Effect of Yellow-Phase Trigger on Driver Behavior at High-Speed Signalized Intersections

The paper characterizes driver behavior at the onset of a yellow-phase transition on high-speed signalized intersection approaches using field data gathered from 60 test subjects (approximately balanced in gender and age). The driver stopping/running decisions are analyzed for five trigger distances as drivers approach the intersection at a speed of 72 km/h (45 mph). The study demonstrates that the probability of stopping varies from 9% at the shortest yellow-phase trigger distance of 32 m to approximately 100% for the longest 111 m trigger distance. The study also demonstrates an increase in the probability of running for male drivers when compared to female drivers. This difference increases as the trigger distance decreases. The data demonstrate that drivers 65 years of age and older are significantly less likely to clear the intersection at short yellow-phase trigger distances when compared to other age groups. Dilemma zone boundaries (distances where 10% to 90% of the vehicles stop) are derived and uncertainty zones for different age groups are also developed