Search Results (71)

To measure the cross-view spacing between adjacent fastener bolts in railway turnouts, this study develops a dual-DLP-sensor structured-light measurement system without overlapping fields of view. A bridge-type calibration device is used to rapidly update the extrinsic parameters of the two DLP sensors. In a unified coordinate frame, the system integrates two-dimensional region-of-interest candidate generation, local three-dimensional geometric fitting, cross-view pairing, and measurement validity assessment to output bolt-spacing results. Experiments were conducted on 23 pairs of adjacent bolts with 15 repeated measurements using two DLP sensors. Under normal conditions, the mean absolute error, root mean square error, and average standard deviation were 0.261 mm, 0.290 mm, and 0.062 mm, respectively. Compared with fixed extrinsic parameters without updating, the bridge-based extrinsic update reduced the mean absolute error from 1.500 mm to 0.261 mm. The results indicate that the proposed task-driven dual-DLP-sensor measurement system can achieve stable cross-view spacing measurement with explicit validity criteria under non-overlapping fields of view, repeated deployment, and varying on-site data quality. Full article

Heavy-haul railways require efficient rail replacement because extreme axle loads and high-density transport accelerate rail wear. Traditional manual-led processes are limited by fragmented operations, high labor demand, and complex equipment scheduling, typically completing about 1 km of rail replacement within a 4 h maintenance window and requiring approximately 340 workers. This study is positioned as construction-process modeling, workflow organization, and simulation-supported feasibility analysis for an integrated rail-changing workflow, rather than the development or field validation of a fully mature rail-changing machine. The proposed workflow coordinates rail unloading, on-board welding, fastener disassembly, rail cutting, exchange-recovery, fastening, closure welding, and final inspection through a highly parallel construction organization. A process-level train-set configuration, including a tractor, a long-rail comprehensive transport vehicle, an exchange-recovery integrated transport vehicle, and a mobile welding vehicle, is used as an engineering carrier to support the closed-loop workflow of unloading, welding, exchange, and recovery. Based on engineering time-study analysis, field experience, expert consultation, and discrete-event simulation, the results indicate that the proposed workflow has the potential to complete a simulated 2 km rail-changing task within a single 4 h maintenance window with an estimated labor demand of 80–95 personnel under the specified assumptions. The study provides conceptual and simulation-supported feasibility evidence for construction-process organization, rather than field-validated machine performance, and offers a technical reference for improving the mechanization and coordination of heavy-haul railway maintenance. Full article

The wheel–rail impact effect is prominent in the low vibration track (LVT) in the curved sections of heavy-haul railways, where fastener failure and the support block hanging void are prone to occurring. To investigate the impact of these issues on the dynamic characteristics of the vehicle–track coupled system, this study establishes a coupled dynamics model of a heavy-haul train and LVT, taking into account the topological relationships of vehicle components, multipoint wheel–rail contact, and track irregularities. Comparative analyses are conducted to evaluate the effects of the location, quantity, and failure degree of fastener failure and support block hanging voids on running safety and stability. The results show that (1) compared to the normal condition, fastener failure and support block hanging voids lead to varying degrees of increases in response indicators, thereby intensifying the wheel–rail impact; (2) bilateral failure exhibits more pronounced dynamic responses than unilateral failure, and when the number of failed fasteners or hanging voids exceeds one, the maximum wheel load reduction rate increases significantly; (3) as the gap of the hanging void increases, the dynamic response also increases, and when the gap reaches approximately 3 mm, the support block can be considered fully suspended; and (4) comprehensive analysis indicates that fastener failure poses a greater threat to running safety than support block hanging voids and thus warrants greater attention in practical engineering applications. This study provides theoretical support for the maintenance and repair of heavy-haul railways. Full article

