Special Issue on Up-to-Date Problems in Modern Railways (Guest Editors: Dragan Marinkovic, Dmytro Kurhan, Mykola Sysyn and Szabolcs Fischer)
Abstract: The Concrete Canvas (CC) material, is a promising material for application in many civil engineering fields, such as, water construction, pipelining, slope protection, military applications, etc. The authors believe that this material has more potential and could be helpful in infrastructure applications. The infrastructure design requirements are known; the CC has to be fit into the track structure. Several relevant investigations were performed to show the materials adequacy, and using collected data, FE (Finite Element) models were built to determine more of the physical parameters. From the results and the hardening experiences, it can be stated, that after the laying of CC and the spraying of water, the material has to be loaded to reach the best shape and push the material down to the supporting protection layer. In FE modeling, it was shown that the material is a composite structure, i.e. one material's physical properties is not enough for modeling (it has to be improved). Moreover, it means that dynamic examinations can be initiated.
Keywords: GCCM; ConcreteCanvas; railway; substructure; FE modeling
Abstract: The work examines the results of the study aimed at minimizing the consumption of lubricants in the wheel/rail interface. A numerical simulation of a circular slip path was carried out based on the theory of experiment planning. The simulation was performed depending on the wheel radius, the difference between the radii of the wheels contacting the flange and rim with the railhead, the taper angle of the flange and the angle of attack. According to Box-Wilkson steepest ascent method, geometrical parameters of the wheel/rail interface were obtained, making it possible to reduce the circular slip path by 30%. These results can significantly decrease the number of relevant field studies and lubricant consumption in the wheel-rail system. Mathematical modeling enabled the analysis of the stress-strain state of the "wheel-rail" system, at lateral contact, with the addition of friction forces to the contact zone. The simulation results show the importance of using rail lateral lubrication as one of the means to extend the service life of this expensive track structure, in small radius curves.
Keywords: slip path; angle of attack; flange angle; regression equation; Box-Wilkson method; track infrastructure; rail lubrication; stationary rail lubricators; mobile rail lubricators; stress calculation; lateral contact; moment of forces
Abstract: This current paper deals with the investigation of the variation of the hardness of the rail steel material in the heat-affected zone (HAZ) of a rail joint made by thermit welding (TW). The tested rail is a normal R260 type rail steel category; its production date is 1977, the rolling mill was Diosgyor (Hungary), rail profile is MÁV 48.5. This rail has not been in railway track before the test. The authors performed hardness tests on the rail head’s surface even after the rail welding, as well. After the welding and hardness tests, the rail joint was cut with +/-200 mm by a rail cutter and transported to the laboratory. Water jet cutting was applied to shape six longitudinal direction slices with five vertical cutting lines from the rail piece’s head. The slices’ length was 400 mm, the width of these slices was approx. 10 mm; the TW rail joint was in the mid-point of the slices. Micro-Vickers (HV10) hardness tests were executed on these slices, in the -150…+150 mm interval lengthwise and in the 3, 6, and 10 mm depth points below the rail head’s top surface. As a result, the authors received a very detailed hardness functions of the HAZ of rail joint made by TW. These variation functions were compared to the official Elektrothermit’s SoW-5 hardness tests’ results. It can be concluded that the variation of the hardness of rail steel in the area of the HAZ correlated with the Elektrothermit’s results; however, there were some critical points where significant differences were able to be found. The highest deviation was concluded in 50 mm distance measured from the axis of welded rail joint. The authors gave possible valuable explanations for these phenomena.
Keywords: thermit rail welding; HAZ; heat-affected zone; welded rail joint; Brinell Hardness
Abstract: The prototype of the on-board Obstacle Detection System (ODS), for GoA2 freight trains, was developed in the frame of H2020 project SMART. The developed prototype uses vision-based sensors, for environmental perception and obstacle detection. As severe image distortions while capturing imaging data can occur due to vibrations of the moving vehicle, the ODS of autonomous rail vehicles must be isolated from vibrations transmitting from the vehicle to have reliable image acquisition and post process analysis. The passive vibration isolation system was specially designed for suppression of moving rail vehicle vibrations during development of the ODS prototype. The paper presents the designed passive vibration system, as well as, experimental verification of its performance in operational conditions. Furthermore, two viscoelastic constitutive models, Voigt-Kelvin and Voigt-Maxwell, were applied to predict the dynamic response of vibration isolated ODS by using the real experimental data as system excitation.
