Urban Rail Transit Net Maturity And Its Effect On Travel Modes

Building rail transit network is treated as one of ways for alleviating urban traffic problems and promoting cities development,as an important project of municipal buidings offered by greater policy and financial support.However,urban rail transit system as an open complicated system not only requires its components to work coordinatedly but also needs mutual connection,promotion,restriction between urban transportation system outside itself,and the development of society`s economy and culture,that is,urban rail transit system will offer not only reliable transport supply but also potential growth of transport demand because of its stimulating economic growth.In the process of the growth of transport supply and demand,whether the role of the urban rial transit network reaches the desired levels or not may be doubted.So,based on the point of urban transportation supply-demand structure,this reseach introduces the concept of urban rail transit maturity in order to discuss coordinated relation between urban rail transit network and city devolopment.The analysis of the transportation system defines its internals as four travel modes such as car,taxi,bus,and rail,because of the widespread characteristics of resident trip in metropolitan citis.Based on causality analysis for the external environment and inner composition of urban transportation supply-demand structure,applying the system dynamics with the complicated system,the quantification model for urban transportation supply-demand structure is established and the urban trasportation supply-demand ratio within a particular period is estimated in order to establish mathematical representation of transportation supply-demand condition.Using data from 15 time periods in eight cities and four transportation supply-demand conditions,such as scarce supply,short supply,supply–demand balance,and excess supply,which are concluded and described,and then mature condition of urban rail transit net is described in terms of trip demand,urban transportation supply-demand and city`s economy.Besed on both offering transport supply and inducing transport demand,the concept of urban rail transit network maturity is developed,and the essential features of a mature rail transit network are described.Maturity indexes,which can reflects the developing lever of urban rail transit net,are provided based on the objective,main adoption methods,influence on cities transport and influence on cities devolopment;network scale maturity,passenger coverage maturity,urban accessibility increase rate maturity,and transportation supply-demand adjustment ability maturity are determined following the principles of practicality,nonoverlapping,and feasibility;mathematical expression of urban rail transit maturity emerged.Then the urban rail transit net maturity is graded to provide better guidance for the development of the rail transit network.When quantifying the urban rail transit network maturity,travel demand model is used to analyze network scale maturity value;estimation model for passenger coverage is developed and numerical simulation method is used to determine the passenger caverage maturity value;estimation model for urban accessibility increase rate is developed and perpendicular analysis method is used to determin its maturity value;and estimation model for transportation supply-demand adjuestment ability is developed and the rate of road capacity decline is a reference value to solve its maturity value;at last,the quantifying model of urban rail transit maturity is taking shape.Referencing transportation system internal definition,travel mode choice in metropolitan is defined as the car,taxi,bus,and rail percentages of the total transport.Evolution game models of travel mode choice in metropolitan are established respectively under the non-transfer and transfer circumstances,and Nash Equilibriums are deduced using the backward induction basen on the Folk Theorem.The models are applied to Beijing inhabitants` travel mode choices during morning peak hours,and changing trends of choice among four travel modes are deducted by the Traffic Performance Index(TPI),and then the suitability of the models are examined.At last,evolution game model of travel mode choice based on passenger coverage maturity is established,and the rail transit allocation proportion at each urban rail transit network maturity grade is deduced.In the applied research,firstly,applicability of urban rail transit net maturity evaluation system is analysized.Secondly,fifteen cities` rail transit network maturity and situation are evaluated to examine the concept and quantifying model of urban rail transit maturity.Thirdly,taking the Harbin rail network planning projects for example,the method system has been proven to assess the development of urban rail transit network,and to select and optimize rail network planning projects,and to provide guidance for realizing the anticipated benefits of urban rail transi network.Finally,the constraints of urban rail transit network maturity are found out,and the resolutions are given.