Optimal Models And Solutions For Multi-modal Transportation System Considering Social Costs

As China enters a fast track of urbanization,some large and medium-sized cities keep improving their transportation infrastructures,and establishing comprehensive urban transportation systems consisting of various traffic modes.The multi-modal traffic systems meet the diversified and personalized travel demands such as convenient,economic,safe and comfortable.However,as motor vehicles are increasing rapidly in number,many cities in China have been faced and will be facing traffic congestion,frequent accidents and many other traffic problems,in the long term.In order to reduce these worsening traffic problems,the government should use new traffic models from the perspective of sustainable development to realize the goal of less pollution and less energy consumption,while satisfying economic development and improving travel quality to the largest extent.This is the underground of the paper.The multi-modal traffic systems enable residents to have more options and convenience in travelling.These are positive externalities of traffic systems.Meanwhile,the multi-modal traffic systems also have many negative externalities,such as air pollution caused by traffic exhaust and its damage to the ecological environment,as well as social fairness problems including traffic congestion and pollution caused among travelers choosing different travel methods and between travelers and non-travelers.The management of the multi-modal traffic systems is aimed at realizing mutual support and coordination among various traffic modes and fully optimize their performance,so as to make travel more efficient and meet different travellers'needs.It is centered on guiding residents'travel behaviors by imposing various traffic regulations and management.Based on the characteristics of China's multi-modal urban travel,this paper studies the structural characteristics of multi-modal urban traffic systems and analyzes the multi-modal urban traffic flow distribution focusing on travellers'traffic choice.It analyzes the externalities of multi-modal urban travel by building a proper model,and studying on optimizing the externalities on this basis.This paper can serve as a theoretical basis for improving and optimizing the multi-modal urban travel structure of an entire city.Meanwhile,it can also be refered to by traffic management departments for developing various management measures.This paper mainly discusses the multi-modal traffic network in pursuit of sustainable traffic development,analyzes the supply and demand and the social externalities of multi-modal travel,and proposes a model optimizing multi-modal traffic systems in consideration of social costs.Specifically,this paper focuses on the following aspects:(1)It describes multi-modal traffic systems with a hierarchical network structure,analyzes the comprehensive selection behaviors of different types of travellers in a multi-modal traffic network,including the choice of travel mode and route selection.lt creates a road section resistence function and a generalized cost function of multi-modal traffic network.It also proposes a flow distribution model of multi-modal traffic network based on the principle of balancing multiple usersand puts forward an algorithm as a solution.(2)Based on a multi-modal super traffic network,it analyzes travellers'transfer pattern and behaviors,taking into consideration travel time,expenses and comfortability.It creates generalized cost functions of various sections and hyperpath,proposes a stochastic equilibrium distribution model of multi-modal traffic system,and designs a search algorithm for effective hyperpath and shortest viable hyperpath with transfer factors considered.(3)Based on the idea of sustainable traffic development,it analyzes the comprehensive cost of multi-modal traffic network,and proposes a total-expense model of multi-modal traffic system.Considering the main factors influencing fuel consumption and exhaust emissions of motor vehicles,it builds an exhaust emission model and an energy consumption model of a traffic network and constructs a multi-objective planning model based on comprehensive cost,and proposes an algorithm as a solution.(4)From the perspective of two traffic evaluation indicators including traffic congestion and exhaust emission,it analyzes the externalities of multi-modal travel;establishes a quantitative relation between the two evaluation indicators and the traffic volume,travel speed,and length of a road section,and quantitatively analyzes the equilibrium flow of a traffic network using sensitivity analysis.On this basis,with traffic management measures(ex.ticket prices)as the variables to make decisions,it builds a multi-modal travel optimization model that takes into account social externalities,and proposes an algorithm as a solution.