Search Results (226)

This work presents the design of a novel multi-component surface-coating system incorporating expandable graphite (EG), ammonium polyphosphate (APP), aluminium tri-hydroxide (ATH), alginate, and D-glucosamine hydrochloride (DGH). Importantly, the coated polyurethane (PU) foams demonstrated performance within the corresponding Hazard Level 3 limits for the measured parameters, including Maximum Average Rate of Heat Emission (MARHE), smoke density, and toxicity, providing preliminary indications of their potential for railway fire safety applications. Systematic variations in EG loading revealed substantial improvements in flammability metrics, with the EG-rich formulation achieving a limiting oxygen index (LOI) of 73%, MARHE of 18 kW m⁻², and significantly reduced smoke production. EG transformed the fire behaviour even at high external heat fluxes from flaming to self-extinguishing and only smouldering, promoting rapid formation of a dense, thermally insulating char. Combined interactions between EG, inorganic, and biobased additives reinforced char integrity, suppressed degradation rates, and enhanced condensed-phase protection. Thermogravimetric analysis confirmed increased residue yields (up to 52 weight percentage at 600 °C). Overall, this multi-functional coating offers a cost-effective, low-toxicity strategy for producing flame-resistant PU foams for demanding transportation and construction applications. Full article

Railway safety is an important component of public security. Ensuring the safety of high-speed rail systems and passengers is also crucial for railway transportation enterprises. The performance of X-ray security inspection systems is one of the key factors in improving intelligent railway security. Previous studies have shown that, due to the complexity of X-ray images, both traditional vision methods and deep learning approaches struggle to meet the requirements of real-world railway security inspection. With the development of vision-language models, this paper proposes XrayCLIP, a CLIP-based method designed to improve the accuracy and robustness of computerized X-ray security inspection. XrayCLIP adapts CLIP to the semantic and imaging characteristics of prohibited-item inspection through security-oriented prompts, texture-aware visual representations, and global–local supervision. The key component of the model is a set of learnable prompt templates, which guide the model to learn generic features of prohibited objects in complex environments. Multi-level global–local (glocal) features enable the model to focus on both global context and local details, while text space optimization, texture enhancement, text–image fusion, and inference enhancement further improve model performance. XrayCLIP is evaluated on the PIDray and derived HiXray(seg) benchmarks against eight conventional and recent single-view baselines under a common evaluation protocol. A railway-station study is additionally conducted using operational X-ray data, including a same-set missed-detection comparison with a commercial system for knives and power banks. The results show that XrayCLIP achieves the best performance among the evaluated methods on PIDray and HiXray(seg), while reducing the missed-detection rate relative to the commercial system on the two categories examined. Full article

This study investigates track sand deposition on the leeward side of subgrade windbreak walls along the Xinjiang section of the Lanzhou–Xinjiang High-Speed Railway. Numerical simulations and wind tunnel tests were conducted to compare flow-field reconstruction, sand transport, and track sand deposition under three structural configurations. The results show that a strong shear layer and a large-scale recirculation vortex form behind a single windbreak wall. The local reverse velocity reaches approximately −10 m/s, which can entrain sand particles back toward the track area. Adding a second wall at the leeward slope toe reduces near-surface wind speed to some extent, but local vortices and high-shear zones remain. In contrast, placing checkerboard sand barriers at the leeward slope toe effectively weakens near-surface recirculation and bed shear. This configuration maintains surface shear stress near the track below 0.5 Pa and reduces sand concentration by approximately 60–80% compared with the single-wall structure. At wind speeds of 15–30 m/s, the checkerboard sand barrier maintains strong sand-reduction performance. Near-surface peak sand concentration decreases by about 38–75%, and track sand deposition decreases by about 42–43% relative to the single-wall structure. These findings indicate that checkerboard sand barriers on the leeward side of windbreak walls can substantially reduce the risk of secondary sand deposition induced by the walls. The proposed leeward-side protection measure can effectively mitigate sand accumulation on railway infrastructure, thereby improving the long-term operational safety, resilience, and sustainability of high-speed railways in desert environments under increasing wind–sand hazards. Full article