Keywords: dynamic response; railway obstacle detection; vibration isolation; transmissibility of vibrations
Abstract: Determining the deterioration of superstructure systems is technical and has national economic importance. In addition to geometric deterioration, it is also very difficult to monitor the changes in the dynamic characteristics of the vehicles. The data from geometric and dynamic measurements should be properly analyzed to determine the deterioration, lifetime/life-cycle costs of superstructure systems and the casual relationships should be researched between the characteristics. In this paper, the geometric and dynamic measurement results of the two examined sections are compared. This analysis is the first step in exploring and understanding the relationship between each feature. The authors recommended methodologies for using the synchronized (static and dynamic) measurements and their evaluation possibilities related to tramway tracks. The method is a well-known solution for public railways; however, the tramways greatly differ. In Hungary, there is a great opportunity to introduce the static-dynamic parallel method, which can be applied for the determination of the life-cycle costs (LCC) of the tramway tracks that are assembled with different (super)structures.
Keywords: tramway track; superstructure systems; geometrical analysis; dynamic analysis, deterioration
Abstract: The purpose of this work is to clarify the causes and mechanism of premature origin of defects in the elements of the bridge deck with the storey connection in steel span structures of railway bridges by studying the stress-strain state of their deck beams. Research aimed at extending the service life and increasing the carrying capacity of metal girder structures with a low load class and at the introduction of a new design solution for connecting the nodes of the deck beams, which is extremely important to ensure the necessary railway capacity and train safety. Service life and reliability of stringer beams of a deck definitively defines a service life and carrying capacity of all span structure. In order to deepen the analysis of the experimental data of the tested structures, calculations of the structure with the initial data, that fully correspond to the experimental span structure, were performed. For theoretical researches the underslung span structure with through trusses, designed by "Proektstalkonstruktsiya" with the nominal span of Ln = 44,0 m with a storey carriageway was chosen, as the one having the greatest number of defects in nodes of stringers support by the floor beams. According to the results of calculations and computer simulations, it is determined that the main cause of cracks is the structural imperfection of the aforementioned nodes, that is typical of similar structures.
Keywords: railway bridge; bridge deck; storey connection; stress-strain state; truss bridge
Abstract: This paper was written concerning a test section with geogrid-reinforced railway ballast based on field tests. I aim to introduce the variation of the alignment track geometry parameter taking into consideration the geogrid reinforcement. The main advantage of the ballast reinforcement with geosynthetic inclusions is the reduction of the longitudinal level faults and the deterioration speed. I observed the alignment (i.e., the horizontal geometry) changes. The duration of the field test is approximately 11.5 years. Five different geogrid types were incorporated below the ballast bed on the Kelenföld-Hegyeshalom state board (No. 1) railway line in Hungary in 2010. The test section is only straight for 700 m in length (with reference sections with the same geometry and structural set-up), i.e., the horizontal geometry of the track does not influence the results. A statistical analysis was executed to compare the behavior of the sections, based on both the geogrid-reinforced sections and reference sections. As a result of the investigation, it can be concluded that there were some geogrid types, which seemed to be adequate to decrease the deterioration speed of the alignment parameter of the ballasted railway track. A very high variance (standard deviation) was observed in the results, this is because they cannot be determined as a general horizontal railway track stabilizing solution.
Keywords: geogrid reinforcement; railway; geometrical stabilization; ballast; alignment
Abstract: Considering the impact of risk events to costs, time and quality of infrastructure projects, it is necessary to invest in risk management in order to prevent or mitigate negative consequences. Risk analysis should monitor the project through the whole project life cycle: from the planning through execution and controlling to finishing. In this paper, we have used Interval Type-2 Fuzzy Logic based Failure Mode and Effects Analysis (FMEA) to get a better insight into the risk events that occur in the railway infrastructure projects. The study’s main contribution is developing and implementing a comprehensive and robust framework for defining and handling with the most important risk events regarding the railway infrastructure projects. The Interval Type-2 Fuzzy Logic is used to tackle the uncertainty in risk assessment. In order to illustrate the validity and capability of the model, the presented approach has been applied to the railway infrastructure projects in the Republic of Serbia. Each risk event has been analyzed through severity, occurrence and detection. The events were ranked based on the Fuzzy Risk Priority Number (RPN). This research also proposes strategies for the most important events in terms of risk.
