Rail Gauge Research Articles

Laser Scan Compression for Rail Inspection

The automation of rail track inspection addresses key issues in railway transportation, notably reducing maintenance costs and improving safety. However, it presents numerous technical challenges, including sensor selection, calibration, data acquisition, defect detection, and storage. This paper introduces a compression method tailored for laser triangulation scanners, which are crucial for scanning the entire rail track, including the rails, rail fasteners, sleepers, and ballast, and capturing rail profiles for geometry measurement. The compression technique capitalizes on the regularity of rail track data and the sensors’ limited measurement range and resolution. By transforming scans, they can be stored using widely available image compression formats, such as PNG. This method achieved a compression ratio of 7.5 for rail scans used in the rail geometry computation and maintained rail gauge reproducibility. For the scans employed in defect detection, a compression ratio of 5.6 was attained without visibly compromising the scan quality. Lossless compression resulted in compression ratios of 5.1 for the rail geometry computation scans and 3.8 for the rail track inspection scans.

A Non‐Iterative Wheel‐Rail Contact Geometry Determination Algorithm and Its Application

AbstractTo ensure a more accurate simulation of the wheel‐rail contact state in vehicle‐track interaction, a non‐iterative contact geometry determination algorithm is proposed. This algorithm decouples lateral movement and roll, independently calculates the minimum wheel‐rail gap on both sides, and overcomes the limitation of simultaneous wheel‐rail contact on both sides. It can be applied to single‐side and two‐side wheel‐rail separation problems. Additionally, by converting track irregularity and rail deformation into the reverse displacement of the wheel, it avoids real‐time calculation of the wheel‐rail spatial position, thereby improving calculation efficiency. The effectiveness of the algorithm is verified through Universal Mechanism software and field measurements. Subsequently, the influence of the measured wheel‐rail profile, rail cant, and rail gauge on the wheel‐rail contact characteristics is analyzed. Finally, vehicle shaking caused by track irregularity and wheel‐rail contact is examined from the perspective of wheel‐rail matching. The study demonstrates that the non‐iterative algorithm is suitable for online simulation by pre‐processing the contact geometry parameters. When the track gauge and rail cant increase, the distribution of wheel‐rail contact points becomes more concentrated. Furthermore, when the excitation frequency of wheel‐rail matching is close to the track irregularity excitation frequency, it causes vibration amplification, resulting in lateral vehicle shaking.

Prediction and analysis of wheel flange wear on small curved track considering wheel-rail conformal and lubricated contact

Wheel flange wear on curved tracks is a significant issue that poses a threat to the safety of rail vehicles and leads to increased maintenance costs for railway operators. This study aims to develop a numerical model to predict wheel flange wear on small radius curves. The model integrates an efficient wheel-rail conformal contact model with laboratory-tested wear coefficients. By using virtual penetration and influence coefficients for conformal geometries, the model accurately simulates the conformal contact between the wheel flange and the rail gauge corner. The validity of the wheel flange wear prediction model is confirmed through field tracking testing. Using the proposed model, the effects of track layout parameters and solid lubricants on wheel flange wear are investigated. This study provides theoretical guidance for the operation and maintenance of the wheel-rail system to reduce wear.

Effect of line parameters on wheel wear of heavy–haul freight vehicle

Purpose The serious wear problem of heavy-haul freight vehicle wheels affects the safety and economy of vehicle operation. This paper aims to study wheel wear evolution law and the influence of line parameters on wheel wear of heavy-haul freight, and provide the basis for operation and line maintenance. Design/methodology/approach The wheel wear test data of heavy-haul freight vehicles were analyzed. Then a heavy-haul freight vehicle dynamic model was established. The line parameters influencing wheel wear in heavy-haul freight vehicles were also analyzed by the Jendel wear model, and the effects of rail cant, rail gauge, rail profile and line ramp on wheel wear were analyzed. Findings A rail cant of 1:40 results in less wheel wear; an increase in the rail gauge can reduce wheel wear; and when matched with the CHN60 rail, the wear depth is relatively small. A decrease of 9.21% in wheel wear depth when matched with the CHN60 rail profile. The ramp of the heavy-haul line is necessary to consider for calculating wheel wear. When the ramp is considered, the wear depth increases by 8.47%. The larger the ramp, the greater the braking force and therefore, the greater of the wheel wear. Originality/value This paper first summarizes the wear characteristics of wheels in heavy-haul freight vehicles and then systematically analyzes the effect of line parameters on wheel wear. In particular, this study researched the effects of rail cant, rail gauge, rail profile and line ramp on wheel wear. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0038/

