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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Modelling and application of yaw damper with frequency-selective damping on railway vehicles</title>
      <link>https://trid.trb.org/View/2673001</link>
      <description><![CDATA[In this study, a new mechanical yaw damper with frequency-selective damping (FSD) is investigated. The structure principle, modelling and simulation of the damper and its core component, the frequency-selective damping valve, are elaborated. Compared with the conventional damper, the static and dynamic characteristics of the FSD damper have been tested in the experimental bench, and the damping variation rate is proposed to evaluate the damping force variation. A physical parameter model of the yaw damper is established by using the AMESim software, and the simulation accuracy has been verified by comparing the simulated results with the experimental ones. A detailed analysis has been performed for the influence of key parameters of the FSD valve on the mechanical characteristics of the FSD damper. Finally, through the AMESim/Simpack co-simulation method, the dynamic performances of a high-speed locomotive equipped with the FSD yaw damper have been simulated. The results indicate that the FSD yaw damper improves the adaptive stability of railway vehicles in different wheel–rail matching states. In addition, the dynamic performance of the vehicle can be improved when passing through the turnout and narrow curves.]]></description>
      <pubDate>Wed, 27 May 2026 13:10:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2673001</guid>
    </item>
    <item>
      <title>Image-traced flow behavior and frequency-dependent response of ballasted trackbed under dynamic loads</title>
      <link>https://trid.trb.org/View/2663870</link>
      <description><![CDATA[The continuous movement of ballast particles beneath the sleeper under long-term dynamic train loads is a primary factor contributing to the development of trackbed settlement, which becomes more pronounced under high-speed train operations. However, due to the concealed nature of such phenomenon, it is challenging to observe experimentally. In this study, a full-scale model test incorporating image-assisted measurement techniques was conducted. Approximately 1000 dyed ballast particles of varying sizes were uniformly distributed over a representative section of the trackbed as tracer particles. A combination of digital and high-speed cameras (recording at 1000 frames per second) was used to capture and analyze the trajectories of ballast particles under varying train speeds, axle loads and long-term loading conditions. The testing results indicate that the ballast layer remained in a stable state with limited particle migration when the loading frequency was below 15 Hz (equivalent to 273 km/h). However, once this threshold was exceeded, ballast migration increased sharply, accompanied by a noticeable loss of stability. Furthermore, a positive correlation was observed between the axle load amplitude and the extent of ballast flow. For axle loads below 8 tons, ballast migration was primarily governed by contact forces between the ballast particles. Beyond this limit, movement near the sleeper end increased sharply, indicating a shift in the controlling mechanism from contact force dominance to interaction between contact forces and boundary constraints. The varying constraint conditions then caused regionalized flow pattern beneath the sleeper, leading to non-uniform compaction within the trackbed. Furthermore, this process induced a characteristic periodic settlement development of the sleeper. The initial stage was marked by rapid settlement due to particle rearrangement. This was followed by a second increase in the settlement rate as the high-frequency energy input caused the particle skeleton to disintegrate. Finally, as a new stable skeleton formed, the settlement approached a shakedown state without further significant development.]]></description>
      <pubDate>Mon, 11 May 2026 08:50:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663870</guid>
    </item>
    <item>
      <title>Line tests of wheel-rail adhesion recovery under braking using an electric multiple unit train</title>
      <link>https://trid.trb.org/View/2657051</link>
      <description><![CDATA[Rail surface contaminations causing wheel-rail low adhesion problems may gradually be cleaned by passing wheelsets, leading to the phenomenon of adhesion recovery. This suggests an enhancement in available adhesion under low adhesion conditions for a train composed of multiple coaches. Using a four-coach Electric Multiple Unit (EMU) metro train equipped with a wheel slide protection system, field tests are conducted on a test line to measure the adhesion recovery rate of braking wheelsets under soapy water contamination. Initial braking speeds range from 100 km/h to 140 km/h, and tests under dry conditions are also conducted for reference and braking force calibration. Instantaneous creepages for different wheelsets are determined by recorded train speeds and rotational speeds of wheelsets, and the corresponding creep forces are calculated by measured vehicle speed, angular speeds of wheelsets, and brake cylinder pressures. Creep curves for different wheelsets are then obtained in consideration of the calculated axle load transfer. Adhesion coefficients corresponding to friction saturation are further derived for sliding wheelsets, typically located in the leading part of the train, with a maximum measured creepage of up to 11%. The number of passing wheelsets required to achieve adhesion recovery meeting braking requirements is also identified. The results indicate that the adhesion coefficient is as low as approximately 0.075 of the 1st axle at speeds between 93 and 132 km/h, with an adhesion recovery rate of 0.0040/axle among the first seven wheelsets. Such measurement technology holds potential application in operational trains, as it requires no significant modifications.]]></description>
