Urban congestion is a major and costly problem in many cities both in China and other countries. The purpose of building urban expressway is to alleviate the growing traffic pressure. In this paper, the mesoscopic traffic flow models are improved by variable speed limits strategy for the dynamic of vehicles on urban expressway network. The models include static queuing model, the velocity model, and the movement model of the vehicle. Moreover the method of the simulation is also proposed. So that we can get the corresponding variable speed limits values and aid traffic managers in making decisions to develop a network traffic flow control strategy. In the end, the elevated expressway of Jinan city is used as a simulation example. We investigated the performance of the transport system with averaged density, speed, and flow on link. We also analysed the dynamic of the traffic system on expressway network at different demand levels. The simulation results show that the models are feasible and effective and the variable speed limits strategy can successfully alleviate the traffic congestion in some extent. The operational efficiency of the transportation system is greatly improved. 1. Introduction The problem of traffic congestion has become more and more serious in the cities around the world; in particular, it is one of the most important issue in big cities. Growing traffic congestion has seriously hampered the economic development and brings inconvenience and damage to people’s work and life. Intelligent transportation system (ITS) is an effective way to solve the above problem, and the dynamic traffic assignment (DTA) is the key technology. The objective of DTA models is one of the most important foundations of intelligent transportation system. It is also the theoretical basis of Advanced Traffic Information System, Advanced Traffic Management System, and Super Smart Vehicle System. It is a forward-positioned research work in traffic and transportation field and has received increasing attention in recent years. DTA has two steps, one is traffic flow model which descript the dynamic of vehicles on the network, and the second is a dynamic network loading. Typically, the traffic flow models are divided into macro-, micro-, and mesoscopic model. The levels of detail in these models range from microscopic to mesoscopic to macroscopic. Macroscopic models depict the traffic at high levels of aggregation in flow, speed, and density without having to explicitly represent vehicles. On the other hand, microscopic models are aimed at describing detailed
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