Rail wear rate on the Belgian railway network – a big-data analysis

ABSTRACT This paper presents a big data-based analysis of the rail wear of the whole Belgian railway network measured in 2012 and 2019. Wear rates are reported, discussed, and quantitatively formulated as functions of critical factors in terms of curve radius, annual tonnage (rail age), high rail in curves, an average from both rails in straight tracks at rail top (vertical wear) and gauge corner (45° wear) and for steel grade R200 and R260. The influence of preventive grinding is also analysed. The wear rates are derived in an aggregated manner for the whole network. The wear rates do not show significant change with changes in rolling stock over the years, implying that the wear rates could also hold for other networks. It is found that R200 shows, on average, a 34% higher wear rate than R260. Also, the wear rate per tonnage is lower for high-loaded tracks. Thus, time is a relevant factor in explaining the wear evolution of low-loaded tracks; for instance, the effect of corrosion may have an important role. The paper provides statistically significant information that can be used for wear modelling, understanding and treating rolling contact fatigue based on the wear rate and developing tailored rail maintenance strategies.

Analysis of the causes of severe side wear of the high rail on metro curves by numerical simulation and field investigation

Two of the Shanghai metro lines suffered from severe side wear on the high rail, not only in sharp curves but also in large curves, and the service life of some rails on sharp curves was reduced by approximately 50% compared with the last rail replacement. Features and evolution rules for the rail side wear and the wheel flange wear were determined by field measurements and long-term monitoring. A rail wear prediction model, verified in our previous work, is used to reveal the influence of factors on rail wear. The results indicate that the poor lubrication condition at the rail gauge face is the main cause of severe side wear of the high rail, and the use of wheel profiles with low conicity and the loss of profile curvature of low rail profiles caused by the untimely maintenance also increase the side wear of the high rail. The service life of the high rail could be greatly extended by some countermeasures, such as repairing the worn shape of the low rail and repairing/improving the wayside lubrication system.

Thermal–Mechanical Coupling Analysis of Wheel–Rail Sliding Friction under Two-Point Contact Conditions

The generation of wheel–rail-sliding frictional heat is often accompanied by transverse displacement of a wheel. To study the thermal problem of wheel–rail sliding friction at two-point contact, this paper uses an LM tread wheel and a 60 kg·m−1 rail as examples. A thermal–mechanical-coupled finite-element model of equal proportion wheel–rail sliding is established. A direct-coupling method is used to analyze the thermal–mechanical coupling of the wheel–rail interface under sliding contact. This model considers the temperature-dependent material properties and boundary conditions, such as thermal convection and thermal dissipation, in the process of nonstationary frictional-heat conduction. Firstly, the effects of different sliding speeds, axle loads, and contact modes on the temperature and stress fields of the contact area are analyzed. Then, the lubrication and cooling effects of friction modifiers on the rail top and rail gauge angle are compared. The results show that, at a sliding speed of 2 m/s and an axle load of 30 t under a sliding condition of 200 mm, on the top and side of the rail, the temperatures at the contact patch centers are 813 °C and 547.7 °C, respectively. Under different operating conditions, the rail-side temperature is 55–75% of that of the temperature at the rail top, and the rail-side contact and friction stress values are 76–96% of those at the rail top. This indicates that frictional thermal damage on the rail side cannot be ignored. With a lower sliding speed, the thermal response of the two contact patches is closer. The impact of axle load on the frictional temperature and stress on the rail side is more critical than the sliding speed. The optimal lubrication choice is overall lubrication, which can decrease the rail top temperature by 47.2% and frictional stress by 56.2%, as well as decreasing the rail side temperature by 70.3% and frictional stress by 77.4%.

