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Keywords = rail squats

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25 pages, 3433 KiB  
Article
Analysis of Local Track Discontinuities and Defects in Railway Switches Based on Track-Side Accelerations
by Susanne Reetz, Taoufik Najeh, Jan Lundberg and Jörn Groos
Sensors 2024, 24(2), 477; https://doi.org/10.3390/s24020477 - 12 Jan 2024
Viewed by 2185
Abstract
Switches are an essential, safety-critical part of the railway infrastructure. Compared to open tracks, their complex geometry leads to increased dynamic loading on the track superstructure from passing trains, resulting in high maintenance costs. To increase efficiency, condition monitoring methods specific to railway [...] Read more.
Switches are an essential, safety-critical part of the railway infrastructure. Compared to open tracks, their complex geometry leads to increased dynamic loading on the track superstructure from passing trains, resulting in high maintenance costs. To increase efficiency, condition monitoring methods specific to railway switches are required. A common approach to track superstructure monitoring is to measure the acceleration caused by vehicle track interaction. Local interruptions in the wheel–rail contact, caused for example by local defects or track discontinuities, appear in the data as transient impact events. In this paper, such transient events are investigated in an experimental setup of a railway switch with track-side acceleration sensors, using frequency and waveform analysis. The aim is to understand if and how the origins of these impact events can be distinguished in the data of this experiment, and what the implications for condition monitoring of local track discontinuities and defects with wayside acceleration sensors are in practice. For the same experimental configuration, individual impact events are shown to be reproducible in waveform and frequency content. Nevertheless, with this track-side sensor setup, the different types of track discontinuities and defects (squats, joints, crossing) could not be clearly distinguished using characteristic frequencies or waveforms. Other factors, such as the location of impact event origin relative to the sensor, are shown to have a much stronger influence. The experimental data suggest that filtering the data to narrow frequency bands around certain natural track frequencies could be beneficial for impact event detection in practice, but differentiating between individual impact event origins requires broadband signals. A multi-sensor setup with time-synchronized acceleration sensors distributed over the switch is recommended. Full article
(This article belongs to the Special Issue Real-Time Monitoring Technology for Built Infrastructure Systems)
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14 pages, 10950 KiB  
Article
Analysis of Axial Acceleration for the Detection of Rail Squats in High-Speed Railways
by Hojin Cho, Jaehak Park and Kyungsu Park
CivilEng 2023, 4(4), 1143-1156; https://doi.org/10.3390/civileng4040062 - 1 Nov 2023
Cited by 4 | Viewed by 2151
Abstract
A squat is a type of fatigue defect caused by short-wavelength rotational contact; if squats are detected early, the maintenance cost of the track can be effectively reduced. In this paper, a method for the early detection of squats is presented based on [...] Read more.
A squat is a type of fatigue defect caused by short-wavelength rotational contact; if squats are detected early, the maintenance cost of the track can be effectively reduced. In this paper, a method for the early detection of squats is presented based on ABA (axle box acceleration) and frequency signal processing techniques. To increase the measurement sensitivity for the squat, ABA was used to measure the longitudinal vibration. Compared to vertical ABA, longitudinal ABA does not include vibrations from rail fasteners and sleepers, so it is possible to effectively measure the vibration signal in relation to the impact of the rail. In this paper, vibration data were measured and analyzed by installing a 3-axis accelerometer on the wheel axle of the KTX; squat signals were more effectively extracted using the longitudinal vibration measurement presented above. The algorithm to detect the position of squats was developed based on wavelet spectrum analysis. This study was verified for the section of a domestic high-speed line, and as a result of conducting field verification for this section, squats were detected with a hit rate of about 88.2%. The main locations where the squats occurred were the rail welds and the joint section, and it was confirmed that unsupported sleepers occurred at locations where the squats occurred in some sections. Full article
(This article belongs to the Section Geotechnical, Geological and Environmental Engineering)
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14 pages, 3135 KiB  
Article
Wayside Railway Switch and Crossing Monitoring Using Isolation Forest Anomaly Scores
by Yang Zuo, Praneeth Chandran, Johan Odelius and Matti Rantatalo
Sustainability 2023, 15(20), 14836; https://doi.org/10.3390/su152014836 - 13 Oct 2023
Viewed by 1556
Abstract
Railway switch and crossing (S&C) systems have complicated moving structures compared with regular rail. They require multiple components that vary in complexity. The complexity of railway S&C, together with the fact that they are discontinuous points of the system, makes them vulnerable to [...] Read more.