      <pubDate>Wed, 29 Apr 2026 09:10:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2657051</guid>
    </item>
    <item>
      <title>Drive-by spatial offset detection for high-speed railway bridges based on fusion analysis of multi-source data from comprehensive inspection train</title>
      <link>https://trid.trb.org/View/2663188</link>
      <description><![CDATA[The spatial offset of bridge has a significant impact on the safety, comfort, and durability of high-speed railway (HSR) operations, so it is crucial to rapidly and effectively detect the spatial offset of operational HSR bridges. Drive-by monitoring of bridge uneven settlement demonstrates significant potential due to its practicality, cost-effectiveness, and efficiency. However, existing drive-by methods for detecting bridge offset have limitations such as reliance on a single data source, low detection accuracy, and the inability to identify lateral deformations of bridges. This paper proposes a novel drive-by inspection method for spatial offset of HSR bridge based on multi-source data fusion of comprehensive inspection train. Firstly, dung beetle optimizer-variational mode decomposition was employed to achieve adaptive decomposition of non-stationary dynamic signals, and explore the hidden temporal relationships in the data. Subsequently, a long short-term memory neural network was developed to achieve feature fusion of multi-source signal and accurate prediction of spatial settlement of HSR bridge. A dataset of track irregularities and CRH380A high-speed train responses was generated using a 3D train–track–bridge interaction model, and the accuracy and effectiveness of the proposed hybrid deep learning model were numerically validated. Finally, the reliability of the proposed drive-by inspection method was further validated by analyzing the actual measurement data obtained from comprehensive inspection train. The research findings indicate that the proposed approach enables rapid and accurate detection of spatial offset in HSR bridge, ensuring the long-term operational safety of HSR bridges.]]></description>
      <pubDate>Fri, 24 Apr 2026 08:55:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663188</guid>
    </item>
    <item>
      <title>Evolution of isolated heaving defects for vertical rail displacements: a multi-disciplinary study</title>
      <link>https://trid.trb.org/View/2655762</link>
      <description><![CDATA[Track heaving defects are likely caused by multiple complex factors, including irregular superstructure displacement and frost-induced expansion of subgrades and subsoils. These defects can significantly disrupt normal train operations. Early detection and trend prediction of such defects are essential for implementing effective predictive maintenance, enabling maintenance prioritization, and reducing both costs and operational disruptions. However, rail geometry profiles often exhibit non-stationary and complex characteristics, making the identification of isolated defects challenging. While most current studies focus on evolution of defect magnitude, the impact of defect length on train–track interaction remains largely unexplored. Furthermore, understanding the natural degradation process of isolated defects is complicated by maintenance activities that disrupt the development of track defects. To address these challenges, a multi-disciplinary approach was employed, incorporating signal processing techniques, multibody dynamics simulations, and geotechnical site investigations to identify, characterize, and analyse the effects of defect evolution on the train-track system. A 50-km section of measurement train data, collected over a five-year period, was analysed to examine the impact of both defect amplitude and length evolution on train performance, including operational risks and passenger comfort. Statistical analysis of the location, magnitude, and length of isolated heaving defects, along with their evolution patterns, was conducted. The findings were synthesized into an evolution diagram of train performance based on changes in defect profiles and applied to real-world railway data.]]></description>
      <pubDate>Thu, 09 Apr 2026 10:08:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655762</guid>
    </item>
    <item>
      <title>On the vibration induced by train operations in tunnels: a comparative study of different track systems through experiments and numerical simulations</title>
      <link>https://trid.trb.org/View/2655753</link>
