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    <title>Transport Research International Documentation (TRID)</title>
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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>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Image-Based Moisture Content Prediction in Railway Ballast Using Deep Learning</title>
      <link>https://trid.trb.org/View/2691491</link>
      <description><![CDATA[Moisture content of ballast fine material is an important property to monitor for minimizing settlement and maintaining stability and safe operation of the railroad track. Conventional methods for assessing moisture content rely on time-consuming sampling-based laboratory tests, limiting their practicality for large-scale field inspections. This study introduces a novel deep learning-based method using images composed of Red, Green, and Blue (RGB) channels for efficient and scalable moisture evaluation of ballast fine material. A new concept named Normalized Moisture Index (NMI) is proposed to represent the moisture content of fine material relative to its Optimum Moisture Content (OMC). The proposed framework estimates the NMI value based on style representations derived from Convolutional Neural Network (CNN) feature maps extracted from the RGB images. Another key innovation is its seamless integration with coarse ballast particle segmentation methods, enabling accurate analysis of field ballast images with mixed particle sizes. The model’s robustness and accuracy were evaluated using a comprehensive dataset established from four distinct ballast locations studied under varied moisture conditions. Extensive testing, including leave-one-spot-out cross-validation and evaluations of training on fine materials to test on mixed sizes of materials, demonstrated high predictive accuracy. This image-based method significantly simplifies moisture measurement compared to traditional methods, offering actionable insights for timely, cost-effective ballast maintenance. By improving moisture content assessment, this method has the potential to make contributions to enhanced track stability, reduced risk of fouling, prevention of mud spots, and optimized drainage and load-bearing capacity.]]></description>
      <pubDate>Fri, 15 May 2026 15:44:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691491</guid>
    </item>
    <item>
      <title>Multiple evaluation on activation-fusion and mechanical performance of rejuvenated asphalt mixture enhanced by pre-heating temperature and steel slag</title>
      <link>https://trid.trb.org/View/2672285</link>
      <description><![CDATA[Reclaimed asphalt pavement (RAP) has been used to prepare hot rejuvenated asphalt mixture (HRAM) for eco-environment and low cost. However, how pre-heating temperature and steel slag affect the activation-fusion behavior as well as performance of HRAM was not reported in detail. This study introduced evaluation methods based on MATLAB image processing, Fourier transform infrared spectroscopy (FTIR) and Dynamic Shear Rheometer (DSR). Black pixel ratio, carbonyl index, sulfoxide index, complex shear modulus, phase angle, flow activation energy and stripping resistance of virgin asphalt on RAP were respectively in assessing RAP asphalt's activation and fusion degree. Mechanical performance of corresponding HRAM was then characterized. Results illustrated that MATLAB image processing was able to semi-quantitatively assess the activation degree of RAP asphalt by analyzing black pixel ratios, which increased with pre-heating temperature and decreased with RAP particle size. FTIR characterization and stripping resistance tests showed that pre-heating temperature positively affected the fusion degree of RAP and virgin asphalt, although excessive pre-heating temperature can lead to significant secondary aging. Cooling rate of asphalt mixture was lowered by steel slag, which also accelerated the activation and fusion of RAP asphalt through reduced corresponding complex modulus. Void volume of the HRAM increased with steel slag addition but decreased with pre-heating temperature. Dynamic stability was positively determined by steel slag content and pre-heating temperature. Fracture energy at low temperatures first increased and then decreased with pre-heating temperature. Moisture resistance could also be improved at appropriate pre-heating temperature. Overall, partial steel slag replacement was beneficial for moisture and freezing-thaw resistance. This study provided a scientific foundation for activation-fusion behavior of RAP, so that mechanical performance of HRAM can be enhanced.]]></description>
      <pubDate>Thu, 14 May 2026 14:00:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2672285</guid>
    </item>
    <item>
      <title>BallastAttN: Occlusion-Robust 3D Railway Ballast Characterization using Data Synthesis and Deep Learning</title>
      <link>https://trid.trb.org/View/2701226</link>
