Citation

Noyce DA, Knodler MA. Proc. Road Saf. Four Continents Conf. 2007; 14: 13p.

Copyright

(Copyright © 2007, Conference Sponsor)

DOI

unavailable

PMID

unavailable

Abstract

This paper provides a review of over 10 years of research by the lead author related to the development and implementation of the flashing yellow arrow indication as the preferred permissive indication in protected-permissive left-turn traffic control at signalized intersections. The results of a series of comprehensive research studies on permissive left-turn operations showed that the flashing yellow arrow (FYA) indication is a recommended application for permissive left-turns. As documented in National Cooperative Highway Research Program (NCHRP) Report 493, a FYA permissive indication was recommended for implementation in the Federal Highway Administration's (FHWA) Manual on Uniform Traffic Control Devices (MUTCD) and has since received interim approval by FHWA. Recommendations suggest that the FYA be implemented in an exclusive four-section vertical signal display centered over the left-turn lane, which differs from the most common application of PPLT signal displays. Many traffic engineers in the USA use a five-section clustered arrangement shared signal head to meet MUTCD requirements of two signal heads per major approach. FYA implementation in this display would require an interim 'retrofit' requiring the FYA to be displayed simultaneously with the through movement indication of circular green (CG), circular yellow, or circular red. Research has focused on traffic operations and human factors contributions to the novel signal indication, using dynamic driving simulator experiments and computer-based static evaluations. A field evaluation of the nearly 300 installation of the FYA is currently underway. All research results show that the FYA permissive indication improves driver comprehension and reduces the number of driver errors common to left-turn crashes at signalized intersections. Both safety and operational improvements are realized.