Search

In this paper a rolling horizon approach is applied for simultaneous optimization of the rail freight car fleet size and allocation problem. Developed dynamic model of loaded and empty rail freight car flows explicitly treats state, control and station capacity constraints in presence of various freight car types under the partial substitutability among them. Demands and traveling times are considered as random variables. Proposed approach is applied to a set of test cases and it shown to be successful, ultimately providing a new managerial tool for more effective and efficient planning and analyzing rail freight car fleets. [ABSTRACT FROM AUTHOR]

In the freight car dispatching problem, empty freight cars have to be assigned to known demands respecting a given time horizon and certain constraints. The goal is to minimize the resulting transportation costs. One of the constraints is that customers can specify the type of cars they want. It is possible, however, that cars of certain types can be substituted by other cars, either in a 1-to-1 fashion or at different exchange rates. We show that these substitutions make the dispatching problem hard to solve and hard to approximate. We model the dispatching problem as an integral generalized transportation problem on a bipartite graph. Using rounding techniques, the LP-relaxation can be transformed to a transportation schedule violating some of the constraints slightly. Under an additional assumption on the cost function, we fix this violation and derive a 4-approximation of the problem. © 2015 Wiley Periodicals, Inc. NETWORKS, Vol. 66(1), 33-39 2015 [ABSTRACT FROM AUTHOR]

The bodies of many railway freight cars in many countries of the world are coupled to the running gear by means of a body centre plate that makes a friction pair with a centre bowl. During motion, the bogie is rotated and moved with respect to the car body. This leads to wear on the contact surfaces. Lubrication is inexpedient in this case because the friction forces damp the vibrations (so-called bogie hunting) during motion. Usually, centre plates exhibit noticeable wear after two years of operation. Reducing wear requires knowing details of the wear process which, in turn, requires computer simulation of freight car motion for an operation period of 10–15 years. The purpose of this paper is to develop a universal method for wear simulation of friction pairs that could be used, in particular, for the centre plate of a freight car. [ABSTRACT FROM AUTHOR]

Freight transport plays a very important role in economic activities. However, in some cases, the local transportation authority often disregards its existence, including in parking management issues. This research is aimed at developing an optimization model for off-street parking space management that considers freight cars and passenger cars as two different entities. Optimization aims at minimizing the joint function of the parking index of freight cars and the parking index of passenger cars. Weighting is given to both parking indexes to represent the interest level of parking operator to both types of vehicles. Parking space of both vehicles is at any time is arranged in a dynamic manner based on the inflow and outflow rate of vehicles at previous times. The parking index is limited by the maximum parking index desired by the management. The proposed model is applied to the parking activity in Jatinegara Trade Center (JTC), Jakarta, and shows that the model solution provides a better parking index than the actual parking index (without optimization). [ABSTRACT FROM AUTHOR]

We consider an operational process at shunting yards, where freight cars are disassembled and reassembled via a system of tracks and switches to form outbound trains with no restriction on the order of the freight cars. Given are due dates for each outbound train and priority values for its freight cars. Furthermore, the composition and the processing time of each inbound train is part of the input. An outbound train is defined by a set of freight cars taken from one or many inbound trains. In this context, we try to minimize the weighted tardiness of all outbound trains by determining the optimal humping sequence of inbound trains. We show that this problem is NP-hard and we present a simple mixed integer problem formulation. Besides two heuristic approaches and an implementation in CPLEX, the main focus of our single stage shunting problem to minimize weighted tardiness (SSSWT) is on developing an exact branch and bound procedure. Therefore, we present powerful precedence constraints and priority rules to reduce the solution space. Further, we compare the runtime and accuracy of the proposed algorithms with the results of CPLEX optimizer in a computational study. [ABSTRACT FROM AUTHOR]

The paper presents features and results of cataloging of gondola carrying system throughout the application of this approach for face wall of one of the basic model of gondolas. [ABSTRACT FROM AUTHOR]

This paper proposes an estimation approach for a commodity origin-destination matrix by using a sample commodity origin-destination (OD) matrix from a Commodity Flow Survey and also mode-specific OD matrices obtained from a transportation record of freight carriers. The proposed approach is formulated as a multi-objective bi-level optimization problem in which the upper-level seeks to minimize the sum of square deviation from the target matrices, while in the lower-level, user-equilibrium assignments of commodity OD matrix from a CFS and mode-specific OD matrices are performed. The developed model and the Genetic Algorithms-based solution algorithm were validated and tested on an intermodal transportation network of Korea. The results show that the model is able to produce an acceptable commodity OD matrix, implying that the proposed approach is applicable for a real-world problem. [ABSTRACT FROM AUTHOR]

The article presents abstracts on non-destructive quality testing topics which include testing of natural stone block, freight car non-destructive testing, and testing technique and system for the rail in service.

