Special Issue on Up-to-Date Problems in Modern Railways - Guest Editors: Dragan Marinkovic, Dmytro Kurhan, Mykola Sysyn and Szabolcs Fischer
Abstract: The Rail Technical Strategy aims to meet the goals that reduce carbon emissions, increase rail speed, lower rail costs and improve customer satisfaction. The reduction of fuel consumption and costs for rail travel depends on more effective maintenance and operation. In a railway system, mainly diesel energy is needed for traction followed by 30 percent energy consumption. The engine will start a reaction to extract this carbon by running the gas supplying hot and reactive. The heat released by the reaction will be adequate to support the reaction under such conditions, resulting in very high local temperatures usually as a thermal wave. Energy efficiency of rail vehicles, expressed in the reduction of the size of diesel engines and the consistent development of battery and supercapacitor systems to promote regenerative braking are in focus. For the accessibility study of these issues with regard to the implementation of the engine control approach, level set calculations approaches were used in this study.
Keywords: optimization; train diesel engine; maximizing efficiency; driving quality
Abstract: The subject of this paper is the structural design of a safety steel device that is located between the standard wagon buffer and the collision energy absorber. The safety steel device is a sacrifical part able to withstand normal operating loads from the buffer across the absorber to the vehicle bearing structure without any permanent deformation, but experiences fully controlled fracture when the load exceeds the defined threshold. Following fracture, the load path is through the energy absorber. The sacrificial part is a ring made from quenched and tempered low alloyed steel with precisely defined heat treatment and material properties. Experimental investigations of scaled samples were performed to get mechanical characteristics of the material and geometry. A full-scale prototype of the safety device was produced, and final quasi-static and dynamic experiments were conducted. The results validate the anaytical predictions, and thus validate the design method used here for dimensioning the safety steel device.
Keywords: Safety Steel Device; Controlled Fracture; Analytical Dimensioning; Experimental Investigations
Abstract: A new railway concept where there is more than one company participating in the transportation chain, Lead Railway Undertaking - LRU, should be in charge of managing and controlling the transportation chain. Using a timed Petri net - TPN, a model of organizing European railway transport will be introduced as a system with discreet events whose state depends on the occurrence of discreet events from the moment of ordering the transportation until the moment of delivering the goods to the client. The tracking of wagons/goods is presented with a token that moves through a designed petri organization model. With the example of a possibility of shortening the estimated time of the wagon retention in stations by shortening the time of commercial checkups of goods, the PN model portrays a strong diagram of all the operations that include wagons, as well as the processes that occur parallel and in sync all along the railway chain.
Keywords: TSI TAF; Petri net; European railway; ITUs
Abstract: This paper analyzes stochastic vibrations of a specialised onboard railway obstacle detection system (ODS). The observed system consists of several vision-based sensors mounted in a special housing attached to the locomotive front profile via rubber metal springs and a mounting plate. In this study, the experimental measurements of acceleration were performed in the vertical, longitudinal, and lateral direction for two positions, on the mounting plate rigidly connected to the vehicle body and inside the sensor housing. The ODS stabilization is presented with the results obtained by the moment Lyapunov exponent (MLE) method. Analytical and numerical determination of MLE is firstly presented on a simply supported Euler-Bernoulli beam. Further, the stochastic vibration analysis was performed using the experimentally obtained data. According to these values, the appropriate system parameters essential for the application of the Lyapunov theory to stochastic stability problems were firstly numerically calculated. By means of the Monte Carlo simulation method, whose example was previously shown on a simple beam, the bounds of the almost sure stability of the observed system are given according to the measured accelerations in all of the observed directions.
Keywords: Vibrations; Obstacle Detection; stability; Moment Lyapunov exponent; Monte Carlo simulation
Abstract: In nature, the mechanical properties of soils, vary from region to region and in some areas, high-strength soil resources lack is a serious difficulty that geotechnical engineers may face where constructing earthworks such as railway and road embankments is required. Although a wide range of soil improvement techniques exists to improve such soils, the effect of geocell, as an effective solution, has not yet been investigated for railway embankments, hence, the present study aims to develop a three-dimensional (3D) Finite Element (FE) model, to fill the gap. To do this, first, six, 1/20 scaled-down railway embankments, including an unreinforced and 5 reinforced ones, were constructed in the lab and their load-settlement behavior, was assessed. Second, a 3D FE model was validated by experimental results and then, using a parametric study, the effect of geocell opening size and geocell layers number, were investigated on bearing capacity and settlement of the embankments, for five various types of soil ranging from poor soils (ST1), to high strength soils (ST5). The outcomes indicated, although adding geocell layers up to 15 layers, results in reducing the exerted stress in railway embankments by a maximum of near 50%, the crest settlement is not efficiently affected. Moreover, it was found that geocell’s opening size has a negligible effect on decreasing the embankment’s settlement, while it affects the bearing capacity significantly, up to a maximum of 50%.
