Research On Traffic Network Design Based On The Level Of Service

With the rapid growth of traffic demand, there is an increasingly contradictionsbetween the traffic supply and demand. For lack of transportation supply andshortage of funds for construction, the research of traffic network design becomes aeffective measures to slove the contradiction of above. The network design willmake the network structure more reasonable, improve the level of network service,and it will also meet the needs of travelers. The results of this paper can provide areasonable strategy for the transportation planning department, and the governmentcan get the best benefit of investment with limited capital investment.The traffic network design is an optimal investment strategy with someconstraints actually. Due to the single index selected by the previous network designproblem related to the service level, the network design can not be able to take intoaccount the integrity and differences at the same time. This paper combinesmicro-level and macro-level of service indicators to study the network design, anduses the two types of indicators as the constraints of the network design problemfrom the perspective of the level of service. Starts from the analysis of the impact ofdifferent levels of service constraints to the network design, the paper combines theindicators in the levels of network service and link service, and then bulids themodel of road network design based on the level of service. It is known thatdifferent circumstances correspond to different traffic demand and trafficassignment models, the paper sets up several traffic state modes which are describedby the different objective function and constraints in order to make the models asmuch as possible consistent with the actual situations. The paper also solves thebi-level programming model based on the simulated annealing.The models of different traffic state are analysed and verified by two examples.Saturation constraint values of the level of link service can be relaxed under thepremise of ensuring the overall level of network service, by which road resourcesare be used fully with little impact of the road network. Finally, the paper selects anetwork in NanShan ShenZhen, and the idea of saturation constraints are applied tothe actual network, and then the paper gets the increasing traffic capacities of theroads based on the comprehensive constraints of level of service.