Although the role of industrial policy in economic development is a frequent topic of debate in both the literature and the political arena, most discussions focus on industrial policymaking at the national level. Using a case study of a potato cluster in China, we show that industrial policymaking at the local level contributes greatly to economic development as well. Many of the industrial policies affecting the cluster--including leveling land, developing better varieties, establishing a potato trade association, lobbying for increasing freight car quotas, and attracting processing firms--were implemented at the local level, highlighting the need for discussion of local industrial policymaking as a major determinant of cluster development. As the case study demonstrates, economic development is a continuous process with constantly evolving binding supply-side and demand-side constraints. Often, after a local policy helps remove one binding constraint, a new one emerges that, in turn, may require a new set of policies. Therefore, the success of clusters depends upon local industrial policies that respond to emerging binding constraints at different stages of the cluster's development. [ABSTRACT FROM AUTHOR]

Statistics of accident rate at Ukrainian and Russian railways is an evidence of increase in the recent years of the accidents, related with failure of cast bearing elements of two-axle three-component freight car bogies. Analysis of service reliability of cast structures of side frame and bolster of 18-100 type bogie shows that appearance of fatigue cracks is the main reason of reject. It is reasonable to search an alternative application of welding technologies in manufacture of indicated parts from sheet products for the purpose of increase of their safety and survivability. It is shown that existing Norms for designing of welded joints and assemblies of railway cars significantly overstate real cyclic load resistance of welded joints in comparison with the Recommendations of the International Institute of Welding. This disadvantage is typical for number of reference documents acting in Russia and Ukraine, which regulate calculation of fatigue resistance of welded joints and assemblies. This promotes negative results in designing with respect to required life of welded elements. Development of safe and technological welded elements of freight car bogie requires application of the recent achievements in the field of fatigue strength of welded joints. [ABSTRACT FROM AUTHOR]

This article is devoted to the current state of the technology of railroad-wheel production. An analysis is made of technological features of their manufacture and the mechanical properties of the steels used to make hard high-quality rails for freight cars, steels of grade L used to make high-quality wheels for passenger cars, and a bainitic steel used to make wrought wheels for railcars whose axles are subjected to loads of up to 27 ton-f. Results of microstructural studies of these steels are presented and a determination is made of the structures which ensure that the parts of the wheels which undergo rapid wear will have the necessary mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: In order to simulate the wheel wear behaviour of freight cars, the rail vehicle's multi-body dynamical model and wheel wear simulation programme were combined as a wheel wear simulation tool in this paper. Multi-body dynamical models of China's heavy haul freight cars such as the C80, C80H, C70 and C70H, were built in SIMPACK software and the track system was built based on the China's Ring-line. For the wheel/rail rolling contact, the semi-Hertzian method and FASTSIM algorithm were applied to solve the normal and tangential problem respectively. The shapes of worn wheel profiles in the simulation agree well with the field measurements, but wear rates from the simulation are larger than those found in field measurements. This discrepancy is contributed to two factors. The first factor is the wheel material. The CL60 wheel steel used in China's freight car, is harder than the BS11 wheel steel used in Zobory's wheel/rail wear experiments. The second factor is the impact of a material's elastic shear deformation on the slip velocity in contact patch. This impact will increase the wear rate and was considered in the present wear simulation. [Copyright &y& Elsevier]

The article offers information on a study regarding the benefits of tele-diagnostic system from rail network Trenitalia for fleet of E464 locomotives in different railroad engine plants in Italy. Topics discussed include different functions of the diagnostic system such as operation, engineering and maintenance of railway vehicle fleets, the idea of subsystem redundancy, and compliance with standard EN 13306 maintainability.

Using a heuristic linear creep model, this study derives the governing differential equations of motion for the railway vehicle traveling on curved tracks. The railway vehicle is modeled as a car system with 27 degrees-of-freedom (DOFs), taking into account the lateral and vertical displacements, roll and yaw angles of the wheelsets and truck frames, as well as the lateral displacement, roll and yaw angles of the car body. The effects of railway vehicle speeds on the derailment quotients and offload factors related to running safety are evaluated by both the linear and nonlinear creep models for various radii of curved tracks. Using the Sperling and modified Sperling index formulas, the effects of railway vehicle speeds on lateral riding quality and comfort are illustrated for the two models with various radii of curved tracks. Furthermore, the effects of railway vehicle speeds on the lateral Sperling comfort index of the 27-DOF car model are presented and compared for various suspension parameters. Finally, the acceptable region for riding quality and comfort are drawn. [ABSTRACT FROM AUTHOR]

Regularized multiple-criteria linear programming (RMCLP) model is a new powerful method for classification and has been used in various real-life data mining problems. In this paper, a new Universum-regularized multiple-criteria linear programming (called $${\mathfrak{U}}$$-RMCLP) was proposed and firstly applied to railway safety field, which is useful extension of RMCLP. Experiments in public datasets show that $${\mathfrak{U}}$$-RMCLP can get better results than its original model. Furthermore, experiment results in the trouble of moving freight car detection system (TFDS) datasets indicate that the accuracy of $${\mathfrak{U}}$$-RMCLP has been up to 91 %, which will provide great help for TFDS system. [ABSTRACT FROM AUTHOR]

