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Summary of Research Study Findings Related to the Flashing Yellow Arrow

The various research activities completed throughout the course of the NCHRP 3-54 Research project consistently supported the use of the flashing yellow arrow indication as an alternative to the MUTCD circular green permissive indication. The Engineering Assessment contained in Working Paper 1 succinctly summarizes many of the aspects by which the flashing yellow arrow display was found to be equal to or superior than existing PPLT displays. Similarly, the Confirmation Study (Working Paper 7) and the Field Implementation Study (Working Paper 8) have demonstrated the viability of the flashing yellow arrow display as well as its performance and acceptance upon introduction to the motoring public.

The Implementation Study (Working Paper 8) results demonstrated that the flashing yellow arrow indication was well understood in almost all deployment cases. Analysis of the conflict data suggests that the flashing yellow arrow indication is at least as safe as the current MUTCD standard (circular green indication). Where deployed, the flashing yellow arrow indication was favored by almost all of the traffic engineers, field technicians, and citizens when compared to the circular green PPLT indication. The Implementation Study identified hardware and software issues related to implementing the flashing yellow arrow display that would need to be addressed before any widespread deployment could be conducted. 

The flashing yellow arrow indication and display was found to have a high level of understanding, and a lower fail critical rate (drivers making an unsafe decision) as compared to the circular green indication. The flashing yellow arrow display offers more versatile field application features (for example, it can be operated in a variety of operational modes by time-of-day, implemented on any signal mount, and any intersection configuration) as compared to the circular green indication.


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