Passenger satisfaction is a key component of sustainable urban mobility, influencing public transport use, customer loyalty, and the attractiveness of railway systems. However, evidence from Latin American commuter rail services remains limited. This study evaluates the satisfaction of frequent users of the Limache–Puerto railway service operated by EFE Valparaíso in Greater Valparaíso, Chile, based on measurements conducted between 2024 and 2025. Using 400 surveys administered on station platforms and onboard trains, the analysis assessed overall satisfaction, Net Promoter Score (NPS), and experience attributes related to safety, predictability, cleanliness, information provision, comfort, and crowding. A repeated cross-sectional quantitative design with quota sampling was employed to compare successive measurement waves. Results indicate that passengers highly value the service’s speed and efficiency. Although NPS experienced a temporary decline during 2025, the final measurement remained comparable to the 2024 baseline. Key concerns included perceived platform safety, peak-hour crowding, onboard environmental conditions (temperature and odors), and service frequency in critical segments. Mentions of informal vendors decreased, whereas concerns regarding criminal incidents and passenger flow difficulties increased. The findings highlight the need for targeted interventions in safety, crowding management, environmental quality, and communication during disruptions. This pilot operational monitoring study proposes a practical framework for evaluating passenger satisfaction and NPS through repeated measurements, providing evidence to support service management and sustainable railway planning. Full article

Railway transport management has changed dramatically over the past 50 years. The advent of computer technology and the capacity for information transmission brought greater safety and the ability to remotely control interlocking devices. These enable the centralisation of railway transport management, leading to higher operational efficiency and reduced staffing costs. At the same time, this technological progress has enabled the development of additional automation functions, which we can abbreviate as ARS (Automated Route Setting). The international designation Automatic Route Setting (ARS) includes actions that enable the automation tool to execute instructions to the signal box without the intervention of operating personnel (the dispatcher). Their importance increases with line speed and the size of the remotely controlled area. Thanks to them, the dispatcher gains time because the ARS can automatically resolve some operational situations or allow the dispatcher to address them in advance, thereby distributing the workload over a wider time window. However, the interlocking system itself remains the primary safety mechanism and will prevent ARS if any element of the infrastructure is occupied. At the same time, it is not possible to automate safety-critical functions that require direct assistance from the operating personnel. In the article, the authors analysed functions in which ARS is currently widely used. In the next part, they focused on the possible expansion of the palette of these functions that could be included in the ARS regime using multi-criteria analysis. The WSA method was applied using data obtained from routine users of the system. This approach enabled the incorporation of practical operational experience into the evaluation process and provided an empirical basis for assessing and prioritising the analysed functions. The next step was a safety-critical analysis and determination of the conditions under which they could be included in the ARS regime. The safety-critical functions are left aside. It is assumed that these will still have to be performed by the operator, not by the ARS. Detailed implementations and quantification of their impacts on the dispatcher’s activities are then carried out for selected ARS functions. The analysis therefore yields a prioritised ranking of ARS functions, indicating the order in which their implementation would be most appropriate from an operational perspective. This ranking provides a systematic basis for the phased deployment of ARS functionalities, considering their expected operational benefits and practical applicability in railway traffic management. The last part of the article is a look into the future, because the development in the field of safe communication between the train and the infrastructure (V2I) and the transmission of valid information provides many new challenges not only in the field of ARS itself, but also in the optimisation of the entire process of managing and organising rail transport. If we can use the ARS functions today, it is only a matter of technical development to be able, for example, to guide trains to the exact time when a train route will be built for this train. This will also enable optimising the train’s energy consumption and tracking capacity use. The ideal state is when the infrastructure fully communicates with the train in GoA4 mode and optimises both the train’s ride and the use of the infrastructure. Full article

Railway transportation networks increasingly share constrained corridors with transmission lines, buried pipelines, and other linear infrastructure. Electromagnetic interference in these corridors is important for safe railway planning and operation, particularly when nearby high-voltage lines cross oil and gas pipelines. This paper investigates transmission-line-induced pipeline potential under crossing conditions in the Zhangbei region. The CDEGS moment-method framework is applied with locally refined segmentation in the crossing regions, and an electromagnetic coupling model for multiple-crossing transmission line-oil and gas pipeline systems is established. The qualitative effects of crossing angle and parallel length on pipeline potential were obtained under both normal operating conditions and single-phase ground fault transient conditions. The results show that induced voltage decreases nonlinearly as the crossing angle increases and rises markedly with crossing length. The contribution of ground potential rise during transient processes to pipeline potential is significantly greater than that during steady-state processes. Installing zinc ribbons as a drainage measure can reduce the pipeline-to-ground voltage. However, supplementary mitigation measures may still be required under severe interference conditions. These findings are relevant to railway transportation because railway corridors often coexist with transmission lines and buried pipelines, making coordinated electromagnetic compatibility assessment essential for infrastructure safety and operational reliability. The proposed framework supports corridor planning, risk assessment, and protective design for railway-related infrastructure in complex shared corridors. Full article

