Rail Transshipment Research Articles

The train-to-yard assignment problem

The train-to-yard assignment problem (TYAP) pertains to freight consolidation in a large rail transshipment yard—also called a multiple yard—that consists of two sub-yards. Inbound and outbound trains need to be assigned to one or the other sub-yard in a way that minimizes the total railcar switching costs. Each inbound and outbound train is processed in one of the two sub-yards, and time-consuming maneuvers may be necessary for railcars that are supposed to be part of an outbound train leaving from the other sub-yard. A lower number of railcar reassignments between the sub-yards reduce train dwell times and avoid train delays that affect the whole rail network. We develop a matheuristic algorithm with a learning mechanism, which we call MuSt, as well as a branch-and-bound procedure that incorporates elements of constraint propagation. We examine the performance of the developed algorithms through extensive computational experiments. Effective optimization approaches for the TYAP have high practical significance since they may reduce the number of avoidable railcar reassignments, which are resource-blocking, traffic-generating, and expensive, by about 20% compared to current practice, as we illustrate in our computational experiments. Our branch-and-bound algorithm solves problem instances for small or medium railyards in less than a minute or within several hours run time, respectively. The heuristic procedure MuSt finds optimal or nearly optimal solutions within just a couple of minutes, even for large railyards.

Solving the single crane scheduling problem at rail transshipment yards

We consider single-crane scheduling at rail transshipment yards, in which gantry cranes move containers between trains, trucks and a storage area. The single-crane scheduling problem arises at single-crane transshipment terminals and as a subproblem of the multiple-crane scheduling problem. We consider a makespan objective function, which is equivalent to minimizing the train dwell time in the yard, and introduce time windows for container moves, for example, as a customer service promise. Our proposed decomposition algorithm with integrated dynamic branch-and-cut or dynamic programming solves practically relevant instances within short time limits.

An improving agent-based engineering strategy for minimizing unproductive situations of cranes in a rail–rail transshipment yard

Nowadays, seaports seek to achieve a better massification (massive transportation of containers) share of their hinterland transport by promoting rail and river connections in order to more rapidly evacuate increasing container traffic shipped by sea and to avoid landside congestion. The attractiveness of a seaport to shipping enterprises depends not only on its reliability and nautical qualities but also on its massified hinterland connection capacity. Contrary to what has been observed in Europe, the massification share of Le Havre seaport has stagnated in recent years. To overcome this situation, Le Havre Port Authority is putting into service a multimodal hub terminal linked only with massified modes. In this study, we focus on rail–rail transshipment of this new terminal, specifically on minimizing unproductive situations of cranes to improve crane productivity and to speed up freight train processing. To this end, an improving agent-based engineering strategy called the “crane anti-collision strategy” is proposed and tested using multi-method simulation software (Anylogic). In a numerical study, the simulation results reveal that our developed model is very satisfactory and outperforms other existing simulation models.

A Multi-Agent Based Simulation Model for Rail–Rail Transshipment: An Engineering Approach for Gantry Crane Scheduling

Le Havre Port Authority is putting into service a multimodal hub terminal with massified hinterland links (trains and barges) in order to restrict the intensive use of roads, to achieve a more attractive massification share of hinterland transportation and to provide a river connection to its maritime terminals that do not currently have one. This paper focuses on the rail–rail transshipment yard of this new terminal. In the current organizational policy, this yard is divided into two equal operating areas, and, in each one, a crane is placed, and it is equipped with reach stackers to enable container moves across both operating areas. However, this policy causes poor scheduling of crane moves, because it gives rise to many crane interference situations. For the sake of minimizing the occurrence of these undesirable situations, this paper proposes a multi-agent simulation model including an improved strategy for crane scheduling. This strategy is inspired by the ant colony approach and it is governed by a new configuration for the rail yard’s working area that eliminates the use of reach stackers. The proposed simulation model is based on two planner agents, to each of which a time-horizon planning is assigned. The simulation results show that the model developed here is very successful in significantly reducing unproductive times and moves (undesirable situations), and it outperforms other existing simulation models based on the current organizational policy.

