The Traffic Demand Forecast And Assignment Method Of Regional Comprehensive Traffic

Regional comprehensive traffic demand forecast is the basis for rational construction of transportation network.In recent years,our country has formed a new passenger and cargo transportation structure,and the transportation environment has become more complex.Changes in the structure of transport urgently need to be more diversified methods of demand forecasting and assignment.Therefore,this article studied the method of demand forecasting and assignment from two transport objects of passenger and cargo.First of all,passenger classification statistical analysis method was proposed based on the specific situation of the statistics and the release of the current regional transportation information in our country.This part extracted and analyzed the traffic information from three aspects,including the traffic demand,the traffic supply,and the actual traffic situation.In the terms of traffic demand,the passenger classification method,which has divided the population into five groups,was proposed,based on the questionnaire survey and the travel characteristics of the group.In terms of traffic supply,the regional trunk network was divided into three categories,that are expressway,national highway,provincial highway,to meet the study need.In the terms of the actual traffic situation,the situation of the traffic flow and saturation were analyzed.Then,the method was applied to the traffic statistics of the beijing-tianjin-hebei region.Secondly,the regional transportation network topology method was analyzed.And a impedance setting method for the sake of distinguishing the difference among passenger groups was put forward.Through the analysis of regional transportation network features and its topology structure,this part summarized the principle of traffic network topology.Then,the calculation methods of the impedance function have been put forward,by the means of questionnaire and data statistics analysis.Finally,the network combined by highway and railway was built,and its impedance properties were set respectivelyThen the passenger and cargo transportation demand of the highway and the railway networks have been forecasted to explore the methods for regional comprehensive traffic assignment,using classic four stage methods.In this part,the process and method of the traffic demand forecast was summarized.The choice of forecasting methods and the relevant calibration can be referred for the study of comprehensive traffic forecast.At last,the traffic assignment method was proposed,in regard to the changing resistance caused by the different passengers’ groups.In this part,all kinds of passengers and cargos were forecasted for its traffic generation and its traffic distribution firstly.Then the predicting ODs for every group were assigned to the networks.The process of passenger assignment is as follows: classifying the passengers to different groups,ensuring the network for passenger transportation,assigning every group to the network one by one.Using the same method,the OD of freight was assigned.