The fatigue failure of railway axles is directly associated with the operational safety of trains. As 25CrMo4 steel is commonly employed for high-speed train axles, precise evaluation of its fatigue life is essential for transportation reliability. This study compared six machine learning models following hyperparameter optimization via a differential evolution algorithm. The DE-optimized Gaussian process regression (DE-GPR) model exhibited superior predictive performance, achieving a coefficient of determination (R²) of 0.8020 and a root mean square error (RMSE) of 0.1250 on the most significant outer test fold. Furthermore, an interpretable analysis of the model utilized a combination of SHapley Additive exPlanations (SHAP) and partial dependence plots (PDP) to elucidate feature importance. The results indicate that the applied stress level is the predominant feature affecting fatigue life predictions and that it slightly interacts with surface residual stress and full width at half maximum to influence the predicted fatigue life. This study can provide valuable insights into the fatigue life assessment and process optimization of 25CrMo4 steel components. Full article

Wind-blown sand threatens railway safety in arid regions. Existing measures mainly protect the windward side and cannot fully prevent particles from crossing the embankment. These particles can be re-entrained by leeward flows and redeposited on the track. This study combines wind tunnel experiments, large eddy simulation, and field observations to examine leeward-side protection for a high railway embankment. Three configurations are tested: no protection, baffles on the leeward slope, and a checkerboard barrier at the slope toe. The results show clear differences in flow structure and sand transport. Without protection, flow reattaches within 2–3 H (H is the height of the embankment) and near-surface velocity reaches 10–11 m/s. With baffles, reattachment shifts to 3–4 H and velocity decreases to 7–9 m/s. With a checkerboard barrier, reattachment is delayed to 4–5 H and velocity reduces to 4–6 m/s, forming a stable low-velocity zone. Surface shear stress decreases from 0.4–0.5 Pa to 0–0.2 Pa, and particle concentration near the shoulder drops by about one order of magnitude. Particle transport is weakened and deposition concentrates at the slope toe. Subgrade sand accumulation decreases from 350–480 g/min to 170–250 g/min. Field results confirm these trends. The checkerboard barrier effectively limits sand movement and improves deposition stability. The proposed leeward-side protection measures can effectively reduce sand accumulation on railway infrastructure, thereby improving the long-term operational safety, resilience, and sustainability of railways in desert environments under increasing wind–sand hazards. Full article

With the integrated development of high-speed railways and urban underground rail transit, large high-speed railway station buildings are often seamlessly connected or even co-constructed with subway structures, forming a complex structural system that integrates high-speed rail, subway, and station buildings. To investigate the dynamic performance of such “ integrated station-bridge” station buildings constructed with subways, this paper takes Yichang North Station as an engineering case study and examines its vertical dynamic characteristics under multi-source train-induced loads. The station adopts a structural configuration where the station tracks are fully integrated with the station building, while the main lines are separated from it. To accurately simulate the entire process of train operation, this study established a refined “train-track-station” spatially coupled dynamics model that incorporates high-speed and subway trains, tracks, and the station structure. Based on this model, various operational scenarios were systematically analyzed, including high-speed trains passing at different speeds, parallel operation of multiple train lines, and combined operation of high-speed and subway trains. The results demonstrate that, when single or multiple high-speed train lines pass through the station at the design entry speed of 80 km/h, the vertical vibration acceleration of the elevated waiting level meets human comfort standards. The train-induced vibration response is transmitted and superimposed along the “column–beam–slab” path, resulting in localized acceleration peaks at the mid-span regions of beams and slabs directly above the tracks. Second, the impact of subway train operation alone on the vibration of the elevated level is significantly weaker than that of high-speed trains. Furthermore, under combined high-speed and subway train operations, the additional vibration contribution from subway trains shows a decreasing trend as the number of simultaneously operating high-speed train lines increases. The findings of this study validate the effectiveness of the structural design of Yichang North Station in terms of train operational safety and passenger waiting comfort. The revealed patterns of multi-source vibration transmission and superposition can provide important theoretical and numerical references for the dynamic optimization design and vibration control of similar integrated transportation hub structures. Full article