      <description><![CDATA[The ground-borne vibration problem has been remarkably relevant in the railway field, particularly concerning annoyance in nearby buildings. This is especially true for vibrations induced by underground railways in densely populated areas. In this article, a train-track interaction model in the frequency domain is integrated with the Pipe-in-Pipe (PiP) analytical formulation. The train-track-tunnel model is employed to examine the influence of various track systems on vibrations transmitted in tunnels. A direct fastening system with hard baseplate is compared to a soft baseplate solution, a track with booted sleepers and a floating slab. The track dynamics is introduced by calibrating the model against impact tests on the track systems installed in different metro lines. These results suggest that, although the installation of floating slabs provides the highest performance in mitigating ground-borne vibrations in the frequency range 20–250 Hz, other solutions still offer significant benefits and could be considered as potentially more cost-effective alternatives for the design of low-vibration metro lines.]]></description>
      <pubDate>Wed, 08 Apr 2026 13:57:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655753</guid>
    </item>
    <item>
      <title>Effect of operating conditions on the time-frequency characteristic of high-speed vehicle-turnout dynamic interaction using synchrosqueezed wavelet transform</title>
      <link>https://trid.trb.org/View/2647000</link>
      <description><![CDATA[Structural irregularities are a primary source of vibration when vehicles traverse turnouts. This study investigates their impact on the time-frequency characteristics of vehicle dynamic responses under varying operating conditions, focusing on the crossing zone of a No. 18 ballastless high-speed railway turnout. A vehicle-turnout coupled dynamic model incorporating rail flexibility is developed, and the time-frequency features of vehicle responses under different conditions are analysed. The results reveal that structural irregularities in the crossing zone lead to higher peak values and more pronounced high-frequency components (250–850 Hz) in vertical wheel/rail forces in the facing direction compared to the trailing direction. Furthermore, the vertical vibration acceleration of the point rail in the facing direction exhibits higher peak values, greater energy in dominant frequency components, and the emergence of a new dominant frequency band (70–150 Hz). Differences in vertical wheel/rail forces and point rail vertical vibration acceleration across vehicle types are primarily evident in the high-frequency range (above 150 Hz). Additionally, increasing speed amplifies dynamic response amplitudes, peak values, and vibration frequencies. This study provides critical insights into the dynamic response characteristics of turnouts under various conditions, offering a foundation for damage detection and operational assessment.]]></description>
      <pubDate>Wed, 25 Mar 2026 16:41:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647000</guid>
    </item>
    <item>
      <title>Research on wheel–rail impact dynamics due to combined rail weld irregularities and polygonal wheel effects considering 3D contact geometry</title>
      <link>https://trid.trb.org/View/2646993</link>
      <description><![CDATA[The geometric irregularities of rail welds and polygonal wheels are common defects observed in high-speed railways, leading to the generation of high-frequency impact forces and vibrations in the wheel–rail contact system. This research establishes a novel vehicle-track coupled dynamic model that incorporates a 3D wheel–rail contact model using meshing grid and conjugate gradient methods to study the high-magnitude wheel–rail impact forces caused by rail weld irregularities and polygonal wheel combinations. The primary objective of this study is to develop a precise 3D contact model that incorporates the actual geometry of wheel and rail surface irregularities into the calculation of vehicle-track dynamic interactions. The study evaluates the effects of 3D rail weld irregularities and polygonal wheels on wheel–rail dynamic interaction by comparing results with those obtained from a conventional vehicle-track coupled model that considers a 2D contact model. The results show that the lengths and depths of polygonal wheels and rail weld irregularities, as well as vehicle speeds, significantly increase the wheel/rail dynamic impact forces. The results also indicate that the widening of irregularities not only significantly affects the wheel–rail contact force but also has an important influence on the contact stiffness.]]></description>
      <pubDate>Fri, 20 Mar 2026 14:47:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2646993</guid>
    </item>
    <item>
      <title>Validating theoretical dynamic amplification factors using in-situ measurements for a wide range of train speeds</title>
      <link>https://trid.trb.org/View/2643036</link>
      <description><![CDATA[The vertical displacement of the whole railway infrastructure, including the natural ground underneath, depends on the train speed. This phenomenon is usually known as dynamic amplification. In the most extreme situation, trains may attain a “critical speed” at which the vertical displacement of the railway system would increase infinitely if no damping were present. Since the current trend worldwide is to increase the operational train speed, the question arises about what vertical displacements can be expected in the track for these new train speeds. The beam on elastic foundation model has been successfully applied to railways at relatively low train speeds for many decades. In this article, the power of this model to predict track vertical displacements at very high train speeds, including values close to the site's critical speed, is empirically proven for the first time. To this end, results predicted by this model are compared herein to direct measurements of track vertical displacement for a broad range of train speeds, including (i) in situ field measurements taken in four different sites (France, United Kingdom, The Netherlands and Sweden), and (ii) data from several tests performed in the CEDEX Track Box facility (CTB, Spain). The match between theoretical results and direct measurements confirms the applicability of the beam on elastic foundation model for predicting dynamic track deflections under future increases in maximum commercial train speeds, providing essential insights for the safe design and maintenance of high-speed railway lines.]]></description>
