Improved Safety and Efficiency of Protected/Permitted Right Turns in Oregon

Christopher Monsere, Portland State University

Co-investigators:

  • Sirisha Kothuri, Portland State University
  • David Hurwitz, Oregon State University

Summary:

This research aimed to develop an understanding of the safety and operational implications of using the flashing yellow arrow (FYA) in permitted and protected/permitted right turn (PPRT) operations to maximize safety and efficiency. This report includes a review of more than 50 scientific and technical articles on the selection of right turn phasing alternatives and a review of Oregon crash data at intersections with exclusive right-turning lanes from 2011-2013. The study had three phases: 1) a web-based survey, 2) a microsimulation model, and 3) and a driving simulator study. The survey measured Oregon driver’s comprehension of right-turn signal display. Analysis revealed a general misunderstanding of the required driver response for the steady red arrow signal indication, but comprehension of the FYA for right turns was high. The microsimulation model of several PPRT phasing alternatives indicated that the pedestrian volumes had the greatest effects on delays. The driving simulator experiment indicated that driver responses were relatively consistent with those observed in the web-based survey. The results suggest that Oregon transportation agencies might improve driver-yielding behavior and pedestrian safety at signalized intersections with high volumes of permissive right turns from exclusive right-turn lanes by using the FYA display in lieu of a steady circular green display.

Impacts:

The Oregon Department of Transportation adopted two new traffic signal head specifications based on this project. The specifications provide clarity to the design of protected / permissive right-turn phasing options by including a flashing yellow arrow.

Project Details

Project Type:
Research
Project Status:
Completed
End Date:
May 01,2018
UTC Grant Cycle:
non-UTC project