Track Geometry Research Articles

Effect of preheating substrates and process parameters on cladding track geometry fabricated by laser cladding

Laser cladding (LC) is an advanced technique used for repairing large-scale components, such as rotors and valves, in thermal power plants and steel rolling mills. This technology is designed to facilitate efficient repairs, minimize repair costs, conserve materials, reduce processing time, and ensure adequate dilution between the substrate material and the deposited coating, while also enhancing corrosion resistance. In this research, the effects of preheating substrates and input process parameters on the geometric accuracy of single-track deposits, as well as the microstructure composition of multi-track deposits, were investigated. The Taguchi method was used to design an L9 orthogonal experimental array. The impact of process parameters, including substrate temperature, laser power, and scanning speed, on the morphology of a single track (track width, height, penetration depth, and dilution) was evaluated through ANOVA statistical analysis. SS316L stainless steel, recognized for its wear resistance, was used as the deposition material. The findings reveal that substrate temperature is the most critical factor influencing the dilution of the coating. Additionally, the microstructure of the deposited layers were systematically analyzed.

Interlayer-free laser coating of AISI H11 tool steel for H11/Cu composite material

Copper-based materials in combination with steels are of great interest for various applications in industry, such as tool manufacture, due to their high thermal conductivity. Additive manufacturing (AM) is beneficial for both tailored part geometry and customized material design. With laser-based AM, the copper-steel interface is highly prone to cracking. This study investigates a strategy of laser coating AISI H11 tool steel for a composite material consisting of AISI H11 tool steel and copper (H11/Cu) without using Ni-based interlayers. As an austenite stabilizing element, Ni dilution in H11 could lead to soft retained austenite, impeding wear resistance. The approach in this work employed presintering of tool steel powder to generate a porous H11 preform. Laser-based directed energy deposition (DED-LB/M) was used for coating H11 tool steel on the porous H11 preform followed by copper infiltration of the preform. The investigation of the effects of the main processing parameters: laser power, feed rate, and powder mass flow on the weld track geometry, clearly revealed different mechanisms when coating the porous preform compared to the conventional substrate. Defects at the coating/substrate interface such as cold crack formation were successfully avoided by adjusting the process parameters and process sequence. The developed processing strategy may in the future combine material extrusion of metals (MEX/M) and DED-LB/M to allow for intricate preform geometries and to generate H11 coatings on H11/Cu, respectively.

A novel Linetype Recognition Algorithm Based on Track Geometry Detection Data

Abstract The detection and recognition of track geometry are crucial for ensuring railway transportation safety and maintenance efficiency. Traditional linetype recognition algorithms struggle to effectively handle the complexities of variable track geometry and noise interference. To address these challenges, a novel linetype recognition algorithm (NLRA) is proposed, which thoroughly analyzes the characteristics of track curvature across straight lines, transition curves, and circular segments. By employing partial differential equations for data preprocessing, NLRA effectively filters out noise. Utilizing curve design parameters and integrating line anti-noise recognition with multi-segment line fitting techniques, the algorithm accurately identifies each line segment and incorporates a single-point recognition method for data gaps. Experimental results demonstrate that NLRA outperforms traditional algorithms in terms of real-time performance, recognition accuracy, anti-interference capability, and noise handling. Notably, NLRA enhances accuracy by at least 35.1% and recall by at least 17.4% on selected typical routes. This work underscores the algorithm's potential to provide efficient and accurate tools for track maintenance, facilitate advancements in track detection software, and significantly contribute to railway transportation safety.

Development of track geometry inspection equipment for high-speed comprehensive inspection train in China

Development of track geometry inspection equipment for high-speed comprehensive inspection train in China

