Analyticall Models For Urban Public Transit Line Investment And Operational Optimization

In recent years,with the rapid economic development and dramatic increase of urban scale,the imbalance of transport supply and demand has been increasingly serious,and become a key factor restricting urban development.As the lacking of funds and shortage of urban land use,the development of convenient and green public transport with large traffic volume has become one of the most effective strategies to alleviate traffic congestion.This dissertation research focuses on the issues of urban public transportation infrastructure investment decision,operation and management in public transport service and investment assessment of electric bus based on optimal operation.It is expected that the research in this thesis can enrich the current urban public transport operation theory,and provide the theoretical and scientific basis for urban public transportation planning and management.Firstly,this paper proposes the theoretical analysis model for studying the decision of the ring line investment in the urban rail transit system,with taking operation benefit and the investment cost of the ring rail line into consideration.Based on the ring-radial rail transit system in a circular monocantric city,the model is mainly used to solve two main problems in the ring line investment: when to invest the ring line,where to locate the ring line under the if ring line investment is beneficial.The model divides the decision problem of ring line investment analytically by introducing the critical density of radial lines and the critical location of ring line,and then determines the equilibrium conditions of route choice of commuting in the city with any length of radius.The social benefit is defined by combining the operation benefit and investment cost and then maximized in the model with a given population density function.A sufficient condition for identifying that a ring rail line should be introduced is first derived,and the corresponding optimal location of the ring rail line is then analytically determined;also,it is found that the larger the radial lines density is,the lower the social benefit is.Moreover,the model is validated through a simple numerical study,and reveals the effects of density of radial line,the length of city radius and population density on investment and optimal location of ring rail line.It also provides some valuable conclusions for studying of the investment problem.Secondly,we propose an analytical game model to study the competition and collusion among operators in the free public transport market.This model is mainly used to address the strategies making of incumbents and the new entrant in competition and collusion situations respectively.The model takes into account the relationship between incumbents and the new entrant: the new entrant evaluates the maximal entry profits based on the operation level of the incumbents,and then formulate the market entry decision and corresponding operation strategy;while incumbents maximize profits by choosing “accommodation” and “deterrence” regimes and the corresponding operation strategies.Under the competition situation,the model examines the regime choice of incumbents,and determines the conditions of choosing different regimes analytically.Moreover,given the regime choice of incumbents,the entry decision of new entrant is determined based on equilibrium operation strategy.Furthermore,the model proposes the collusion conditions of incumbents and the effects of collusion on new entrant under “accommodation” and “deterrence” regimes respectively.In addition,the model compares the services level of public transport and social welfare under different regimes in competition and collusion situations,and determines whether to introduce a new entrant from the perspective of government.Thirdly,a cost-benefit analysis model is proposed,which is based on the optimal operation strategy of transit and used to study the feasibility and strategy of electric bus investment.The model determines the optimal operation strategies of bus service for different operation objectives under fixed and elastic demand respectively;and thus,the analytical conditions of investment feasibility of electric bus are obtained respectively.In the meantime,the emission cost is involved in the model,which also analyzes the impact of emission costs on investment feasibility of electric bus through comparing operation benefit.Referring to comparison of operation costs of traditional and electric buses,the model investigates investment strategies of electric bus through introducing critical demand level: withdraw investment,investment with subsidy,and investment without subsidy;and corresponding subsidy is determined analytically.In addition,the paper explores the mixed operation of electric and diesel buses on promotion of electric bus.