Optimization Method Of Traffic Restriction On Urban Road Traffic Network

With the development of society and the improvement of people’s living standard, the urban peak traffic congestion problem is becoming increasingly outstanding. This traffic congestion problem does not only perplex users, bring troubles to traffic mangers and cause environmental pollutions but also reduce the social welfare and consume resources. In order to solve the urban traffic congestion caused by a sharp increase of demand or a serious degradation of road capacity, it is an effective traffic management method that the traffic restriction scheme restricts a certain proportion of automobile into assigned traffic restriction district, which forces a part of restricted automobile users turn their travel modes into public transit. Actually traffic restriction scheme optimization problem is a Stackelberg game between traffic managers and travelers. Therefore in this paper a bi-level programming model is established to describe the traffic restriction scheme optimization problem. Its upper optimization decision is traffic restriction scheme, whose major purpose is minimizing overload flows and minor is maximizing consumer surplus; its lower programming is to determine elastic demands, mode choice and multi-class user equilibrium assignment based on current traffic restriction scheme. A genetic algorithm with variable length codes is designed to solve the bi-level programming model. In the solving process of the algorithm the road sectic whose flow exceeds its capacity add into feasible field dynamically. Ther gradient projection algorithm is proposed to solve the lower programming. On the basis of traffic restriction scheme obtained by solving the bi-level programming, practical traffic restriction scheme can be achieved through the road-to-district treatment and circuity judgment. The optimization method can provide efficient means and great theoretical support to the formulation of traffic restriction scheme.