Assessment of a mixed-mode vertical solar dryer for experimental turmeric drying

Solar drying, an eco-friendly and sustainable approach harnesses solar radiations to remove moisture from a drying commodity, thereby preventing its spoilage and extending shelf life. Turmeric (Curcuma longa), a popular herb is being used for centuries in Ayurveda as a traditional medicine. Since, fresh turmeric contains 80–90 % moisture content, therefore, it is quite difficult to store for a longer period. An innovative and compact mixed-mode vertical solar dryer (MVSD) with a circular solar collector (solar tracking geometry) is developed and tested for turmeric slices drying under partial and fully loaded conditions. Turmeric samples of 2, 3 and 4 mm slices thicknesses were used for experimentation under partial loading condition. The thickness of the turmeric slices was observed to affect the performance of the MVSD. The drying rate and thermal efficiency were observed to be highest for 3 mm thick turmeric slices sample under partially loaded condition. The MVSD was further tested with full loading capacity for 3 mm thick turmeric slices drying under natural and forced convection (NC and FC), respectively modes. The drying behavior of turmeric slices was well described by Midilii-Kucuk model. Heat transfer coefficients and efficiency (thermal and exergy) were observed to be higher under FC mode. Embodied energy and energy payback time were observed as 554.44 and 585.53 kWh; and 4.39 and 4.55 years under NC and FC modes, respectively. Annualised cost and payback period were observed to be desirable for NC mode.

Positioning method of track irregularities in high-speed turnout area based on multi-resolution analysis

The assessment and evaluation of complex track geometry parameters (TGP) in turnout areas present challenges for track recording cars due to uncertainties in their positioning on short sections. To obtain precise and reliable measured TGP in the turnout area, a multi-resolution technology based on maximal overlap discrete wavelet transform (MODWT) is used to perform multi-layer decomposition of the longitudinal level. By utilizing the zero-phase characteristic of MODWT, the TGP can be determined by aligning the decomposed weld spacings with their corresponding theoretical lengths. The positioning error is assessed through statistical analysis of measured TGP and numerical simulation using a virtual track inspection method. Finally, a 70 m length of TGP, including the entire turnout section, was extracted with a positioning error of no more than 1.5 m.

Quantifying the impact of rail longitudinal level changes on dynamic load magnitudes through instrumented wheelset measurements

Track geometry significantly influences train-track dynamic interactions, primarily due to irregularities at the wheel-rail interface. These irregularities generate dynamic load excitations, leading to defects and damage. This study evaluates how track surface profile longitudinal level vertical changes affect vertical wheel-to-rail loads, quantified by the dynamic load factor ( ϕ ), due to the importance of ϕ in track design. A limitation of the existing studies is their focus on instrumented sections and numerical modellings without considering different track structures. This study conducted dynamic load measurements using two instrumented wheelsets (IWS) over a 340 km section operated by a North American Class 1 freight railway in the Canadian Prairies under various track structures and train speeds. Rail surface longitudinal level measurements were obtained as routine measurements through a track geometry car. The paper presents statistical distributions of rail longitudinal level across different track structures and evaluates two widely used and recently developed ϕ equations within the context of North American freight railways to quantify the impact of rail longitudinal level (i.e. profile) changes on dynamic load magnitudes. The study also evaluates regulated threshold values by considering observed trends in the measured data, which aims to quantify and compare these values with our current understanding.

Influence of the inner roughness of powder channels on the powder propagation behavior in laser metal deposition

The powder propagation behavior of powder nozzles for the laser metal deposition process has a significant influence on powder utilization rate and track geometry. A well-focused powder stream will lead to a higher process efficiency and lower material loss. Powder channels with different roughness and a constant diameter of 1.5 mm were placed by wire electrical discharge machining into a copper alloy printed by powder bed fusion. Nickel base powder with a size of −106 to +45 μm was delivered through the powder channels with varied carrier gas flow rates and varied powder mass flow rates. High-speed imaging was used to analyze the powder flow. From these recordings, the dispersion angle of the powder stream from single channels could be measured as well as the velocity of particles. Moreover, the relationship between individual particle velocity and individual particle flight angle was investigated. It was found that the inner roughness of powder channels has a major impact on powder propagation behavior. It could be shown that with a decrease in Ra from 2.16 to 0.27 μm the divergence angle decreased by around 61% while the particle velocity was increased by at least 28% for all varied parameters. Particles with a high velocity tend to have a lower particle flight angle.

