WALK were quite low in all scenarios evaluated.
Abstract