Study On The Optimal Model Of Urban Road Network Reliability

Urban road network reliability is the level at which the various service it offers can satisfy the demand of trip makers.And,it is one of the important indexes to measure the quality of the road network.Modern urban road network becomes more and more huge and complex;the requirement of people for trip quality is more and more high.those all make road network reliability problem more and more important and outstanding.Road network reliability has now become an important performance measure for evaluating road networks,especially when considering changes in OD traffic demand and link flow capacity over time. So, based on the existing road network reliability and relevant researchs, this article has started the study for the following contents.First of all, this paper has analysed various concepts and progress of the reliability based on reading the research literatures, and has learned that there are the link reliability,the reliability of travel time,capacity reliability and unblocked reliability and so on. And analysed the methods of calculation of various reliabilities.This paper has analysed the basic theory and related models of the reliability of travel time, based on the research of the eigenvalue (mean value,standard deviation and so on)of the reliability of travel time, deduced the expression of the route travel time reliability by the link travel time reliability, and establish the bilevel programming model under the conditions of random by the edge capacity reliability model.This paper discussed that the reliability of travel time and the capacity reliability are not independent of each other, they often contact through the traffic flow and the traffic capacity of a section of a highway or railway. Synthesized the reliability of travel time and the capacity reliability based on their relation,and proposed new reliability index.The new reliability index is defined as the probability of the traffic flow does not exceed a variable, it is a index that can reflect the overall performance of a network. And established the bilevel programming model of capacity based on the new reliability index.This paper analysed the method of calculation of the unblocked reliability of a section of a highway or railway,route,OD and the road network, and established model whose goal is that the unblocked reliability of the entire road network is maximum. Taking into account the common point between the model above and the equilibrium traffic assignment model of probability users (the behavior of travelers for choose route), and established the bilevel programming model of capacity whose lower program is the mode of unblocked reliability of the entire road network, and gived an example to validate its feasibility. This paper analyzed and studied briefly the application of the reliabilities and their models, namely, analyzed the application of the new reliability index in the traffic assignment and the traffic system evaluation; researched into the application of the models of reliabilities in calculating the capacity reliability of road network and traffic control.