Multistage methods for freight train classification

Jacob, Riko; Márton, Peter; Maue, Jens; Nunkesser, Marc

doi:10.1002/net.20385

Cited by 56 publications

(48 citation statements)

References 11 publications

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“…In addition, the author describes several practical extensions of the problem, and an integer programming formulation is developed to solve the classification problem. Finally, [7] completes an open proof from [12] and show that identifying optimal classification schedules in constructing one long outbound train from multiple inbound trains is NP-Hard.…”

Section: Literature Reviewmentioning

confidence: 75%

A matheuristic approach to integrate humping and pullout sequencing operations at railroad hump yards

Haahr

Lusby

2015

NETWORKS

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This paper presents a novel matheuristic for solving the Hump Yard Block-to-Track Assignment Problem. This is an important problem arising in the railway freight industry and involves scheduling the transitions of a set of rail cars from a set of inbound trains to a set of outbound trains over a certain planning horizon. It was also the topic of the 2014 challenge organised by the Railway Applications Section of the Institute for Operations Research and the Management Sciences for which the proposed matheuristic was awarded first prize. Our approach decomposes the problem into three highly dependent subproblems. Optimization-based strategies are adopted for two of these, while the third is solved using a greedy heuristic. We demonstrate the efficiency of the complete framework on the official datasets, where solutions within 4-14% of a known lower bound (to a relaxed problem) are found. We further show that improvements of around 8% can be achieved if outbound trains are allowed to be delayed by up to two hours in the hope of ensuring an earlier connection for some of the rail cars.

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Section: Literature Reviewmentioning

confidence: 75%

A matheuristic approach to integrate humping and pullout sequencing operations at railroad hump yards

Haahr

Lusby

2015

NETWORKS

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“…The four most commonly mentioned sorting schemes, Sorting by trains, Sorting by block, Triangular Sorting and Geometric Sorting, are described in e.g. Gatto et al (2009), Boysen et al (2012 and Jacob et al (2011). The sorting schemes take a set of inbound wagons and sort them into outbound trains without considering arrival or departure times.…”

Section: Related Workmentioning

confidence: 99%

“…The best model, AI-IP, returns optimal solutions for all instances within 340s. Jacob et al (2011) establishes a binary representation of a marshalling schedule and use it to analyse various marshalling planning methods. The encoding incorporates the ordering of wagons in the arriving and departing trains, and assumes that the roll-in order has been pre-determined.…”

Section: Related Workmentioning

confidence: 99%

Towards a comprehensive model for track allocation and roll-time scheduling at marshalling yards

Gestrelius

Aronsson

Joborn

et al. 2017

Journal of Rail Transport Planning & Management

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This paper considers multi-stage train formation with mixed usage tracks at a marshalling yard without departure yard. A novel integer programming model for scheduling shunting tasks as well as allocating arrival yard tracks and classification bowl tracks is presented. By taking a comprehensive view of the marshalling yard operations, more effective schedules can be found, and a variety of characteristics can be optimised, including shunting work effort, number or cost of tracks, and shunting task start times. Two different objective functions are evaluated: minimising work effort in terms of wagon pull-backs and minimising track costs. A procedure for finding a hot-start solution with few wagon pull-backs is also presented. The proposed model is tested on real data from Sävenäs marshalling yard in Sweden. The results show that the method is able to return an optimal schedule for a planning period of 4 days if the hot-start solution is optimal or the remaining problem is tractable for the heuristics in CPLEX.

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“…There are earlier appearances of some of these methods with Flandorffer [5] and Pentinga [14], while Siddiqee [15] and Daganzo et al [2] give more recent descriptions. For the practical case of classification tracks of bounded length, minimizing the number of sorting steps is shown to be an NP-hard problem in [8] by introducing an efficient encoding of classification schedules. This encoding is applied in [9] to obtain a 2-approximation for the same setting and in [12] for an exact integer programming approach.…”

Section: Introductionmentioning

confidence: 99%

Experimental Evaluation of Approximation and Heuristic Algorithms for Sorting Railway Cars

Hauser

Maue

2010

Experimental Algorithms

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Abstract. In this paper we consider a sorting problem from railway optimization called train classification, which is NP-hard in general. We introduce two new variants of an earlier developed 2-approximation as well as a new heuristic for finding feasible classification schedules, i.e. solutions for the train classification problem. We evaluate the four algorithms experimentally using various synthetic and real-world traffic instances and further compare them to an exact IP approach. It turns out that the heuristic matches up to the basic approximation, but both are clearly outperformed by our heuristically improved 2-approximations. Finally, with an average objective value of only 5.4 % above optimal, the best algorithm gets close to the real-world schedules of the IP approach, so we obtain very satisfactory practical schedules extremely quickly.

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Multistage methods for freight train classification

Cited by 56 publications

References 11 publications

A matheuristic approach to integrate humping and pullout sequencing operations at railroad hump yards

A matheuristic approach to integrate humping and pullout sequencing operations at railroad hump yards

Towards a comprehensive model for track allocation and roll-time scheduling at marshalling yards

Experimental Evaluation of Approximation and Heuristic Algorithms for Sorting Railway Cars

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