Video-based approach to analyze driver decisions at signalized intersections

A study to analyze the speed profile of individual vehicles and the drivers' decisions to stop or go at the onset of the yellow signal was performed. Events were recorded continuously from 480 feet (146 m) until the stop bar using video cameras. Based on the time to stop line data at the yellow onset, it was observed, that in addition to the group of “normal drivers” who stop or cross the intersection in a reasonable time after the yellow onset, there are two groups of drivers: aggressive drivers who decide to accelerate even though the yellow phase had ended and conservative drivers stopped although they could have passed the intersection during the 3.0 seconds assigned for the yellow period. It is observed that most of the vehicles that stopped took 5.0 seconds or more to reach the intersection and most of the passing vehicles took 4.0 seconds or less to cross the intersection. For passing vehicles at the intersection, the results of the yellow and red entry time of 3.00 and 2.46 seconds, respectively, show a high degree of driver aggressiveness at the intersection. A dilemma zone (DZ) model calibrated from the data showed values of driver’s perception-reaction time, and maximum acceleration and deceleration rates consistent with the theoretical values recommended for the design of a signal timing plan. The proposed technique can be extended to other intersections with similar characteristics using the parameters suggested in this study. A practical manner to avoid involuntary RLR events is proposed.