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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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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>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Track Geometry and Vehicle Performance Parametric Study Using NUCARS®</title>
      <link>https://trid.trb.org/View/2742765</link>
      <description><![CDATA[The Federal Railroad Administration (FRA) sponsored an all-inclusive parametric study using NUCARS® to assess vehicle performance of five vehicle types over analytically-defined track perturbations. The research team performed the vehicle performance assessment using criteria from both the Association of American Railroads’ Chapter 11 and FRA Title 49 Transportation Code of Federal Regulations Part 213 Track Safety Standards. In the simulation work, a matrix of the maximum allowable limits for track alignment, surface and cross-level deviations over Track Classes 1 through 5 was used. The simulation matrix included single track deviations as well as synchronized combined track deviations.]]></description>
      <pubDate>Tue, 25 Aug 2026 09:22:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2742765</guid>
    </item>
    <item>
      <title>Study on the causes and development patterns of metro rail corrugation on ladder sleeper track</title>
      <link>https://trid.trb.org/View/2703894</link>
      <description><![CDATA[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.]]></description>
      <pubDate>Mon, 10 Aug 2026 11:16:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2703894</guid>
    </item>
    <item>
      <title>On the influence of wheel-rail combination on active wheelset steering control with wheelset angular velocity feedback and countermeasures</title>
      <link>https://trid.trb.org/View/2691014</link>
      <description><![CDATA[Active wheelset steering using wheelset angular velocity feedback has been proposed and proven effective in achieving one of the goals for perfect steering condition, i.e. minimising longitudinal creep forces and thus wear. This control strategy relies on the contact parameters of wheel-rail pairs to generate a desired angular velocity by using the wheel rolling radii. Some wheel-rail combinations give a non-monotonic function of the average rolling radius with respect to curve radius, which therefore poses a difficulty in controlling active steering with the angular velocity feedback. This study aims to investigate the effect of different wheel-rail combinations and wheel wear. Worn wheels in general tend to cause a non-unique function whereas the original profile gives a monotonic one. Two countermeasures are then investigated to cope with the raised challenges. First, the reference signal generated from the approximated average rolling radius method has proven to be effective for both the original and the least worn profile; however, a wheel with higher wear depths would require a new tuned scaling factor. The control strategy based on equal wheelset angular velocity is then investigated with two schemes: equal wheelset angular velocity within the same running gear and equal angular velocity of all wheelsets within the vehicle. Both schemes provide significant wear number reduction, but the second approach results in better distribution of wheel-rail lateral forces among all wheelsets. This control strategy can also relax the demanded knowledge of wheel-rail contact properties and vehicle travelling speed.]]></description>
      <pubDate>Mon, 13 Jul 2026 10:45:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691014</guid>
    </item>
    <item>
      <title>Impact of slip velocity-dependent friction coefficient on surface traction, wear, RCF and curve squeal noise prediction in wheel-rail contact</title>
      <link>https://trid.trb.org/View/2685647</link>
      <description><![CDATA[Wheel-rail contact friction coefficient is often assumed to be constant through the entire contact patch for the calculation of surface traction. In reality, however, the friction value in a certain point decreases when transitioning from adhesion to slip regimes. Including this friction coefficient behaviour in the estimations of surface traction on the contact patch can potentially provide more accurate calculations of wear and rolling contact fatigue (RCF). In the present work, a slip velocity-dependent friction coefficient is implemented in the tangential contact solver using the concept of ‘Friction Memory’. The effect of this implementation on traction estimations and on the prediction of wear and RCF is analysed by comparing the results with a case with constant friction coefficient in the contact patch. Furthermore, the slip velocity-dependent friction coefficient provides a creep curve with a maximum creep forces value, and a decreasing creep force for higher creepages. This is commonly known as one of the possible mechanisms of curve squeal noise generation. The results provide insights into the likelihood of curve squeal generation, and an on-set curve squeal noise detection technique is proposed that also accounts for the influence of profile changes due to wear.]]></description>
      <pubDate>Wed, 01 Jul 2026 09:39:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2685647</guid>
    </item>
    <item>
      <title>Analytical Model for Longitudinal Displacement of OCL and Method for Calculating the Equilibrium Point</title>
      <link>https://trid.trb.org/View/2675865</link>
      <description><![CDATA[Overhead contact lines (OCLs) are subject to longitudinal displacement due to factors such as temperature changes and external forces. Excessive OCL longitudinal displacement may prevent tensioning devices from performing their proper tension adjustment function. It is therefore important to develop a method for calculating and predicting OCL longitudinal displacement in response to changes in temperature and external forces. This paper presents a model for representing OCL longitudinal displacement on a curved track installing tensioning devices and hinged cantilevers at each support point and proposes a method for calculating the equilibrium points of this displacement.]]></description>
