Platoon dispersion downstream of traffic signal

Abstract

The potential benefits of studying platoon dispersion downstream of traffic signal are already known in traffic flow analysis, modelling and traffic engineering design. However, presently there is a lack of information on platoon dispersion on Malaysian roads. This study determines the arrival distribution pattern downstream of traffic signal which includes vehicle headway, intra-platoon headway and inter-platoon headway. It also looked into the roadway characteristic that affects platoon dispersion. Data for more than 1000 vehicles were collected using video cameras to record traffic movement at Saleng, Kulai. Vehicle type and time were determined for each vehicle on a per lane basis during the morning peak and off peak hours at several consecutive points downstream of traffic signal for analysis. Four mathematical distribution models namely shifted negative exponential distribution, erlang distribution, schuhl distribution and double displaced negative exponential distribution were fitted to the actual distribution data. It was observed that vehicle headways follow the shifted negative exponential distribution with shift equals to 1.0s, the intra-platoon headways have normal distribution and inter-platoon headways do not fit to any of the tested distribution models under peak and off peak hours. The level of friction at this road section is of low friction. The values of platoon dispersion factor and travel time factor are 0.16 and 0.86 during peak hour and 0.22 and 0.82 during off peak hour. The values of smoothing factor under these conditions are 0.21 (peak hour) and 0.17 (off peak hour). The higher value of smoothing factor indicates that the vehicles are able to travel on the road section more smoothly compared to lower value.