Freight Service Design for the Italian Railways Company

In this paper, we present a mathematical model to design the service network, that is the set of origin-destination connections. The resulting model considers both full and empty freight car movements, and takes into account handling costs. More specifically, the model suggests the services to provide, as well as the number of trains and the number and type of cars traveling on each connection. Quality of service, which is measured as total travel time, is established by minimizing the waiting time of cars at intermediate stations. Our approach yields a multi-commodity network design problem with concave arc cost functions. To solve this problem, we implement a tabu search procedure which adopts ``perturbing\u27\u27 mechanisms to force the algorithm to explore a larger portion of the feasible region. Computational results on realistic instances show a significant improvement over current practice

Cost optimization for the capacitated railroad blocking and train design problem

This paper considers the combined problems of railroad blocking, train design and train assignment as observed in the railroad industry. The problem of railroad blocking deals with finding the least cost paths for a given set of shipments over an entire railroad network. Blocking is defined as an activity where a set of shipments arriving at or commencing from a certain node station and departing to another particular node station, or further, are grouped together and sent across as the same train to minimize costs and exploit economies of scale. This problem has marked similarities with the airline scheduling which operates flights across a predetermined hub and spoke network. The problem considered here not only necessitates determining the “right” hubs and “right” trains to be scheduled on the network, but also scheduling the shipments on appropriate trains between the hub station yards and spoke station yards so that the overall costs are minimized. There are a large number of practical and logical constraints associated with the problem. Apart from the capacity related constraints on the arcs, nodes and trains as observed in prior literature, it is required that the trains run only on crew segments, which act as the transit nodes for crew members. The main objective of our efforts would be to find a cost minimizing set of feasible trains that operate entire on crew segments. Our algorithm will also determine the least cost assignment of shipments to these trains. The results of our method are validated and reported for two real-life problem instances and demonstrate the advantage of using a joint mixed integer mathematical formulation over greedy heuristics that have largely been employed for this problem in literature

Optimized shunting with mixed-usage tracks

We consider the planning of railway freight classification at hump yards, where the problem involves the formation of departing freight train blocks from arriving trains subject to scheduling and capacity constraints. The hump yard layout considered consists of arrival tracks of sufficient length at an arrival yard, a hump, classification tracks of non-uniform and possibly non-sufficient length at a classification yard, and departure tracks of sufficient length. To increase yard capacity, freight cars arriving early can be stored temporarily on specific mixed-usage tracks. The entire hump yard planning process is covered in this paper, and heuristics for arrival and departure track assignment, as well as hump scheduling, have been included to provide the neccessary input data. However, the central problem considered is the classification track allocation problem. This problem has previously been modeled using direct mixed integer programming models, but this approach did not yield lower bounds of sufficient quality to prove optimality. Later attempts focused on a column generation approach based on branch-and-price that could solve problem instances of industrial size. Building upon the column generation approach we introduce a direct arc-based integer programming model, where the arcs are precedence relations between blocks on the same classification track. Further, the most promising models are adapted for rolling-horizon planning. We evaluate the methods on historical data from the Hallsberg shunting yard in Sweden. The results show that the new arc-based model performs as well as the column generation approach. It returns an optimal schedule within the execution time limit for all instances but from one, and executes as fast as the column generation approach. Further, the short execution times of the column generation approach and the arc-indexed model make them suitable for rolling-horizon planning, while the direct mixed integer program proved to be too slow for this. Extended analysis of the results shows that mixing was only required if the maximum number of concurrent trains on the classification yard exceeds 29 (there are 32 available tracks), and that after this point the number of extra car roll-ins increases heavily

Формалізація процесу управління парком вантажних вагонів операторських компаній

The technology of freight car fleet management of operators company in the subsystems of UZ has been investigated and analyzed. It has been determined that the choice of the optimal plan of distribution of car operators according to the route of a freight car (schedule lines) mainly depends on the volume of cars being present at freight stations of railway network and their location in space and time. The topology variants of railway network has been analyzed using theory of graph taking into account all the above said. Relying on a systematic approach it has been proved, that the increase of railway transport competitiveness is possible at the expense of the provision of railway subsystem with invariance properties. The railway subsystem itself should be considered as a compromise between its stability and flexibility.Thus, optimization model which formalizes technological process of freight car fleet management of operator companies has been mode.The objective of the given model is presented in the form of total operating cost and relevant set of constraints that takes into account technological conditions of route formation. The mode optimization model adequately reflects the terms of transportation process, ensures the reduction of transportation costs under the condition of satisfaction of clients’ requirements and provides for the formation of automated technology of management of car fleet of different forms of ownership. Taking into account the theory of computational complexity, it is reasonable to choose heuristic method, based on mathematical apparatus of genetic algorithms, to obtain the optimal plan of car distribution according to the routesСформировано математическую модель, которая формализует технологический процесс управления парком грузовых вагонов операторских компаний в виде оптимизационной задачи с целевой функцией, предоставленной в виде суммарных эксплуатационных расходов за период планирования и системой ограничений на технических и технологических условиях. Для решения задачи предложено использовать математический аппарат генетических алгоритмов.Сформовано математичну модель, яка формалізує технологічний процес управління парком вантажних вагонів операторських компаній  у вигляді оптимізаційної задачі з цільовою функцією, яку надано у вигляді сумарних експлуатаційних витрат за період планування і системою обмежень на технічних і технологічних умовах. Для рішення задачі запропоновано використовувати математичний апарат генетичних алгоритмів

