Optimization For Train Plan Of Full-length And Short-turn Routing In Urban Rail Transit

With the rapid development of urban rail transit(URT)in China,the urban rail transit systems in some large cities,like Beijing,Shanghai and Guanzhou,have entered into a network operation stage,and the networked structure of URT in other cities are gradually forming.At the same time,the continued growth of passenger volume and the people’s attentions to service level,operation safety and economic efficiency,are promoting the single-line operation and management mode of URT into the network operation.The multi-routing operation mode is one important part of the network operation technologies,and the full-length and short-turn routing operation method,as one part of the multi-routing operation technologies,has become the mostly used operation mode of URT in China.Therefore,to optimize the train operation plans and achieve the optimal organization of URT under the background of network operation,is very significant for improving the operation efficiency and service quality.Based on the existing literatures,this dissertation generalizes the key factors influcing the train operation plan,and analysis the length of lines used full-length and short-turn routing and their nonequilibrium factor of sectional passenger flow.Then,three optimalization models are developed for URT with full-length and short-turn routing.The main contents and conclusions of the dissertation are as follows.(1)Influence factors of making train operation plans,i.e.,passenger flow demand,train running conditions and transport resources,are systematically analyzed according to the existing research results.In addition,the URT lines operated with full-length and short-turn routing are counted,and their characteristics of passenger flow are also analysized.The number of URT lines whose length are longer than 35km,operating with full-length and short-turn routing mode,is accounts for 91.3 percent of the total lines,and the unbalanced coefficient of sectional passenger flow ranges from 1.80 to 2.99.(2)After analyzing the properties of full-lenth and short-turn routing operation mode,an optimization model is porposed for a diametrical transit line,where the objective functions are minimum passenger waiting time,running kilometer fo rolling stocks,and operation time of trains,the decision variables are frequencies,train formation plans,and positions of turnback stations.Furthermore,the linear weighted method and penalty function method are applied to reduce the above model into a single objective model,then the controlled random search algorithm is designed to solve it.The validity of the model is verified by a case,and the sensitives of frequency of short-turn train and positions of turn-back stations are also analyzed.The results indicate that the full-length and short-turn routing operation mode can significantly reduce the spatial inequality of load factor and the total number of rolling stocks;the shorter length of short-turn routing is not conducive to the passengers,and it can not lead to a more saving of operator’s cost.(3)A method of computing the mean waiting time of passengers in the short-turn routing section is proposed according to the train working diagram.Through calssifying the passengers according to their aim stations,a computing method of passenger sharing ration between the full-length train and short-turn train is presented.Then,a bi-level optimization model is established condidering the equlibrium of load factor between different trains.The upper-level model is an optimization model of train plan,solved by the CRS,which is used to determine the optimal positions of turn-back stations and frequencies of two types of trains(full-length and short-turn).The lower-level model is an optimization model of equilibrium of load factor,solved by the enumeration method,which is to determine the optimal formation plans and departure interval.At last,the effectivenesses of the algorithm and model are verified by a sample.The results indicate that the operation mode,i.e.,the full-length train with more rolling stocks and the short-turn train with fewer rolling stocks,is beneficial to improve the equilibrium of load factor,and decrease the operation cost.Besides,selecting a reasonable length of the short-turn section is not only to ensure the equilibrium of load factor,but also to maximize the profits of passengers and enterprise.(4)Through considering the time-dependent characteristics of passenger demand,a scheduling model of full-length and short-turn routing mode is established,where the objective functions are minimum passenger waiting time,running kilometer of rolling stocks,and operation time of trains,with the constraints of departure interval,load factor and maximum number of trains.Then,a solution method is developed,which is combined with simulation method and genetic algorithm.The results show that the disequilibrium train operation scheme can better satisfy the benefits for both the passengers and the operation enterprise,and effectively relieve the morning rush-hour crush.Comparing with the equilibrium operation scheme,the optimal scheme can reduce the waiting time of passengers by 16.3%,1266.2 hours,while the operation cost of transit enterprise remain unchanged.