OPTIMIZATION OF TRAFFIC SIGNAL CHANGE INTERVALS. FINAL REPORT

Utilizing data from field studies of intersections in Arizona and information from the literature, an indepth examination of the traffic signal change interval was undertaken. 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. Because the majority of the first vehicles to stop after the onset of the yellow interval did not conform to a constant and uniform deceleration model, the last vehicles through the intersection were found to be more critical in the design of the change interval. Factors such as approach speeds, approach grades, and the duration of the yellow interval had little or no influence on driver behavior relative to decisions to stop or continue through the intersection. Based on analyses of the time distance of vehicles from the intersection at the onset of the yellow interval, the research suggests that a uniform yellow interval could be utilized.