Multi-group Train Operations Of Urban Rail Transit

With the rapid development of economy and the process urbanization in China,the urban rail transit construction has been widely implemented around the world.Some large cities,like Beijing,Shanghai and Guangzhou have been the first to enter the era of urban rail transit network operation.By the end of 2016,there have been 21 cities with more than 2 operating lines in China.At the same time,the continued growth of passenger volume,unbalanced distribution of passenger flow increase the complexity of the relationship between service level,operation safety and economic efficiency,which puts forward higher requirements for the operations of urban rail transit.Multi-group train operations is one important part of the network operation technologies,which can better adapt to the fluctuation of passenger flow and realize the effective matching transportation capacity and passenger demand.Therefore,the research of multi-group train operations is very significant to optimize the train operation organization of urban rail transit under the background of network operation,improving the operation efficiency and service quality.Based on the existing literatures,this dissertation analyzes the key factors influencing the multi-group train operations,and generalizes the practice of lines adopting this new organization pattern.Moreover,an optimization model for train operational schemes of urban rail transit based on multi-group train,a method for load factor equalization with multi-group train and the strategy of strengthening transport capacity considering multi-group train are put forward.The main contents and conclusions of the dissertation are shown as follows.(1)According to the existing research results,based on the characteristics of the line and passenger flow,the urban rail transit lines operated with multi-group train in domestic are presented.Moreover,this paper analyzes the influence factors of multi-group train operations from five aspects,namely,social and economic benefits,distribution characteristics of passenger flow,train running conditions,facility instrument and transport resources,which lays a foundation to further study on multi-group train operations.(2)A multi-objective optimization modal for train plan of urban rail transit based on multi-group train is established,which is aimed to minimize the passengers' travel cost and operator's cost.The constraints are transport supply,policy headway and fleet size.And a two phase programming algorithm based on Pareto search and entropy theory is also proposed.At last,the validation of the proposed model and the algorithm has been tested with an urban rail transit line in China.The results show that compared with the traditional train plan of single train formation,the train plan based on multi-group train can reduce the waiting time of passengers and the vehicle kilometers by 16%and 17%,but increase the number of vehicle operating on line by 10%.The results illustrate that,when the unbalanced coefficients of passenger flow is 2.85,the train operational schemes based on multi-group train can reduce fleet size,improve passenger service level but increase driver cost.In particular,when the vehicle is insufficient,multi-group train operations are efficient.Moreover,when the passenger demand is unbalanced distribution and line capacity is relatively rich,the multi-group train operations are preferable.(3)Because of the train with fewer vehicles is over oversaturated and the train with more vehicles has a lower load factor,a bi-level optimization model is established considering the equlibrium of load factor between different trains.The upper-level model is an optimization model of train operational schemes,which is used to determine the optimal frequencies of two types of trains.The lower-level model is an optimization model of equilibrium of load factor,which is to determine the optimal train formation plans and departure interval.And a nested genetic algorithm is also proposed.The results indicate that under even headways the number of vehicles of two kinds of trains has minor differences can improve the equilibrium of train load factor.Besides,adjusting the headways between different train formations under uneven headways can realize the equilibrium of load factor.(4)Aimed at the transportation capacity strengthen of urban rail transit line,the strategy of strengthen the train capacity is presented under the condition of certain line capacity.A generalized cost function which concludes vehicle acquisition cost,passenger travel cost and operating cost.An optimization modal for vehicle purchase strategy of urban rail transit based on multi-group train is established,which is aimed to minimize the generalized cost.The constraints are maximum purchase number,minimum purchase interval,and the biggest purchase vehicles.At last,the effectivenesses of the algorithm and model are verified by a sample.The results indicate that compared with the traditional train operational schemes of single train formation,the strategy of strengthen the train capacity based on multi-group train can reduce the passenger travel cost and the operation cost by 16.48%and 25.99%,but increase the driver cost by 18.6%,which has a better overall efficiency.