Gap Acceptance Modelling by Traffic Signal Analogy

Abstract

New capacity and performance (delay, queue length, proportion queued and queue move-up rate) models are presented for unsignalised intersections (roundabouts and give-way and stop-sign control). The new models were developed by converting the block and unblock periods in traditional gap acceptance modelling to effective red and green periods by analogy to traffic signal operations. This enabled the modelling of performance statistics in a manner consistent with models for signalised intersections. The models are based on the bunched exponential model of arrival headway distributions for all traffic streams, and are also applicable to simple negative exponential and shifted negative exponential distributions. Data generated by a modified version of the microscopic simulation model MODELC were used for model calibration. The new capacity model is compared with various existing formulae based on gap-acceptance modelling.