Gantry crane and shuttle car scheduling in modern rail–rail transshipment yards

Modern rail–rail transshipment yards serve as hub nodes in railway networks and enable a rapid consolidation of containers among freight trains. The container transshipment is executed by parallel gantry cranes supported by a sorting system, where shuttle cars preposition containers to relieve the cranes from excessive movement along the spread of the yard. An important decision problem in this context is the scheduling of the gantry cranes, which is considerably complicated by the need to synchronize cranes and shuttle cars whenever container moves are executed via the sorting system. We formalize the resulting interdependent crane and shuttle car scheduling problem, introduce suited solution algorithms, and apply them in order to explore important managerial aspects. Our main findings in this regard are that the position of the sorter either in the middle of the tracks or at the outside has negligible impact on yard performance, while it is a challenging task to match the number of cranes with an appropriate fleet size of shuttles.

A coupled linear programming model with geospatial dynamic trip assignment for global-scale intermodal transportation

We present an ad hoc geospatial origin–destination model that utilizes the rudiments of operations research optimization techniques to estimate feasible multimodal routes that may or may not be geospatially connected. The model is designed to determine and optimize large-scale container flows from US trade partners to inland markets mainly located within the lower 48 states. The dynamic traffic assignment for the freight flow considers several factors such as congestion, volume/capacity (V/C) ratio, throughput and distance-based impedance and the Geographic Information Systems platform provides a visualization environment for all feasible routes. Visual analytics with the resultant geographical distribution maps indicate that maritime containers are concentrated on the West Coast whereas rail shipments are densely concentrated along rail transshipment points such as Chicago, Memphis and Dallas. The highway transportation densities are mainly visible with origins from marine ports to associated market destinations starting from hinterland and radiating further away from these primal areas to other inland intermodal terminals that serve major landlocked metropolitan cities that are not served by railway networks. Our critical finding indicates that some routes, which are not generally considered as prime routes, may actually offer the best alternatives especially when considering global supply chains.

A branch-and-bound algorithm for the acyclic partitioning problem

We focus on the problem of partitioning the vertex set of a directed, edge- and vertex-weighted graph into clusters, i.e., disjoint subsets. Clusters are to be determined such that the sum of the vertex weights within the clusters satisfies an upper bound and such that the sum of the edge weights within the clusters is maximized. Additionally, the graph is enforced to partition into a directed, acyclic graph where the clusters define the vertices. This problem is known as the acyclic partitioning problem and is NP-hard. Real-life applications arise, for example, in VLSI design and at rail–rail transshipment yards. We propose an integer programming formulation for the acyclic partitioning problem and suggest an exact solution approach based on a branch-and-bound framework that integrates constraint propagation. Computational results are reported to confirm the strength of our solution proposal.

A Survey on Container Processing in Railway Yards

In spite of extraordinary support programs initiated by the European Union and other national authorities, the percentage of overall freight traffic moved by train is in steady decline. This development has occurred because the macroeconomic benefits of rail traffic, such as the relief of overloaded road networks and reduced environmental impacts, are counterbalanced by severe disadvantages from the perspective of the shipper, e.g., low average delivery speed and general lack of reliability. Attracting a higher share of freight traffic on rail requires freight handling in railway yards that is more efficient, which includes technical innovations as well as the development of suitable decision support systems. This paper reviews container processing in railway yards from an operations research perspective and analyzes basic decision problems for the two most important yard types: conventional rail–road and modern rail–rail transshipment yards. Furthermore, we review the relevant literature and identify open research challenges.

How to park freight trains on rail–rail transshipment yards: the train location problem

In modern rail---rail transshipment yards huge gantry cranes spanning all railway tracks allow for an efficient transshipment of containers between different freight trains. This way, multiple trains loaded with cargo for varying destinations can be consolidated to a reduced number of homogeneous trains, which is an essential requirement of hub-and-spoke railway systems. An important problem during the daily operations of such a transshipment yard is the train location problem, which assigns each train of a given pulse to a railway track (vertical position) and decides on each train's parking position on the track (horizontal position), so that the distances of container movements are minimized and the overall workload is equally shared among cranes. For this problem a mathematical model is presented; different heuristic solution procedures are described and tested in a comprehensive computational study. The results show that our procedures allow for a remarkable reduction of train processing time compared with typical real-world train location policies.