Railway switch and crossing (S&C) systems have complicated moving structures compared with regular rail. They require multiple components that vary in complexity. The complexity of railway S&C, together with the fact that they are discontinuous points of the system, makes them vulnerable to defects such as squats. A squat on the switching rail could potentially cause rail breakage and lead to catastrophic results, such as derailment. In this study, a method based on anomaly scoring was investigated to estimate the status of an S&C system with respect to squat defects. The proposed method was tested in a real environment under controlled measurement sequences. The results show that the methods can differ between an S&C with squats and another one without them. Full article
(This article belongs to the Special Issue Sustainable Design and Risk Assessment for Railway Engineering)
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17 pages, 3570 KiB  
Article
Squat Detection and Estimation for Railway Switches and Crossings Utilising Unsupervised Machine Learning
by Yang Zuo, Jan Lundberg, Praneeth Chandran and Matti Rantatalo
Appl. Sci. 2023, 13(9), 5376; https://doi.org/10.3390/app13095376 - 25 Apr 2023
Cited by 6 | Viewed by 2651
Abstract
Switches and crossings (S&Cs) are also known as turnouts or railway points. They are important assets in railway infrastructures and a defect in such a critical asset might lead to a long delay for the railway network and decrease the quality of service. [...] Read more.
Switches and crossings (S&Cs) are also known as turnouts or railway points. They are important assets in railway infrastructures and a defect in such a critical asset might lead to a long delay for the railway network and decrease the quality of service. A squat is a common rail head defect for S&Cs and needs to be detected and monitored as early as possible to avoid costly emergent maintenance activities and enhance both the reliability and availability of the railway system. Squats on the switchblade could even potentially cause the blade to break and cause a derailment. This study presented a method to collect and process vibration data at the point machine with accelerometers on three axes to extract useful features. The two most important features, the number of peaks and the total power, were found. Three different unsupervised machine learning algorithms were applied to cluster the data. The results showed that the presented method could provide promising features. The k-means and the agglomerative hierarchical clustering methods are suitable for this data set. The density-based spatial clustering of applications with noise (DBSCAN) encounters some challenges. Full article
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15 pages, 22723 KiB  
Article
Squat Detection of Railway Switches and Crossings Using Point Machine Vibration Measurements
by Yang Zuo, Jan Lundberg, Taoufik Najeh, Matti Rantatalo and Johan Odelius
Sensors 2023, 23(7), 3666; https://doi.org/10.3390/s23073666 - 31 Mar 2023
Cited by 5 | Viewed by 2681
Abstract
Railway switches and crossings (S&C) are among the most important high-value components in a railway network and a failure of such an asset could result in severe network disturbance. Therefore, potential defects need to be detected at an early stage to prevent traffic-disturbing [...] Read more.
Railway switches and crossings (S&C) are among the most important high-value components in a railway network and a failure of such an asset could result in severe network disturbance. Therefore, potential defects need to be detected at an early stage to prevent traffic-disturbing downtime or even severe accidents. A squat is a common defect of S&Cs that has to be monitored and repaired to reduce such risks. In this study, a testbed including a full-scale S&C and a bogie wagon was developed. Vibrations were measured for different squat sizes by an accelerometer mounted at the point machine. A method of processing the vibration data and the speed data is proposed to investigate the possibility of detecting and quantifying the severity of a squat. One key technology used is wavelet denoising. The study shows that it is possible to monitor the development of the squat size on the rail up to around 13 m from the point machine. The relationships between the normalised peak-to-peak amplitude of the vibration signal and the squat depth were also estimated. Full article
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15 pages, 4135 KiB  
Article
Squat Detection of Railway Switches and Crossings Using Wavelets and Isolation Forest
by Yang Zuo, Florian Thiery, Praneeth Chandran, Johan Odelius and Matti Rantatalo
Sensors 2022, 22(17), 6357; https://doi.org/10.3390/s22176357 - 24 Aug 2022
Cited by 9 | Viewed by 2739
Abstract
Railway switches and crossings (S&Cs) are critical, high-value assets in railway networks. A single failure of such an asset could result in severe network disturbance and considerable economical losses. Squats are common rail surface defects of S&Cs and need to be detected and [...] Read more.
