Refinement Methodology for Modeling of Urban Road Traffic Networks

Abstract

This paper proposes a modular frame based on hybrid Petri nets for modeling the signalized urban traffic network for control purpose. A kind of level of detail modeling methodology is used. After an aggregate model of the urban traffic network system is defined, the key elements such as traffic lights and intersections, which describe the typical feature of the traffic network in the aggregate model, are refined to introduce detail models. The proposed model of the intersection describes the turning direction of each traffic flow explicitly and takes into account the conflicts among the traffic flows. Furthermore, the time factor is considered in the system model. As a result, the total model obtained can not only reflect the logical relationship among the traffic flows, but also describe and calculate the physical characteristics of the vehicles such as the location, velocity, and passing time interval. Consequently, the performance index can be calculated with less effort for a given traffic timing plan and different timing plans can be compared in order that an optimal or suboptimal traffic control plan may be chosen. Finally, the implementation issues of the methodology are discussed.