Figure 2 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
![Track buckling due to high temperatures (source: [7]).](publication/351648280/figure/fig2/AS:1024647944499202@1621306515212/Track-buckling-due-to-high-temperatures-source-7.png)
Source publication
![Figure 2. Track buckling due to high temperatures (source: [7]).](publication/351648280/figure/fig2/AS:1024647944499202@1621306515212/Track-buckling-due-to-high-temperatures-source-7_Q320.jpg)
The correct operation of the continuous welded track requires diagnosing its condition and preparation of track metrics requiring measurements of displacements of rail under operation. This is required as there are additional thermal stresses in the rails with values depending on the temperature changes of the rails. Therefore, the climatic conditi...
Similar publications
![Fig. 3 Magnetization in a [110] direction of Si-Fe. A: domain...](profile/Helen-Wu-22/publication/353026146/figure/fig3/AS:1042697385172997@1625609837751/Magnetization-in-a-110-direction-of-Si-Fe-A-domain-structure-B-D-orientation_Q320.jpg)
Citations
... Some methods employ magnetoelastic effect [14][15][16][17], acoustoelastic effect [18][19][20][21][22], and X-rays [23] to determine the relationship between thermal stress and certain physical properties of the track. However, as these physical properties are also affected by residual stress, steel crystals, and rail temperature, these methods can only measure the surface stress, and it is extremely difficult to obtain the absolute thermal force [24]. Some researchers have attempted to use the higher-harmonics generated by the elastic wave propagation in rails to determine the neutral temperature [25][26][27]; however, this method requires measuring the wave patterns when the thermal force becomes approximately zero. ...
Measurement of thermal forces is an important process that aids in reducing the maintenance cost of continuous welded rails (CWRs). But it is still a very challenging problem. Axial force can be measured through vibration modal changes, and vibration measurement methods have several merits compared to conventional measurement methods using piles, strain sensors, magnetoelastic and acoustoelastic effect sensors, and X-rays. Vibration measurement methods have the ability to measure the absolute thermal force in a local interval and are robust against abrasion, surface residual stress, and material grains. However, they are affected by both axial force and track parameters, thereby restricting their engineering applications. To address these limitations, this study proposes a novel method called ‘modal utilization method of periodic structure’ (MUMPS). Its novelty lies in proving that variations in frequency constitute a random sequence satisfying the constraints of Chebyshev’s law of large numbers. It can determine the influence of track parameters on the vibration modes by averaging across different eigenfrequencies without investigating what they correspond to respectively. First, MUMPS is introduced through a hypothesis that the mean value of the natural frequency variations caused by the track parameter variations approaches a stable value. Second, MUMPS is validated using finite element simulation results, which show that the probability density function of the measurement error of the neutral temperature obey N(0.5,2.6). Finally, the accuracy of MUMPS is investigated through experiments, the results are compared with the strain-gauge method results, and they show good agreement. The experimental results show that as the number of the eigenfrequencies reaches 12, the mean value becomes stable, and the measurement error of neutral temperature is less than 4 ∘C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ {\textrm{C}}$$\end{document}. Engineering applicability of MUMPS is demonstrated by conducting real-time measurements on railway tracks. The results show that the proposed method is simple, as sophisticated instruments are not employed to determine the axial forces on railway tracks.
... Differential settlements of the soil induce additional bending moments on the rail, causing its deformation. The introduction of continuous welded track also came with the problem of additional stresses in the rails [8][9][10]. These issues are mainly related to complex interactions between the three system components: subgrade-rail-train. ...
