Distribution Path Of Urban Rail Transit Based On Fuzzy Time Window

With the advancement of urbanization,the growth of population and the increase of travel demand,urban rail transit plays an increasingly important role and develops vigorously.But at the same time,many of its operational problems have been exposed.As it only serves passengers,it takes a long time to recover the capital and make profits.It is urgent to carry out new business and adopt diversified ways of operation.Besides that,with the rise of green logistics,the disadvantages of traditional distribution are becoming increasingly prominent.In order to take full advantages of urban rail transit and eliminate the disadvantages of traditional distribution,it was proposed to use urban rail transit to carry out distribution services.Once this idea was put forward,many cities began to try to use urban rail transit for distribution,and relevant research already started.However,the current research is still in its infancy,failing to consider sufficiently the connection between distribution links,ignoring the impact of station used for goods moving in and out when making decisions.When analyzing the distribution path of urban rail transit,it mostly adopts soft time window and hard time window,which cannot reflect customer’s time requirements fully.Therefore,the fuzzy time window is introduced to research the distribution path of urban rail transit.Firstly,the background is explained.The substandard passenger transport intensity and operating loss of urban rail transit,as well as the traffic congestion and environmental pollution caused by traditional distribution are introduced.The superiority and inferiority between the two ways of urban rail transit and freight car distribution are compared,and the attempts made by major cities for the former distribution way are sorted out.Secondly,the feasibility of new distribution way and various elements involved in the distribution path are analyzed.From the aspects of construction technology,operation management and economy,the feasibility of three operation modes proposed by the industry is compared and analyzed.These modes,namely,passengers and freights are on the same train simultaneously,passenger and freight train running on their own line,passengers and freights are transported on the same line.The similarities and differences between new distribution way and traditional distribution are analyzed from the aspects of constituent elements and characteristics of distribution network,distribution strategy and distribution process.The selection principles of station used for goods moving in and out are analyzed and summarized.Thirdly,considering the advantages of the first operation mode,the distribution path model based on fuzzy time window is established.The residual capacity of trains during off-peak time is considered in this model.After the calculation method of residual capacity is proposed,the trapezoidal fuzzy time penalty cost function is constructed according to the fuzzy time window.Considering the capacity and quantity constraints of vehicles available for terminal distribution,the distribution path model is established while minimizing the time penalty cost and the distribution cost are taken as the objective functions.NSGA-Ⅱ algorithm is also designed to solve the model.Finally,Xi’an Metro Line 3 is taken as an example for numerical study of the model.The results showed that the distribution cost of the new distribution way was much lower than that of truck distribution alone.When goods were moved in the station nearest to the distribution center,the distribution cost could be reduced largely.When only one station prepared for goods moving out was the farthest one,the distribution strategy would not be optimized.If the speed or the number of vehicles available for terminal distribution was increased blindly,the distribution strategy would not be optimized yet.In order to obtain a better distribution strategy,the capacity of these vehicles should not be too low.