Method Of The Bridging Bus Organization Under Disruption Of Urban Rail Transit

The network operation of urban rail transit has changed the demand for emergency disposal from post analysis to pre prevention.Due to its advantages of considerable capacity and convenient scheduling,the bridging bus has become an effective mode to provide alternative travel services under the disruption of urban rail transit.The analysis of the transmission mechanism of the disruption,the construction of a reasonable evaluation system for the necessity of starting bus bridging,and the formulation of a specific operation scheme of bus bridging service according to the OD demand of passenger flow can provide a reference for the emergency evacuation plan,which is helpful to reduce the adverse impact of operation disruption and improve the service quality of public transportation system.The definition of urban rail transit operation disruption events is defined and classified according to the cause,location,influence scope and duration of the event;the transmission mechanism of different severity of the disruption occurring in the radiation line and the loop line is analyzed;the rail transit emergency management system including pre-warning and post decision-making are summarized.Emergency response strategies are put forward from two aspects of operation organization adjustment and the bridging bus strategy,the design theoretical framework of bus bridging service is proposed.The thesis analyzes the start-up conditions of the bridging bus,studies the index selection and the determination method of subordinating degree function,constructs the evaluation index system of starting necessity from two aspects of accident risk and transportation capacity risk.Four indexes of route importance,time importance,time duration and transportation capacity loss are selected to establish the start-up necessity analysis method of the bridging bus based on the AHP and the fuzzy comprehensive evaluation method.The breadth first search(BFS)shortest path method considering the transfer times is used to match the OD pair travel path set obtained from AFC data,and the affected passenger flow is screened,and the passenger flow demand is quantitatively analyzed from the affected form and the subsequent travel behavior.According to the equivalent superposition rule,the OD demand of the whole network is transformed into the OD demand of the disruption section.Considering the travel choices of passengers under different travel purposes,travel distances and disruption duration,the actual OD demand under disruption of the disruption section is obtained.Based on the passenger flow demand,the bridging bus scheme is designed according to the definition of bridge environment,bridging route design and resource allocation.The operation scheme model is constructed with the objective function of minimizing the total travel time of passengers and is solved by the elite genetic algorithm.The model takes the departure frequencies of each route and the operation coefficient determining whether to operate the line as the decision variables,and the constraint conditions include the full load ratio,departure frequency,the number of available bridging buses,the number of bridging bus lines and passenger flow.Taking the bridging bus organization of Suzhou rail transit network under assumed disruption situation as an example,the above method is applied to verify its effectiveness.