Increasing the efficiency of the railway industry requires the creation of solutions aimed at improving the technical, economic, and operational performance of wagons. It would contribute to reducing the cost of their operation. One of the most damaged elements of wagon bodies is their paneling. Its damage not only affects the loss of cargo during transportation but also threatens the safety of the movement of goods. The article is aimed at the load analysis of the body of an open wagon, whose paneling is sandwiched with corrugated panels. This solution will improve the strength of the side walls of the body of the solved freight wagon. This hypothesis has been accepted based on the dynamic load as well as the strength calculated for the body of the solved freight wagon. The dynamic load of the open wagon body has been studied with a mathematical model of its oscillations during the lateral roll. The solution to this model has shown that the maximal values of accelerations are lower by 5% than those acting on the standard design, and they act on the body of the solved freight wagon. The values of accelerations, which act on the body of the solved freight wagon, were calculated by means of numerical simulations using the finite element method implemented in the SolidWorks Simulation software. The discrepancy between the results of mathematical modeling and computer modeling is 6.5%. The strength of the open wagon body has also been calculated. It has been found that the maximal values of stresses in the paneling were lower by 17% than those acting in a standard body structure and 12% lower than the stresses in the body with corrugated panels. The study has also included an analysis of the modal properties of the body of the solved freight wagon, which demonstrates that the safety of the open wagon in motion is observed. The studies conducted will be useful in developing proposals for the creation of the newest wagon designs, including the improved economic, operational, and technical characteristics. Full article

High friction composite brake shoes containing reinforced steel fibers are now widely used in freight train tread braking systems. With the demand for higher transportation efficiency on railway lines with long steep slopes, it is necessary to explore the braking capabilities of existing general freight train high friction composite brake shoes under continuous braking conditions. In this paper, continuous braking tests at different speed levels were conducted using a friction and wear test rig. Through material characterization and interface damage analysis, it was found that reinforced steel fibers can exist as a contact platform at the brake shoe friction interface. Due to the strip-like morphology and high strength features of steel fibers, even after the steel fiber layer is fragmented, it can still promote the formation of a continuous contact platform with complex material composition on the surface, maintaining the progress of the braking process. For existing general freight train high friction composite brake shoes, at speeds up to 80 km/h, although the friction coefficient decreases to some extent, the wear rate maintains a relatively low range. When the speed increases to 100 km/h, the friction coefficient of the braking interface deteriorates severely, and the wear rate of the brake shoe increases sharply, seriously endangering braking safety. The research results reveal the evolution of wear behavior of high friction composite brake shoes containing reinforced steel fibers at different speed levels, providing theoretical support for exploring the braking capabilities and design optimization of brake shoes. Full article

The Unmanned Aircraft System Traffic Management (UTM) system is designed to autonomously coordinate dense Unmanned Aerial Vehicles (UAVs) within shared airspace, ensuring both the efficiency and safety of aerial traffic. With the rapid proliferation of UAV applications, autonomous UTM systems have become increasingly essential, motivating various stakeholders to develop their distinct UTM solutions. However, due to the lack of common guidelines, these emerging solutions exhibit substantial incompatibilities, which hinder the transferability of existing techniques and the overall standardization of UTM. To address the fragmentation, this paper provides a systematic survey of existing UTM research and identifies commonalities across various UTM systems. Specifically, this paper summarizes core UTM service modules and groups them with similar objectives, thereby proposing a unified UTM framework with four layers: Fundamental Infrastructure, Pre-flight UTM, In-flight UTM, and UTM Application. Based on the framework, existing solutions for each module are reviewed in detail. Furthermore, this paper draws analogies between UTM systems and more mature transportation systems, like railways, to identify transferable solutions and derive UTM future trends. This survey aims to clarify the current state of UTM research and provide guidance for future studies in this field. Full article

