Research On Dynamically Accessible Path During Last Train Period Of Urban Rail Transit

With the rapid development of China’s urban rail transit system and improvement of network operation level,it is imperative to continuously improve the system operation service level.In the last train period,as lines in the urban rail transit network ending their operation one after another,the path becomes dynamically accessible,so passengers traveling at night need to consider whether the path they choose is accessible.Study on dynamically accessible path in the last train period of urban rail transit plays an important role in helping passengers to choose accessible paths,optimizing the connection between the last train of different lines and clearing the actual distribution of passengers in the network.This paper puts emphasis on the search and selection of the dynamically accessible path in the last train period of urban rail transit,and the main research contents and results are as follows:(1)By taking current operation status of the last train period of typical urban rail transit system as an example,this paper summarizes and analyzes the operation characteristics of the last train period.Then this paper discusses the network accessible status changing with time,and illustrates the dynamic accessibility characteristics of the path in the last train period.After that this paper analyzes the travel characteristics of passengers in the last train period and the dynamic transfer connection situation,and points out that transfer connection is the key to determine whether the path is accessible or not.Finally,the paper puts forward the main factors affecting the route choice of passengers,including accessibility factor,time factor and transfer factor,by considering the psychological factors and individual characteristics of passengers.(2)A model of urban rail transit network with train schedules is constructed,and the concept and calculation method of path reliability are proposed in this paper.Besides,by considering individual characteristics of passengers and path reliability,this paper constructed a dynamically accessible path search model in the last train period of urban rail transit,as optimization objective being minimizing passengers’ generalized travel cost.Finally,calculation method of the path generalized cost function is given and a twostage path search algorithm: static path search and dynamic path search is designed in this paper.(3)This paper introduces the basic principle and method of prospect theory and discusses the applicability of prospect theory in the study on passengers’ path selection behavior.Via considering the characteristics of "bounded rationality" of passengers and analyzing the passengers’ choice behavior and dynamic adjustment process in the last train period of urban rail transit,this paper presents a passenger accessible path selection model and algorithm based on "prospect theory".Meanwhile,this paper explains the calculation method of reference point,value function,decision weighting function and path prospect value in the specific problem of urban rail transit path selection decision.(4)A case study of a local urban rail transit network is carried out.The results present a dynamically accessible path scheme considering passengers’ individual characteristics and path reliability,and the influence of the difference of passenger transfer speed,departure time,and operating intersection mode on the scheme of dynamically accessible path is analyzed.This paper explains passengers’ path selection process when facing unreachable risks using prospect theory,and analyzes the influence of passengers’ different risk preferences on path selection results.Based on the results of case study,the function and relation between the dynamically accessible path search model and selection model are illustrated.28 figures,27 tables and 82 references.