      <pubDate>Thu, 04 Jun 2026 11:57:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2675865</guid>
    </item>
    <item>
      <title>3D stress intensity factor evaluation of subsurface cracks in a railway curve</title>
      <link>https://trid.trb.org/View/2657048</link>
      <description><![CDATA[Curved tracks and certain conditions may result in two-point contact, in which the rail experiences a multiaxial stress state. The initiation and propagation of subsurface cracks follow this. Studying these cracks is crucial for railway safety. In this work, a validated finite element model of the rail and wheel, developed using the weight function method and half-space modeling, is applied to study the three modes of stress intensity factors (SIFs). The equivalent SIF is also extracted to assess 3D subsurface elliptical cracks. The principle of LEFM is applied to obtain the variation of SIFs of subsurface cracks along their fronts. In the rail, three areas have been selected for analysis. Two of these areas are located in the head, and one is located in the web of the rail. The objective of this study is twofold. First, the SIFs of subsurface cracks will be assessed under two-point contact conditions. Second, the lateral load resulting from the effect of passage in a curve, in conjunction with a vertical load, will be examined. Different subsurface crack arrangements and angles are compared to determine the critical state. The outcomes indicated that 45-degree and horizontal cracks have higher stress intensity factors. In the gauge area, the nearly horizontal subsurface crack exhibits the largest equivalent stress intensity factor compared to all other conditions. This makes the zone more susceptible to failure in the curved tracks.]]></description>
      <pubDate>Wed, 22 Apr 2026 16:15:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2657048</guid>
    </item>
    <item>
      <title>Dynamic Characteristics Analysis and Enhancement for Superconducting EDS Trains at Curved Track</title>
      <link>https://trid.trb.org/View/2659166</link>
      <description><![CDATA[The studies of superconducting electrodynamic suspension (EDS) have gradually received more and more attention in recent years. As the inevitable line condition, the horizontal curved track would change the relative spatial position between the onboard superconducting magnet (SCM) and ground levitation/guidance (LG) coils, resulting in different vehicle–track coupled forces compared to straight track conditions, which prominently influences the dynamic performance of EDS trains. This article proposed an analytical calculation method of vehicle–track force that can describe arbitrary curved track parameters. Based on this calculation method, the dynamic model of EDS trains considering the curved track conditions was built. Meanwhile, an equivalent loading method for track irregularities was proposed, which is applicable to both real electromagnetic force case and fitting force case in dynamic scenarios. The calculation results indicate that under curved track conditions, the lateral and rolling dynamic characteristics of vehicles deteriorate significantly, and the effect of the higher harmonics of electromagnetic forces is enhanced. In order to suppress the violent vibration of SCMs, a ground-hook semi-active strategy at the primary suspension was adopted, and the results indicate that it can effectively improve the lateral displacements and accelerations of SCM units, but the suppressing effect of high-frequency vibrations is moderate. This research provides valuable references to clarify the dynamic characteristics of EDS trains at curved track and a new approach to suppress the vibrations of SCMs.]]></description>
      <pubDate>Wed, 15 Apr 2026 11:32:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2659166</guid>
    </item>
    <item>
      <title>Optimization of the Speed Curve of Permanent Magnetic Maglev Trains Based on Improved Genetic Algorithm</title>
      <link>https://trid.trb.org/View/2113863</link>
      <description><![CDATA[The optimization of the speed curve of the permanent magnet maglev trains is of utmost importance for the automatic train operation. This work proposes a weight-adaptive genetic algorithm to effectively solve the problems of low efficiency, poor robustness, and vulnerability to falling into local optimum in the traditional biological evolutionary algorithm in the automatic train driving speed curve. Based on the traditional genetic algorithm process, the improvement of this algorithm lies in setting the weight of the penalty function, the value of the crossover factor, and the value of the mutation factor to be variable in real-time. First, the weight of the penalty function of the unsatisfied item should be doubled when the constraints are not met; otherwise, its weight remains unchanged. Second, smaller crossover and mutation factor values should be chosen when the solution obtained in this round is better than that in the previous round; otherwise, larger crossover and variation factor values should be used. Simulation experiments show that the improved algorithm in this work has the advantages of fast convergence and high robustness compared with the more widely used traditional genetic algorithm.]]></description>
      <pubDate>Wed, 15 Apr 2026 08:31:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113863</guid>
    </item>
    <item>
      <title>Detecting support modulus of curved railway tracks by a double-beam model using a moving test carriage</title>
      <link>https://trid.trb.org/View/2654647</link>