Keywords: Geocell-reinforced Railway embankment; railway embankment FE model; railway embankment improvement; Geosynthetics
Abstract: From the aspect of safety, brakes of rail vehicles are an extremely important system on the vehicle. Braking performance affects the normal functioning of vehicles and interoperability of rail vehicles in classic railway train compositions. All trains, classic and different type of motor trains must conform with the available stopping distances, which are predefined by the railway signalling, i.e. control length of a signal and depends on the maximum allowable speed for which the track section is designed. Apart from that, in classic wagons, which are combined and participate in the formation of different train compositions, mutual compatibility must be ensured from the aspect of used braking equipment and connection subassemblies, but even more important, braking performance of all wagons in the train has to be uniform within certain tolerances. This prevents weaker braked wagons from running into stronger braked ones, which can cause longitudinal jerks and may in extremes lead to a train rupture. Stopping distance during brake application depends on train braking performances, longitudinal running resistance and presence of wind and its direction. This paper deals with the influence of wind conditions on the results of slip brake tests and the estimation of a single vehicle's braking performance. Based on experimental measurements, simulations using CFD and comparison with the obtained results, this paper proposes a possibility to extract air drag resistance and wind force from the total resistance force. Presented methodology and obtained results may serve for further simulations of aerodynamic characteristics apart from braking performance, such as vehicle running resistance, energy consumption, etc. and for optimization of the wagon shape and design.
Keywords: stopping distance; slip brake tests; head wind influence; drag coefficient; numerical simulations
Abstract: The railway, by its physical size, is a specific continuous object in an area whose impact on the environment can be extremely unfavorable. The changes occurring under the influence of these effects have a strong feedback effect that can lead to new negative states and often very dramatic consequences. In this paper, within the General project for the construction of infrastructure corridor in the central part of the Kolubara basin, the evaluation of alternative solutions for rail sections is shown for the protection of the environment through methodology of multi-criteria compromise ranking. Identified and quantified are adverse impacts on the environment in an area that is a potential corridor. To analyze the impact, taking into account their specific characteristics and spatial relationships, certain indicators for each of the alternative solutions are determined. The procedure and results of multi-criteria evaluation is also presented.
Keywords: General Design; railroad; environmental protection; multi-criteria evaluation
Abstract: Based on the conducted monitoring of the railway track operation, it is shown, that most curves fail to meet the source nameplate data. Proposals have been developed to reduce the intensity of the track disorder, due to the reduction of curve parameters to the normative requirements, operating in Ukraine. Recommendations obtained in this work will contribute to the effectiveness of design decisions, determine the quality of the reconstruction projects in general and the expediency of its implementation in particular, they will be useful for carrying out activities to improve the smoothness of trains movement, increase the speed and level of travel comfort, in the curved tracks, especially in the future development of high-speed train implementations.
Keywords: railway; railway curve; survey of curves; accuracy assessment; reliability
Abstract: Wheel ground borne vibrations, may have a significant impact on human activity and on nearby buildings. In metropolitan cities, metro lines and their development may cause such vibrations. Despite many works and solutions for path and receiver, the excitation source could also have a great effect. Wheel and rail damages are the two sources of vibration which can increase the damage impact by a factor of 5x. Wheel damage would increase dynamic vertical force noticeably and an increase in ground-borne vibration is expected. In this study with the help of finite element modelling, wheel damage including wheel flat, spalling and wheel oval is studied for a slab track and results are discussed. The studied parameters are velocity and wheel damage and their effect on ground-borne vibrations are examined.
Keywords: ground-borne vibration; FEM; metro; wheel defect; moving load
Abstract: The purpose of this research is to provide an accurate and low degree of freedom model to analyze critical hunting velocity for a rail vehicle. Two types of simplifications have been commonly used in investigations, including linearization of nonlinear and trigonometric terms and applying static coefficients in linear wheel/rail contact models such as Kalker model. To find the effect of these simplifications in the accuracy of computed hunting velocity a 3DOF single-axis bogie model with a wheelset possessing 3D motion mobility and constant wheel/rail contact is used. The creep forces and spin moment in the contact model are obtained from the linear Kalker model with dynamic creep coefficients. The contact model coefficients are updated in each moment based on the instant values of normal wheel force and wheelset yaw angle using a proposed algorithm. The critical speed and bifurcation diagram of the hunting frequencies are obtained and a comparison is made between the static creep coefficient model and dynamic creep coefficient model. According to the results, dramatic changes in stability margins and starting point of period doubling in the bifurcation diagram are observed under the presence of dynamic creep coefficients. Also, an increase of normal external load on the wheelset causes the reduction of critical velocity, which is merely predicted in the dynamic coefficient model. This means the static creep coefficient models do not have enough reliability for analyzing the variable weight wagon problems such as freight trains. Another important result is that the simplification of most trigonometric terms has a negligible effect on the accuracy of results.