      <pubDate>Wed, 18 Mar 2026 09:01:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2643036</guid>
    </item>
    <item>
      <title>Mechanical behavior and track geometry evaluation of long-span cable-stayed bridges with ballastless tracks</title>
      <link>https://trid.trb.org/View/2663637</link>
      <description><![CDATA[Ballastless tracks have been widely used in China’s high-speed railways; however, they have only recently been laid on 300 m-class cable-stayed bridges. For cable-stayed bridges with a longer span, the mechanical behavior of ballastless tracks is unclear, and the track construction acceptance method is incomplete, restricting the development of cable-stayed bridges with ballastless tracks. Taking four 300–1000 m-class cable-stayed bridges as research objects, this study established static track–bridge interaction models and dynamic vehicle–bridge coupled models. By evaluating static and dynamic indices, the feasibility of laying ballastless tracks and operating high-speed trains at 350 km/h on cable-stayed bridges was analyzed. Based on the results of dynamic analysis and track geometry evaluation, a 40 m chord was proposed for track geometry acceptance on cable-stayed bridges. The accuracy of the simulation results was verified through the measured data from the Xi-Cheng Railway. The numerical results showed that the 300–1000 m-class cable-stayed bridges with ballastless tracks had good static and dynamic characteristics. The 300 m baseline was unsuitable for the long-wave irregularity evaluation of tracks on cable-stayed bridges, and the 60 m chord was easily affected by wavelengths above 200 m, leading to misjudgment of the evaluation results. The 5 mm limits of the 40 m chord could be used for track geometry acceptance on cable-stayed bridges. Finally, a comprehensive evaluation method for track geometry, namely 10 m chord, 40 m chord, and minimum vertical curve radius, was formed.]]></description>
      <pubDate>Tue, 03 Mar 2026 14:48:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663637</guid>
    </item>
    <item>
      <title>Impact of vertical girder deformations on the high-speed train operation performance</title>
      <link>https://trid.trb.org/View/2663635</link>
      <description><![CDATA[The deformation of bridge structures will cause deterioration of geometry on the rail surface during the service period, which will threaten the normal operation of train. A train–track–bridge coupling dynamics model was established. In order to simulate real operational conditions, initial geometric irregularity was taken into account, which was combined with rail irregularity caused by different vertical deformation of girder and was superimposed as external excitation. The probabilistic and statistical characteristics of operational performance indexes were analysed. The sensitivity of operational performance indexes to different deformation modes was studied. The vertical deformation thresholds of girder based on probability guarantee rate were obtained. The results show that unloading rate of wheel and wheel/track vertical force are more sensitive to single vertical rotation deformation mode. Vertical acceleration of the train and sperling index are more sensitive to bilateral vertical rotation deformation mode. Unloading rate of wheel is more sensitive to single vertical translation deformation mode. In the process of enhancing daily operation, single vertical rotation and multiple vertical translation should receive significant attention.]]></description>
      <pubDate>Fri, 27 Feb 2026 11:00:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663635</guid>
    </item>
    <item>
      <title>A spectral element-based dynamic model for train-track-tunnel-soil interaction</title>
      <link>https://trid.trb.org/View/2643933</link>
      <description><![CDATA[To address the challenges of complex modeling and low computational efficiency in the train-track-tunnel-soil (TTTS) system, this study develops a TTTS dynamic interaction model based on the spectral element method (SEM). To accurately described the complex geometry of the tunnel-soil system, this research employs iso-parameter hexahedral and triangular prism spectral elements to simulate the tunnel and surrounding soil, respectively, and describes the tunnel-soil interaction utilizing multiscale coupling method. Leveraging the low-frequency nature of infrastructure vibration, this study introduces Gaussian precise integration method, combined with multi-step hybrid solution, enables accurate resolution of infrastructure vibration with arbitrary integration step. The reliability of the proposed model and solution method is validated through comparison with the FEM model and general solution method. Subsequently, the aforementioned model is applied to the dynamic analysis of the TTTS system to investigate the ground vibration distribution induced by the train, and to examine the effects of the TTTS system parameters on the ground vibration in terms of time–frequency domain vibration and vibration level.]]></description>
