Study On Dynamic Route Guidance Method Of Vehicle Based On Traffic Flow

Urban traffic problem has already become the bottleneck that restraints the development of economy. In this paper, vehicle dynamic route guidance system based on traffic flow is discussed and studied by using the latest technologies, such as GIS and GPS. The studies are as follows:First, guidance information component, function, structure and developing method of dynamic route guidance system (DRGS) are analyzed, then solution to DRGS, which suits the situation of China and software, hardware of developing the system are determined.Secondly, the problem about predicting the traffic flow at present is analyzed and studied, gray system theory and main component analysis method are given; then, a predict model is established to predict the traffic flow of crossing without detectors by analyzing the traffic flow of crossing with detectors. The models are tested by practical data.Thirdly, minimum travel time and the traffic load are looked as the main optimization object and the status variable respectively in the research of dynamic traffic distribution. Queue length models at the crossing are established based on traffic flow gather-disperse theory and dynamic travel time is described by the concept of density; Regarding delay at the crossing, the delay time is calculated according to different forward direction, so travel time functions of different forward direction and route weight of vehicles in dynamic traffic flow are determined.Fourthly, route network model, construction of route network database, optimization route algorithm and coordinate transformation are studied, the urban route network model, which incarnates the direction, crossing delay and restraint of urban traffic is introduced. The route network model is described by some basic components, such as crossing and route. Route characters are described by using united structure of node—arc. Using the thought of directed graph in graph theory, route network is turned into the mathematical model. The resolution to optimization route of turning delay and restraint is introduced on the basis of improved Dijkstra algorithm and programs realize algorithm.Finally, Dynamic Route Guidance Archetypal System with Windows graphics interface has developed by using Visual C++ and MapObjects components based on above theories. The map in the system can be displayed, moved and zoomed, optimization route can be displayed by selected start point and end point, and orientation information can be received and displayed dynamically by using GPS receiver.