Research On The Target-oriented User Equilibrium Considering Travel Time Variability

In reality,there exists variability on the traffic network generally,which can come from the supply side and demand side of the traffic network,such as the surge of demand during the peak-hour period and traffic accidents,which will lead to the variability of the travel time on the traffic network.Therefore,the influence of this variability should be considered in the route choice behavior of travelers.At the same time,empirical research shows that travelers’ route choice behavior is affected by multiple attributes,such as travel time,travel time reliability and travel time unreliability.Studies have also shown that travelers exhibit behavioral characteristics.Under this background,this paper propose a target-oriented analysis method to study the impact of travel time variability on travelers’ route choice from the two aspects,namely travel time reliability and travel time unreliability.The detailed research contents are as follows:In this paper,a target-oriented analysis method is used to investigate travelers’ route choice behavior considering the influence of travel time variability in the stochastic traffic network,and a route utility model considering this travel time variability is proposed.In terms of the two aspects of travel time variability,there are two targets in this model,namely the target of travel time and the target of latearrival.The former is used to ensure the travel time reliability and the latter is used to mitigate the impact of travel time unreliability.In the proposed route choice model,there is the stochastic correlation between travel time and latearrival,which is characterized by the Copula function,and the analytic form of the Copula function can be derived from the proved comonotonicity relationship.At the same time,the model can also describe the interaction between the two targets,that is,the simultaneous achievement of the two targets can bring more utility to travelers,and thus they intend to achieve the two targets at the same time during the process of their route choice.Secondly,based on the proposed route utility model,this paper further proposes a target-oriented user equilibrium model considering the variability of travel time,where no travelers can increase his or her route utility by unilaterally changing the path.This user equilibrium expands the research scope of Wardrop user equilibrium.In the user equilibrium,the target of travel time is endogenously determined by the traveler’s expected probability of arriving on time,which can be obtained by questionnaire survey in practice.The target of latearrival is exogeneously given,which is the acceptable delay time for the traveler.this paper formulates the user equilibrium as a variational inequality problem,and study the existence and uniqueness of the solution,as well as the properties of the equilibrium solution based on the target setting rules.Finally,the method of successive average is used to solve the model on the Braess traffic network and Nguyen-Dupuis traffic network.Based on the equilibrium results and the target-oriented characteristics of travelers,the impact of travel time reliability and travel time unreliability on travelers’ route choice are analyzed.Findings of this paper can provide new insights into travelers’ route choice behavior,especially for the analysis considering the travel time variability,which can provide implications for the policy design.