ABSTRACT This paper proposes a multifunctional barrier that can integrate anti-glare, noise reduction, and wind resistance functions on highway-railway bridges. A cross-river cable-stayed bridge is used as a representative case to evaluate multifunctional barrier performance. Optical simulations shows that the barrier effectively reduces the glare of the train headlights and reduces the maximum threshold increment of the inner and outer lanes to 3.77% and 4.26%, respectively, far below the limit of 10%. COMSOL acoustic simulations and experimental measurements confirmed that the barrier achieves an insertion loss of 7 ~ 8 dB(A), meeting design expectations. Parametric analysis identified optimal configurations with a barrier height of 3.0 m, a shielding angle of 8°, and an opening rate of 40%. The results demonstrate that the proposed barrier effectively balances anti-glare, noise reduction, and wind resistance, providing a technical reference for the integrated design of multifunctional barriers on road-rail same-deck bridges.

ABSTRACT Identifying the combined wheel-track irregularity power spectral density (PSD) from the vibration response at the tunnel wall (vibration source) has been demonstrated as an efficient approach. However, there is currently no model-driven analytical framework available for this inversion problem. This paper proposes an efficient approach to quantify the combined wheel-track irregularity spectrum from the vibration source. By integrating the periodic train-track and Pipe-in-Pipe (PiP) analytical models with the pseudo-excitation method (PEM), the relationship between the wheel-track combined PSD and the PSD of the vibration source is effectively established. Subsequently, an objective function is formulated within specific frequency bands and minimized to accurately identify the combined PSD. Finally, the proposed method is validated through two theoretical examples and one experimental case. The results demonstrate that the proposed inversion process is both accurate and efficient in identifying the wheel-track combined PSD whether derived from calculated or measured vibration sources while also maintaining robustness against white noise. A single identification event takes approximately 2 min while solving the optimization function requires only 10 s. The proposed method for identifying the combined wheel-track irregularity spectrum holds significant potential for practical application in actual engineering scenarios.

ABSTRACT A novel pile-supported box-type subgrade (PBS) is proposed to address the seismic shortcomings of traditional earthwork (TE) in high-speed railways. Three-dimensional finite element models of PBS and TE were established and compared under PGA levels of 0.1 g, 0.2 g, and 0.4 g. PBS reduced dynamic displacement by 33%-39%, showed lower peak accelerations with stronger high-frequency attenuation, and achieved a stress attenuation rate of 89.6%, indicating enhanced energy dissipation and wave-impedance matching. Fragility curves (PGA as IM, displacement as demand) further shifted right for PBS with higher IM50, implying a lower probability of damage exceedance than TE at the same intensity. The rigid “box-pile-soil” collaborative system therefore substantially improves seismic stability, supporting PBS deployment in seismically active and geologically complex regions.

ABSTRACT Aerodynamic noise from high-speed trains passing underground stations significantly affects the platform environment. This study investigates its generation mechanism and spatial distribution. An improved delayed detached-eddy simulation (IDDES) method captures the transient flow structures. Aerodynamic noise sources are predicted using the Ffowcs Williams-Hawkings (FW-H) equation, followed by far-field propagation via ray acoustics methods (RAM). Results indicate that the dominant frequencies of train components remain consistent across different operating stages. While train entry into the enlarged cross-section does not alter the distribution of surface sound pressure levels (SPLs), the overall source intensity significantly decreases. Train’s surface aerodynamic sources are the primary contributors to platform noise, with the maximum SPL reaching 77.9 dBA. The contribution of the train body (including head, middle, and tail cars) to platform noise ranges from 11.9% to 13.2%, making it the dominant source. Platform noise exhibits no dominant frequency, with its energy primarily concentrated below 1 kHz.

ABSTRACT This paper designs distance-constrained reference trajectories for trains that respect speed, acceleration, and jerk limitations. It constructs a piecewise-linear (with respect to distance) acceleration profile that verifies the specified jerk constraints, based on a specific first integral of the system. Inspired by the minimal-time synthesis, it provides a complete characterization of the points that can be connected while respecting the constraints imposed on the system. Allowing a maximum of three switches, it provides distance intervals that define the switching policy between two waypoints. Unlike the optimal synthesis, which defines a unique trajectory between two points, it proposes multiple trajectories, each adapted to the imposed distance. These trajectories are described in the mathematical proofs of two propositions that summarize our main results. These propositions are illustrated in three complete examples where a speed profile is generated between two stations in a distance-based framework. It is important to stress that all the provided results are analytic and, thus, compatible with a real-time implementation.

ABSTRACT The obstacle deflector is installed at the front end of trains to sweep obstacles from railways. Conventional obstacle deflectors neglect the obstacles caused by debris flows. To enhance the sweep and resistance reduction performance against debris flows, soil animal claw profiles served as references for the bio-inspired design of a novel obstacle deflector. A parametrization method for claw profiles was proposed based on a Bezier curve of three control points, which was applied to the bio-inspired profile design of obstacle deflectors, thereby proposing a design method for bio-inspired obstacle deflectors (BODs) defined by design parameters α and β. Based on an experimentally validated numerical method which coupled the smoothed particle hydrodynamics (SPH), the discrete element method (DEM) and the finite element method (FEM), the effects of scenario parameters (impact speed and debris depth), design parameters (α and β) and debris flow types on the obstacle deflector-debris flow interaction were investigated. The results indicate that higher impact speed causes greater resistance. Higher debris depth reduces the sweep performance. Through changing the geometric shape of BODs, decreasing α and increasing β enhance the sweep performance, but increasing α and decreasing β reduce platform resistances. Changing the debris flow type does not affect correlations between design parameters and platform resistances. The final BOD configuration (α = 80°, β = 5°) reduces Z-platform resistance by 56.72% while increasing X-platform resistance by only 2.67%, demonstrating a superior performance of resisting the vertical impact of debris flows compared to the prototype obstacle deflector.

