Driver Comprehension of Flashing Yellow Arrows

Summary:

In 2009 the FHWA’s Manual on Uniform Traffic Control Devices (MUTCD) introduced flashing yellow arrow (FYA) traffic signals as an alternative to circular green (CG) to indicate permitted left-turns. FYA is arguably a more intuitive indication that left turns are permitted but not protected and, in addition, FYA signal heads can support time-of-day changes between protective and permissive left turn phasing. In 2019 a Research Needs Statement stated that “Research is needed to examine driver comprehension of flashing yellow arrow in different light arrangements and the role of signage.” Our objective in this project was to assess drivers’ understanding of FYA signal indications, and to see if the presence or absence of “Left Turn Yield” signs affected gap acceptance. This was accomplished by conducting an online survey of drivers regarding their understanding of FYA signals, and by carrying out a field study of drivers’ gap acceptance at a set of Twin Cities intersections.

Final Deliverables:

• Report #2023-42
• Research Summary

Related Materials:

• New Project: Driver Comprehension of Flashing Yellow Arrows  - (Blog Post)
• Flashing yellow arrow traffic signals  - (Website)

Related Research:

• Development of Guidelines for Permitted Left-Turn Phasing Using Flashing Yellow Arrow
• Development of Guidelines for Flashing Yellow Arrows for Protected/permissive Use