Abstract:In the domain of freight transportation, road transport has occupied a leading position over the past years. Unfortunately, this has contributed to increasingly air pollution. Consequently, countries around the world have been concentrated on attracting freight transportation into rail. To improve the rail transportation efficiency and then to motivate shifting bulk cargo transportation to rail, the optimization of rail operation plan becomes ever-important. As part of operation plan, the multi-shipment train … Show more
“…However, the solving approach of the models and numerical examples were missing in this work. Zhao and Lin [22] proposed a linearized programming model based on the collection delay in loading stations, whereas the costs in unloading stations and intermediate reclassification yards were not taken into consideration, and the pattern of train formations was not universal.…”
Section: Literature Reviewmentioning
confidence: 99%
“…However, the solving approach of the models and numerical examples were missing in this work. Zhao and Lin [22] proposed a linearized programming model based on the collection delay in loading stations, whereas the costs in unloading stations and intermediate reclassification yards were not taken into consideration, and the pattern of train formations was not universal. For other transportation modes, for example, maritime navigation, in the work of Iris et al [23], the flexible ship loading problem (FSLP) was optimized, including the management of loading operations, and the planning and scheduling of transport vehicles.…”
This paper presents the formulation of a train formation problem in rail loading stations (TFLS) from the systematic perspective. Several patterns of train formation are analyzed thoroughly before modeling, including direct single-commodity trains, direct multi-commodity trains created in the loading stations, and direct trains originating from reclassification yards. One of the crucial preconditions is that the loading and unloading efficiencies in the loading stations and the relational unloading stations are symmetric. Based on this, a non-linear 0–1 programming model is designed with the aim of minimizing the total car-hour cost incurred by the loading, unloading, and reclassification operations, and the commercial software Lingo is employed as the solving approach. A small-scale example is carried out first to illustrate the validity of the presented model and the effectiveness of the proposed method. Then, a series of numerical cases are devised to test the model and solving approach. The computational results show that our model can be regarded as a theoretical foundation of the TFLS problem.
“…However, the solving approach of the models and numerical examples were missing in this work. Zhao and Lin [22] proposed a linearized programming model based on the collection delay in loading stations, whereas the costs in unloading stations and intermediate reclassification yards were not taken into consideration, and the pattern of train formations was not universal.…”
Section: Literature Reviewmentioning
confidence: 99%
“…However, the solving approach of the models and numerical examples were missing in this work. Zhao and Lin [22] proposed a linearized programming model based on the collection delay in loading stations, whereas the costs in unloading stations and intermediate reclassification yards were not taken into consideration, and the pattern of train formations was not universal. For other transportation modes, for example, maritime navigation, in the work of Iris et al [23], the flexible ship loading problem (FSLP) was optimized, including the management of loading operations, and the planning and scheduling of transport vehicles.…”
This paper presents the formulation of a train formation problem in rail loading stations (TFLS) from the systematic perspective. Several patterns of train formation are analyzed thoroughly before modeling, including direct single-commodity trains, direct multi-commodity trains created in the loading stations, and direct trains originating from reclassification yards. One of the crucial preconditions is that the loading and unloading efficiencies in the loading stations and the relational unloading stations are symmetric. Based on this, a non-linear 0–1 programming model is designed with the aim of minimizing the total car-hour cost incurred by the loading, unloading, and reclassification operations, and the commercial software Lingo is employed as the solving approach. A small-scale example is carried out first to illustrate the validity of the presented model and the effectiveness of the proposed method. Then, a series of numerical cases are devised to test the model and solving approach. The computational results show that our model can be regarded as a theoretical foundation of the TFLS problem.
“…A nonlinear 0-1 planning model was constructed, and the model was solved by a simulated annealing algorithm. Zhao and Lin [10] took the car hour cost at the loading station of stepped direct trains and non-direct trains, as well as the time delay caused by loading sequence as the optimization target, and took the train length and reclassification station capacity as constraints. In order to improve the railway rail freight services, many European companies and research institutes in the field of railway transport have focused on research and development projects.…”
Section: Literature Reviewmentioning
confidence: 99%
“…As early as 1913, Harris [10] first proposed the importance of integrating transportation and inventory systems research, and discussed models with constant demand rates. He gave the classic economic order quantity (EOQ) model to minimize inventory cost and transportation cost.…”
It is well known that the shift of transporting bulk cargo from roads to railways is an important measure to reduce carbon emissions of the overall transportation systems. In order to increase the attractiveness of railway transport, companies usually provide some discounts to the customers with great transport demand so that entire trains can be operated. Since the operation of entire trains can reduce the reclassification times of shipments, the expenses of railway operations can be reduced. However, when the volume of shipment is not sufficient, the door-to-door direct transportation (in the railway industry specifically, “door-to-door” means running trains from supplier’s warehouse to customer’s warehouse) of the entire train often leads to a decrease in the frequency of delivery, which increases the average stock of users, thus increasing the inventory cost of users. Therefore, how to balance the pros and cons of the two is exactly the problem to be studied. In this paper, the optimal operation plan is obtained by minimizing the total cost of the stockholding of suppliers and customers, as well as the transportation costs of an entire train and non-direct train. Based on the classic economic order quantity (EOQ) model, a 0-1 integer programming model with the constraint of the maximum stock level is proposed to solve this problem. And an innovative approach is used to calculate the actual average stock of the customer. Finally, the model is validated and its effectiveness is confirmed using a real-world case, which is carried out using data from the China rail system.
“…Chen et al [18] developed a binary linear model to minimize the total sum of accumulation costs and classification costs, and a novel tree-based decomposition algorithm was proposed. Zhao and Lin [19] formulated the multi-shipment train formation problem as a nonlinear binary model, which was linearized and then solved by LINGO. They reported the linear model has better performance than the nonlinear one in terms of solving efficiency.…”
As the core of the rail freight flow organization process, train formation problem (TFP) has attracted much attention. In Chinese practice, car flow routing, TFP, and train routing are usually optimized sequentially to reduce the complexity of computation, which may result in a local optimum, and even no feasible solution. To address this issue, this paper studies the integrated optimization of the three sub problems with aims to minimize the total cost of transportation cost, accumulation cost, and classification cost. An integer linear arc-based model incorporating the unitary and in-tree rules of a shipment is first formulated and solved by the state-of-the-art solver GUROBI. Since GUROBI can't deal with the large test cases, a path-based model is built and solved by a bespoken two-phase algorithm. The first phase of the algorithm is Benders-and-Price approach that combines Benders decomposition and column generation, and the second phase is to solve the arc-based model with some variables fixed as the corresponding values fetched from the first phase. The results show that the proposed algorithm outperforms GUROBI, and the acceleration techniques, i.e., trust region and Pareto-optimal cuts, can improve the convergence efficiency of Benders decomposition significantly.INDEX TERMS Train formation problem, car flow routing, train routing, benders decomposition, column generation.
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