Search Results (149)

The railway industry is increasingly pressured to adopt sustainable practices, seeking alternatives to virgin natural aggregates that reduce environmental impact and lifecycle costs. The extraction of slate for ornamental purposes generates significant waste, approximately 30% by mass, which is typically disposed of in landfills, causing environmental and economic concerns. This study comprehensively investigates the potential of slate waste as a primary component in sub-ballast layers for railways. Laboratory tests were conducted on mixtures of slate waste and a clayey soil, with granular contents ranging from 60% to 90%. The key geotechnical parameters evaluated included the California Bearing Ratio (CBR), Resilient Modulus (RM), compaction characteristics, granulometry and Atterberg limits. In addition, the DNIT ISF-212 standard was used to verify compliance with the Brazilian requirements for the use of materials in sub-ballast layers. The results indicate that mixtures with slate waste (SLT) exhibit performance comparable to conventional gneiss aggregate mixtures (REF); however, verification against the DNIT ISF-212 standard showed that only the SLT 80/20 and SLT 90/10 mixtures fully meet the requirements for use as railway sub-ballast. The RM and CBR values for the SLT mixtures increased by 48.5% and 38.4%, respectively, when the slate waste content was raised from 60% to 90%. A non-linear relationship was found between RM and CBR for both material types. Furthermore, the study integrates findings from related research on recycled ballast and tropical soils, highlighting the synergistic benefits of using industrial by-products. It concludes that slate waste presents a viable, high-performance, and sustainable solution for railway sub-ballast, contributing to circular economy principles in railway infrastructure. Full article

This article deals with the possibility of using a recycled aggregate from railway ballast and platforms for the production of cement composites with a full or partial replacement of natural aggregates. This study evaluates the physical and mechanical properties of fresh and hardened concrete, as well as its resistance to water pressure, microstructure, and environmental safety. Four concrete recipes using an aggregate at the end of its life cycle from railway ballast (0/25 mm) and from the layers under the asphalt covering of the platforms (0/32 mm) were designed, with a 100% replacement for 0/25, 55% replacement (coarse fraction) for 0/32, and 45% sand for 0/4. The results have shown a significant influence of the type of aggregate on the strength, bulk density, and watertightness of the concrete. At 28 days, the compressive strengths of mixes R250, R400, R250N, and R400N were approximately 8, 20, 30, and 35 MPa, respectively, while after 90 days they increased to 10, 22, 37, and 45 MPa. The corresponding fresh concrete bulk densities ranged from about 1.95 to 2.27 g/cm³, and the water penetration depths ranged between 16 mm (best) and 27 mm (worst) among the mixes. Analyses of aqueous leachates have confirmed that the cement matrix effectively stabilizes the contaminants contained in the recycled aggregate and that the resulting products comply with the legislative limits. This study shows that an aggregate at the end of its life cycle from railway ballast and platforms can be effectively used to produce sustainable cement composites (concrete) with suitable mechanical properties and minimal environmental risks. Full article

The objective of this work is to propose a novel mechanical model of under ballast mats (UBMs) that can replicate the phenomenon of energy dissipation under static loads. UBMs installed in the ballasted track structure can reduce the levels of vibration emitted by the railway system to the surrounding environment, affecting both people and the natural and built environment. A particular feature of UBM isolators is energy dissipation, which is manifested in load-deflection graphs in the form of so-called hysteresis loops. Notably, the hysteresis loop occurs not only under dynamic loads but also in the case of static loading. The constitutive equations of the UBM model will be formulated as a nonlinear set of ordinary differential equations. The parameters of the constitutive relations will be selected based on an optimization procedure to match the results of integrating the differential equations describing the theoretical model to the results of experimental tests of UBMs in the static range, in accordance with European standard EN 17282:2020-10. Full article

