Research On China Railway Express Operation Scheme Optimization Considering Time Cost Of Classified Goods

It has been nearly ten years since the China Railway Express(CR Express)was first launched in 2011.Its number of trains,scope of travel,return source,transportation capacity,brand building and service system have been significantly improved.But with the rapid growth,there are also many problems highlighted.The main problems in the operation scheme are that there is no refined classification management of the transported goods,the combination of train's transportation mode and freight classification is less optimized.In response to this problem,this article attempts to establish a method of calculating the time cost of classified goods and a " dismantleable " transportation service network based on the "direct + transit" compound mode of the train.By combining the multiple modes of the train and the time cost of goods,an optimized model of CR Express operation schedule is established.Case analysis further verifies the feasibility and effectiveness of the model built in the paper.First of all,this article summarizes the existing research results on cargo time cost,container traffic volume forecast and container train operation schedule,etc.It summarizes CR Express from the aspects of train construction,types of transported goods,advantages analysis and development trends.It focuses on explaining the CR Express operation schedule with the organization form of the container train,the definition,content and influencing factors of the train operation schedule,and further gives the optimization steps of CR Express operation schedule.Next,this article summarizes and analyzes the basic connotation and influencing factors of the time cost of freight transported by CR Express,gives the calculation method of the time cost,and gives specific calculation formulas and parameters for each influencing factor.And through the three methods of curve regression forecasting,grey forecasting and combined forecasting,the container traffic volume of the selected four CR Express lines is predicted.This forecast data is used as the basic data of the case analysis part.Then,a "disassembled" train transportation service network based on the "direct + transit" transportation mode of trains was designed on the basis of the actual transportation network of CR Express.we minimize the total cost of CR Express(including train operation cost,container operation cost and cargo time cost)as the model goal,and build constraints on service network traffic,train capacity,train operation,transportation mode,and variable value.An optimization model of CR Express operation schedule considering the time cost of goods and multiple modes of trains was constructed.Aiming at the solution method of the model,the hybrid genetic algorithm is designed to realize the intelligent solution of the model.At the same time,the branch and bound method is selected to accurately solve the model.Finally,this paper selects Urumqi as a Tran-shipment station,Alataw Pass as a port station and four CR Express lines of Zhengzhou-Hamburg,Chongqing-Duisburg,Changsha-Duisburg,Hefei-Hamburg to form the CR Express service network for case analysis.The results show that,compared with the existing train transportation organization,the model built in this paper can effectively reduce the combined cost of trains,and realize the optimization of multi-mode trains and classified cargo time cost.And it has advantages in expanding the scope of the trains 'attraction,integrating the transportation resources and taking into account the interests of both the trains' operators and customers.At the same time,this paper further discusses and analyzes the impact of the freight holding cost coefficient and the value of the goods on its transportation organization mode,and gives suggestions for the transportation organization of different goods transported by CR Express,which has certain reference significance.