A REASSESSMENT OF THE TRAFFIC SIGNAL CHANGE INTERVAL

Data from field studies of intersections in Arizona and information from the literature were used to make an in-depth examination of the traffic signal change interval. This examination included a review of the traditional concept and theory on which the determination of the change interval has been based and an evaluation of the applicability of this theory. The analysis of driver behavior and characteristics indicates that the majority of drivers do not conform to the model, which assumes a constant or uniform deceleration rate. In fact, the deceleration profile is related to the approach speed. An analysis of the first vehicle to stop at an intersection and the last vehicle to clear the intersection was made based on the time from the intersection at the onset of the yellow interval. This analysis revealed that the time for the last vehicle to clear the intersection is more critical in the design of the yellow interval. It is concluded that a uniform 4-sec yellow interval would be acceptable.