With the rapid development of railway and intelligent transportation systems, the construction of security systems along high-speed railways has attracted more and more attention. In this paper, we propose a fiber distributed acoustic sensing (DAS) intrusion detection system to detect and identify the intrusion events that threaten the operational safety of high-speed railways. Firstly, we use the DAS system to collect the optical fiber signals around the high-speed railway. Then we design a window to slide the optical fiber signals along the time axis to form the intensity images with the spatio-temporal signal features. After that, we propose a novel framework that integrates the feature pyramid network (FPN) and the Faster R-CNN to extract the features from the fiber signal intensity images to improve the detection rate and recognition rate of the system for high-speed railway intrusion events. Experimental results indicate that the system can identify five kinds of intrusion events. The average detection accuracy can reach 95.51%, and the F1 score of each intrusion event is above 93% on the real dataset. In addition, the system can identify the background noise interference generated by passing trains, and the detection accuracy is 95%, which can significantly reduce the false alarm rate. Full article

Reliable high-precision positioning in railway tunnels is essential for intelligent train operation and safety monitoring, yet GNSS signals are severely degraded by blockage and multipath. This paper proposes a deployment-oriented numerical framework to optimize pseudolite layouts in tunnels by explicitly modeling visibility obstruction and controlling worst-case geometry along the train trajectory. A high-fidelity 3D tunnel–train model is established, in which line-of-sight (LoS) availability is screened under vehicle occlusion and trajectory-level geometric quality is evaluated accordingly. Instead of optimizing only the average PDOP, the proposed framework minimizes the trajectory 90th-percentile PDOP (qPDOP) to suppress tail-risk geometric degradation, while interpreting PDOP as an error amplification factor that directly affects positioning reliability under measurement noise and local multipath. The core contribution is a Voronoi-partition-constrained improved genetic algorithm (IGA) for tunnel pseudolite deployment. Voronoi partitioning enforces segment-wise coverage by requiring at least one pseudolite in each partition cell and avoids clustering-induced blind zones. Meanwhile, the IGA incorporates improved search and constraint-handling mechanisms to satisfy practical engineering requirements, including feasible installation regions, minimum spacing, mounting-face balance (ceiling/side walls), communication range, and continuous satellite visibility. Comparative simulations and ablation studies demonstrate that the proposed method achieves more uniform coverage and significantly improves full-trajectory geometric stability, reducing high-quantile PDOP and mitigating local spikes in occlusion-sensitive sections under cost-constrained sparse deployments. The proposed framework provides a practical and flexible toolchain for designing positioning-oriented pseudolite infrastructures in underground transportation environments. Full article

Mixed steel/polyethylene gas distribution pipelines are increasingly used in congested urban environments where conventional layouts are restricted by existing underground utilities, safety constraints, and site-specific construction conditions. In such systems, buried steel transition sections may become particularly vulnerable to electrical perturbation and corrosion, especially when installed near electrified transport infrastructure. This paper presents a field case study on a recently installed mixed steel/polyethylene gas distribution pipeline located on Lunca Street, Petroșani, Romania, approximately parallel to an electrified railway. Electrical and electrochemical investigations were carried out eight months after installation and included 24 h monitoring of pipe-to-soil potential versus Cu/CuSO₄, 24 h monitoring of alternating current pipe-to-soil voltage, mixed alternating current and direct current signal visualization, and coating insulation resistance measurements. The results showed that alternating current pipe-to-soil voltage was present at all monitored points, with weighted mean values ranging from 0.41 to 1.23 Vrms, while pipe-to-soil potential values ranged from −0.120 to −0.238 V versus Cu/CuSO₄. Although the measured average coating insulation resistance remained relatively high, the combined electrical and electrochemical data indicate that alternating current interference associated with the nearby electrified railway is the most plausible dominant contributing source of the recorded electrical perturbation. Within the analyzed site perimeter, no other nearby electrical infrastructures with comparable interference potential were identified. The highest alternating-current exposure and the least favorable electrochemical values were recorded on the longer metallic segment, showing that metallic length and local configuration strongly influenced the severity of the effect. A mitigation strategy based on polarized electrical decoupling and dedicated grounding is proposed as a practical means of improving electrical safety and reducing corrosion risk in the exposed and buried steel sections. Full article