THE IMPROVED EFFECTIVENESS OF TRAFFIC SIGNAL SYSTEMS SEMI-ACTUATED SIGNALS ON ARTERIAL STREETS

This report describes an investigation of the effectiveness of semi-actuated signal controllers compared to fixed-time signal controllers at minor cross streets along progressively timed arteries. The effectiveness was determined by measuring the stopped-time delay and travel time on the artery during three times of the day, AM peak period, off-peak period, and PM peak period at three types of sites at five locations: a heavily travelled arterial with 1/4 mile signal spacing and very little cross traffic at the minor cross street, a heavily travelled arterial with moderate cross traffic at the minor cross street, and a heavily travelled arterial with a great deal of circulatory and cross street traffic. Fixed-time signal control was found to be as effective as, and sometimes more effective than, semi-actuated control at the majority of the locations studied. As installation costs are slightly higher for semi-actuated control, fixed-time control would be more cost-effective. However, the differences in delay and travel time for the two modes of control are slight. Recommendations are made for further investigation to aid in selecting the most effective mode of control at minor cross-street intersections.