| With the advance of urbanization, increasing the national level of urbanization, thenumber of urban vehicles growthes also accelerated. In order to lighten the pressure ofmotor vehicles i.e., traffic jamming and air pollution for the city, many cities had begun,have been beginning, and will begin to build urban freeway system to improve roadefficiency, shorten time residents travel costs. Urban expressway is a special road betweenfreeway and urban road. From the development of our urban expressway, the systematicstudies and analysis have not been discussed for urban expressway, which include theappropriate traffic flow mode of urban freeway, design optimization, management controland other related research and application of the specific project. Now the theory andmethods of freeway were used in the analysis and the study of urban express.The characteristics of traffic flow and the influenting factors of speed limit on urbanfreeway system were analyzed in the paper. A cellular automatation model of urban freewaywas established. The simulation results were doned in order to determine the optimizedvalue of the speed limit in the general urban freeway conditions by the geometric shape ofthe road, the optimized value of variable speed limits when a lane was closued in a roadmaintenance and a traffic accidents. The results were proved in the expressway system ofXingtai City. The concrete scopes were discussed about the setting the physical facilities,roadside pavement electronic facility and speed restrictions phase combined. The decisionsupport was proved for decreasing traffic accidents, ensuring traffic safe and enhancingroad traffic efficiency. |
