Research On The Interrelated Problems Of EMU Routing Scheme

Electric Multiple Unit(EMU)is an important tool for railway passenger transportation.With the continuous construction of high-speed railway network in China,EMU’s operating range will be further expanded.However,the high purchase cost and the expensive maintenance cost occupy a large proportion in railway infrastructure investments and future operating costs.Improving the efficiency of EMU and making reasonable maintenance arrangement will directly affect railway’s economic benefits.Therefore,the research on the planning of EMU Routing Scheme,one important project in railway transportation,is of great significance.Based on the study of relevant literature at home and abroad,this paper summarizes the existing problems in the existing research,explains the EMU Routing Scheme,and analyzes the relationship between EMU Routing Scheme and EMU Operational Scheme.In addition,factors that affect EMU Routing Scheme are discussed and EMU operational mode and maintenance mode are elaborated.Finally,the paper presents common modeling methods of EMU Routing Scheme and provides clear thoughts for the scheme’s optimization.Issues of EMU Routing Scheme’s planning are summarized as a special traveling salesman problem.Knowing the train diagram and drawing on the classic traveler’s modeling methods,a planning model of EMU Routing Scheme is established.The model is under the restriction of EMU operation,only connection among train running lines,one-level maintenance,correlation between operation and maintenance and train paths sub loop’s elimination,which is with multiple constraints and multiple objective functions considering least EMU routing and shortest total connection time of train paths as its objective function.Some difficult problems are analyzed and handled,such as integer programming problems and multi-objective problems.Through the comparative analysis of the commonly used algorithms to solve the traveling salesman problem,it is determined that the genetic algorithm is used to solve the model.The basic theory of genetic algorithm is introduced,including the decoding and encoding,initial population,fitness function,selection operator,crossover operator and mutation operator.Based on the characteristics of EMU routing problem,the operator,the selection operator,the crossover operator and the mutation operator in the genetic algorithm are improved.In the end,the improved algorithm is validated by the Wuhan-Shenzhen high speed railway and compared with the Simulated annealing algorithm and manual method,which shows great efficiency and practicability in the planning of EMU routing.