The railway sector is crucial for transportation, but infrastructure maintenance generates significant waste and requires large amounts of materials, increasing environmental impact. Circular economy integration mitigates this impact through material recovery. This study focused on the recycling of bushes embedded in railways sleepers, currently disposed of in landfills, obtaining high-density polyethylene (HDPE). The developed scalable process converted contaminated bushes into pellets, whose environmental sustainability was assessed through life cycle analysis. Challenges of the recycled material, such as high viscosity and heterogeneity, were partially addressed with a slipping agent and a compatibilizer, increasing the material melt index from 0.71 to 1.62 g/10 min. Carbon fiber waste addition improved thermal stability, mechanical stiffness, and electrical conductivity. Compatibilized blends offered the best balance of mechanical properties but lower electrical conductivity. The Young modulus was increased from 1.20 GPa for the neat matrix to 4.40 GPa for the system containing 30% carbon fibers in weight, with no significant decreases in the yield stress, while showing the lowest electrical conductivity. To reduce environmental impact and produce a tougher material without compromising conductivity, the compatibilizer was replaced with HDPE from PET bottle caps, resulting in comparable mechanical properties and higher electrical conductivity but reduced fiber/matrix interface. Full article

The railway track system is a complex assembly of rails, sleepers, and fastenings designed to ensure operational stability and safety. Within this framework, rail pads play a critical role in load transfer, vibration attenuation, and noise control. This study provides a comprehensive bibliometric analysis of research on railway components published between 2015 and 2024, based on 288 documents retrieved from Scopus, Elicit, and Web of Science. Publication trends reveal a steady increase in research output over the study period, primarily driven by Spain and China. Keyword co-occurrence analysis yielded 51 keywords organized into seven thematic clusters, with the highest frequency terms being “rail pad”, “noise”, “dynamic property”, and “MTHDRP”. The analysis highlights a significant focus on materials such as TPEs, EPDM, and EVA, with static preload and stiffness identified as the most scrutinized performance factors. Findings indicate a clear thematic shift from traditional field testing toward advanced material science and sensor-integrated monitoring technologies. Ultimately, this review outlines future research trajectories emphasizing sustainability, smart sensor integration, and predictive maintenance. By synthesizing a decade of academic contributions, this study serves as a strategic roadmap for optimizing the long-term durability and efficiency of modern railway infrastructure. Full article

This study investigates the transient wheel–rail contact mechanics of welded joints in heavy-haul rails via a validated 3D finite element model, and analyzes the stick-slip behavior, dynamic response and elastoplastic characteristics in the base material zone, heat-affected zone and weld bead zone. Results show a distinct contact state transition from stick-slip in the base material to predominant slip within the welded zones, indicating higher wear susceptibility. Dynamic response analysis reveals the highest and lowest contact-point acceleration amplitudes in the base material and heat-affected zone, respectively, due to material heterogeneity. Plastic deformation consistently initiates at the rail surface, where stress and strain concentrate, establishing it as the primary site for damage nucleation. A systematic parametric study shows that plastic deformation can be effectively mitigated by increasing the yield strength and elastic modulus of the welded joint material, or reducing the wheelset velocity, unsprung mass and wheel–rail friction coefficient. In contrast, adjusting the primary suspension and fastener parameters exerts a negligible influence on plastic deformation control. These findings provide a mechanistic basis for optimizing the performance and maintenance of welded joints in heavy-haul rail operations. This study reveals the coupling law of multiple mechanisms among contact behavior, dynamic response and material failure during the damage initiation process of rail welded joints from the mechanistic perspective, which provides a theoretical basis for the structural optimization, condition assessment and maintenance of rail welded joints in heavy-haul railways. Full article

In order to study the influence of the under-track foundation disease on the track system, based on the CRTS II slab ballastless track in ABAQUS, this paper analyzes the influence of the overall temperature, temperature gradient, CA mortar layer stiffness and voiding, and fastener system stiffness changes on the track system. The results show that the tensile stress of the track slab, the vertical displacement of the rail and the track slab and the vertical compressive stress of the mortar layer are all linearly related to the change of the temperature field, and increase with the increase of the temperature load. The stiffness of the fastener mainly affects the deformation of the rail. The damage of the CA mortar layer deteriorates the service performance of the track structure. The stiffness of the CA mortar layer has a great influence on the transverse tensile stress of the track slab. Both the length and width of the void have adverse effects on the rail, track slab and mortar layer. And when the void width reaches 1.5 m, the transverse tensile stress of the track slab reaches the maximum value, while the impact of the void height on the track system is relatively small. The outcomes provide a quantitative basis for establishing scientific maintenance thresholds and optimizing repair strategies, essential for ensuring the long-term serviceability of high-speed railway infrastructure. Full article