      <pubDate>Thu, 26 Feb 2026 09:21:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2643933</guid>
    </item>
    <item>
      <title>Characteristics and prediction of over-track building vibration response due to train operation in turnout areas</title>
      <link>https://trid.trb.org/View/2643914</link>
      <description><![CDATA[Train-induced vibrations in metro depot turnout areas present critical challenges for over-track building developments, significantly impacting human comfort and vibration-sensitive equipment through elevated environmental pollution levels. To address this, propose an integrated two-stage simulation framework combining high-fidelity train-track-turnout dynamics with soil-building wave propagation modeling. A train-track dynamic model incorporating the turnout structure was developed to calculate the wheel-rail interaction forces, which serve as input for the subsequent track-soil-building model. The track-soil-building system was established using a combined finite element and infinite element method to simulate ground-borne vibrations and the associated structural responses effectively. Field validation demonstrates exceptional accuracy, with simulated 1/3-octave band acceleration levels showing a good agreement with measurements across 4–80 Hz frequencies. Key findings reveal that turnout areas generate wide-spectrum vibrations from combined impacts at switch and crossing panels, exhibiting distinctive propagation characteristics. High-frequency components attenuate rapidly while low-frequency energy propagates extensively with minimal loss. Critically, building responses show resonance-driven amplification at 10–20 Hz frequencies due to soil-structure interaction, necessitating targeted vibration control in turnout areas to mitigate structural vibration risks. This research establishes a validated methodology for predicting turnout-induced building vibrations, providing essential data for optimizing metro depot designs.]]></description>
      <pubDate>Wed, 25 Feb 2026 09:05:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2643914</guid>
    </item>
    <item>
      <title>Method for Proposing Countermeasures against Ground Vibrations along Railway Lines Based on Numerical Simulation</title>
      <link>https://trid.trb.org/View/2635986</link>
      <description><![CDATA[This paper introduces a new method for proposing measures to reduce train-induced ground vibration, which considers three primary factors: source, structure, and ground. In this method, the primary factor is first extracted by using a numerical simulation consisting of a running train, tracks, supporting structures and the ground. Second, candidate countermeasures targeting the primary factor are selected from a provided list. Thirdly, the vibration reduction of each countermeasure is evaluated quantitatively. Finally, based on results a countermeasure is selected.]]></description>
      <pubDate>Tue, 24 Feb 2026 15:39:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2635986</guid>
    </item>
    <item>
      <title>Probabilistic analysis of train running safety on bridges: a state-of-the-art review</title>
      <link>https://trid.trb.org/View/2627381</link>
      <description><![CDATA[Train running safety when crossing bridges is an important issue due to the catastrophic consequences of possible derailments. Recent developments in railway technology have led to a great increase in operational speeds and axle loads, leading to significant dynamic amplifications and possibly structural and running safety issues. Assessment of derailment coefficients and running safety indexes is performed using train–track–bridge interaction models, which have advanced in recent decades and reached a mature state. However, most sources of excitation to which train–bridge coupled systems are subject are stochastic in nature, such as winds, earthquakes, track irregularities, and others. Structural and vehicle properties are also associated with uncertainties, which play a major role in the estimation of dynamic responses and evaluation of train running safety. Therefore, probabilistic methodologies are essential to accurately assess the bounds of dynamic responses and derailment coefficients and explicitly evaluate their reliability. Safety coefficients and dynamic amplification factors associated with both direct and indirect train running safety indexes are currently not calibrated with target reliability indexes, which results in possibly inefficient or unsafe design of bridges. This paper aims to present the state-of-the-art of stochastic analyses in train running safety assessment, discuss the main train–track–bridge dynamic interaction models and probabilistic methods used, and systematically evaluate recent applications regarding different stochastic sources of excitation. Gaps identified in the literature are also presented along with guidance for the development of further research.]]></description>
      <pubDate>Mon, 02 Feb 2026 09:33:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2627381</guid>
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