Accuracy of Turning Flow Estimates at Road Junctions

Abstract

Several methods for obtaining turning probabilities have been suggested to help in estimating turning flows. One of these methods is based on historical data of approach counts available for each intersection. The turning proportions are then estimated for each individual intersection rather than using average values according to intersection type. This paper investigates the accuracy of turning flow estimates using this technique when applied to intersections in Kuwait. The turning flow estimates are compared with the observed, flows. The variations of the magnitude of the errors in estimates with the magnitude of the estimated flows are thoroughly investigated, and the implications of these variations are discussed. The results show that reasonable estimates were obtained at some intersections, but locations where the network has undergone major changes showed higher errors.