Evaluating the efficiency of rail gauge maintenance in Siberia

The state of gauge geometry is the basis for safe and uninterrupted train operations under the mixed traffic conditions, as well as in the sections where trains with increased weight and length, including wagons with an increased axle load, are handled. When passing such trains, the state of gauge geometry deteriorates. This leads to increased labour costs for track maintenance, which is also caused by climatic features. Under such conditions, it is important to carry out effective gauge maintenance works. To analyse an impact of maintenance on gauge geometry, it is offered to determine the effect of uneven settlement of the under sleeper base in spring on the dynamics of each type of deviation. To evaluate the efficiency of preventive track alignment in the plan and profile, an analysis of graphical charts for the state of gauge geometry depending on track maintenance by gangs of track fitters and preventive track alignment by machine systems was carried out. It is also revealed that the efficiency of preventive alignment is significantly reduced under harsh climatic conditions, especially for the tonnage handled exceeding 600 million tonnes gross, and should therefore be carried out more frequently.

Remaining Fatigue Life Predictions of Railway Prestressed Concrete Sleepers Considering Time-Dependent Surface Abrasion

One of the safety-critical components of ballasted track systems is railway sleepers whose main functions are to (i) transfer vertical load, (ii) maintain rail gauge, and (iii) restrain longitudinal rail movement. Railway sleepers can be manufactured using timber, concrete, steel, composite, and any other engineered materials. Prestressed concrete sleepers are the most commonly used type worldwide because of their superior value-for-money performance. In practice, railway sleepers experience thousands of cycles of aggressive wheel–rail dynamic loads and wear deterioration can be observed over their service life. Not only does the deterioration affect track quality and geometries, but it also undermines the structural integrity of the track structures. The wear and abrasion directly decrease the capacity of railway sleepers, resulting in the reduction in service life. In this paper, the emphasis is placed on the assessment of the fatigue life of prestressed concrete railway sleepers with imperfect geometry. This study is the world’s first to establish a new fatigue simulation of railway concrete sleepers considering accumulative non-constant amplitudes, which has been validated using full-scale experimental results and empirical analyses. Parametric studies have been conducted to obtain new insights into the fatigue performance of the worn sleepers. The new findings will improve railway sleeper maintenance and inspection criteria, and will provide a new guideline on track-condition monitoring networks.

Understanding and treatment of severe flange wear of metro train wheels

Urban rail transit usually contains many small radius curved tracks, and wheel flange wear is prominent, which greatly reduces the service life and increases the maintenance and replacement costs of wheelsets. Two metro lines in Shanghai of China had suffered from severe flange wear since 2017, and the flange wear rate increased gradually over the next three years. This paper presents the understanding and treatment of severe flange wear through field measurement and numerical simulation. The investigation results indicated that the key factors causing severe flange wear were poor rail gauge face lubrication, the use of a low conicity wheel profile for trains running on the two metro lines containing many small radius curved tracks, and the lack of timely maintenance of low rail profiles. Three countermeasures were proposed to mitigate wheel flange wear, which were evaluated through wheel–rail matching analysis and wheel wear prediction. Then, two countermeasures, i.e. improving rail gauge face lubrication and employing the LM-30 wheel profile, were verified through field tests.

