Social Externalities Analysis And Optimization Of The Urban Multi-modes Traffic Travel

Although the diversification of traffic modes makes residents’travel more convenient and improve their life quality, which can reflect its positive externalities, a lot of negative externalities were brought meanwhile. These negative externalities show not only their influence on the external environmental such as the air pollution of traffic exhaust and the destruction of the ecological environment, but also problems like traffic congestion and environment pollution, etc. between users and non-users or the users with each other of the urban multi-modes travel. Based on the urban multi-modes traffic network, the paper analyses externalities of the urban multi-modes travel according to establish the appropriate models. In addition, it also analyses and studies the optimization problems of externalities, which can provide reference for the social externalities optimization of the whole urban multi-modes traffic network. The main contents include the following aspects:(1) Introducing a hierarchical network structure to describe the urban multi-modes traffic network and analyzing the choice behaviors of the travelers in the multi-modes traffic network. On the basis of constructing the generalized cost functions and links’ resistance functions of the multi-modes traffic network, proposing the urban multi-mode network traffic assignment model and verifying according to a simple example by using MSA algorithm.(2) In light of externalities problems of the urban multi-modes travel, analyzing the relationship between two targets-exhaust and traffic congestion evaluation-and links’ flow, length, travel speed, etc. Then considering the given respective model and according to an example to analyze the externalities of the urban traffic system by using methods of sensitivity analysis.(3) Proposing the multi-objective programming model based on social external costs and the solution algorithm. Regarding traffic prices as a decision variable, the paper establishes the urban multi-modes traffic travel optimization model based on the social external costs, which is multi-objective and bi-level programming model. The upper model considers the social external costs of the urban traffic travel network as the optimization objective function, which is a multi-objective programming model considering vehicles’exhaust emissions and congestion costs and decision makers are the traffic management departments. The lower programming model is multi-modes traffic assignment model considering travelers’ travel behaviors and its decision makers are the travelers themselves. Finally, analyzing and verifying according to an example by using solution algorithm.