Traffic signals which forms the integral part of urban road network play a prominent role in maximizing roadway capacity to serve the growing demand for travel, while maintaining a high level of safety. Once released from a signalised stop-line, vehicles normally proceed as platoons and disperse as they progress along the arterial link. Hence modelling of dispersion of vehicle platoon is a key element to measure vehicle arrivals at traffic signals so as to enable efficient coordinated operation of closely spaced traffic signals. At present Robertson’s dispersion model is the most extensively used platoon dispersion modeling method. This method relies on the proper calibration of its model parameters – platoon dispersion factor and travel time factor for its application. Studies pertaining to calibration of these two parameters have been conducted extensively under homogeneous traffic conditions, but similar studies have not been conducted adequately considering the diversity of traffic and lack of lane discipline exhibited under heterogeneous traffic conditions. The data for describing platoon dispersion was collected from an urban arterial using videography and was analyzed for each platoon upto 420m at every 30 m interval. The present study developed an empirical modelto express travel time factor as a function of parameters describing the nature of heterogeneous traffic (link travel time, vehicle composition and traffic volume). The analyses reveals the trend of variation of platoon dispersion parameters and provide an insight into the platoon dispersion along urban corridors operating under heterogeneous traffic conditions.
Praveen P. S and Ashalatha R
Govt. College of Engineering Kannur
General, Urban Mobility