A Comparison of Three Delay Models for Sign-Controlled Intersections and Roundabouts

Abstract

The results of an evaluation of three analytical delay models for unsignalised intersections are presented. The delay models studied are the Highway Capacity Manual Chapter 10 (HCM 94) Model, the Ak_elik - Troutbeck model, and the SIDRA 5 model. These models are applicable to sign-controlled intersections and roundabouts. The evaluation work was reported in this paper is for sign-controlled intersections. Each delay model was used with its associated capacity model. The models were compared by means of extensive tests using microscopic simulation program ModelC for a basic gap-acceptance case. Delays predicted by the current form of each model were first compared against simulated delays. Modified forms of the three models were then calibrated against simulation data. Generally, the modified models improved delay predictions to a small extent. Overall, the SIDRA and Ak_elik-Troutbeck models indicated similar levels of prediction ability whereas the HCM 94 model displayed poor performance. improved predictions of capacities appeared to give larger levels of improvement in delay prediction. The HCM 97 delay and capacity models gave similar results compared with the HCM 94 models. Similar model comparison work is recommended using real-life data collected at sign-controlled intersections and roundabouts.