Use of flashing yellow operations to improve safety at signals with protected-permissive left turn (PPLT) operations

PDFTech ReportReport 0-6568-1FHWA/TX-09/0-6568-1Project 0-6568Left turn lanesYellow interval (Traffic signal cycle)TexasTexas Southern UniversityQi, YiChen, XiaomingYu, LeiWang, YubianZhang, MinYuan, PeinaPersad, Khali R.Texas Southern University. Dept. of Transportation StudiesTexas. Dept. of Transportation. Research and Technology Implementation OfficeUS Transportation CollectionMUTCD 2009 Edition suggests the use of Flashing Yellow Arrow (FYA) indication in replacement of green ball indication for permissive left-turn signal in presence of separate signal heads. Currently, there is no clear guidance on how to implement flashing yellow operations with PPLT in Texas. The objective of this research project is to developed guidelines for FYA with PPLT operations. To fulfill this goal, the researchers (1) reviewed and synthesized national and peer state practices on FYA PPLT; (2) surveyed traffic engineers and drivers ; (3) deployed FYA PPLT operation at five selected intersections in Texas cities; (4) identified software and hardware issues associated with the deployment of FYA PPLT; and (5) evaluated the safety performance of FYA PPLT based on the historical crash data analysis and field traffic conflict studies. According to the findings of this research, it is recommended that FYA signal indication can be used at most of signals with PPLT operations to improve intersection safety and to comply with the requirements of the MUTCD. However, FYA PPLT operation is not recommended at busy intersections that have high left-turn volumes and opposing volumes, and it should be implemented with great cautions at intersections where lead-lead left-turn phasing is used