Most analysis procedures recommend the use of measured saturation flows rather than estimates because they are notoriously erratic and are dependent on a multitude of local conditions. However, it is often impractical to measure prevailing saturation flow rates so it is necessary to develop estimates of saturation flow that are based on readily available geometric, environmental and traffic characteristics. This paper outlines the principal results of a major research project into saturation flows at signalised intersections in Melbourne. The models used by SIDRA (Signalised Intersection Design and Research Aid) for saturation flow estimation are recalibrated for a recently collected data set. The new models enable enhanced saturation flow estimation for a range of traffic, geometric and environmental conditions. The models can be adopted easily in SIDRA by editing a default values file and are, therefore, of immediate use to traffic engineers and planners. (A)
Abstract