Research On Route Optimization Of Pick-up And Delivery Of Trackless Railway Freight Station

The trackless freight station is directly opened by the railway freight department to solve the problems of weak receiving and delivery services at both ends of railway transportation and delay in receiving and delivering.For this reason,reasonable planning of the receiving and delivery path improves the timeliness of the service and reduces Service cost and improvement of customer satisfaction are important issues to be solved urgently in the construction and operation of trackless stations.Therefore,this paper focuses on solving the problem of pick-up and delivery path planning for trackless freight stations in order to reduce pick-up and delivery service costs and improve customer service satisfaction.Firstly,the construction and operation of the railway trackless freight station is still in the exploratory stage.Based on the positioning of the trackless freight station,this paper analyzes the business functions,operation characteristics and the business process of receiving and delivering.Based on the trackless freight station’s receiving and delivering goods flow direction as "CNRS RS ",the optimal model of 2-echelon Vehicle Routing Problem with Simultaneous Pick-up and Delivery and Time Windows(2E-VRPSPDTW)is established aiming at the minimum total distribution cost and the maximum customer satisfaction.The constraints of capacity constraints,vehicle heterogeneity,soft time window and simultaneous delivery of trackless freight stations are considered.Secondly,in the classical vehicle routing problem with time window,the penalty function of time window cannot reflect the customer’s satisfaction with the arrival service in or out of time window.By introducing the value function of cumulative prospect theory,this paper constructs the time window service prospect value function of conservative,intermediate and aggressive customer styles,which reflects the psychological behavior characteristics of customers in the time window and outside the window,and better describes the customer satisfaction.Aiming at the dual-objective nonlinear model established in this paper,the improved Nondominated Sorting in Genetic Algorithm Ⅱ(NSGA Ⅱ)are used to solve the problem.Through non-dominated sorting and niche operators,random allocation of initial populations,genetic operations using binary tournament selection,partial matching crossover operators,and two-point mutation swap operators are used to perform an improved NSGA-Ⅱalgorithm.Finally,combined with the actual survey data of a railway express distribution center in Chengdu,a case experiment is built based on 50 customer demand points and time windows to verify the effectiveness of the model and algorithm.The results show that: the pickup and delivery based on the trackless freight station can reduce the total distribution cost and improve customer satisfaction;the time window service prospect value function can better describe the customer satisfaction with the service in and out of the time window,and there is a benefit reverse relationship between it and the distribution cost;the influence of customer style on the distribution cost and the average time window service prospect value is quite different;with the decrease of customer’s revenue loss sensitivity coefficient,the same distribution cost can get higher time Window service prospect value,but it is difficult to obtain higher time window service prospect value when the revenue loss sensitivity is too low or too high.Aiming at the path problem of receiving and delivering vehicles in a trackless freight station,this paper establishes a two-level dual-objective optimization model for pickup and delivery with time windows,and improves the NSGA-Ⅱ algorithm to solve it.Provide a scientific reference method for trackless freight station path planning,which is beneficial to improve the delivery timeliness of trackless freight station,reduce distribution costs,improve customer satisfaction,and enhance corporate competitiveness.Therefore,this article studies the development of railway pickup and delivery services And related theoretical research is of great significance.