Study On The Service Level Of The Ring Expressway

With the expansion of the city,some functions of the early ring expressway have changed.The original purpose of the construction of the ring expressway mainly serves the transit traffic.As the traffic demand changes,the ring expressway is also responsible for serving short-distance transport.The service level of the ring expressway provides a theoretical basis for traffic managers.If we can accurately evaluate the service level of the ring expressway,and provide effective road conditions information for the traveller in time,we can effectively guide the traveler to make the correct travel plan and choose the appropriate travel time and the optimal travel route,and reduce Traffic jams,more rational use of transportation resources,in the meanwhile,we can reduce travel time,fuel consumption and pollution.Therefore,the study of the service level of the ring expressway is particularly important.The content of this paper includes the following aspects:(1)It defines the definition of service level of the ring expressway and analyzes the functional characteristics of the expressway around the city,and clarifies that the ring expressway is the inevitable result of the expansion of the central city.At the same time,it is pointed out that the service definition of the ring expressway is based on the service system of the ring expressway,providing conditions,activities and environment for the spatial displacement of people and vehicles,to meet the structure and process of the user's driving needs.(2)The concept of the service level indicator system of the ring expressway is clarified.The factors affecting the service of the ring expressway are divided into three aspects:road condition factors,traffic flow characteristics,Traffic environment factors.At the meantime,according to the establishment of the evaluation index system of the service level of ring expressway,the four principles of the principle of purpose,systemic principle,conciseness principle and applicability should be followed to analyze the influencing factors of the ring expressway.It gets the initial index of service level evaluation of the ring expressway.Next,The DEMATEL method was used to analyze the relationship between the 16 initial indicators and filter out the indicators for the evaluation of the service levels of ring expressway.Finally,according to the principle and division criteria of the traditional highway service level classification,combined with the traffic flow characteristics and functional positioning of the ring expressway,the standard of service level classification of the expressway is given.(3)According to the traffic flow characteristics of the ring expressway and the requirements of the service level evaluation of the ring expressway,a service level classification model based on Projection Pursuit is established.With the help of MATLAB platform,the Particle Swarm Algorithm is used to solve the optimal projection direction,and the projection value z(i)is obtained.Finally,based on the projection value z(i)and the corresponding level y(i),the scatter plot at z(i)?y(i)is implemented on the MATLAB software platform.(4)The service level of Changsha Ring Expressway(Northwest Section)was evaluated.From a practical point of view,it analyze the conditions of the Changsha Ring Expressway(Northwest Section)and obtain evaluation index data from relevant departments.According to the scatter plot of the projection value z(i)and the level y(i),a interpolation model of the projection value and the level is constructed.Finally,according to the calculation of the projection value of Changsha Ring Expressway(Northwest Section)by MATLAB,the interpolation model is used to obtain the corresponding grade evaluation.The grade evaluation result of the Changsha Ring Expressway(Northwest Section)is that the service level of the XingCheng Expressway Inter-Channel Section of HuangHuaHang Toll Station is Level II and the service level of the XingCheng Expressway Inter-Channel XinGang Express Interchange Section is Level 2 and the service level of XinGang Expressway to WanJiaLi Toll Station is Levels III.The example verifies that the Projection Pursuit model is applied to the feasibility of the service level evaluation of the ring expressway,and provides a new way for the study of the ring expressway system.