In recent years accidents related to fracture of cast load-carrying elements of three-piece bogies of freight cars have become more frequent in the railways of Ukraine and Russia. The work substantiates the rationality of development and application of all-welded load-carrying elements of freight car bogie (FCB), improving their operational reliability. Welded structures of FCBs are widely applied in West Europe. Attempts to develop structures of all-welded elements of FCBs irreplaceable with cast structures are made in Ukraine and Russia. However, none of the developed welded structures is currently applied at regular cargo transportation, because of non-optimal design of bogie welded elements in terms of ensuring the required fatigue resistance margin. To develop a competitive welded solebar and bogie bolster it is, first of, all necessary to increase the fatigue resistance of bogie elements, improve the accuracy of solebar fabrication to avoid skewing of wheelset axles, leading to fast wear, lower their weight and cost, increase element run between scheduled depot repairs. Strength analysis of bogie welded elements should be performed in keeping with the norms currently in force, as well as current world standards, norms and recommendations, allowing for the most recent achievements in the field of dynamics of railway cars and methods to determine welded joint fatigue resistance. [ABSTRACT FROM AUTHOR]

Techniques to improve freight car fleet use are of considerable interest to the railroad industry. In this paper, we present a fuzzy inventory control approach applied to the sizing of empty cars on a rail network. We address the problem of deciding the optimal inventory level and the optimal ordering quantity for a rail freight car fleet system in which demand and travel time are uncertain variables represented as triangular fuzzy numbers. Based on the fuzzy economic order quantity (EOQ) formula, a modified fuzzy EOQ model is set up and the optimal policy is developed using the signed distance method to defuzzify the fuzzy total cost. Computational results made for the Serbian rail network case verify the proposed model as well as the efficiency of the approach. [ABSTRACT FROM AUTHOR]

This paper investigates the freight empty cars allocation problem in railway networks with dynamic demands, in which the storage cost, unit transportation cost, and demand in each stage are taken into consideration. Under the constraints of capacity and demand, a stage-based optimization model for allocating freight empty cars in railway networks is formulated. The objective of this model is to minimize the total cost incurred by transferring and storing empty cars in different stages. Moreover, a genetic algorithm is designed to obtain the optimal empty cars distribution strategies in railway networks. Finally, numerical experiments are given to show the effectiveness of the proposed model and algorithm. [ABSTRACT FROM AUTHOR]

During the 20th century, freight transport in South Africa was employed to attain politico-economic ideals, resulting in the overprotection of rail and overregulation of road transport. Increasing industry pressure, combined with the international deregulation trend, led to deregulation in 1988. Myopia resulted in a rail investment hiatus and exponential growth in high-value, long-distance road transport, causing excessive logistics and externality costs for the country. The aim of this study was to propose a freight rail reform agenda based on, (1) lessons from past freight transport policy efforts and (2) the results of freight transport market segmentation driven by models developed over the past two decades. For the study, freight flows were modelled by disaggregating the national input-output model into 372 origin-destination pairs and 71 commodity groups, followed by distance decay gravity-modelling. Logistics costs were calculated by relating commodity-level freight flows to the costs of fulfilling associated logistical functions. The standard management approach of founding strategy development on market-driven segmentation provides a neutral input to steer rail reform discussions in South Africa. Market segmentation points to a dualistic rail reform agenda, enabling both a profit-driven core and a development-driven branch line network. Freight flow insights are steering the policy reform debate towards long-term freight strategy development and optimal freight logistics network design. [ABSTRACT FROM AUTHOR]

A country's competitiveness can be severely hampered by an uncompetitive freight logistics system. During the first decade of the 21st century, two in-depth models were developed for South Africa which provide a framework for measuring and improving the country's freight logistics system - the cost of logistics survey and the freight demand model. These models also allow for the development of scenarios for key identified risks. The objectives of this study were to provide an overview of South Africa's surface freight transport industry, identify key risks to national competitiveness and suggest ways in which these risks could be mitigated. Freight flows were modelled by disaggregating the national input-output model into 372 origin-destination pairs and 71 commodity groups, followed by distance decay gravity-modelling. Logistics costs were calculated by relating commodity-level freight flows to the costs of fulfilling associated logistical functions. South Africa's economy is highly transport intensive. Excessive dependence on road freight transport exacerbates this situation. Furthermore, the road freight transport's key cost driver is fuel, driven in turn by the oil price. Scenario analysis indicated the risk posed by this rising and volatile input and should provide impetus for policy instruments to reduce transport intensity. As such, this study concluded that a reduction in freight transport intensity is required to reduce exposure to volatile international oil prices. [ABSTRACT FROM AUTHOR]