Consideration of 24-hr Volumes in Selection of Traffic Signal Control Strategies for Isolated Intersections

Abstract

Selection of the most appropriate traffic signal control strategy for isolated intersections is a difficult and complicated process. TRAF-NETSIM was used to evaluate the operational performance of an isolated intersection under pretimed, semiactuated, and actuated control for continuous 24-hr traffic volumes. Guidelines were developed for selecting the most effective control strategy. Findings include the following: either pretimed or actuated control is the most effective strategy for isolated intersections without flashing for the 24-hr and peak 8-hr traffic volumes. The conventional three-dial pretimed controller is still a valuable control strategy and should not be eliminated from consideration. The most effective strategy for the peak 8-hr operation of an isolated intersection is probably the most effective one for overall 24-hr operation, as well. The combined control strategy (which consists of one or more of the pretimed, actuated, and semiactuated controls dependent on the hourly volumes) without flashing is the most effective strategy for the 24-hr and peak 8-hr traffic volumes. The signal flashing mode is very effective during the night when the total intersection critical lane volume falls below 500 vehicles per hour. Advanced pretimed controllers are generally more effective than conventional three-dial pretimed controllers. There is no direct, universal method to determine the most effective combined traffic signal control strategy for isolated intersections.