A comparative study of the efficiency of a pre-timed signalized intersection and a traffic circle

Abstract

This study considers problem of comparing the efficiency of a traffic circle with that of a signalized intersection. Current analytical methods which compare level of service will not provide an accurate determination of relative efficiency because the level of service criteria for each configuration is different ~ stopped delay per vehicle for a signal, and minimum average delay or reserve capacity for a circle. To provide the basis for an accurate comparison, computer modelling was used. The analysis was carried out using the simulation software TRAF-NETSIM*. Cases of varied approach volume, approach volume ratios and turning traffic were considered. The comparison was made by the output measures of effectiveness. These were travel time, stopped time, average speed, fuel consumption and the ratio of free flow travel time to actual travel time. Traffic circles were found to give a superior performance to signalized intersections when approach volumes were low and balanced, and when turning traffic was high.