Railway switches and crossings (S&Cs) are critical, high-value assets in railway networks. A single failure of such an asset could result in severe network disturbance and considerable economical losses. Squats are common rail surface defects of S&Cs and need to be detected and estimated at an early stage to minimise maintenance costs and increase the reliability of S&Cs. For practicality, installation of wired or wireless sensors along the S&C may not be reliable due to the risk of damages of power and signal cables or sensors. To cope with these issues, this study presents a method for collecting and processing vibration data from an accelerometer installed at the point machine to extract features related to the squat defects of the S&C. An unsupervised anomaly-detection method using the isolation forest algorithm is applied to generate anomaly scores from the features. Important features are ranked and selected. This paper describes the procedure of parameter tuning and presents the achieved anomaly scores. The results show that the proposed method is effective and that the generated anomaly scores indicate the health status of an S&C regarding squat defects. Full article
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9 pages, 2655 KiB  
Article
Evaluating Short-Wave Effects in Railway Track Using the Rail Surface Signal
by Markus Loidolt and Stefan Marschnig
Appl. Sci. 2022, 12(5), 2529; https://doi.org/10.3390/app12052529 - 28 Feb 2022
Cited by 13 | Viewed by 2722
Abstract
Condition assessment and maintenance planning of railway infrastructure is a prerequisite for safe and reliable train operation. As the loads are constantly increasing, condition assessment of the track must also be further developed. Existing methods can describe the condition of the track well [...] Read more.
Condition assessment and maintenance planning of railway infrastructure is a prerequisite for safe and reliable train operation. As the loads are constantly increasing, condition assessment of the track must also be further developed. Existing methods can describe the condition of the track well in many cases, but they will reach their limits with faster deterioration processes and shorter time windows for inspection and maintenance, both associated with higher loads. This development can only be countered with an increased understanding of the system and the associated better planning of component specific measures. Among others, short-wave effects of the track need to be considered. The aim of this paper is to demonstrate the possibility of describing short-wave effects with an already existing data source. Insulated rail joints, welding joints, switch components, but also rail corrugation of different wavelengths and squat can be detected, evaluated and monitored by a measuring system based on optical distance meters. These assets and wear phenomena form essential parts of track asset management, but still are not described sufficiently by established methods. Although the so-called rail surface measurement system has been installed on the main Austrian measuring car for years, its full potential could not be exploited due to insufficient positioning accuracy. The method presented in this paper intends to change that. This allows for a holistic assessment of track condition when planning maintenance activities. Full article
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11 pages, 5155 KiB  
Article
Study of Rail Squat Characteristics through Analysis of Train Axle Box Acceleration Frequency
by Hojin Cho and Jaehak Park
Appl. Sci. 2021, 11(15), 7022; https://doi.org/10.3390/app11157022 - 29 Jul 2021
Cited by 18 | Viewed by 3571
Abstract
In this study, a method for detecting the railway surface defects called “squats” using the ABA (Axle Box Acceleration) measurement of trains was proposed. ABA prototype design, implementation, and field tests were conducted to derive and verify the results. The field test was [...] Read more.
In this study, a method for detecting the railway surface defects called “squats” using the ABA (Axle Box Acceleration) measurement of trains was proposed. ABA prototype design, implementation, and field tests were conducted to derive and verify the results. The field test was performed using a proven precision measurement system, and the measured data were signal-processed using a Matlab program. The algorithm used to determine the position of the squats was developed based on wavelet spectrum analysis. This study was verified for a section of a domestic general line and, following field verification for the section, squats was detected with a hit rate of about 88.2%. The main locations where the squats occurred were the rail welds and the joint section, and it was confirmed that in some sections, unsupported sleepers occurred at the locations where the squats occurred. Full article
(This article belongs to the Topic Advances on Structural Engineering)
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17 pages, 6496 KiB  
Article
Inductive Thermography as Non-Destructive Testing for Railway Rails
by Christoph Tuschl, Beate Oswald-Tranta and Sven Eck
Appl. Sci. 2021, 11(3), 1003; https://doi.org/10.3390/app11031003 - 22 Jan 2021
Cited by 27 | Viewed by 4998
Abstract
Inductive thermography is a non-destructive testing method, whereby the specimen is slightly heated with a short heating pulse (0.1–1 s) and the temperature change on the surface is recorded with an infrared (IR) camera. Eddy current is induced by means of high frequency [...] Read more.
