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Top1. Introduction
Road network capacity is not a new problem. Ford L. R. Jr and Fulkemon D. R.(1956), professors in operational research at Princeton University, firstly studied the road network capacity by applying the max flow/min cut theory, which was subsequently developed into exploring the maximum traffic entities that the road network can bear by applying the method of traffic distribution simulation and single-double layer planning [C. Chen, 2002].French engineer Lewis Ma Shang (1980s) introduced the concept of “the consumption of urban time and space”,which regards the road network as a container, extended in two dimensions of time and space. The movement of any traffic entity shows the consumption of time and space in the container, from which the capacity of road network can be determined. Yasunori lida, a professor from Kyoto University in Japan, uses the graph theory to study road network capacity of single logistics and uses the traffic assignment method [Yasunori, 1993], to consider the maximum capacity under the conditions of drivers’ route choice, whose study idea and methods are similar to that of the United States.
Our country begins the research on road network capacity later than other countries, which mainly focuses on improving foreign research achievements. Yang Tao from the Southeast University (1995) improved the Ford-Fulkson algorithm and proposed the evolving Cut Set Method based on the max flow/min cut theory, which solved the problem of random and open road net [Yang, 1995]; Li Shuo (1999) from Hunan University proposed the theory and models on road network capacity in a narrow way [S. Li, 1999].In addition, Yang Dongyuan et al. (1995) from Tongji University. proposed road network capacity models from the perspective of the system, which satisfy the balance needs for both users and the system [Yang, 1995]. From the perspective of facilitating computation, Xu Lunhui from South China University of Technology put forward a method of determining the maximum traffic volume under constraints of road capacity [L. Xu, 1997].Based on the uniform distribution of the link capacity, Kuang Aiwu et al. (2007) from Changsha University of Science and Technology analyzed the random change of road travel time in degenerated road network and constructed a model of probabilistic users equally distributing traffic [Kuang, 2007].Based on the analysis of OD structure characteristic of the city road traffic network, Cheng Lin (2007) from Southeast University, proposed basic ideas and models expressing the road network capacity, and illustrated network capacity modelling based on influential factors [L. Chen, 2007].Laura Eboli et al. (2012) form the University of Calabria, explored the factors which affecting transportation and land-use systems interactions, and the results showed that travel behaviour was more influenced by the economic characteristics of population [Eboli, 2012].