New bounds and algorithms for the transshipment yard scheduling problem

In a modern rail---rail transshipment yard huge gantry cranes transship containers between different freight trains, so that hub-and-spoke railway systems are enabled. In this context, we consider the transshipment yard scheduling problem (TYSP) where trains have to be assigned to bundles, which jointly enter and leave the yard. The objective is to minimize split moves and revisits. Split moves appear whenever containers have to be exchanged between trains of different bundles, whereas revisits occur if a train has to enter the yard twice, because some container dedicated to this train was not available during its first visit. We extend the basic TYSP, so that additional real-world requirements of modern rail---rail yards, e.g., the one currently constructed in Hannover-Lehrte, are considered. We provide complexity proofs for different problem settings and present several heuristic procedures as well as one exact algorithm. The paper concludes with computational results showing the efficiency of the proposed algorithms.

Determining fixed crane areas in rail–rail transshipment yards

To enable rapid container transshipment between freight trains in modern rail–rail transshipment yards efficient computerized scheduling procedures are indispensable. This paper proposes a dynamic programming approach, which determines yard areas for gantry cranes, so that the workload is evenly spread among cranes and, thus, train processing is accelerated. In a straightforward simulation of transshipment yard operations, the effect of optimal crane areas vs. equally sized areas is studied, the latter being a common real-world policy. The results indicate a remarkable speed-up of train processing if optimal crane areas are applied.

Rail vs Truck Transport of Biomass

This study analyzes the economics of transshipping biomass from truck to train in a North American setting. Transshipment will only be economic when the cost per unit distance of a second transportation mode is less than the original mode. There is an optimum number of transshipment terminals which is related to biomass yield. Transshipment incurs incremental fixed costs, and hence there is a minimum shipping distance for rail transport above which lower costs/km offset the incremental fixed costs. For transport by dedicated unit train with an optimum number of terminals, the minimum economic rail shipping distance for straw is 170 km, and for boreal forest harvest residue wood chips is 145 km. The minimum economic shipping distance for straw exceeds the biomass draw distance for economically sized centrally located power plants, and hence the prospects for rail transport are limited to cases in which traffic congestion from truck transport would otherwise preclude project development. Ideally, wood chip transport costs would be lowered by rail transshipment for an economically sized centrally located power plant, but in a specific case in Alberta, Canada, the layout of existing rail lines precludes a centrally located plant supplied by rail, whereas a more versatile road system enables it by truck. Hence for wood chips as well as straw the economic incentive for rail transport to centrally located processing plants is limited. Rail transshipment may still be preferred in cases in which road congestion precludes truck delivery, for example as result of community objections.

Models and Algorithms for Container Allocation Problems on Trains in a Rapid Transshipment Shunting Yard

Multimodal transport of containers can be an alternative to the road transportation but it requires to be competitive in terms of quality of service and price. In rail–rail container terminals, new techniques are developed to facilitate rapid transfers of the containers between trains. In this article, we address the problem of the optimization of the operations management of rapid rail–rail transshipment shunting yards. We are interested specifically in the optimization of containers allocation on trains (for the initial loading and their reloading after transshipment). We have developed a class of models with different levels of complexity and realism and we have proposed optimal and heuristic methods to solve them. The experimental results on realistic datasets are very promising in terms of the minimization of the container moves in a terminal as well as the use and sizing of the handling equipments.

Great Lakes Transport of Western Coal: Economic and Technical Analysis

An investigation into the economics of transporting Western coal to consumers in the Midwestern and Eastern demand regions has been conducted, with a particular emphasis on the Great Lakes waterborne link. The design characteristics of Great Lakes coal-carrying vessels are discussed in detail. Specific problems involved in the transport of coal in bulk are related to design decisions, particularly in the areas of cargo-handling gear, cubic requirements, ship maneuvering, cargo thawing, and dust control. The relative performance of taconite carriers, specially built colliers, and combination vessels in the coal trade is discussed, together with a consideration of potential problems facing coal carriers diverted to the taconite trade. The economic effects of systematic variations in ship characteristics, including dimensions, materials, proportions, and speed are considered. The impact of fuel price and of operation through the winter is also examined. A comparison of transport alternatives for various pairs of sources and destinations, based on total delivered cost and energy expenditure, including rail transport and transshipment, is made. Finally, some conclusions are offered regarding the future of Great Lakes operations in view of the emerging coal traffic.