Keywords: Creep Forces; Creep Coefficients; Stability; Hunting; Bifurcation
Abstract: Angled guide plates are used to transmit the forces induced by trains, from the rail seat, to the concrete sleepers. Additionally, the design of the angled guide plates, with an appropriate width, supports tilting protection. Considering the updated requirements of the ML-1 railway line, in the Islamic Republic of Pakistan, an optimization design of the angled guide plate of the Vossloh W14-PK fasteners was carried out herein. The design requirements of the angled guide plate need to meet the requirements of structural stress and protect the plates from deterioration. Given the conducted refined model of the Vossloh W14 - PK fastener, it is shown that the force and deformation of the angled guide plate, in the bearing groove adjacent and the outside bolt hole area, are small. Therefore, it was preliminarily recommended that the optimization area of the angled guide plate be divided into the section I, close to the rail groove and section II, outside the bolt hole. The Finite Element Model (FEM) of angled guide plate was established, which is used to analyze the influences of length, width, depth and the number of holes, in section I and section II, on the force distribution, across the angled guide plate. The results show that the scheme of reducing the amount of material and minimizing the influence of force on the structure of the angled guide plate, is to punch three holes in section I and two holes in section II. The holes in section I/II are 20/30 mm in length, 8/8 in width, and 15/8 mm in depth, respectively. The fatigue test showed that the optimized angled guide plate, had good application effects.
Keywords: Ballasted track; Fastening system; Angled guide plate; Structural design; Fatigue test
Abstract: Modern requirements for reduction of the carbon footprint and toxic emissions of internal combustion engines, as well as their operation cost may be fulfilled by conversion of diesel engines for operation on natural gas. Methane, which is the main component of natural gas, contains by 15% less carbon than diesel fuel, and its heat value is by 15% higher (by mass). Therefore, an engine fed by natural gas may reduce its CO2 emissions by up to 30% compared to the base diesel engine. The price of natural gas in Russia is almost twice as much less than that of diesel fuel. As locomotive engines often operate 24 hours a day 7 days a week, the gain in fuel costs may be large. Two basic methods of diesel engine conversion for operation on natural gas were analyzed: gas engine and gas diesel (dual-fuel) engine. Simulation of diesel, gas diesel and gas engines for a shunting locomotive was done using the multi-zone AVL FIRE model and one-zone model developed in MADI. The simulation showed that transfer from diesel cycle to gas and gas diesel cycles resulted in considerable decrease in fuel consumption and emissions of particles and NOx. The gas engine had lower mechanical and thermal stresses compared to diesel and gas diesel versions.
Keywords: conversion of diesel engine; gas engine; dual-fuel engine; engine simulation; one-zone model; multi-zone model; Viebe formula
Abstract: The current paper aims to investigate stability of side’s slops of geocell-reinforced railway embankments. For this purpose, firstly a set of six 1:20 scaled models including a reference embankment and geocell-reinforced embankments was constructed in a loading chamber and their load-settlement behaviour was assessed. In the next stage, 3D FEM models of the embankments were developed and the relevant results were verified against the laboratory test outcomes. In continue, on the basis of verified models, the scaled up railway embankments were simulated and the real train loading applied to the models. In this matter, a wide-ranging parametric study was performed on the embankment soil properties ranged from poor (ST1) to high strength (ST5) materials, geocell elasticity modulus (E), number of geocell layers (N) and their vertical location in the embankment body (U) to achieve a minimum embankment sliding safety factor (SF) of 1.5. Outcomes indicate that geocell opening size, stiffness and the placement position play an important role where the concern is to stabilize the embankments' sides slopes. It was found that middle of the embankment was the best position of geocell layers. Elasticity modulus of 1400 MPa and opening size of 245*210 mm were also determined as the optimum for geocell layers.
Keywords: Geosynthetics; Geocell-reinforced embankment; ballasted railway tracks
Abstract: Waste rubber tires and glass powders, are hazardous materials for the environment. One of the methods to consume them, is their application in railway engineering projects. Rubber and glass materials, in this research, are provided from waste tires and glass bottles. Therefore, a modification is conducted to the concrete railway sleeper mix design, incorporated with waste rubber (R) and glass powder (GP). Three mechanical tests, including compressive, flexural and tensile splitting, have been studied on rubber and glass powder concrete specimens. Three different percentages of 5%, 10% and 15% by cement weight, for GP and by fine aggregate volume for R, are investigated herein. The results show that GP concrete has a better performance over the rubber concrete (RC), but lower than Ref. specimens. 5%GP as the best mix design, has compressive, flexural and tensile strengths of 45.4 MPa, 7.5 MPa and 5.82 MPa, respectively. Moreover, these strengths, for compressive and flexural, of 5%GP are about 24% and 6% lower than the Ref. strengths, respectively, while, tensile splitting strength is almost 14% higher than Ref. strength.
Keywords: Concrete railway sleeper; waste rubber; waste glass; recycled materials