Study On Safety Evaluation Of Urban Expressway Exit Based On Traffic Conflict Technology

Urban expressways are of great importance in urban transportation system. A large number of urban expressways are built in cities of China in recent years. With the increasing number of automobiles, however, the urban transportation system has become worse and worse. Traffic accidents and traffic jam always happen on urban expressways. Research shows that traffic accidents always happen at the entrances, exits and ramps on highways and urban expressways. These traffic accidents not only make damages to persons and property, but also lead to traffic jam. So measures should be taken to make these points safer.At present, there is a little research on design of entrance and exit on urban expressways. Research overseas is mainly on the safety of ramp, research in our country mainly focus on the traffic flow and traffic capacity of exit on urban expressways.In this paper, the characteristic of traffic accidents on urban expressways is analyzed based on data of an area in Beijing. The number of accidents that happen near the entrances and exits accounts for 14.4 percent of all that happen on urban expressways, in which the number of accidents that happen at exits is about 4.1 times of that at entrances. It is necessary to study the safety characteristic of exit on urban expresswaysThe situation of exits on Ring 3^th and Ring 4^th in Beijing is investigated, data of traffic conflict and traffic flow is collected. The risk of traffic conflict is analyzed, and the influence factors are studied. Traffic conflict model of exit on urban expressway is built.A measure of safety evaluation of urban expressway exit is established based on traffic conflict technology. Two examples of the safety evaluation are given.A design of urban expressway exit is proposed at last.