Railway condition information modelling in a BIM framework for maintenance applications

ABSTRACT Railway maintenance management involves various interventions that, considering safety and use needs, require an integrated approach for supporting decisions. Defining an infrastructure digital twin can represent an efficient basis to implement management processes. BIM, offering a simplified and realistic digitalized model, may ensure immediate benefits for asset administrators in maintenance management and planning. It would permit to properly maintain full control of infrastructure degradation, to optimize investments and ensure adequate quality levels. In this context, a preliminary procedural framework for modelling railway condition information in an I-BIM environment is proposed, using specific survey data acquired by scheduled diagnostic trains. The authors developed customized routines and scripts to elaborate rail track geometry attributes (with real-time checks of the dynamic effects on the track) and simplify asset quality evaluation for the administrators. This may suggest a novel vision and framework to support maintenance management procedures in future developments of the overall approach.

Pre- and Post-Improvement Performance of a Railway Embankment Stabilized with Ductile Inclusions

Large deflections and accumulation of permanent track geometry defects at railway soft spots cause significant operational issues including increased maintenance costs, decreased train speed, and, at an extreme, derailments and track failures. Reinforcing inclusions placed between the ties are a promising rehabilitation scheme to locally stabilize the embankment and transfer the loads to deeper, more suitable soils. In this paper we report the results of a long-term monitoring program to assess the performance of ductile inclusions, known commercially as “GeoSpike® elements”, to stabilize a rapidly deteriorating railway soft spot. Observations of track bed behavior are presented for 8 months prior to installation and 15 months after installation using a combination of LIDAR, Digital Image Correlation (DIC), and ShapeAccelArrays (SAA). Through the monitoring program, it was determined that the ductile inclusions decreased the average rate of deterioration by a factor of approximately 3, which allowed the frequency of site maintenance to be decreased from three times a year to once a year.

Innovative Approaches in Railway Management: Leveraging Big Data and Artificial Intelligence for Predictive Maintenance of Track Geometry

Innovative Approaches in Railway Management: Leveraging Big Data and Artificial Intelligence for Predictive Maintenance of Track Geometry

Enhanced measurement and optimization of railway profile parameters for large tamping machine operations

Abstract In the realm of modern railway maintenance, the employment of large tamping machine for the enhancement of track geometry and elasticity, and the minimization of disturbance to the roadbed, has become a key operational approach. However, factors such as repeated load applications, changes in topography and geology, and ongoing maintenance activities have been known to cause significant deviations of the actual track location from its original design. These deviations present challenges, such as increased construction difficulty and workload, during tamping operations predicated on the original design. Moreover, methods based on manual intervention have rendered large machine maintenance operations inefficient. In this paper, an optimisation method for railway profile parameters suitable for large tamping machine operations is proposed. The method integrates the total least squares method and the direct search method, enabling the accurate fitting of slope segments preceding and following the slope change points and the alignment of circular curve segments to determine the optimal curve radius. Consequently, optimised profile parameters for the continuous track section are obtained. Focusing on the Beijing–Guangzhou line, the operational efficacy of the proposed optimisation method is compared with that of the artificial slope method. The results showed that the proposed optimisation method is not only more accurate and efficient but also adheres to the principle of ‘prefer lifting rather than descending’ of the railways. The method further provides a theoretical basis and practical guidance for the optimisation of railway profile, underscoring the potential for improved maintenance efficiency and enhanced safety in train operations.

A Performance Evaluation Method for Long and Steep Uphill Sections of Heavy-Haul Railway Lines

Any system for evaluating the safety service performance of heavy-haul railway lines must effectively reflect the real-time service status of the line. The working conditions of heavy-load lines are complex and diverse, particularly on uphill sections. Existing evaluation systems struggle to accurately reflect the service conditions of long and steep uphill sections bearing heavy loads, posing a significant threat to the safe operation of these lines. To address this problem, we propose a new method for evaluating the safety service performance of long and steep uphill sections of heavy-haul railway lines by establishing a scoring system based on the Analytic Hierarchy Process (AHP). First, damage indicators for heavy-haul lines are categorized into three groups: track geometry status indicators, track structure status indicators, and track traffic status indicators. Using data from existing heavy-haul lines and maintenance experiences, we determine a score deduction standard, classifying lines into four levels based on their safety service quality. Next, we establish a coefficient table for the service performance of long and steep uphill sections after the corresponding scores are deducted. Using data for the length and elevation grade of the actual uphill section, we adjust the deducted scores of the track structure status indicators, enhancing the evaluation system’s accuracy in describing the working conditions. Finally, we verify the stability of the entire system by conducting a sensitivity analysis of the indicator evaluation results using the One-At-a-Time (OAT) method. This method fills a critical gap in the safe operation and maintenance of heavy-haul railways and provides a safety guarantee for the operation of long uphill sections of heavy-haul railways.

