A planning approach for freight transportation operations in railway networks Simona Sacone and Silvia Siri Department of Communications, Computers, and Systems Science Italian Centre of Excellence for Integrated Logistics University of Genova, Italy {simona.sacone, silvia.siri}@unige.it Abstract—The development of new technologies for the auto- matic transfer of loading units between rail and road will enable faster handling operations at railway terminals in the next years. For this reason, railway transportation can be thought as a transportation on networks where cargo units change different trains, at different terminals, before reaching their destination. This paper aims at the definition of an optimization problem for planning transportation operations in railway networks in order to meet the demand defined as aggregated orders, by defining, for each container, the path, the sequence of trains and wagons and the sequence of terminals. This problem is faced in two phases: firstly, a preprocessing analysis is realized in order to compute some data sets which do not depend on planning decisions but only on problem data; secondly, the planning phase is realized by the definition of a linear binary integer programming problem. Index Terms—Freight transportation, railway networks, plan- ning procedure, mathematical programming. I. I NTRODUCTION The economic activities related to intermodal freight trans- portation have been growing in the last decades and are likely to be growing in the next future. For this reason planning methods and decision support systems are required in this field, yielding interesting research opportunities for the development of optimization models. Some general review works in the field of planning and optimization of logistic and freight transportation systems can be found in [1], [2], [3], [4]. Another survey paper, focused only on intermodal freight transportation, is [5], where the authors argue that few Operational Research methods exist in the field of in- termodal freight systems. Actually, intermodal transportation has emerged as a new research application field, requiring different models and optimization procedures than those applied to uni-modal transportation systems. In that review paper, only inland intermodal freight trans- portation (rail-truck or barge-truck) is considered, as the one analysed in the present paper where road and rail trans- portation is concerned. Moreover, in [5] road-rail transport is described as composed by a first part realized by road (pickup), then a long-haul transportation realized on train and then the last part realized by road (delivery), while the transhipment is performed in railway terminals. This is exactly the same structure of the logistic chain analysed in the present paper and described in the following sections. According to the classification made by [5], the scientific literature on intermodal freight transportation can be cate- gorized depending on the operators facing the optimization problems and on the planning time horizon (thus yielding the standard classification in strategic, tactical and operational problems). Problems related to drayage operators deal with planning pickup and delivery phases, thus providing opti- mization models for scheduling of trucks, redistribution of empty chassis, and so on. Then, there are problems related to terminal operators, which concern the optimal management of handling and storage activities performed at the terminal. The third class of problems is associated with network operators and concerns the planning and organization of railway (or barge) transport: we can find problems about infrastructure planning (strategic level), about the definition of service schedules and pricing policies (tactical level), about the scheduling of daily operations and assignment of containers to flatcars (operational level). Finally, there are problems faced by intermodal operators that make use of the logistic network, buying the services provided by drayage, terminal and network operators: these are operational deci- sions, mainly devoted to the optimal route selection and the definition of the optimal combinations of network services. The problem described and analysed in the present paper can be classified as belonging to the fourth class (problems faced by intermodal operators) because it concerns the defini- tion of the best path to be covered and the best transportation resources to be taken in an intermodal network. Anyway, in this paper, we only focus on rail transportation without considering the optimization of road transportation operations and we define an optimization procedure for deciding the best path on the network and the optimal assignment of trains to orders (these latter being characterized by an origin, a destination, a required delivery time window, a number of load units to be moved). Many research works can be found about planning railway operations, in which the main objective is the optimal scheduling and routing of trains (see [7] for a review work on this field); for instance, in [6] a model is proposed for scheduling loading and departure