ABSTRACT The rail corrugation observed on ladder sleeper tracks in small-radius curves is often attributed to resonance and self-excited vibration theory, but reliable field validation remains scarce. This study conducted long-term field monitoring of rail corrugation on small-radius subway curves, analysing its geometric characteristics, profiles, straightness, hardness, and metallographic evolution over time and space. The relationship between track vibration and rail corrugation was also studied using finite element modelling and steady-state dynamic analysis. The results reveal that rail corrugation exhibits mixed wavelengths. After rail grinding, low rail wear increases rapidly before stabilizing, while high rail wear initially progresses slowly and then accelerates. The high rail undergoes more severe plastic deformation and work hardening than the low rail. Within two months of grinding, White Etching Layers (WELs) begin forming, leading to slow corrugation development. From two to six months, WELs form in wheel-rail sliding regions, increasing hardness at corrugation peaks and accelerating wear. The lateral overturning resonance of the entire ladder sleeper track aligns with the frequency band associated with the 200–250 mm wavelength corrugation excitation, while the coupling of vertical and lateral modes may contribute to the generation of 100–125 mm wavelength corrugation. The frequency response analysis indicates show that the 40–60 mm short-wavelength corrugation observed on small-radius curved ladder sleeper tracks is more likely related to lateral force excitation. This study provides a foundation for the optimization of track structures.

ABSTRACT Numerical simulation of rail vehicle dynamics has been developed over more than half a century, progressively enhancing the scope and accuracy of the numerical models with the increasing availability of computational resources. The rapid advancement of Hardware-in-the-Loop (HiL) testing and digital twin is recently fostering further development of numerical methods for the design of rail vehicle technologies. However, these promising technologies impose stringent demands on the computational efficiency of the numerical models to facilitate real-time simulations, imposing the search of a trade-off between accuracy and computational efficiency. A critical aspect for enhancing both model accuracy and efficiency is the modelling of wheel-rail contact. In this paper, we propose the use of the Kalker Book of Tables for Non-Hertzian Contact (KBTNH) in a case study addressing the feasibility of HiL testing of suspension components. In our tests, a bogie model incorporating a real yaw damper was used to assess the damper’s impact on vehicle stability. The assessments show that the model with the KBTNH contact algorithm not only significantly improves accuracy compared to the Vermeulen-Johnson algorithm but also remarkably reduces computing time compared to FASTSIM, demonstrating excellent performance in balancing accuracy and computational demands. Consequently, the KBTNH model is considered as an effective solution for meeting the challenging demands of real-time simulations and can be broadly applied in HiL testing and extended in the future to digital twin applications.

ABSTRACT Wheel wear is an unavoidable consequence of high-speed train operation, and the life of a wheel depends on its maximum wear limit. The regular turning of wheels in order to counteract wear results in a progressive reduction in wheel diameter. A comprehensive understanding of the temporal pattern of wheel tread wear and the consequent changes in wheel performance following diameter reduction is fundamental to reducing the wear limit value and thereby extending wheel life. This thesis focused on the wheels of CRH3 high-speed trains, with an analysis of the distribution characteristics of tread wear over a distance of 100,000 km in service. A wheel refinement simulation model was developed to calculate and discuss the stress variation laws during the wheel diameter reduction process. Furthermore, the study investigated the change in metallographic organization and hardness on the tread surface during the diameter reduction process. The results indicate that the average tread wear over 100,000 km is around 0.25–0.4 mm, with no clear pattern of increase over the years. As the diameter of the wheel decreases, the strength factor of the wheel decreases at a significantly accelerated rate. Meanwhile, the microstructure of the tread material undergoes significant changes, with the ferrite strengthening effect essentially diminishing. This observation is confirmed by subsequent hardness tests on the tread.

ABSTRACT The increasing prevalence of railway transportation has exacerbated rail vibration, which predominantly occurs in the wide frequency range of 500–2500 hz. While conventional rail absorbers effectively suppress rail vibration at specific frequencies, broadband suppression remains challenging. An innovative rail absorber utilizing acoustic black hole (ABH) effects is presented in this paper. The absorbers, distributed periodically along the rail length, entail exceptional flexural wave focusing effects through thickness tailoring to the power-law profile. Numerical analyses reveal three distinctive flexural wave suppression mechanisms enabled by this absorber: bandgaps near pinned–pinned resonance frequencies arising from periodically mounting, ABH-enabled broadband energy focusing and damping at medium and high frequencies, and dynamic absorber effects at specific resonance frequencies. The integration of these suppression effects leads to effective broadband rail vibration control. Parametric studies are conducted to provide guidance for absorber optimal design, and experiments validate the effectiveness of the ABH absorbers in broadband rail vibration control, advancing the development of next-generation rail absorbers.