Transportation Modal Split Optimization Of Multimodal Traffic System Based On Supply-demand Equilibrium

Guided by the national policy for transit system promotion,and for trip modes selection optimization,multimodal transportation system is showing up.Facing the fact that the outcomes of modal split related researches with multimodal transportation system is lacking,this thesis is supported by the National Key Basic Research and Development Program 973(2012CB725402).The primary objective of this paper is to optimize the urban modal split,and to improve the efficiency of urban transportation system.Based on the analysis of characteristics of each trip modes,urban modal split optimization algorithms,models and their applications are developed,considering the impact of multimodal transportation system.The thesis is consist of five main parts:urban trip modes characteristics analysis,modal split optimization modelling,modal split optimization under determinate traffic demand and variable traffic demand,and practice and application of the outcomes.The detailed information about each part of this research is as follows.(1)Based on the definition of multimodal transportation system,a group of proper modal split with multimodal transportation system is proposed.Then,characteristics of multimodal transportation system are studied.The factors that influence the modal split of urban transport models are summarized from the macroscopic view,and from the microscopic point of view,traffic economic characteristics of each trip modes are extracted for further analysis.(2)The meaning of the best modal split with multimodal transportation system is clearly discussed.The cost of a single trip is analyzed from both the transportation system aspect and traveler aspect.Then,two travel cost calculation models are proposed,one is the model for transportation system cost calculation,another one is for traveler cost estimation.Based on the two cost calculation models,two kinds of trip modes,namely,public transportation and private transportation,are further analyzed to make the cost of each mode clear.A general modal split optimization model is proposed to minimize the total cost of traffic system,which takes traffic demand,traffic supply and traffic policy into account.For simplification purpose,standardization process is applied to the modal split optimization model.(3)Demand characteristics during peak hour are first studies.Then,under the situations that travelling with space constraint and without space constraint,the best modal split is discussed when the traffic demand remains constant.Considering that the new energy vehicle is strongly supported by the government,the influence of electric vehicle(one typical new energy vehicle)to modal split optimization is discussed.A case study with the field data from Nanjing is conducted to test the performance of the proposed models.In addition,sensitivity analysis is adopted to find the influence of different factors on the best modal split.(4)In this part,the best modal split is discussed when the traffic demand varies.Two different kinds of traffic demand varying are considered,one is caused by individual differences,another one is time-varying travel demand.For the first kind of traffic demand varying,parameters that can represent the individual differences are introduced.The influences of different factors on demand varying are analysis,and two most important factors,i.e.,time value and travel distance are picked up.Based on probability theory,distribution functions of time value and travel distance are fitted,and modal split optimization model is modified with the distribution functions.The data from the case study city Nanjing are used for distribution function calibration,and the best modal split when considering individual differences is calculated.For the time-varying travel demand,the changing tendency of demand over time is analyzed,and the impact of time-varying travel demand on modal split is discussed.Then arrival-departure curve of travel demand is proposed to calculate the travel delay under different demand.In the end,a modified modal split model is presented to reflect the influence of time-varying travel demand.(5)In order to guide practice and to simplify the theoretical models,the role of this research to engineering practice is summarized in the end.In the respect of traffic planning,the principle of advantage travel distance of each mode is proposed based on the thesis.The conventional four-step planning model is modified,and a simple but quick algorithm to evaluate the modal split result is proposed.In the respect of traffic strategy and policy making,ticket pricing optimization for transit rides and extra taxes and dues for private car users is determined by the proposed models of this paper,and suggestions are proposed for adding new or cancel traffic mode.