Research On Performance Reliability Dynamic Evaluation Methods For Road Traffic Flow

Since 1980's, the high-speed development of our national economy and promotion of the urbanization process have brought the rapid growth of the urban transportation. But with the quantity of motor vehicle and traffic volume increase sharply, increase of traffic jam and traffic accident, aggravation of the environmental pollution are come forth. Transportation problem has already become an important problem of influencing national economy development and people's living quality, and it needs to be solved urgently. So what people generally cared about is how to solve the traffic problem, and people hope to analyze the traffic question from each angle of traffic characteristic, improve urban road network through certain feasible methods, in order to meet traffic demandThe domestic and international studies on traffic system performance indexes are limited to normality indexes more at present. But the traffic system is a big dynamic system, and road capacity and traffic demand are constantly changeable because of the existence of various kinds of influence factors, so this makes traffic system performance and blocking probability change at random constantly. The normality index is often gotten from some one time or is the observation result in a short time. Regarding the normality index as the appraisal ground of the traffic system performance during a regular period which unavoidably have randomicity and will bring difficulty to the traffic management, layout and planning. So it is necessary to use the probability index to analyze and study urban road network.Reviewing the traffic performance evaluation indexes, speed and delay are respectively confirmed to evaluate the road segment and intersection performance in the paper. And according to different operation states of vehicle, consulted the grading of the service level, transportation performance is divide into five grades: very unblocked state, standard unblocked state, basic unblocked state, not very unblocked state, and not unblocked state.Traffic flow depends on the road capacity and traffic demands. Road capacity and traffic demands change because of influence by all kinds facts, which make state of taffic flow change continuously. But nowadays, scholars at home and abroad study indexes of traffic flow limiting to static states, these indexes commonly come from one time or shorttime observation. Evaluating traffic flow only by using these indexes has biggish randomicity,and makes traffic management difficult. So it is necessary to evaluating traffic flow by probable indexes of the state of road operation. Depending on such background, traffic flow credibility as a probable index is thought much of by inside and outside scholars, they have done much work about these, and got some research fruits. Firstly, the paper introduces research background and meanings, and reviews traffic flow credibility and evaluating methods inside and outside. Aslo the paper introduces network,plot theory and analysis methods of network credibility involved, and make these be research foundation.Then, the paper puts forward the definition of traffic flow credibility and dynamic evaluating methods of road basic element of traffic flow credibility reference to systems engineering. In order to holding the operation state of traffic flow of the whole network, the paper builds path,OD pairs and evaluating methods of traffic flow credibility based on evaluating of road basic element of traffic flow operation state. The paper puts forward the definition of focus route and intersection based on evaluating methods of traffic flow credibility, designs estimating method of focus route's basic elements reference to importance analytical method and as making traffic flow credibility most to be the target, which being used to confirm focus route's basic elements of the network, finally puts forward filter standards of focus route's basic elements considering traffic management.Based on these above, the paper evaluates the operation state of traffic flow credibility of express roads network in some city, calculates its road basic elements,path,OD pairs and the operation state of traffic flow of the whole network, further uses results calculated to screen out focus routes and intersections of the network during each period of time, and anysizes its validity, proving that the research result of the paper can be used in traffic management and can provide decision-making for traffic managers.Finally, the main research results are summarized in the thesis and the research direction in the future is put forward.