Less than ten percent of intersections are signalized; however, more than 30 percent of intersection fatalities occur at signalized intersections. Signal phasing strategy is considered to be one of the most important factors influencing the safety and operations of signalized intersections. Because drivers respond differently to different signal phasing sequences, engineers need to evaluate how drivers interpret each phasing sequence and the message that they are trying to convey. The goal of this project is to assess the safety of different left turn movement treatments at signalized intersections by using crash, video, and survey data. In particular, the project will compare the safety of protected left turns to protected-permissive left turns with a flashing yellow arrow. It will compare the safety of doghouse displays to four-section vertical displays with a flashing yellow arrow. And it will assess the safety of including flashing yellow arrow phases in protected-permissive left turns at different times of the day to identify whether changes create driver confusion. The results of this research will help decision makers select more suitable signal phasing plans under various operational conditions.
Principal Investigator: Ali Hajbabaie, Civil and Environmental Engineering, WSU
Sponsor: PacTrans
Scheduled completion: January 2018