Keywords: Risk analysis; Railway infrastructure project; FMEA; Fuzzy logic; Interval Type-2 Fuzzy Sets
Abstract: Concrete railway sleepers have been used for years without an update in production and design, to be compatible with demands for increasing train axle loads and speed. In the current research, concrete railway admixture is modified with consuming (0.5% straight-1.5% hooked), (1.5% straight-0.5% hooked) and (1% straight-1% hooked) steel fibers combinations. Three main mechanical experiments as compressive, flexural and splitting tensile strengths and fresh mortar “flowability” were performed. Results showed that the hybrid of 1% straight and 1% hooked steel fibers shows the optimal performance among other hybrid combinations. This hybrid admixture efficiently improves the compressive, flexural and splitting tensile strengths of the concrete railway sleeper mix design.
Keywords: Concrete railway sleeper; Steel fibers; Optimal hybrid reinforced concrete
Abstract: The purpose of the research is to test models of sections with transient stiffness on approaches to railway bridges in the laboratory. The feasibility of the proposed methods of reinforcing the transient stiffness areas to ensure normal operation and avoid the formation of significant deformations had been tested. Centrifugal simulation of three types of reinforcement of transition section had been performed. The deformations of the models of the section with transient stiffness on approach to the railway bridge had been obtained. A comparative analysis of the results of centrifugal experiments had been performed. The effectiveness of each of the reinforcement options had been determined and the most rational method of reinforcement had been concluded.
Keywords: centrifugal modeling; reinforcement; railway bridge
Abstract: Progress in air and fuel management has greatly increased the efficiency of modern automotive train diesel engines, also achieving significant reductions of pollutant emissions. The increased flexibility of the air and fuel management systems also means a higher number of control parameters and complex interactions between different parameters. The task of tuning the engine control parameters to find the right combination to maximize the efficiency and reduce pollutant emissions is referred to as engine calibration. The task of engine calibration for modern automotive diesel engine has become extremely challenging, requiring large amount of time and money to be spent on engine test bench. The main aim of the study was to test and evaluate driving quality of train diesel engine. The subject of this test is a diesel engine train. The diesel engine train series was made with respect to running safety and dynamic behavior, under the test conditions fulfilled. It meets the prescribed requirements of the standard EN 14363: 2005.
Keywords: train; diesel engine; engine calibration
Abstract: In this work, considering the MÁV’s (i.e., the Hungarian Railways) five small and five high-traffic railway lines, the statistical distribution and change of the track gauge parameter were analyzed, under a ten year, on time-series analysis, related to straight track sections. The analysed data, were bottom track gauge measurements, of the FMK-004 and FMK-007 type railway track geometry, measuring and recording car & wagon. Taking into account the railway tracks, the track gauge parameter cannot be controlled and improved upon by large machine methods, but its permitted value depends on the allowed speed (and vice versa). The main independent variables were the elapsed time and the through-rolled axle tons (as a function of time, i.e., the MGT). To generate the statistical analyses, Vaszary-like shape numbers were computed, considering the distribution functions of the measured data series of the track gauge parameter every 25 cm. The authors examined the change of the shape numbers, the average and standard deviation values of the track gauge, and the shape of the distribution functions (skewness and kurtosis properties). In the end, a spectrum analysis of the measured data series was produced. In conclusion, the Authors provide relevant statements regarding the track gauge parameter.
