Modeling And Simulation Study On Operational Status Evaluation Of Freeway Network And Technical Realization

In recent years, with the growing number of vehicles, traffic congestion is worsening. Therefore, to accurately grasp the real road network operational status is particularly important. It not only can supply some valuable information to the travelers on the freeways, but also can improve the management level of freeways, so as to make full use of the existing freeways. This thesis is supported by the major demonstration project of Jiangsu Provincial Science and Technology Department—The demonstration system based on the detection, mining, convergence and publishing of the freeway traffic sensor network information and assisting decision, and mainly doing the research from following the aspects:1、Evaluation of freeway network operational status. In order to better grasp the freeway network operational status, you need to have a comprehensive evaluation index system. Basing on the research of the evaluation index system architecture and the evaluation index choosing principle, the thesis establishes a three layers structure of freeway network evaluation index system. Meanwhile, use average speed and time occupancy ratio as the basic evaluation index for traffic operational status of sections; get the evaluation index for traffic operational status of roads by using vehicle hours traveled and the number of lanes as the weight; get the evaluation index for traffic operational status of network by using the length and level of roads as the weight.2、Traffic incident detection. Considering the blind area of video surveillance, the thesis has a research on the automatic traffic incident detection algorithm based on the change of traffic flow parameters. In order to further improve the event detection rate, the thesis proposes a traffic incident detection optimization algorithm based on SVM, using the improved grid search algorithm to optimize the parameters of the model, and uses the historical data through PeMS system to evaluate the testing results of the model.3、Freeway network operational status evaluation system. On the basis of the Web Service technology research, the thesis builds a freeway network operational status evaluation system, and displays the operational status of freeway network by the visual map interface. And the system can detect the incident in real time, so that users can intuitively and accurately understand the freeway network operational status.The innovations and features of the thesis are as follows:1、Existing traffic operational status assessment methods only consider the sections or the roads operational conditions, the thesis proposes an evaluation index system architecture of freeway network operational status for the fully assessment of the overall freeway network. Also, the thesis defines the especial calculation method of the traffic congestion index, and the simulation results show that the model has a certain practical significance;2、Aiming to overcome the shortcomings and deficiencies of the existing traffic incident detection algorithm, the thesis proposes an incident detection optimization algorithm based on SVM, using the improved grid search algorithm to optimize the two parameters of the model. Simulation results show that the algorithm can greatly improve the incident detection rate and has better instantaneity;3、To overcome the deficiencies of the traffic management systems in our country, the thesis builds a feature-rich freeway network operational status evaluation system. It displays a map interface with the Baidu Maps API, and has many functions, such as real-time display of operational status, traffic index calculation, traffic incident detection, and so on. The system has strong applicability.