Study On Urban Traffic Guidance System Based On Real Time Traffic Information

The study on the dynamic route guidance systems (DRGS) is an important research in the field of Intelligent Transportation Systems (ITS), which guide the behaviors of travelers by providing them with optimal route based on real-time traffic information. As a result the travel time can be saved and the traffic congestion can be avoided. The purpose of the dissertation is to provide theoretical basis and technological schemes for dynamic route guidance systems developed with respect to the real traffic data obtained from urban Traffic Management Center (TMC)? under the hybrid traffic condition in the urban areas of China.Considering the function requirements of Urban Traffic Guidance System (UTGS), based on the prevailing condition obtained in China and the analysis of DRGS developed outside China, the important architecture information of UTFGS is decided. It is studied how to convert the flow rate and occupancy data coming from Traffic Management Center (TMC) to link travel time data used by UTFGS. The urban traffic flow characteristics are analyzed based on measured data and, it has been proved statistically that there is a kind of statistical relationship between link travel time and the flow rate, occupancy of the same link during the same period. The prediction of link travel time is the essential theory problem of dynamic route guidance system. How to transform the current link travel time estimated by the real time traffic information into future link travel time is the key of the route guidance system. In this paper a forecasting method using Taylor series is discussed.The frequently occurrence of traffic accidents results in the blockade of roads, the increase of travel time and the delay of traveling. The influence on vehicles after traffic accident happen in urban road net is analyzed in this paper. According to the degree of the accident, the capacity of the accident point is determined. The formula of travel time after accident when traffic demand upriver exceed the capacity of the accident point is given based on the dynamic law of waiting queue, which is regarded as the gist of circumambulating or not. According to the standard of route selection, method of selecting circumambulating route is given.