Railway tracks at bridge approaches experience significant vertical stiffness transitions, leading to adverse effects such as settlement and increased dynamic loads, accelerating track degradation. This study explores various structural solutions, including geosynthetics, reinforced ballast, transition slabs, under sleeper pads (USPs), under ballast mats (UBMs), jet grouting, and special rail fasteners. Despite their application, these solutions often fail due to their static nature. This paper introduces an adaptive approach using special rail fastenings with real-time adjustable stiffness. This system dynamically modifies rail support characteristics based on train speed and track conditions, improving track durability, ride quality, and maintenance strategies. The findings demonstrate the potential of adaptive systems to enhance railway infrastructure performance. Full article

The ballast consists of angular particles whose main function is to transmit and distribute train loads to the soil. However, under repeated loads, these particles wear down and break, causing permanent settlement, reducing track stability, and increasing maintenance. Characterizing stresses and deformations under monotonic and cyclic loading is essential to predict short- and long-term performance of railway systems. This numerical study evaluates the behavior of improved ballast materials, considering particle breakage. A hybrid Finite Difference and Discrete Element model was used to simulate the multiscale response of the track system under realistic loading conditions. The model was calibrated using data from laboratory tests conducted by various researchers. The performance of conventional ballast was compared with alternative mixtures, analyzing vertical displacements, stress distribution, safety factor, and particle breakage rates. Results show that the basalt-rubber composite significantly enhances ballast performance by reducing settlements and subgrade stresses while improving resistance to particle breakage. The FDM-DEM coupled approach effectively captures micromechanical interactions and breakage mechanisms, offering valuable insights for optimizing track design based on quantifiable performance criteria. Overall, the findings indicate the hybrid model and breakage–contact criteria approximated system behavior, while alternative ballast compositions improved durability, reduced maintenance, and supported resilient railway solutions. Full article

Turnouts are critical components of railway infrastructure, ensuring operational flexibility but also representing a significant share of track maintenance costs. The frog, as the most vulnerable part of a turnout, is subject to severe wear and degradation, requiring frequent inspection and maintenance. Traditional manual inspection methods are costly, labour-intensive, and susceptible to subjectivity. This study explores a data-driven approach to condition monitoring of fixed-turnout frogs using standard track recording car measurements. By leveraging over 20 years of longitudinal level and rail surface signal data from the Austrian track-recording measurement car, we assess the feasibility of using existing measurement data for predictive maintenance. Six complementary approaches are proposed to evaluate frog condition, including track geometry assessment, ballast condition analysis, rail surface irregularity detection, and axle box acceleration-based monitoring. Results indicate that data-driven monitoring enhances maintenance decision-making by identifying deterioration trends, reducing reliance on manual inspections, and enabling predictive interventions. The integration of standardised measurement data with advanced analytical models offers a cost-effective and scalable solution for turnout maintenance. Full article

Rail transport is widely regarded as a sustainable and environmentally friendly option for long-distance freight and passenger movement during its operation phase. However, its construction and maintenance phases often result in substantial environmental impacts, which must be addressed to improve the overall sustainability of railways. This study aims to identify solutions that improve the performance of railway tracks, reduce maintenance requirements, and minimize environmental impact. With this objective, the potential of artificial inclusions and innovative composite materials in enhancing the sustainability of railway tracks is investigated through a comprehensive methodology, combining experimental, analytical and numerical approaches. A novel composite material, comprising soil, scrap tire aggregates and an adhesive, demonstrated strong potential as a sustainable base layer for ballastless railway tracks, exhibiting minimal strain accumulation (0.29–0.98%) under 50,000 load cycles and adequate damping. Incorporation of cellular artificial inclusions in the substructure layers of ballasted tracks reduced cumulative settlement by up to 33% and slowed track geometry deterioration. Use of planar artificial inclusions beneath a pile-supported railway embankment enhanced the load transfer efficiency and curtailed settlement, while also lowering environmental impact by reducing concrete usage. The findings of this study highlight strong potential of these approaches in improving track performance and the overall sustainability of railways. Full article