      <description><![CDATA[Curved tracks are prone to derailment, but have not been well treated. This paper establishes a theoretical framework for extracting rail-related vertical frequencies and track moduli of curved tracks subjected to a moving test carriage for the first time. The curved track is modeled as a double-beam system to represent both the rail and the supporting bridge structure, with an intermediate layer incorporated to simulate the effects of ballast and sleepers. Closed-form solutions for vehicle and contact responses are obtained via modal superposition. The contact acceleration spectrum, free from vehicle frequencies, enables clearer frequency identification. The rail-related vertical frequency, linked to track modulus, shows the highest identifiability, first appearing in the high-frequency range. The finite element method (FEM), validated by analytical solutions, is used for robustness analysis, leading to the following conclusions: (1) track modulus extraction is minimally affected by curvature radius, and support stiffness; (2) a medium vehicle speed of 20 m/s (72 km/h) offers a balance between efficiency and accuracy; and (3) in the presence of track irregularity and damping, track modulus can still be reliably retrieved.]]></description>
      <pubDate>Tue, 31 Mar 2026 16:35:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2654647</guid>
    </item>
    <item>
      <title>Multi-objective optimization and sensitivity analysis of forced-steering bogies using surrogate models and NSGA-III</title>
      <link>https://trid.trb.org/View/2643045</link>
      <description><![CDATA[This research proposes a multi-objective optimization methodology to enhance the curving and tangent performance of forced-steering passenger trains. Using the Non-dominated Sorting Genetic Algorithm-III (NSGA-III), we optimize a set of parameters — primary suspension stiffness (longitudinal and lateral) and steering linkage — to minimize wheelset unloading, derailment risk, rail rollover risk, and car body lateral acceleration. A 167-degree-of-freedom high-fidelity simulation model of the train is developed and validated against conventional rail vehicle data. Sensitivity analysis via the Sobol’ method identifies key design parameters, reducing the number of variables for optimization. A Kriging surrogate model is then employed to approximate the simulation model, making optimization feasible. Post-optimization, the robustness of the Pareto optimal solutions is evaluated under varying track conditions. Key findings reveal that steering ratio and longitudinal primary suspension stiffness are critical, while yoke-to-yoke parameters have minimal impact. The optimization results show a trade-off between curving performance and car body lateral acceleration, with solutions varying based on lateral stiffness. Two out of four Pareto optimal sets demonstrated improved robustness under varying curve radii and equivalent conicity, while all Pareto optimal sets exhibit equal robustness and significant improvements in performance under varying track friction. These findings emphasize the importance of robust design optimization across different operational conditions to achieve balanced performance.]]></description>
      <pubDate>Wed, 18 Mar 2026 09:01:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2643045</guid>
    </item>
    <item>
      <title>Curve squeal of modern tramcars: comparison between independently rotating wheels and solid axles</title>
      <link>https://trid.trb.org/View/2613684</link>
      <description><![CDATA[Curve squeal noise is still one of the most serious problems related to the operation of trams in urban networks. Several mitigation solutions have been proposed in past research, usually dealing with friction modifiers or damping elements installed on the wheels or on the rails. In this paper, the role of the bogie architecture on curve squeal occurrence is investigated. Vehicle dynamics simulations and a wheel/rail coupled model in the frequency domain are used to compare curve squeal predictions in case of Independently Rotating Wheels (IRW) and Solid Axles (SA). The SA configuration results in higher longitudinal creepage compared to IRW. This modifies the transverse creep curve, making this design solution less susceptible to curve squeal induced by falling friction. Despite the well-known improved curving behaviour in sharp curves, the IRW architecture has been found to be more prone to curve squeal compared to the SA tramcar.]]></description>
      <pubDate>Mon, 26 Jan 2026 14:44:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2613684</guid>
    </item>
    <item>
      <title>Bi-Directional Dynamic Vibration Absorber for Small-Radius Curved Track Systems: Design and Performance Evaluation</title>
      <link>https://trid.trb.org/View/2647069</link>
      <description><![CDATA[Low-frequency vibration amplification in steel-spring floating slab track is especially significant in small-radius curves. To mitigate this issue, a novel bi-directional dynamic vibration absorber (Bi-DVA) is proposed to effectively suppress such vibrations and improve the stability of the track system. A coupled dynamic model, which integrates the vehicle, curved track segment, floating slab, and Bi-DVA, was developed using extended fixed-point theory, vehicle-track coupled dynamics theory, and finite element analysis. The optimal configuration of the Bi-DVA’s parameters was thoroughly explored, and its performance under various operational conditions was assessed in terms of vibration reduction and enhancement of wheel-rail safety metrics. The vertical and lateral vibration amplitudes of the floating slab were reduced by up to 10.2?dB and 8.9?dB. The vertical and lateral accelerations of the rail were decreased by 11.7?m/s2 and 1.82?m/s2, and the peak vertical and lateral accelerations of the vehicle body dropped by 0.44?m/s2 and 0.19?m/s2, respectively. Additionally, the derailment coefficient was reduced by 0.08, and the wheel load reduction rate decreased by 0.06.]]></description>
