Solving Freight Train Formation Plan

The train formation plan(TFP)is one of the most important research areas in railway transportation planning.The TFP models correspond to the determination of the trains that are assembled,involving the definition of assignments,frequencies,sizes and profiles of shipments and traction,according to a defined objective to the physical and operational restrictions of the railway network.A train formation plan aims at determining:assignment of rail freight flows(shipments)into railcars and which pairs of yards(terminals)are to provide with direct train services(which is provided between yards);workload of rail links or lines through which the trains may pass;how the individual OD pairs are consolidated into the available train services and the physical paths of these trains and frequencies of the train services provided.It also determines:how to form trains,which kinds of trains to be formed,at which stations these trains are formed,types,origin and destinations of train as an objective to minimize the transportation time/cost while forwarding all wagons from their original stations to their destinations.It is usually very complicated to determine which pairs of yards(terminals)are to provide with direct train services(provided between yards)and how the individual OD pairs are consolidated into the available train services.The train formation plan models are often formulated as a capacitated service network design problem,and the optimal solution is normally difficult to find.Solving train formation plan problem aims to route and reclassify car flows while satisfying line carrying capacity and railway station capacity constraints and trying to minimize the total operational costs(converted car hours or converted car kilometers)of all cars.As a result,a solution of this problem can not only ensure the economical delivery of shipments and get better use of locomotives and railcars,but also coordinate the utilization of the capacity of rail lines and yards,fully explore the potential capacity of railway transportation,improve transport efficiency,and reduce train's blocked.Railways all over the world progressively implement computer software for improvement in efficiency and for better management as well as for good decision making.The transportation community should identify and prepare for future revolutions in Information technology that will have an impact on Railway transportation.One of the computer software is Apache Spark which is an open-source in-memory cluster-computing framework.It is a general-purpose&lightning fast computing system.By using Apache Spark,we achieve a high data processing speed of about 100 times faster in memory and 10 times faster on the disk.In this paper,a Tabulation Method with Apache Spark software by using Scala programming language is proposed for the train formation plan problem.The basic idea of the proposed solution is to use a computer software application to solve train formation plan problem in a more powerful way.The test results based on practical examples in Addis Ababa-Djibouti railway network show that solving Train Formation Plan Problem by the method we proposed in this paper can significantly reduce the total car-hour consumption at the technical yards and the methodology uses effective time in solving the problem.The results show the efficiency and effectiveness of the proposed approach.It is possible to save significant time and cost through solving the train formation plan problem by using the proposed solution and developing the efficient train formation plan in the railway networks.