Point cloud intelligence integrates advanced technologies such as Light Detection and Ranging (LiDAR), photogrammetry, and Artificial Intelligence (AI) to transform transportation infrastructure management. This review highlights state-of-the-art advancements in denoising, registration, segmentation, and surface reconstruction. A detailed case study on three-dimensional (3D) mesh generation for railway fastener monitoring showcases how these techniques address challenges like noise and computational complexity while enabling precise and efficient infrastructure maintenance. By demonstrating practical applications and identifying future research directions, this work underscores the transformative potential of point cloud intelligence in supporting predictive maintenance, digital twins, and sustainable transportation systems. Full article

To address the insufficient multi-layer optimization of fastener and cushion stiffness in ballastless tracks for mixed passenger and freight railways, a vehicle–track coupled dynamic model is developed, and the effects of individual and combined stiffness parameters on track and vehicle dynamics are systematically analyzed. Based on this model, a multi-dimensional stiffness matching approach is proposed to determine appropriate stiffness ranges for mixed-use railways. Results indicate that fastener stiffness primarily affects the local dynamic response of the rail, whereas cushion stiffness has a stronger influence on overall track performance. When the damping pad stiffness exceeds 600 MPa/m, the fastener force increases sharply, posing a risk of accelerated structural deterioration. Differences in axle load and speed between passenger and freight trains induce distinct excitation patterns, leading to nonlinear variations in interlayer forces. The optimal stiffness combination is 50 kN/mm for fasteners and 600 MPa/m for damping pads under passenger conditions, and 40 kN/mm and 600 MPa/m, respectively, under freight conditions. Considering the operational requirements of mixed lines, a fastener stiffness of 40–50 kN/mm and a damping pad stiffness of 600 MPa/m are recommended. This study provides theoretical support for stiffness design and parameter optimization in ballastless tracks for mixed-use railways. Full article

Minor displacements and deflections of rail fastener clips pose a critical risk to railway safety, which are difficult to quantify accurately using traditional object detection methods. This paper proposes an improved YOLOv8-pose-based method, You Only Look Once version 8-pose with GAM, SPPF-Attention, and Wise-IoU (YOLOv8-pose-GSW) for automated and quantitative pose detection of fastener clips. Firstly, a high-precision keypoint detection network is constructed by integrating a Global Attention Mechanism (GAM) into the neck, enhancing the Spatial Pyramid Pooling Fast (SPPF) module to Spatial Pyramid Pooling Fast with Attention (SPPF-Attention) in the backbone, and adopting the Wise Intersection over Union (Wise-IoU) loss function. Subsequently, a posterior verification mechanism based on spatial constraint error is designed to eliminate unreliable detections by leveraging the inherent geometric priors of fasteners. Finally, the deflection angle, longitudinal displacement, and lateral displacement of the clip are calculated from the verified keypoints. Experimental results demonstrate that the proposed method achieves an Average Precision at IoU threshold from 0.5 to 0.95 (AP@0.5:0.95) of 77.5%, representing a 3.6% improvement over the baseline YOLOv8s-pose model, effectively balancing detection accuracy and computational efficiency. This work provides a reliable technical solution for the refined maintenance of rail fasteners. Full article

To address the challenges of improving energy balance and extending the operational lifetime of wireless sensor networks for Automated Railway Track Fastener Maintenance Robots (ARTFMR) along railways, this paper proposes an enhanced LEACH protocol incorporating Particle Swarm Optimization (PSO). Initially, network nodes are deployed, and their energy consumption is calculated to formulate a non-uniform deployment model aimed at improving energy balance, followed by network clustering. Subsequently, a routing protocol is designed, where the cluster head election mechanism integrates two critical factors—dynamic residual energy and distance to the base station—to facilitate dynamic and distributed cluster head rotation. During the communication phase, a Time Division Multiple Access (TDMA) scheduling mechanism is employed in conjunction with an inter-cluster multi-hop routing scheme. Additionally, a joint data-volume and energy optimization strategy is implemented to dynamically adjust the transmission data volume based on the residual energy of each node. Finally, simulations were conducted using MATLAB, and the results indicate that the proposed energy-balanced non-uniform deployment optimization strategy improves network energy utilization, effectively extends network lifetime, and exhibits favorable scalability. Full article