      <pubDate>Fri, 09 Jan 2026 16:59:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647069</guid>
    </item>
    <item>
      <title>Experimental evaluation on dynamic performance of medium–low-speed maglev vehicle running on low-positioned subgrade</title>
      <link>https://trid.trb.org/View/2613679</link>
      <description><![CDATA[As a novel urban rail transit system with relatively low construction costs, medium–low-speed maglev transportation is currently experiencing rapid development in China. However, there have been rare studies on the experiments of medium–low-speed maglev vehicle passing curves and low-positioned subgrade. Therefore, this paper systematically conducts on-site dynamic tests on the Qingyuan Maglev Tourism Line. The experiment provides a detailed analysis of the dynamic characteristics of the vehicle system and subgrade under varying speeds up to 132 km/h. The study explores the impacts of operating speed, track layout, and type of girder structure. The results indicate that a significant increase in operating speed and the application of emergency braking intensify the dynamic response of the vehicle system. When passing through the R700m curve and low-positioned subgrade sections at different speeds, the primary vibration frequency of the sprung structure is below 2.5 hz, while the unsprung structure shows a wide frequency distribution. The peak frequencies of the vibration for the low-positioned subgrade are mainly distributed in the 60–140 hz range, and the vibration response of the girder remains at a low level. The Sperling index values, levitation gap, and lateral offset of the levitation electromagnet of the testing vehicle do not exceed 2.5, 4 mm, and 10 mm, respectively, indicating excellent ride comfort and stable levitation performance. The results of this test study provide a reliable assessment of the safety of the vehicle and subgrade system and would help precise modelling of vehicle and subgrade system in the future.]]></description>
      <pubDate>Tue, 30 Dec 2025 09:46:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2613679</guid>
    </item>
    <item>
      <title>Curving and running resistance of freight trains: current experience with on-track measurements</title>
      <link>https://trid.trb.org/View/2604155</link>
      <description><![CDATA[Curving resistance affects the railway vehicle running through curves. For its estimation in train dynamics calculations, different empirical formulas are used in various countries. It is practically impossible to determine its exact value because of its dependency on various – to some extent random – parameters. In the framework of the experimental research of running resistance of freight trains at the Faculty of Transport Engineering of the University of Pardubice, measurements in regular operation conditions on the Czech railway network were realised in recent years. Because some of these results can be used to quantify the curving resistance, the applied evaluation methods and the relevant results are presented in this paper. Besides that, a new general formula of running resistance for freight trains, based on the measurement results, is proposed. Attention is also paid to the effect of track quality on the vehicle running resistance.]]></description>
      <pubDate>Fri, 05 Dec 2025 14:12:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2604155</guid>
    </item>
    <item>
      <title>An efficient method for high-dimensional reliability analysis of heavy-haul-train curved-track system via the fractional moment</title>
      <link>https://trid.trb.org/View/2596334</link>
      <description><![CDATA[With the development of rail transport towards high density and heavy loads, the dynamic reliability of heavy-haul-train curved-track system (HTCTS) has become the focus of attention. Under long-term operating conditions, the system suffers from geometric random evolution, including track irregularity, wheel and rail profile. On the other hand, there are multi-dimensional uncertainties in the heavy-haul-train and track structure itself, like random parameters. Further, the system combines strong non-linearities. These complexities present a major challenge to the accurate assessment of the dynamic reliability of the system. To address this problem, a HTCTS dynamics model is established, incorporating random track irregularities generated by the harmonic function method and random wheel profile samples generated by the Karhunen-Loève (KL) expansion to simulate wheel randomness, respectively. Besides, this paper proposes to use an efficient reliability analysis method based on fractional moments-based maximum entropy method (FM-MEM) with improved sampling method called good lattice point method and partially stratified sampling (GLPM-PSS) to assess the operational safety reliability of HTCTS. For high-dimensional non-linear problems, a genetic optimisation algorithm is used to determine the model parameters, allowing precise fitting of the dynamic response probability distributions. The implementation starts with the generation of a limited set of low-discrepancy samples using advanced sampling techniques. Fractional moments of the heavy-haul trains responses are then derived through optimisation functions based on these samples. The numerical results presented in this study demonstrate the computational efficiency and predictive accuracy of this methodology in dynamic reliability analysis for HTCTS, demonstrating significant practical applicability in probabilistic risk assessment frameworks.]]></description>
      <pubDate>Wed, 22 Oct 2025 16:46:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2596334</guid>
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