A novel design concept of cost-effective permanent rail-track monitoring system

This paper presents a novel design concept of low-cost permanent monitoring system for rail-track problems. The introduced design is theoretically overcome the currant in-use designs in terms of providing permanent accurate observations for detecting rail-track irregularities for all railway network during service time using low-cost integrated sensors. The paper investigates the rail-track common irregularities by identifying the issues, presenting challenges, and highlighting the limitations of currently in-use rail-track monitoring techniques. Then, the potential of using cost-effective sensors and intelligent techniques for detecting the rail-track geometric parameters and rail irregularities is theoretically studied. This includes using low-cost GPS, MEMS-INS & high frequency single-point and multi-spot laser distance sensors for detecting rail surface cracks, fractures, cross-level, wrap, gauge and vertical & horizontal rail alignments. Different levels of GPS/MEMS-INS integration are covered, illustrating the advantages of each solution and the optimal utilization in the system. Vision-based monitoring using low-cost HD non-metric digital cameras is also investigated, showing the optimal specifications required for fulfill the system requirements. Data logging and GPS-time-based synchronization method is presented as a part of the design concept of the suggested system. The processing techniques and unit outputs are illustrated in details, showing how each unit works for detecting the rail-track irregularities, providing the geodetic positioning and the vision-based assessing. The main part of the system, which is Automatic Adjusted Wheeled Carrier Frame (AAWCF) is discussed in more details, showing simple and clear different views for all details and integrated sensors. It is recommended to carry out this idea, by building up and evaluating the performance of AAWCF in real railway environments, evaluating the design concept of each unit individually to know the weaknesses of each technique, and then evaluating the whole system in all expected railway cases to find out the advantages and limitations of this design concept.

Исследование точности определения пространственного положения железнодорожного пути путеизмерительной тележкой Gedo

The implementation of the concept of integrated development of the scientific and technical project "Digital Railway" provides for the development of digital technologies in all areas of activity of JSC "Russian Railways", including the track economy. In order to monitor the current state of the tracks, digital models of the tracks are created and maintained at the level of modern requirements, used to collect, store and evaluate spatial data on the current state of the tracks and develop recommendations for the prevention and elimination of identified malfunctions. The most effective and universal means of controlling and straightening the track is the coordinate method based on a system of continuous coordinate-digital description of the track in a single coordinate system. Track measuring wagons widely used in the railway network do not allow obtaining the geometric parameters of the track in a single coordinate system. Because of this, in our country and in foreign countries, various track-measuring systems have been developed and are used, allowing to obtain the CMR in coordinates. Therefore, the purpose of theoretical and experimental research is to identify the accuracy of determining the geometric parameters of the railway track using the Gedo track measuring trolley. The method of determining the track geometry, technical characteristics and distinctive features of the Gedo track measuring trolley are considered. A program of experimental studies is described and comparative accuracy estimates of the railway track geometry determination by the geodetic method, using a Gedo track measuring trolley and a rail gauge template are given. It is shown that in connection with the transition of the railway industry to digital technologies for modeling infrastructure facilities, it is most expedient to use the Gedo track measuring trolley for monitoring the geometry of the railway track, which provide the required accuracy of determining the geometry of the track, productivity and obtaining the necessary information in a single coordinate system.

Study on a Heuristic Wheelset Structure without Rail Corrugation on Sharply Curved Tracks

Rail corrugation on low rails of sharp railway curves is still a difficult problem to solve worldwide. Nearly all low rails of the sharp railway curves incur rail corrugation. In the present study, an active method to remedy rail corrugation was studied. From the viewpoint of the frictional self-excited oscillation of a wheelset-track system causing rail corrugation, the effect of wheelset structures on rail corrugation was studied. Three frictional self-excited oscillation models of wheelset-track systems with different wheelset structures were established, which include a heuristic wheelset structure and two being used in the railway industry. The incidence trends of the self-excited oscillations of these three wheelset-track systems were studied. It was found that the wheelset structure has an important effect on rail corrugation, and that the heuristic wheelset structure can restrain or get rid of rail corrugation. With the parameter sensitivity analysis, it was found that when the friction coefficient between the wheel and rail, rail gauge, rail cant, and sleeper span changes to some extent, the heuristic wheelset structure is robust enough to prevent rail corrugation. The proposed heuristic wheelset structure can be used as a potential solution to rail corrugation on sharply curved tracks.

