Module 4 : Macroscopic And Mesoscopic Traffic Flow Modeling

Lecture 19 : Traffic Progression Models

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	Introduction A majority of the metro cities in India are facing the problem of traffic congestion, delays, which have further resulted in pollution. The delays are caused mainly due to the isolated functioning of the traffic signals at closely located intersections. For better regulation of traffic flow at these intersections, the traffic signals need to be coordinated or linked. For the linking of signals, the vehicle movement characteristics from upstream signal to downstream signal need to be considered and simulated. Traffic Progression Models model the vehicle movement characteristics and help in the linking of signals. First, the concept of platoon, platoon variables is discussed and then platoon ratio is defined which is required for determination of arrival type. Then, the phenomenon of platoon dispersion and platoon dispersion model is introduced for understanding dispersion behavior of the vehicles. Finally, one of the platoon dispersion models i.e., Roberson's platoon dispersion model is discussed, which estimates the vehicle arrivals at downstream locations based on an upstream departure profile.