Optimization Theory And Method For Reconstruction Of Urban Road Traffic Micro-circulation System

This paper discussed the theory and method for reconstructing urban traffic micro-circulation system, whose aim is to provide a feasible and effective solution for alleviating traffic congestion of arterial roads. The road resources between arterials that are left unused are explored to shunt the traffic of arterial network, not only alleviating traffic pressure but also saving land and investment. As a solution of traffic congestion, traffic micro-circulation has been practised in our country, but the systematic theory and method especially for designing traffic micro-circulation system have not been established yet. So aiming at the reconstruction problem of urban traffic micro-circulation, from multi-aspect of system function, network design, traffic onganization, systhetical evaluation, this paper discussed the key theoretical problems and optimization methods in the reconstruction of urban traffic micro-circulation, provided the theoretical and methodological guidance for the reconstruction of traffic micro-circulation.Firstly, compared with blood micro-circulation, the principle of urban traffic micro-circulation was analyzed, the meaning of traffic micro-circulation for solving traffic congestion was explained, and the function characteristics of traffic micro-circulation was analyzed and concluded.Through analysis of function in urban traffic, feasibility of reconstruction, reconstruction expense and goals of urban branch road network as "urban traffic micro-circulation system", with the decision-making variables of the capacities of branch roads and the targets of lowing the saturation of arterial roads and reconstruction expense of the branch roads; the bi-level programming model for reconstructing the branch roads was set up. With this model which roads are selected as traffic-chunting channels for constructing reasonable traffic micro-circulation network can be determined, and the capacities of the selected roads after reconstruction can also be obtained.In order to maximize traffic efficiency of micro-circulation network and improve traffic conditions, the one-way traffic organization method of micro-circulation network was researched. From the target of lowing the saturation of arterial roads and micro-circulation roads, considering the restriction of the maximum saturation, the bi-level programming model for optimizing one-way traffic organization was set up. With this model the one-way traffic organization scheme of micro-circulation network can be obtained, including the determination of whether each micro-circulation road is set as one way and its direction.Integrative optimization model for reconstruction and one-way organization of the micro-circulation road network was established, namely considering whether a road link is two-way or one-way when it is reconstructed and regarding the decision of whether it is two-way or one-way as a part of reconstruction optimization. With this model the traffic-organization form and required capacity of each branch road after reconstruction can be determined simultaneously. Combined decisive coding of one-way organization and reconstructed capacity was used to design the genetic algorithm to solve the model.Based on the real characteristics of micro-circulation roads——narrow width, low level and subtle capacity, this paper discussed the ways of preventing the possible traffic congestion of micro-circulation network. Considering the real traffic conditions and taffic demand of micro-circulation network, the fuzzy control model for micro-circulation traffic was proposed. The congestion sensibility of micro-circulation network was analyzed and the method with "orthogonal experiments+traffic assignment" was developed to find out the key road links of micro-circulation network so that the effective measures can be taken to ensure the fluency of the key roads.On the one hand, traffic micro-circulation can shunt traffic of arterial roads and smooth traffic running; on the other hand, it can also cause adverse influence to intra-regional traffic (e.g. pedestrians and bicycles), normal resident living and ecological environment. Integrating the advantages with disadvantages of traffic micro-circulation, this paper established the evaluation index system and proposed the evaluation method of using the multi-classification fuzzy pattern recognition theory to evaluate the total effect of reconstruction of urban traffic micro-circulation.Finally, through a practising example the main theoretical models and algorithms in this paper were verified, the principle of traffic micro-circulation solving traffic congestion was showed, and the whole thought and process of designing traffic micro-circulation was demonstrated.