Формалізація процесу управління парком вантажних вагонів операторських компаній

The technology of freight car fleet management of operators company in the subsystems of UZ has been investigated and analyzed. It has been determined that the choice of the optimal plan of distribution of car operators according to the route of a freight car (schedule lines) mainly depends on the volume of cars being present at freight stations of railway network and their location in space and time. The topology variants of railway network has been analyzed using theory of graph taking into account all the above said. Relying on a systematic approach it has been proved, that the increase of railway transport competitiveness is possible at the expense of the provision of railway subsystem with invariance properties. The railway subsystem itself should be considered as a compromise between its stability and flexibility.Thus, optimization model which formalizes technological process of freight car fleet management of operator companies has been mode.The objective of the given model is presented in the form of total operating cost and relevant set of constraints that takes into account technological conditions of route formation. The mode optimization model adequately reflects the terms of transportation process, ensures the reduction of transportation costs under the condition of satisfaction of clients’ requirements and provides for the formation of automated technology of management of car fleet of different forms of ownership. Taking into account the theory of computational complexity, it is reasonable to choose heuristic method, based on mathematical apparatus of genetic algorithms, to obtain the optimal plan of car distribution according to the routesСформировано математическую модель, которая формализует технологический процесс управления парком грузовых вагонов операторских компаний в виде оптимизационной задачи с целевой функцией, предоставленной в виде суммарных эксплуатационных расходов за период планирования и системой ограничений на технических и технологических условиях. Для решения задачи предложено использовать математический аппарат генетических алгоритмов.Сформовано математичну модель, яка формалізує технологічний процес управління парком вантажних вагонів операторських компаній  у вигляді оптимізаційної задачі з цільовою функцією, яку надано у вигляді сумарних експлуатаційних витрат за період планування і системою обмежень на технічних і технологічних умовах. Для рішення задачі запропоновано використовувати математичний апарат генетичних алгоритмів

Формалізація технології організації групових поїздів оперативного призначення

The study suggests an improved procedure of correcting train formation plans (TFPs) on the basis of calculations on the agreed network arrangement of tactical group trains. Our aim is to improve the Ukrainian technology fortactical acceleration of long-distance and low-capacity train streams that do not meet the current TFPrequirements. The problem can be solved by means of the suggested formalized technology of correcting TFPs on the basis of arranging tactical group trains. The devised mathematical model allows selecting a reasonable route for arranging groups of wagons into agreed group trains with variable combinations of wagon groups within the network. The mathematical model belongs to integer linear programming tasks and can be solved with the help of the genetic algorithm. The suggested approach allows an effective distribution of work between technical sorting stations of the railroad network and ensures timely delivery of cargoes to the customer at the agreed time.Работа посвящена усовершенствованию процедуры корректировки плана формирования поездов на основе формализации технологии организации групповых поездов оперативного назначения. Разработана математическая модель, которая позволяет выбирать оптимальный маршрут объединения групп вагонов для организации согласованных групповых поездов со сменными сочетаниями групп вагонов на сетевом уровне. Для решения данной математической модели предложено применить генетический алгоритм.Робота присвячена удосконаленню процедури корегування плану формування поїздів на основі формалізації технології організації групових поїздів оперативного призначення. Розроблено математичну модель, яка дозволяє вибирати раціональний маршрут об’єднання груп вагонів для організації погоджених групових поїздів зі змінними сполученнями груп вагонів на сітьовому рівні. Для рішення даної математичної моделі запропоновано застосувати генетичний алгоритм

Формалізація технології організації групових поїздів оперативного призначення

The study suggests an improved procedure of correcting train formation plans (TFPs) on the basis of calculations on the agreed network arrangement of tactical group trains. Our aim is to improve the Ukrainian technology fortactical acceleration of long-distance and low-capacity train streams that do not meet the current TFPrequirements. The problem can be solved by means of the suggested formalized technology of correcting TFPs on the basis of arranging tactical group trains. The devised mathematical model allows selecting a reasonable route for arranging groups of wagons into agreed group trains with variable combinations of wagon groups within the network. The mathematical model belongs to integer linear programming tasks and can be solved with the help of the genetic algorithm. The suggested approach allows an effective distribution of work between technical sorting stations of the railroad network and ensures timely delivery of cargoes to the customer at the agreed time.Работа посвящена усовершенствованию процедуры корректировки плана формирования поездов на основе формализации технологии организации групповых поездов оперативного назначения. Разработана математическая модель, которая позволяет выбирать оптимальный маршрут объединения групп вагонов для организации согласованных групповых поездов со сменными сочетаниями групп вагонов на сетевом уровне. Для решения данной математической модели предложено применить генетический алгоритм.Робота присвячена удосконаленню процедури корегування плану формування поїздів на основі формалізації технології організації групових поїздів оперативного призначення. Розроблено математичну модель, яка дозволяє вибирати раціональний маршрут об’єднання груп вагонів для організації погоджених групових поїздів зі змінними сполученнями груп вагонів на сітьовому рівні. Для рішення даної математичної моделі запропоновано застосувати генетичний алгоритм