      <description><![CDATA[Accurate characterization of railway ballast is critical for track safety and maintenance; however, traditional field sampling/sieving or two-dimensional images captured are often labor-intensive and limited for a representative analysis. Three-dimensional (3D) point cloud analysis may offer a more comprehensive approach; the dense packing and heavy occlusion of ballast particles restrict image segmentation. This study introduces a novel deep learning pipeline designed for robust 3D railway ballast characterization, BallastAttN. Its core contributions include a comprehensive synthetic training data set from high-fidelity 3D scans of new and degraded ballast particles, an enhanced point cloud segmentation model upgraded with edge-aware voxelization and curriculum learning, and the novel BallastAttN partial point cloud completion model architected to reconstruct complete particle shapes from the highly incomplete views typical of field conditions. The proposed pipeline was comprehensively validated using controlled laboratory experiments with isolated and clustered configurations of real ballast particles in new and degraded conditions. The results show that BallastAttN consistently outperforms the baseline completion framework that utilizes an encoder–decoder architecture mechanism built on attention mechanisms across commonly used size and morphological properties. The performance gap widened substantially in clustered scenarios that are close to the field ballast appearance, demonstrating the model’s enhanced ability to handle occlusion. The predictions were precise in differentiating between new and degraded ballast based on morphological properties, such as 3D sphericity, the Flat and Elongated Ratio, and the Angularity Index. This study establishes a practical framework for automated ballast inspection, for example, with the use of an innovative ballast scanning vehicle developed, paving the way for more efficient and reliable railway ballast maintenance.]]></description>
      <pubDate>Mon, 11 May 2026 12:24:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2701226</guid>
    </item>
    <item>
      <title>Performance evaluation of recycled asphalt using dual-activated kaolin via wet grinding and KH550</title>
      <link>https://trid.trb.org/View/2665979</link>
      <description><![CDATA[Recycled asphalt faces limitations in widespread application due to poor rheological properties and insufficient aging resistance. As a soft clay mineral, kaolin can improve aging resistance of asphalt when combined with silane coupling agent (KH550), while its effectiveness remains limited with unclear anti-aging mechanisms. This study developed a mechano-chemically treated kaolin (MTK) via an innovative dual activation technology combining wet grinding and KH550 modification to improve the comprehensive properties of recycled asphalt. The particle size distribution, infrared spectra, mineral composition and micromorphology of original kaolin (ORK), conventionally treated kaolin (CTK) and MTK were characterized. Then the rheological properties and surface energy of recycled asphalt modified with ORK, CTK and MTK (ORA, CRA, and MRA) were investigated. And their aging resistance and mechanisms were also systematically explored. The results indicate that mechano-chemically activation reduces the average particle size of kaolin by 97 % to 0.90 μm, while simultaneously decreasing crystallinity and inducing structural defects on the surface. This process exposes more active sites, indicating a significant enhancement in both surface activity and dispersibility of MTK. Compared with ORA, MRA exhibits an increased surface energy of 14.11 mJ/m² along with a significantly higher proportion of dispersive components. Under all three aging methods, aged MRA reveals the lowest fatigue factor and the glass transition temperature, representing superior fatigue resistance and low-temperature performance. Incorporating MTK substantially declines the carbonyl index, sulfoxide index and surface roughness of aged recycled asphalt. MRA with MTK retains the highest aromatic hydrogen atom (HA) content after short-term, long-term and UV aging, reaching 10.62 %, 9.22 % and 9.45 %, respectively, indicating that MTK effectively suppresses the substitution reaction and chain-extension kinetics during aging process, thereby significantly retarding the aging progression of recycled asphalt.]]></description>
      <pubDate>Mon, 11 May 2026 08:50:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665979</guid>
    </item>
    <item>
      <title>Enhancing rheological and ageing performance of asphalt binders using hazelnut shell biochar additives</title>
      <link>https://trid.trb.org/View/2668677</link>