Keywords: railway track; track gauge; statistical analysis; time-series analysis; distribution
Abstract: Defects on the rail surface will hasten the wear of the wheels. At the same time, when the wheel is periodically hitting and rolling surface defected, the defects will gradually develop into the interior, which significantly increases the possibility of a train derailment and serious safety accidents. A timely checking of the railway tracks to find defects as early as possible is a basic condition for ensuring the safety of railway operations. It also prolongs the service life of railways because most of the rolling contact fatigue (RCF) can be eliminated during rail grinding. Such defects appear as spalling and cracks in the first stage of the rail surface. Manual detection has been challenging to meet the large-scale railway running mileage. Therefore, a more efficient automatic detection method is indispensable. This article reviews the latest research and exploration on the defect inspection of rail surfaces in recent years. In the article, not only the application of traditional ultrasonic and acceleration detection methods but also contributing computer vision and deep learning to detect defects on the rail surface. The new detection technology can even classify and evaluate the damage, further improving the efficiency of the detection system. Besides, the emerging research on defect state prediction to reduce inspection costs is interesting.
Keywords: rail surface defects; machine learning; detect; CNN
Abstract: Traffic safety of fully automated train operations is one of the most complex challenges in the field of railway traffic automation. One of the biggest problems with the introduction of driverless trains to the public railway infrastructure are the risks associated with the obstacles on the line, which represent one of the most common and most significant safety risks in railway traffic. The Obstacle Detection System (ODS), should meet the safety requirements, but also should not lead to a deterioration of the railway traffic. In addition to the purely technical issues of ODS development, the issue of determining the necessary requirements in terms of safety, reliability and efficiency must be considered. The paper analyses the current European regulations in the field of railway safety, safety requirements for certification of ODS, as well as risk control measures by the types of obstacles on the line. A survey of train drivers in the Republic of Serbia was conducted to understand the significance of particular obstacles and the manner of reaction of train drivers in case of their occurrence. The results of the survey and the available statistical indicators were used to assess the impact of certain categories of obstacles on railway safety. The criteria for defining the safety requirements necessary for the certification of ODS in autonomous vehicles have been proposed.
Keywords: safety; autonomous railway vehicles; certification; obstacle detection
Abstract: Most European countries successfully solve the problem of national passenger transportation due to a significant increase in speed. Such measures are carried out both on existing railways through their modernization, and on specially built lines. Mass passenger transportation along the HSN has confirmed their extremely high reliability, safety, economic efficiency, ecological cleanness, and attractiveness for passengers. The creation of international networks based on the potentials of individual countries leads to the need for establishing the following operational and technical parameters of domestic high-speed railway lines, which would have operational compatibility with the Trans-European HSN. The interconnection between the volume of passenger traffic with the specified factors allows to predict promising passenger flow and evaluate the effectiveness in the organization of high-speed running in a particular direction. The economic integration of countries in the European Union allows increasing passenger flows on international travel. This circumstance leads to the problem solution in connecting national high-speed highways into a single European network.
Keywords: railway; train traffic; high-speed network; Net Present Value
Abstract: The main purpose of a rail fastening system is to provide the strength and reliability of joining rails to sleepers and, thus, prevents the longitudinal rail displacement and track disturbance. In a railway fastening, the joining function is performed by an elastic clamp. Over time, the clamping force of the elastic clamp is decreased due to various factors. The elastic clamp relaxation phenomenon is studied in present work. The observation of the clamp residual deformation was carried out on predetermined sleepers in different operating conditions. According to the research results of the elastic clamp relaxation of the rail fastenings, the following conclusions can be made: there is a relaxation process in the elastic clamps of the rail fastening, which has a curvilinear dependence on time; the intensity of the elastic clamps relaxation attenuates after one year of operation; in addition to the time factor, the relaxation of elastic clamps is influenced by the level of operating stresses; greater value of operating stresses corresponds to greater relaxation.
Keywords: elastic clamp; residual deformation; relaxation
Abstract: It is shown that in the mixed traffic of trains compared to the directions specialized for transportation of freight and passengers, the traffic capacity is sharply reduced, and costs on repairs and maintenance of track infrastructure increase by 1.5-2 times. The paper outlines ways to solve the problem in the distribution of directions with mainly freight and passenger traffic to increase the traffic capacity of transportation on the rail network. Among the activities, there is the transmission of transit freight flow on parallel runs. Furthermore, changing the operation conditions of railways in the case of implementing the high-speed trains traffic requires strengthening the existing railway lines in the event of insufficient reserves.
Keywords: railway; high-speed trains; trains traffic; traffic capacity