The study of railway dynamics is still a productive area of research given the rapid technological evolution of this transport system regarding load and speed. Morocco is no exception to this rule, especially after the commissioning of the first high-speed line in Africa. This study describes herein an experiment to measure vertical and transverse accelerations in a locomotive on a railroad line connecting the two cities of Mchraa Ben Abbou and Marrakech. The observed accelerations constitute the vehicle's dynamic responses while running at a constant speed on a track with irregularities (also known as track geometry), which is considered the main driving force of train dynamics and the track system. They are used to evaluate passenger comfort and safety. It can also be observed that body accelerations increase with the introduction of track irregularities as compared to a smoother track. In this study, an analysis of these experimental measurements is performed based on boxplot simulations comparing the distributions of the transverse and vertical components of vehicle acceleration. It was found that the medians and first and third quartiles of both distributions are very close. Doi: 10.28991/CEJ-2022-08-10-014 Full Text: PDF
... An important role in preventing damage propagation in CWR is the regular monitoring of the geometry and temperature condition of the rails [11], [12]. Kukulski et al. in [13] presented an effective analytical method for diagnosing the condition of CWR based on experimental measurements. Supporting the decision process in the area of track repair or maintenance. ...
... Supporting the decision process in the area of track repair or maintenance. In addition, in [13] they recognise that in the case of a CWR, the costs of its maintenance are about 25% lower than those of a classic track. There is also significantly less wear and tear on vehicles and traction energy consumption, with better ride smoothness and less noise. ...
... The interest in the issue of CWR is connected, among others, with the change in operating conditions of modern railway by increasing the speed of passenger trains and the permissible axle loads on the rails. The CWR, in comparison with the classic track, provides better ride smoothness together with a reduction of the acoustic wave emission associated with the passage of the train [13]. ...
Continuous Welded Rails (CWR) are a key infrastructure element in the safety and efficiency of rail transportation. Their correct exploitation (operational) requires surveying and diagnostic monitoring based not only on the results of rail displacement measurements, but also on the geometric parameters of the track in the horizontal (H) and vertical (V) planes. Many researchers have proposed different approaches for surveying and diagnostic monitoring of CWR. However, they do not refer to the determination of railway track defectiveness (parametric defects, track defectiveness) respectively on straight and curvilinear segments. Research topics involving CWR constitute a continuous openness to research with particular application of synergy effects in the optimization of monitoring of CWR geometry shaped by exploitation processes. In this study, based on real measurement data of six geometric parameters (H: track gauge, gradient of track gauge, horizontal irregularities and V: cant, twist, vertical irregularities), the most sensitive parameters in sustainable development CWR are defined. The research answered that the most sensitive parameters in the sustainability development of CWR belong in the range of the plane H: gradient of track gauge and horizontal irregularities, and in the plane V: vertical irregularities. These escalate especially on curvilinear sections, requiring more significant maintenance capacity. Due to the growing importance of rail transportation as a sustainable, environmentally friendly, and mass transit mode, the research results provide a basis for life cycle management of CWR.
... In the past, railway transition curves were not used. Instead of it, a simple connection of the straight track and circular arc was applied (Gołębiowski and Kukulski, 2020), (Kukulski et al., 2019), (Kukulski et al., 2021). Nowadays, such simplicity is not allowed due to the increasing vehicle operating velocities. ...
In the past, railway transition curves were not used. Instead of it, a simple connection of the straight track and circular arc was applied. Nowadays, such simplicity is not allowed due to the increasing vehicle operating velocities. It is mainly visible in the high-speed train lines, where long curves are used. The article aims to develop a new shape of railway transition curves for which passenger travel comfort will be as high as possible. Considerations in this paper concern the polynomials of 9th- and 11th-degrees, which were adopted to the mathematical model of the mentioned shape of curves. The study's authors applied a 2-axle rail vehicle model combined with mathematically understood optimisation methods. The advanced vehicle model can better assign the dynamical properties of railway transition curves to freight and passenger vehicles. The mentioned model was adopted to simulate rail vehicle movement in both cases of the shape of transition curves and the shape of circular arc (for comparison of the results). Passenger comfort, described by European Standard EN 12299, was used as the assessment criterion. The work showed that the method using the 2-axle railway vehicle model combined with mathematically understood optimisation works correctly, and the optimisation of the transition curve shape is possible. The current study showed that the 3rd-degree parabola (the shape of the curve traditionally used in railway engineering) is not always the optimum shape. In many cases (especially for the long curves), the optimum shape of curves is between the standard transition curves and the linear curvature of the 3rd-degree parabola. The new shapes of the railway transition curves obtained when the passenger comfort is taken into account result in new railway transition curves shapes. In the authors' opinion, the results presented in the current work are a novelty in optimisation and the properties assessment of railway transition curves.
