Analysis Of Urban Road Network Operation Reliability And Optimization

The healthy development of urban economy and urban function is largely dependent on stable and reliable transport network, and this dependence will increase with the accelerating rhythm of urban life and work efficiency. Therefore, whether a transportation network is reliable will be a direct impact on economic development and urban function. Urban road network system is the key part of the transport network system, so it is significant to study the reliability of it.With the development of the society, the road network's ability of dealing with daily and urgent problems is required in deeper degree. It must ensure that vehicles on important road network sections or OD pairs run smoothly. Through the studies of road network system reliability, we can find out conflicts and stochastic laws of supply and demand in the network and take effective measures to reduce the blocking probability caused at random.At present, some other scholars have made great achievements on the study of the road network system reliability and optimization of road network, but there are still many deficiencies requiring of improvement. The deficiency is mainly embodied in the calculation of reliability index which is only tested in small networks but never used in practical road networks, and there are many strict assumptions that are often not coincide with the actual situation, more over, the reliability of the existing indicators of reliability can not fully assess the performance of road network; the problems still need to be resolved about optimization research of road network include the network optimization algorithms, the method of dealing with network node changes, and how to consider the road network reliability in the road network optimization etc.As a probability-based evaluation index, the reliability of urban road network has been developed rapidly in the field of urban road network state evaluation. Based on the research and application of the reliability of urban road network, it puts forward the analysis indicators of Travel time reliability under the limit of capacity(TRC), and then it establishes the relevant model and applies it in the road network optimization model.As to the urban road network system reliability issues and the optimization problem, this article does the following researches on the basis of existing researching results: 1,Analyzes the uncertainty Of urban road network system, and puts forward the supply and demand model of the system. Analyzes the travel time reliability and capacity reliability comprehensively and puts forward a reliability evaluation indicator of road network - Travel time reliability under the limit of capacity(TRC). Analyzes the impact of urban road network operators deeply in the people, road, environment and management on the basis of the urban road network characteristic analysis,analyzes the law and operating mechanism of each feature and explores the real failure reasons and proposes the conceptual model of the mechanism of these influencing factors.2,Analyzes the path choice behavior and its influencing factors in uncertain conditions which include the qualitative analysis of time, economy, information and psychological factors; expounds the route choice theory in uncertainty, and proposes the "prospect theory" on the basis of the expected utility theory and random utility theory. Based on this theory it analyzes the route choice action in the traveler's decision-making node, the decision-making time and decision-making stage and establishes the relevant model ,and then it gives out the alternative route collection generating methods and defines the traveler decision-making "reference point".3,Analyzes the characters of the urban road network unit (links and intersections), puts forward the organization method of the road and intersection, analyzes the organizations of the links ,including traffic lanes, speed, transit and organizations of pedestrians crossing the street, and makes deep analysis of the organization of unsignalized intersection and signalized intersection. Based on the analysis of organization method, it establishes the analyzing model of urban road network operating reliability in accordance with the normal school of traffic supply and demand , and then it studies the analyzing method of TRC.4,Analyzes the basic principles of GO method (a success-oriented system probabilistic analysis technology),and gives the probability combination formulas of relevant operators. Analyzes the characteristics and constitution of urban road network system based on it,studies the analyzing method of urban road network system reliability based on GO method , establishes the GO map of the system,calculates the system reliability indicators based on GO algorithm with probability Combination formula and demonstrates it.5,Gives clear optimization objectives, methods and decision-making variables of urban road network based on the TRC; sets up the urban road network optimization bi-level programming mode. The upper model is based on traffic efficiency as the objective function and the TRC reliability and pollution emissions as constraints, while the lower model is based on traffic volume as the objective function and constraint conditions. The upper model impedance is generated in the lower model. Then, it calculates the model and come to the solution of it in final.