Extreme rainfall events characterized by small catchments with high-velocity flows pose critical challenges to infrastructure resilience, particularly the rail infrastructure, due to its partial location near rivers and in mountainous regions, and the limited availability of alternative routes. This can lead to severe damages, often resulting in long-term route closures. To mitigate flash flood damage, detailed information about affected structures and damage processes is necessary. Therefore, this study presents a newly developed multi-criteria flash flood damage assessment framework for the rail infrastructure and a QGIS-based analysis of the most frequent damages. Applying the framework to Eifel route damages in Western Germany after the July 2021 flood disaster shows that nearly 45% of the damages affected the track superstructure, especially tracks and bedding. Additionally, power supply systems, sealing and drainage systems, as well as railway overpasses or bridges, were impacted. Approximately 30% of the railway section showed washout of ballast, gravel and soil. In addition, deposit of wood or stones occurred. Most damages were classified as minor (47%) or moderate (34%). Furthermore, damaged track sections were predominantly located within a 50 m distance to the Urft river, whereas undamaged track sections are often located at a greater distance to the Urft river. These findings indicate that the proposed framework is highly applicable to assess and classify damages. Critical elements and relations could be identified and can help to adapt standards and regulations, as well as to develop preventive measures in the next step. Full article

In railway infrastructure, particularly where concrete sleepers are employed, certain critical zones exhibit pronounced degradation of the ballast layer. Previous studies have identified several contributing factors, including the presence of welds, heterogeneity in the substructure beneath the sleepers, and variations in the track’s geometric parameters. Of these factors, the presence of welds seems to have the most significant influence. This article aims to determine whether differences in the ballast railway track’s response to traffic loads at weld locations can be identified in the initial phase, before obvious damage appears. Vibration responses in terms of displacement, velocity, and acceleration were measured on upgraded concrete sleepers equipped with rubber under-sleeper pads. The results indicate that velocities and accelerations at rail weld locations differ significantly from those in adjacent track sections, when the railway track is in an intact, undamaged condition. These results suggest a high likelihood of damage formation in these critical locations, indicating the necessity of preventive measures to mitigate damage. Possible mitigation measures that could help reduce the formation of damage are proposed. Full article

In the context of global environmental pollution and energy shortages, the use of lightweight designs of railway vehicles has become a key technological approach to improve energy efficiency and reduce carbon emissions. The use of lightweight and high-strength materials such as carbon-fiber-reinforced composites to replace traditional metal vehicle structures holds great application potential. In this study, random track loads and ballast impact loads that may occur during service were considered, and a finite-element model of the electric locomotive coupling protective cover was established. The impact resistance of CFRP, GFRP, and their interlayer hybrid configurations (C/G/C and G/C/G) against structural and ballast impacts were investigated. The calculation results showed that the CFRP protective cover exhibited the best structural impact resistance (with the lowest Tsai–Wu strength failure values), but it also had the largest maximum deformation displacement (2.36 mm) under ballast impact conditions. In contrast, the GFRP protective cover had a higher Tsai–Wu strength failure value, indicating that it had worse structural impact resistance, but it had a lower maximum deformation displacement (2.20 mm) under ballast impact conditions, demonstrating superior ballast impact resistance. The impact resistances of the hybrid-layered protective covers fell between those of the CFRP and GFRP in terms of the structural impact, while their ballast-impact resistance surpassed those of single-fiber configurations. Full article

Railway infrastructures necessitate the inspection of various elements to ensure operational safety. This study concentrates on five key components: rail, sleepers and ballast, track geometry, and catenary. The operational principles of the primary defect measurement sensors are elaborated, emphasizing the use of ultrasound, eddy currents, active and passive optical elements, accelerometers, and ground penetrating radar. Each sensor type is evaluated in terms of its advantages and limitations. Examples of mobile inspection platforms are provided, ranging from laboratory trains to draisines and track trolleys. The authors foresee future trends in railway inspection, including the implementation of IoT sensors, autonomous robots, and geospatial intelligence technologies. It is anticipated that the integration of sensors within both infrastructure and rolling stock will enhance maintenance and safety, with an increased utilization of autonomous robotic systems for hazardous and hard-to-reach areas. Full article