      <description><![CDATA[This study evaluated the effect of biochars derived from European hazelnut shells as modifiers of the antioxidant, physical, and rheological properties of asphalt binders used in road construction. Two types of biochar (BH) were produced via slow pyrolysis at 300 °C (BH1) and 550 °C (BH2) with a residence time of 1 h, and were incorporated into unaged, short-term aged (RTFO), and long-term aged (PAV) asphalt binders. Phenolic compounds of the BHs were identified by liquid chromatography, while their antioxidant effect on asphalt binders was assessed using spectroscopic analyses. Physical properties (rotational viscosity, penetration, softening point, Fraass breaking point) and rheological properties (rutting parameter G*/sin(δ), Rheological Ageing Index, multiple stress creep recovery (MSCR), fatigue parameter (G*∙sin(δ), crossover temperature, and complex modulus |G*|) were measured in all ageing states. The results revealed that both BHs mitigated binder ageing, as evidenced by reductions in ageing indices and oxygenated structures. BH1’s antioxidant effect was attributed to its phenolic compounds, whereas BH2’s effect was attributed to its porous morphology, which facilitated the adsorption of volatiles. Physically, BH reduced viscosity by up to 16 % after PAV ageing, maintained penetration, and lowered the softening point, although Fraass breaking points increased due to particle stiffening. Rheologically, BH improved rutting resistance by up to 8 % during the early ageing stages. After PAV ageing, it mitigated stiffness gain, preserved viscoelastic behaviour, and reduced |G*| at low temperatures compared with the controls. Overall, recycled hazelnut shell BH enhanced the ageing resistance and thermal stability of bituminous binders through distinct mechanisms, offering a potentially viable option to extend the service life of road pavement materials.]]></description>
      <pubDate>Mon, 11 May 2026 08:50:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2668677</guid>
    </item>
    <item>
      <title>Performance evaluation of pyrolytic carbon black-modified asphalt mastic with fly ash/calcium carbide slag fillers: Rheology, microwave susceptibility, and self-healing behavior</title>
      <link>https://trid.trb.org/View/2657726</link>
      <description><![CDATA[This study develops a synergistic modified asphalt mastic system using three typical wastes: Pyrolysis Carbon Black (PCB) from waste tires as a modifier, and Fly Ash (FA)/Calcium Carbide Slag (CCS) as alternatives to traditional Limestone Mineral Powder (LMP) fillers. Besides the microscopic characteristics of the PCB and the fillers were analyzed using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The rheological properties, the energy utilization efficiency and the self-recovery efficiency were evaluated via Dynamic Shear Rheology (DSR), microwave heating, and fatigue-healing cycle tests. The experimental results show that FA/CCS, which are characterized by small particle sizes and large specific surface areas, show higher integration potential with asphalt. Additionally, FA/CCS enhance the microwave heating efficiency and self-healing capability of asphalt mastic. While PCB can improve most of the characteristics of asphalt mastic, the saturation point and degree of improvement vary form the type of asphalt mastic. The FAM with 10 % PCB shows a 17.1 % higher microwave energy utilization efficiency compared with FAM without PCB. It also exhibits a higher complex shear modulus (G*) and a higher energy-based self-healing index (HI₁) at 46°C. The CCSM with 10 % PCB also outperforms CCSM without PCB, with a 7.3 % increase in microwave energy utilization efficiency, a 30 % increase in G* at 46°C, and a 56.3 % increase in HI₁. These results confirm that FA/CCS combined with PCB can significantly improve the high-temperature performance, microwave responsiveness and self-healing ability of asphalt mastic. A high-value utilization path for industrial solid wastes in pavement engineering is also provided.]]></description>
      <pubDate>Tue, 21 Apr 2026 14:30:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2657726</guid>
    </item>
    <item>
      <title>Multi-parameter optimization based on a surrogate model for improving vehicle dynamics and reducing wheel wear in high-speed EMUs</title>
      <link>https://trid.trb.org/View/2659285</link>
      <description><![CDATA[With the continuous development of China's high-speed railways, the problems of vehicle dynamics and wheel wear in high-speed electric multiple units (EMUs) are becoming increasingly prominent, and the suspension parameters of these vehicles have a significant effect on improving vehicle dynamics performance and reducing wheel wear. This paper first establishes a vehicle dynamics model using the Ultra-Latin Hypercube sampling method to select suspension parameters, and targets the improvement of vehicle dynamics performance and the reduction of wheel wear, and finally a Kriging Surrogate Model-Compression Particle Swarm Optimization (KSM-CPSO) model used to optimise the suspension parameters. The vehicle dynamics and wheel wear of the before and after optimisation are analysed. The results showed that the use of optimised suspension parameters effectively increased the vehicle's critical speed. The optimised parameters further improved the vehicle's ride index, safety index, and reduced the lateral force of the wheel axle. In addition, the optimised parameters suppressed the lateral vibration of the vehicle. When the wear mileage reached 200,000 km, the wheel wear depths before and after optimisation were 1.086 and 0.9806 mm, respectively. Therefore, the optimisation of the suspension parameters can effectively improve the vehicle dynamics performance and subsequently reduce wheel wear.]]></description>