Inductive thermography is a non-destructive testing method, whereby the specimen is slightly heated with a short heating pulse (0.1–1 s) and the temperature change on the surface is recorded with an infrared (IR) camera. Eddy current is induced by means of high frequency (HF) magnetic field in the surface ‘skin’ of the specimen. Since surface cracks disturb the eddy current distribution and the heat diffusion, they become visible in the IR images. Head checks and squats are specific types of damage in railway rails related to rolling contact fatigue (RCF). Inductive thermography can be excellently used to detect head checks and squats on rails, and the method is also applicable for characterizing individual cracks as well as crack networks. Several rail pieces with head checks, with artificial electrical discharge-machining (EDM)-cuts and with a squat defect were inspected using inductive thermography. Aiming towards rail inspection of the track, 1 m long rail pieces were inspected in two different ways: first via a ‘stop-and-go’ technique, through which their subsequent images are merged together into a panorama image, and secondly via scanning during a continuous movement of the rail. The advantages and disadvantages of both methods are compared and analyzed. Special image processing tools were developed to automatically fully characterize the rail defects (average crack angle, distance between cracks and average crack length) in the recorded IR images. Additionally, finite element simulations were used to investigate the effect of the measurement setup and of the crack parameters, in order to optimize the experiments. Full article
(This article belongs to the Special Issue Infrared Imaging and NDT)
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18 pages, 8671 KiB  
Article
Peridynamic Analysis of Rail Squats
by Andris Freimanis and Sakdirat Kaewunruen
Appl. Sci. 2018, 8(11), 2299; https://doi.org/10.3390/app8112299 - 19 Nov 2018
Cited by 29 | Viewed by 5367
Abstract
Rail surface defects are a serious concern for railway infrastructure managers all around the world. They lead to poor ride quality due to excess vibration and noise; in rare cases, they can result in a broken rail and a train derailment. Defects are [...] Read more.
Rail surface defects are a serious concern for railway infrastructure managers all around the world. They lead to poor ride quality due to excess vibration and noise; in rare cases, they can result in a broken rail and a train derailment. Defects are typically classified as ‘rail studs’ when they initiate from the white etching layer, and ‘rail squats’ when they initiate from rolling contact fatigue. This paper presents a novel investigation into rail squat initiation and growth simulations using peridynamic theory. To the best of the authors’ knowledge, no other comprehensive study of rail squats has been carried out using this approach. Peridynamics are well-suited for fracture problems, because, contrary to continuum mechanics, they do not use partial-differential equations. Instead, peridynamics use integral equations that are defined even when discontinuities (cracks, etc.) are present in the displacement field. In this study, a novel application of peridynamics to rail squats is verified against a finite element solution, and the obtained simulation results are compared with in situ rail squat measurements. Some new insights can be drawn from the results. The outcome exhibits that the simulated cracks initiate and grow unsymmetrically, as expected and reported in the field. Based on this new insight, it is apparent that peridynamic modelling is well-applicable to fatigue crack modeling in rails. Surprisingly, limitations to the peridynamic analysis code have also been discovered. Future work requires finding an adequate solution to the matter-interpenetration problem. Full article
(This article belongs to the Special Issue Computational Methods for Fracture)
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3 pages, 299 KiB  
Extended Abstract
Peridynamics Modelling of Rail Surface Defects in Urban Railway and Metro Systems
by Andris Freimanis, Sakdirat Kaewunruen and Makoto Ishida
Proceedings 2018, 2(16), 1147; https://doi.org/10.3390/proceedings2161147 - 14 Sep 2018
Cited by 1 | Viewed by 1611
Abstract
Rail squats and studs, which are one of critical rail surface defects, are typically classified as the propagation of any cracks that have grown longitudinally through the subsurface. [...] Full article
(This article belongs to the Proceedings of i-RISE 2018)
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