Transit Network Design Models Accounting For Stochastic Headways

Highly diversified public transportation system is an essential part of the urban transportation system.With the acceleration of urbanization and the rapidly-increasing number of vehicles,governments from all around the world have recognized the importance in the development of public transportation system,yet the proper design of the complex system that meets the demand of ever-changing economic and social environment remains a challenge for all decision makers.Making use of the recent advancement in science and technology,researchers are striving to integrate various sources of information to optimize the design of public transportation system.This study is focused on the public transportation network optimization problem.Firstly,we summarized the previous research results on the transit network design problems,including target optimization,restraining condition selection,decision variables,model structure and equation analysis methods,through extensive literature review.Based on these findings,we propose a single-level mathematical model which takes passenger assignment into consideration.Through the analysis and observation of the IC cards data,we conclude that the inter-arrival time between bus stations is a random variable instead of a constant.As a result,the expected waiting time of passengers at the station is affected.We analyze the randomness of inter-arrival time based on linear and multi-linear regression methods and introduce the randomness into the optimization model.The proposed model is a single-level mathematical model which takes passenger assignment into consideration.Furthermore,other constraints are also included into this model,such as transfer constraints,road capacity constraints,bus capacity constraints,etc.Finally,the proposed model is tested using both example data and real data.The results reveal that the randomness of inter-arrival time has significant effects on the expected passenger waiting time.It is also shown that in certain cases,shortening bus lines will improve the service level by reducing this randomness.The main contribution of this study can be summarized as follows: First,a new transit network design model is proposed,which incorporates the inter-arrival random factor,thus making the results of optimization more practical.Second,we estimated the inter-arrival time by data fitting using IC cards data and provided a method to quantify this factor.Finally,by analyzing the real data with the model developed in this paper,it is shown that our method could be successfully utilized in the optimization and evaluation of the transit network.In addition,it is illustrated how the randomness of inter-arrival time can inspire the process of decision making.