Research On The Emergency Shuttle Bus Design Under The Metro Disruption Scenarios

The research on Metro disruption is one of the hot issues in metro operation management,which is of great significance to the theory of subway operation.This paper analyzes the classification and propagation mechanism of accidents after the metro disruption,and based on this,the choice behavior of passengers after the disruption is then analyzed.The bi-level programming model of metro transit network is established,and UE assignment theory is introduced into the study of Metro disruption.An overload arc oriented heuristic algorithm and bi-directional search algorithm are designed to solve the model.This paper can provide advice for emergency rescue after metro disruption.This paper firstly analyzes the classification as well as its impact of subway disruption accidents.The propagation of disruption has different mechanisms between a loop metro line and a ray line.As there are a large number of transfer passengers on the loop line,its influence would be more serious.In order to meet the travel demand of the passengers during the disruption period,connecting bus has been obtained to transport passengers in the disruption area.Generally,when the estimated duration time of the disruption exceeds 20-30 minutes,the bus connection scheme would be carried out.And either the number of passengers in the disruption area is less than the threshold or the disruption has stopped,the connecting bus service can be canceled.During the actual engineering operation,the on-site staff needs to report the accident situation to the supervisor,then the supervisor would inform the relevant dispatching staff to take corresponding measures.At the same time,the disruption information would be reported from lower staff to upper staff,and the leading department should coordinate all departments to take emergency measures.Secondly,As our research can be classified into the urban traffic network design problem,this paper introduces three types of traffic network design problems: discrete network design problem(DNDP),continuous network design problems(CNDP),mixed network design problems(MNDP).The universal mathematical formulations of discrete network design problem and continuous network design problem are given,and the modeling method and solution algorithm of bi-level programming model are introduced.Generally,the lower level model of traffic network design problem is a passenger assignment model.Therefore,this paper presents the mathematical formulations and algorithms(Frank-Wolfe algorithm and successive average method)of two assignment models(user equilibrium assignment model and system optimal model).Thirdly,this paper uses the method of adding the bus arc to the original subway network,and uses the connection of shuttle bus to build a metro-bus composite transportation network.By optimizing the bus arc adding scheme in the network,the number of passengers stranded in the network can be reduced.The network design problem is formulated as a bi-level programming model: the upper model minimizes the number of added bus arcs,and the constraints restrict the number of passengers stranded in the station;the lower model assigns the passenger flow into the network based on the user equilibrium(UE)theory.In order to solve the bi-level programming model,an overload arc oriented heuristic algorithm is designed to find a high-quality initial feasible solution.Based on the initial solution,a bi-directional search algorithm is designed to get the global optimal solution of the original bi-level programming model.Finally,this paper takes part of Beijing metro network as an example,and designs a peak hour case.The case shows the applicability of the model and algorithm.