Research Of Congestion Pricing Considering Environmental Carrying Capacity With Combined Travel Modes

With the rapid growth of traffic demand and traffic volume of motors, traffic congestion is increasing, bringing about low efficiency of travel, increase of exhaust emissions and deteriorate of city environment. In order to improve the current situation of urban traffic, Traffic Demand Management (TDM) is widely used all around the world. Among various TDM policies, congestion pricing is an economy measure which can regulate the traffic demand, optimize the structure of urban travel. Setting price, one of the key point in congestion pricing policy research, directly impacts on the effect of policy implementation. Therefore, the research on price setting method has important significance to establish an effective congestion pricing policy and to improve the efficiency in the use of road resources. Firstly, theoretical studies and practices of congestion pricing are summarized in this paper. The existing studies mainly focus on the feasibility of policy and single travel mode network congestion pricing strategies. Among researches on price setting method most aim to alleviate congestion, without considering environmental constraints. Secondly, definitions, causes and harm of traffic congestion are introduced in this paper, and the economic principles are explained. Moreover, the following chapter introduces the traffic environmental capacity, environmental carrying capacity, traffic assignment method, super-network theory and bi-level programming model, which laid the theoretical foundation of this paper.Based on the multi-mode network, a bi-level programming model of congestion pricing is established, which uses the maximum social surplus as the upper level objective and a stochastic user equilibrium assignment under flexible demand in the lower. The upper model is on behalf of the pricing process of traffic management department. In order to meet the requirements of traffic sustainable development, the upper model comprehensive considers environmental carrying capacity and physical capacity constraints of the sections. The lower level is the passengers’feedback on upper pricing results, which is divided into two stages:the first stage is the changes in the total travel demand, the second is a stochastic user equilibrium traffic flow distribution using the Nested-Logit method.The paper uses Chongqing Yuzhong peninsula as an example, the traffic network of Yuzhong peninsula is simplified containing three travel modes including cars, buses and metros. The network topology is built using the theory of super-network. By solving the numerical example, we get the price of congestion pricing withe is 2.14 Yuan. Due to the congestion pricing, the traffic flow of the road where car is charged descends 30%; morever the dirving flow descends about 26%, the flow on metro rises 63%. Results show that congestion pricing can ease the traffic jam in a certain degree, and will balance the requirements of the operation efficiency of road network and traffic environment sustainable development better. However, with the coordinate of other TDM measures, congestion pricing policy will act better.