The implementation of a collision warning system in Formula racing

Advanced Emergency Braking (AEB) is used to reduce rear-end collisions in critical traffic scenarios. The racing environment contributes critical cases. In Formula races, critical collisions occur during cornering. Drivers may not concentrate on the boundary regions at high speeds. For this reason, an AEB system may support the drivers in such cases. On the other hand, this system is not permitted to be implemented in racing cars. Therefore, an AEB system may be implemented into the environment of the track by using several Long-Range Radars (LRR) at critical points. The originality of this study is the approach in the implementation of an AEB system into the racing environment as a collision warning system. The effectiveness of the implementation of the AEB system into the racing environment depends on the reaction time of the racing drivers. A fuzzy logic controller was proposed to control Time to Collision (TTC) during cornering according to the track geometry. The controller design was established in MATLAB/Simulink interface with the simulations in the IPG/CarMaker environment. According to the simulation results, the approach in the implementation of the AEB system prevented a pile-up.

An overhead line virtual test track for the assessment of railway catenary pantograph interaction

This paper presents the infrastructure geometry of a virtual test track for investigating the dynamic performance of train pantographs and overhead line systems with discrete features including height transitions and overlaps. This has been developed to support cascade of legacy fleets to new regions of the rail network and to better understand how legacy electrification infrastructure can support more modern fleets. The geometry is developed as an ‘obstacle course’ representative of overhead line fitted to legacy routes which have been electrified after their initial construction and is reusable across overhead line equipment types and modelling packages. A range of demonstration results are presented to illustrate application of three pantograph models. The virtual test track geometry and dynamic modelling can be used to assess the performance of catenary/pantograph combinations for overhead line geometries with discrete features and large height variations that are not currently covered by validation methods such as described in BS EN50318. The approach is applicable as a planning tool to establish safe working speeds across a range of overhead line features when full overhead line geometry is not available, or will be too costly to obtain, in the context of extending the utilisation of legacy assets.

The Influence of Seasonal Effects on Railway Vertical Track Modulus

Adequate vertical track support is essential for safe and efficient railway operations. Insufficient support leads to distorted track geometry, increased dynamic loads, component stress, poor ride quality, rolling stock damage, and derailment risks. Current inspection practices focus on assessing the condition of the track components and geometry, rather than the root causes of degradation. To improve this condition, this study presents the use of a methodology that utilizes an autonomous vertical track deflection measurement system mounted on a loaded rail car (36 tonnes/axle) to support track maintenance decisions in a heavy haul railroad located in southeast Brazil. The system continuously measured substructure stiffness along the railway line. Over one year, data were collected from over 8000 km of track. The study highlighted seasonal effects on track degradation over time, identifying areas with significant deflections and high deflection rates, which contribute to issues such as differential settlement and reduced lifespan of track components. Additionally, the study revealed seasonal effects, with deflections peaking during wet weather and decreasing during dry cycles. A method to classify weak track areas was developed, facilitating monitoring and enabling more effective maintenance planning, contributing to the reduction of overall track maintenance costs and enhancing safety and operational efficiency.

Effect of unsupported sleepers on vertical levelling loss of heavy-haul railway track geometry under cyclic loadings

With an emphasis on the combined degradation of railway track geometry and components, an improved numerical approach is proposed for predicting the track geometrical vertical levelling loss (VLL). In contrast to previous studies, this research unprecedentedly considers the influence of unsupported sleepers (US) configuration on VLL under cyclic loadings, elasto-plastic behaviour, and different operational dynamic conditions. The nonlinear numerical models are performed adopting an explicit finite element (FE) package, and their results are validated by field data. The outcomes are iteratively regressed by an analytical logarithmic function that cumulates permanent settlements, and by a power function factor, which innovatively extends the response of US on VLL over a long term. Results shows that at 3 million cycles (or 60 MGT) the worst configuration for 20-ton axle load is at 5 US with 5-mm gap (5,51%), whereas for 30 and 40-ton axle loads is at 5 US with 2-mm gap (1.23% and 0,89%, respectively). This indicates that the axle load affects considerably the VLL as expected, however, the US condition plays an important role to accelerate it. Based on this study, the acceptable configuration of US can be specified for a minimum effect on VLL (thresholds) and, therefore, supports the development of practical maintenance guidelines to prolong the railway track service life.

