Research On Road Reserve Network Capacity Considering Road Network Service Level

With the rapid development of social economy, the scale of urban population and motor vehicle is expanding, which makes the contraction between traffic supply and traffic demand more serious. Therefore, how to improve the road network capacity to meet the increasing traffic demands so that ease the traffic pressure is our urgent problem. Urban network capacity is traffic supply system, and which is influence on the sustainable development of urban traffic、the city’s economic development level and the quality of people’s travel, in order to improve the comfort that passenger pay more attention to when travelling. So, studying the network capacity based on road network service level has an important practical significance.This paper sees the basic theory of road network capacity as the point-cut, and redefined the road network capacity aimed at the purpose of this article, combining the existing knowledge and the basic research, then it will be classified according to different conditions, and thorough analyze the main influencing factors of the road network capacity and come up with corresponding optimization methods, thereafter, this paper analyzes the service level evaluation index from the viewpoints of both micro and macro, and finally, the saturation of road network is chosen as the key indicator to evaluate the traffic network. So this paper set the division standards of road network service level and did a simple analysis on the relationship between road network capacity and road network service level, finding that there is a closed relationship between them. Therefore, this paper built a bi-level programming model of network reserve capacity based on road service level restraint to study the change of road network capacity under specified service level:In the model, the basic OD traffic demand multiplier is maximized with service level restraint in the upper problem and a stochastic user equilibrium assignment model is used in the lower model. A algorithm that combined incremental assignment method with method of successive averages is proposed for this bi-level programming model. A numerical example on a small road network is presented to demonstrate the effectiveness of the model and algorithm, and it indicates a positive correlation between the threshold of road network service level and road network reserve capacity:the more serious the traffic congestion degree is, the larger the traffic demand multiplier will be.