Gregory W Davis

Evaluation of Driver Deceleration Behavior at Signalized Intersections

This study analyzes field data gathered from 60 test subjects to characterize driver deceleration rates at the onset of a yellow-phase transition on high-speed signalized intersection approaches using an in-vehicle Global Positioning System. The driver rate of deceleration is analyzed for five yellow-phase trigger times to stop line (1.6, 2.7, 3.3, 4.4, and 5.6 s) as drivers approach the intersection at a speed of 72 km/h (45 mph). Results of the study, based on a sample of 821 deceleration events, indicate that driver deceleration rates range between 1.51 and 7.47 m/s2 (5–24.5 ft/s2) with a mean value of 3.27 m/s2 (10.7 ft/s2). Mean deceleration rates varying from 2.2 m/s2 (7.2 ft/s2) for the longest time to stop line (5.6 s) to 5.9 m/s2 (19.4 ft/s2) for the shortest time to stop line (1.6 s) demonstrate that drivers use more time to decelerate if they are sufficiently away from the intersection. Statistical analyses were used to investigate the effects of the time to stop line, gender, age group, and grade on the average deceleration rates. Results demonstrate that male drivers appear to show slightly higher rates of deceleration when compared with female drivers. This difference increases as the trigger time to stop line decreases. Younger drivers (younger than 40 years old) and older drivers (60 years of age or older) exhibit greater deceleration rates when compared with drivers in the 40- to 59-year age group.

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