A novel three-dimensional wheel–rail contact geometry method in the switch panel considering variable cross-sections and yaw angle

Solving the wheel-turnout contact geometry is complex because the rail section is varying along its longitudinal position. Besides, a large yaw angle will occur, especially when the vehicle passes the switch panel in a diverging route. However, previous researches seldom considered the aforementioned factors simultaneously in performing wheel–rail local contact analysis. This paper therefore proposes a novel three-dimensional (3D) contact geometry method considering the combined effects of varying rail profiles and the yaw angle. This study uses S1002CN wheels and the switch panel of a 1:12 turnout as research objects to study the contact geometry, normal and tangential contact solution. The results indicate that the combined influences of rail profiles varying within the contact patch and the yaw angle on the contact solution are significant. The variable rail profiles obviously affect the position of the contact point. With a yaw angle, the normal gap, contact patch shape and stress distribution calculated by the novel 3D contact geometry method are asymmetric along the lateral and longitudinal directions, especially when the wheel flange contacts with a rail gauge corner. The proposed method can improve the accuracy of the wheel–rail contact solution and help predict rail damage in switch panels.

Effect of in-service work hardening on the sliding wear resistance of a heavy haul rail in the gauge corner

This work evaluates the tribological behavior of three samples taken from a pearlitic steel rail with different hardness values (550, 450 and 370 HV0.1) due to the in-service work hardening effect. A pin-on-disc sliding wear test was selected to simulate the sliding wear conditions among the wheel flange and rail head corner and gauge face. The influence of the stress level was evaluated by varying the applied normal loads; the 50 and 500 N loads were associated with large and small radius curves, respectively. Pins were made from the rail samples, and the counter body (disc) used was H-13 steel (600 HV30). The mass loss was measured, and the coefficient of friction (COF) for each condition was calculated. Scanning electron microscopy (SEM) was carried out for microstructural characterization of the samples before and after the sliding wear test. The results showed a monotonic correlation between the superficial hardness and the sliding wear resistance under the low severity condition. The sample with the intermediate hardness (450 HV0.1) has the greatest sliding wear resistance under the low severity, 50 N condition, and under the high severity test condition (500 N). For the tests performed at 50 N, the wear facilitated crack propagation, and the preexisting cracks were removed from the pin (rail) interface. In contrast, for the tests performed with a 500 N load, the material removal rate did not overcome the crack propagation. In addition, the energy at the sliding interface was enough to promote a white etching layer (WEL), which reproduced the surface of the in-service rails, and the material removal was not sufficient to remove the cracks from the pin (rail) surface.

Development and application of a multi-sensor integration detection and analysis device for metro gauge and track geometric state

In order to ensure the safe operation of subways, it is necessary to detect the metro gauge and track geometry in time. However, the manual detection and the large rail inspection car is inefficient and expensive. Therefore, we have developed a multi-sensor integration detection and analysis device. Sensors, such as a laser scanner, a gauge sensor, an angle sensor, and a single-chip computer, are integrated into a rail inspection trolley, and the functions of gauge detection, gauge analysis, rail gauge calculation, and superelevation calculation are realized. Through the calibration of an odometer and a sensor, the accuracy of the device can meet the requirements of the standard. The device is applied to Changsha Metro Line 3 to detect and analyze the gauge and track geometry state. Finally, the device realizes the functions of the gauge intrusion alarm, automatic input of graphics and gauge intrusion data, automatic identification of sleepers, and automatic collection of track geometry data.

Time-dependent behaviours of railway prestressed concrete sleepers in a track system

The main functions of railway sleepers are: (i) to safely transfer loads from wheel axles to foundation; (ii) to secure both rails ensuring correct track gauge at all time; and, (iii) to restrain movements of rails to control longitudinal creeps. In reality, railway industry can experience costly problems of railseat twists and tight gauges, for instance, due to time-dependent actions and poor workmanship. These problems prevent trains to navigate over tracks safely, effectively and quietly. They require additional, expensive maintenance activities much more frequently over time such as rail renewal, rail reprofiling/grinding, rail pad replacement, curve lubrication adjustment, etc. On this ground, it is very important to maintain the geometry and topological/dimensional stability of railway sleepers. The long-term geometric performance of sleepers can be significantly influenced by time-dependent actions and behaviours. The creep and shrinkage in prestressed concrete sleepers result in internal actions that is led to geometric deformation, which change the rail gauge and influence the safety and reliability of track components. Time-dependent behaviours also lead to increased complex internal stresses, which can cause cracking on prestressed concrete railway sleepers. The cracks stemming from creep and shrinkage can be observed in real life, at a certain time after construction, along the sleepers and near the fasteners such as anchorage, bolt holes, and web openings. In this study, unprecedented experimental and numerical investigations are conducted to evaluate time-dependent behaviours of full-scale prestressed concrete sleepers. An empirical calculation method is also introduced and the empirical results are compared with both experimental and numerical results. Insights into creep and shrinkage effects are highlighted in order to essentially aid predictive and preventative track maintenance, supporting the effective and efficient decision making of both (i) engineers and manufacturers and (ii) infrastructure managers and owners.