The composite primary structures of railway vehicles endure not only mechanical loads including tension, compression, bending, and torsion, but also external impacts, such as by the crushed stone in ballast. In the present study, the low-velocity impact response of preloaded hybrid composite laminates with different thicknesses is examined using a finite element method based on a progressive damage model. The hybrid plate consists of carbon fiber-reinforced unidirectional and woven prepregs. The progressive damage model, based on the 3D Hashin model, is validated by experiments on hybrid laminate, and further compared with the post-impact appearance obtained from CT scans. Preloading, considered to be tensile, compressive, or shear, corresponds to different positions in a bending beam with flanges and a web. Finally, the effects of impact energy, preloading, thickness, and impact angle on the dynamic response are analyzed, with an emphasis on new results and failure mechanism analysis comparing the influence of preloads under a given impact energy and different thicknesses. Full article

Transition zones are located at points on a track where there has been a change in the main composition of the railway infrastructure; as such, there are many sections that undergo a sudden change in the stiffness of the structures built. When trains are running, a longitudinal shockwave is created by the wheels, hitting these building objects with a greater stiffness and deforming the surroundings of these zones. The greatest amount of attention should be paid to the transition points from the fixed track to the classic track with a track bed, including objects of the railway substructure, such as bridges and portals of tunnels. As part of the research on the main corridor lines, long-term inspection and monitoring studies were carried out using a trolley with a continuous measurement system; height changes in the deflections of rails are evidence of their behaviour. The measurements took place on a fixed track and a track with ballast. The changes in the height jumps between the fixed railway track and the track with a gravel bed are significant. These height deflections allow designers to develop new, more durable construction designs. Full article

During railway operations, changes in the support conditions of sleepers, owing to various internal and external factors, can damage rails and concrete sleepers and alter the structural characteristics of gravel-ballasted tracks. However, current methods for evaluating gravel ballast conditions primarily rely on visual inspection. This study proposes a quantitative approach using modal testing to assess ballast conditions. This is achieved by analyzing and experimentally verifying the relationship between track ballast loosening (caused by subgrade deformation) and track support performance. Finite element analysis results and field experimental values were compared using spring stiffness as a parameter. The results showed that natural frequencies and mode shapes changed in response to variations in the vertical spring stiffness of the gravel-ballasted track. Therefore, the sleeper support condition of a gravel-ballasted track can be readily identified by analyzing the natural frequency corresponding to different sleeper support conditions. Full article

This study investigates the influence of ballast and sub-ballast thicknesses on the structural behavior of a heavy-haul railway platform by using finite element modeling with SysTrain software (v. 1.84) A parametric analysis was conducted to assess how variations in layer thickness affect key performance parameters, including total deflection, bending moments in the rails, and vertical stresses within the railway track. The results indicate that reducing ballast thickness increases deflection and vertical stresses, while excessive thickness elevates system stiffness, reducing its ability to dissipate stresses. This condition can intensify the transmission of dynamic loads to track components, accelerating rail and sleeper wear and requiring more frequent corrective interventions, thereby increasing maintenance costs. Deflections remained within the 6.35 mm limit established by AREMA, except for one case (6.85 mm), where an excessive ballast thickness (160 cm) combined with low material stiffness resulted in non-compliance. Vertical stresses in the substructure ranged from 106.9 kPa to 155.9 kPa, staying within admissible limits. Additionally, the study highlights the significant role of material properties, particularly the resilient modulus, in the overall track performance. The findings enhance the understanding of how ballast and sub-ballast geometry affect railway structural behavior, demonstrating how numerical modeling with SysTrain can support decision-making in track design and maintenance strategies. Full article