... It is found that the limit lateral resistance depends neither on the chosen experimental technique, nor on the compaction level of the ballast bed, whereas the peak lateral resistance appears to be dramatically altered if it is evaluated by mean of the Single Tie Push Test. The paper [40] presents an effective analytical method for diagnosing the condition of continuous welded track based on experimental measurements. The method allows for an appropriate repair or maintenance recommendation. ...
Continuous welded rail (CWR) track has great advantages of low-cost maintenance, environmental influence , and ride comfort. However, the CWR track is subjected to the longitudinal stresses in rails due to temperature influence as well the inhomogeneous stress accumulation due to train loadings. The stresses cause the accelerated track lateral irregularity accumulation that without timely maintenance can cause track buckling. The present paper present a method of the CWR track lateral stability estimation during its lifecycle using the track geometry monitoring information from the track measurement cars. The methods proposes a systematic approach of track stability evaluation based on multiple criteria of track stability evaluation. It takes into account the lateral resistance of the track, actual temperatures, and the lateral geometry condition of the track. The presented case study of a half-year track geometry monitoring and the track stability evaluation in a track curve shows the practical possibility of the recent detection of the track sections with low lateral stability and buckling prevention.
... The selection of rolling stock for the implementation of tasks is one of the elements of planning the railway transport system [36][37][38][39][40]. As already mentioned in the previous point of the article, it is required that a timetable be ordered from the infrastructure manager in order to be able to physically move cargo via rail transport within the railway network [41]. A few necessary parameters need to be specified while placing an order. ...
The issues addressed by the article concern the assessment of energy efficiency in rail transport, resulting from the proper organization of rail traffic. The problems related to energy consumption and, thus, the negative impact of rail transport on the natural environment are highly significant in terms of the green deal concept, climate change and sustainable development. In this article, energy efficiency is investigated in the context of minimizing the energy consumption necessary to satisfy a specific transport requirement. The essence of this article is to present an approach to energy-efficient planning of rail freight traffic. This article aims to develop a method covers the allocation of railway vehicles dedicated to freight traffic (locomotives and railcars) to perform a defined transport task, taking into account the energy efficiency assessment of the solution, routing the train launched with regard to the accomplishment of the defined transport task on the railway network, and determining the conditions of transport for a defined transport task, taking into account the allocated rolling stock (locomotives and railcars) and the route. In this article, based on the presented state of knowledge, a decision-making model has been proposed, including the model’s parameters, the values being searched for, indicators for assessing the quality of the solution, as well as the limitations and boundary conditions of the problem. The function of minimizing the energy consumption necessary to transport a shipment within the railway network (determining the energy efficiency of the proposed solution) has been proposed as the criterion. In addition, a description of the proprietary method of selecting rolling stock for accomplishing tasks, based on the assessment of the energy efficiency of the solution and a case study illustrating the operation of the method on the example of the area of Poland, has been presented.
The paper evaluates the effectiveness of the electromechanical shock absorber for a sub�way car based on dynamic quality indicators. To determine them, a method of synthesis
of random forced vertical oscillations of a dynamic model of a subway car was developed,
which is based on the method of sliding summation taking into account the spectral density
obtained when processing the test results of a subway car. Also in the work the technique on
definition of indicators of dynamic quality of the metrocar with electromechanical shock�absorbers which is based on modeling of processes of movement of the subway car on a site
of a way with casual roughness and definition, by results of modeling, indicators of dynamic
quality is created. The study of forced random oscillations of the dynamic model of a
subway car showed that the spring suspension based on electromechanical shock absorbers
has a significant advantage over the central spring suspension for all quality indicators in
the entire range of speeds. The dependence of the average power generated by the shock
absorber is established.