Detection of Rail Geometry Irregularities Using Point Cloud Data from Terrestrial Laser Scanner (Study Case: Curve No. 106, Railroad between Cipatat-Tagogapu, Indonesia)

Geometry railroad irregularities can disrupt safety of the train that passes through it and the comfort of train users. In geometric inspection of rail, it requires reliable accuracy from survey data. Terrestrial Laser Scanner (TLS) offers the advantage of obtaining accurate measurements of objects or 3D model. This study aims to examine irregularities of widening gauge and cant rail in curve no. 106, railroad between Station Cipatat – Station Tagogapu based on Minister of Transportation Regulation No. 60 of 2012. The 3D rail model from the point cloud TLS can be used to extract changes of the gauge and height differences with the help of cross- sections. Extraction of gauge and height differences is carried out per 1 meter and given numbering. The results of both gauge and height differences are adjusted to the type of track from the results of the design of the curve, then compared with the value of the standard widening gauge and cant based on the Minister of Transportation Regulation No. 60 of 2012. The result extraction of the rail gauge in curve no. 106, shows the highest irregularities of widening gauge on the gauge number 24 with deviation value +0,017 m. The results of obtaining height differences rail extraction at curve no. 106, shows the highest irregularities of rail cant on the height differences number 15 and 16 with deviation value +0,022 m.

Effect of the worn status of wheel/rail profiles on wheel wear over curved tracks

The worn status of wheel/rail profiles could change the wheel-rail contact and influence the wear rates of the wheel and rail. Worn wheel profiles of a Chinese intercity train and the worn rail profile of curved tracks were taken into account in this work. According to the dynamics model of the vehicle, teh wheel-rail three-dimensional steady-state rolling contact model, and the Archard wear model, a new fast calculation method of wheel wear rate was proposed. Simulation results show that obviously severe wear would distribute in the flange when the wheel and rail were worn. The side wear of rail gauge corner will seriously aggravate the wear of new wheel flange. The wear of the wheel is serious for teh worn wheel in the initial phase of service. Therefore, the re-profiling of wheels and rails should be scheduled cooperatively, and the wear of flange in the initial phase of service should addressed.

A Comprehensive Detection System for Track Geometry Using Fused Vision and Inertia

The track line suffers from track irregularity, subgrade settlement, rail surface defects, and gauge distortion. Measuring the track geometry quality plays an important role in rail administrations to safe operation and track maintenance. In order to meet the requirements of track daily inspection, this article describes a comprehensive detection system for the track geometry, which is designed by four cameras, an inclinometer, and an inertial measurement unit. Moreover, the detection system has the characteristics of simple structure, automatic detection, and multiple measurement parameters. First, to measure track alignment and irregularity, a multisensing calibration method is established to fuse visual sensors and inertial sensors. An accelerometer and a Kalman filter are used to eliminate accumulated unrealistic drifts of accelerometer and gyroscope. Second, to measure the rail surface defects and gauge, the model of laser and machine vision is deduced to obtain the coordinate values in a unified coordinate system, and an improved iterative closest point method is developed to improve the matching accuracy. Finally, a series of experiments is carried out to validate the measuring performance. The results indicate that the proposed method can accurately measure the track geometry, with the maximum deviations of track alignment, track irregularity, rail defects, and gauge that are less than 0.5, 0.4, 0.3, and 0.1 mm, respectively. The detection system is not only simple in structure but also has multiple detection parameters, which is especially suitable for track daily maintenance.