A geometrical theory of gliding motility based on cell shape and surface flow

Gliding motility proceeds with little changes in cell shape and often results from actively driven surface flows of adhesins binding to the extracellular environment. It allows for fast movement over surfaces or through tissue, especially for the eukaryotic parasites from the phylum apicomplexa, which includes the causative agents of the widespread diseases malaria and toxoplasmosis. We have developed a fully three-dimensional active particle theory which connects the self-organized, actively driven surface flow over a fixed cell shape to the resulting global motility patterns. Our analytical solutions and numerical simulations show that straight motion without rotation is unstable for simple shapes and that straight cell shapes tend to lead to pure rotations. This suggests that the curved shapes of Plasmodium sporozoites and Toxoplasma tachyzoites are evolutionary adaptations to avoid rotations without translation. Gliding motility is also used by certain myxo- or flavobacteria, which predominantly move on flat external surfaces and with higher control of cell surface flow through internal tracks. We extend our theory for these cases. We again find a competition between rotation and translation and predict the effect of internal track geometry on overall forward speed. While specific mechanisms might vary across species, in general, our geometrical theory predicts and explains the rotational, circular, and helical trajectories which are commonly observed for microgliders. Our theory could also be used to design synthetic microgliders.

Собственные напряжения в рельсах, возникающие вследствие эксплуатации железнодорожного пути с отступлениями по его содержанию

Purpose: approaches to the maintenance of the railway track play a significant role in the interaction between the track and the rolling stock. The analysis [1–10] shows that existing methods for assessing the impact of rolling stock on the track have not completely resolved the issues of taking into account the residual deformation of the track, which does not allow us to have the most complete understanding of the ongoing interactions and processes between the railway track and the rolling stock in real operating conditions. In developing the issue of the need to take into account the residual deformation of the track, deviations in the geometry of the rail track in the profile, the article considers the “intrinsic” stresses in the track that are not under the influence of any load, arising as a result of the operation of a railway track with deviations in its contents. Methods: statistical analysis of the accumulation of residual deformations of a section of the railway track, review of existing methods for assessing the impact of rolling stock on the track, simulation modeling of the stress-strain state of the rail. Results: an analysis of the accumulation of residual deformations of a section of the railway track, a review of existing methods for assessing the impact of rolling stock on the track, modeling of the stress-strain state of a rail under load in two states (straight beam, curved beam) were carried out. Practical significance: the results can be applied when solving the problem of interaction between rolling stock and the railway track.

The Characteristics of Long-Wave Irregularities in High-Speed Railway Vertical Curves and Method for Mitigation.

Track geometry measurements (TGMs) are a critical methodology for assessing the quality of track regularities and, thus, are essential for ensuring the safety and comfort of high-speed railway (HSR) operations. TGMs also serve as foundational datasets for engineering departments to devise daily maintenance and repair strategies. During routine maintenance, S-shaped long-wave irregularities (SLIs) were found to be present in the vertical direction from track geometry cars (TGCs) at the beginning and end of a vertical curve (VC). In this paper, we conduct a comprehensive analysis and comparison of the characteristics of these SLIs and design a long-wave filter for simulating inertial measurement systems (IMSs). This simulation experiment conclusively demonstrates that SLIs are not attributed to track geometric deformation from the design reference. Instead, imperfections in the longitudinal profile's design are what cause abrupt changes in the vehicle's acceleration, resulting in the measurement output of SLIs. Expanding upon this foundation, an additional investigation concerning the quantitative relationship between SLIs and longitudinal profiles is pursued. Finally, a method that involves the addition of a third-degree parabolic transition curve (TDPTC) or a full-wave sinusoidal transition curve (FSTC) is proposed for a smooth transition between the slope and the circular curve, designed to eliminate the abrupt changes in vertical acceleration and to mitigate SLIs. The correctness and effectiveness of this method are validated through filtering simulation experiments. These experiments indicate that the proposed method not only eliminates abrupt changes in vertical acceleration, but also significantly mitigates SLIs.