The mechanical performance of rail fasteners plays a crucial role in the track–structure interaction of high-speed railways. A reasonable lateral stiffness of the fastener system can enhance the stability and safety of train operation and prevent derailment accidents. Under seismic action, adjacent bridge spans undergo reciprocating displacement, causing the rail-fastener system near the beam ends to be subjected to lateral cyclic forces. To investigate the mechanical and deformation behavior of the WJ-8B fastener system under lateral loading, low-cycle reciprocating loading tests were conducted on the rail-fastener system considering different bolt torques. The load–displacement curves and torque–rotation curves of the fastener system were obtained, and formulas for calculating the characteristic values of the mechanical properties of the WJ-8B fastener system were fitted, which show good agreement with the experimental results. The results indicate that the lateral mechanical behavior of the WJ-8B fastener exhibits significant nonlinear characteristics, marked by three distinct inflection points in the load–displacement curve that delineate five stages: initial stage, rail shearing stage, rail sliding stage, rail contact stage, and three-point contact. The bolt torque is positively correlated with the lateral stiffness of the fastener system. Increasing the torque from 115 N·m to 190 N·m enhances the lateral bearing capacity by 29.06% in the push direction and by 38.74% in the pull direction. Meanwhile, the system torque decreases by 21.45% in the push direction and increases by 21.14% in the pull direction. Full article

Current research on the vibration characteristics of fastener clips primarily employs modal experiments combined with finite element simulations; however, limited attention has been given to the dynamic vibration behavior of clips during actual train operations. This study investigates both the quasi-static and dynamic vibration characteristics using an integrated approach of finite element simulation and dynamic testing. Based on the Vossloh W300-1 fastener system, a three-dimensional model is established. Modal and frequency response analyses, together with field test validation, reveal two significant vibration modes within 0–1000 Hz: a first-order mode at 500 Hz and a second-order mode at 560 Hz. These modes are characterized by vertical overturning of the clip arm. Dynamic testing demonstrates that the dominant frequency of the arm acceleration is strongly correlated with the second-order natural frequency, confirming that wheel–rail excitation readily triggers second-order mode resonance. The study further shows that, at train speeds of 200–350 km/h, rail corrugation with wavelengths of 99.2–173.6 mm induces high-frequency excitation at 560 Hz, resulting in resonance fatigue of the clip. As a mitigation measure, regular rail grinding is recommended to eliminate corrugation at critical wavelengths. Additionally, optimizing the clip structure to avoid resonance frequency bands is proposed. These findings elucidate the coupling mechanism between the vibration characteristics of the clip and dynamic loads, providing theoretical support for the safety evaluation of high-speed rail fastener systems and the vibration-resistant design of clips. Full article

Railway track fasteners, serving as critical connecting components, have a reliability that directly impacts railway operational safety. To address the performance bottlenecks of existing detection methods in handling complex scenarios with diverse fastener types and co-occurring multiple defects, this paper proposes a Type-Guided Expert Model-based Fastener Detection and Diagnosis framework (TGEM-FDD) based on You Only Look Once (YOLO) v8. This framework follows a “type-identification-first, defect-diagnosis-second” paradigm, decoupling the complex task: the first stage employs an enhanced YOLOv8s with Deepstar, SPPF-attention, and DySample (YOLOv8s-DSD) detector integrating Deepstar Block, Spatial Pyramid Pooling Fast with Attention (SPPF-Attention), and Dynamic Sample (DySample) modules for precise fastener localization and type identification; the second stage dynamically invokes a specialized multi-label classification “expert model” based on the identified type to achieve accurate diagnosis of multiple defects. This study constructs a multi-label fastener image dataset containing 4800 samples to support model training and validation. Experimental results demonstrate that the proposed YOLOv8s-DSD model achieves a remarkable 98.5% mean average precision at an Intersection over Union threshold of 0.5 (mAP@0.5) in the first-stage task, outperforming the original YOLOv8s baseline and several mainstream detection models. In end-to-end system performance evaluation, the TGEM-FDD framework attains a comprehensive Task mean average precision (Task mAP) of 88.1% and a macro-average F1 score for defect diagnosis of 86.5%, significantly surpassing unified single-model detection and multi-task separate-head methods. This effectively validates the superiority of the proposed approach in tackling fastener type diversity and defect multi-label complexity, offering a viable solution for fine-grained component management in complex industrial scenarios. 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