      <pubDate>Tue, 14 Apr 2026 10:11:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2659285</guid>
    </item>
    <item>
      <title>Aging mechanisms of rubber-modified asphalt: Particle effect and interaction effect</title>
      <link>https://trid.trb.org/View/2651654</link>
      <description><![CDATA[The recycling of waste tires is promoted through the use of rubber-modified asphalt, leading to a reduction in solid waste pollution and significant environmental benefits. However, the current understanding of its aging mechanisms remains unclear, limiting the accurate prediction of long-term performance and the development of regeneration technologies. To investigate the aging mechanisms of rubber-modified asphalt, this study conceptualized it as a biphasic system consisting of rubber and asphalt phases. The evolution of rheological properties during aging was systematically investigated, and the contributions of the Particle Effect (PE) and the Interaction Effect (IE) between the asphalt and rubber phases were quantified. Using crumb rubber modified asphalt (CRMA) and electromagnetically activated crumb rubber modified asphalt (ACRMA) as research objects, low-, intermediate-, and high-temperature rheological tests were conducted in combination with a phase separation method to analyze performance evolution under different aging conditions. Results indicated that rubber activation significantly improved workability. At 135°C in the unaged state, the viscosity of ACRMA was 79.7 % lower than that of CRMA. After aging, non-activated rubber demonstrated superior high- and low-temperature performance, whereas activated rubber exhibited better fatigue resistance, with a fatigue life 6.6 times that of CRMA under PAV aging and at a strain level of 12.5 %. At low temperatures, the dominant mechanism underlying the rubber-enhanced performance of asphalt shifted from being predominantly governed by the PE to a synergistic combination of PE and IE as aging progressed. At intermediate temperatures, fatigue performance relied primarily on PE. At high temperatures, PE contributed significantly to rutting resistance, while IE dominated deformation resistance. The parameter G*/(sinδ)⁹ was more accurate than conventional indicators in reflecting the elastic response of rubber particles. The study revealed that with progressive aging, rubber-modified asphalt generally exhibited a transition characterized by "a gradual decrease in the Particle Effect and a gradual increase in the Interaction Effect". These findings provide an experimental basis for establishing a dual-effect performance prediction index system and advancing the regeneration technologies for rubber-modified asphalt.]]></description>
      <pubDate>Mon, 30 Mar 2026 17:10:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2651654</guid>
    </item>
    <item>
      <title>Optimal allocation of distributed generation units and fast electric vehicle charging stations for sustainable cities</title>
      <link>https://trid.trb.org/View/2655608</link>
      <description><![CDATA[The rise of electric vehicles (EVs) in sustainable cities has fueled interest in Distributed Generation (DG) units allocation. A well-planned and efficient charging infrastructure is required for effective e-mobility. The paper examined the single-objective frameworks of optimal simultaneous allocation of DG units and fast EV charging stations (EVCS). The applications are employed on the IEEE 69 bus network and a real part of the Ghana network in the Ashanti region. The optimization tasks are carried out by using Particle swarm optimization (PSO) and artificial bee colony (ABC) algorithms. The impact of optimal placement on the networks was analyzed. The results show that with high penetration levels of DG units (up to 40%) and fast EVCS, PSO, and ABC can achieve a significant power loss reduction that reaches 68%. Furthermore, PSO outperforms ABC in relation to the voltage deviation index on both the test network and the 33 kV Ashanti region network, while still satisfying the IEC standards' 5% margins. The results indicate that PSO and ABC are viable swarm algorithms for mitigating active power loss and enhancing the voltage profile of a system through concurrent allocation.]]></description>
      <pubDate>Fri, 27 Mar 2026 10:20:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655608</guid>
    </item>
    <item>
      <title>Quantifying the anisotropic electrical resistivity of marine clays: A comprehensive model integrating index properties, gradation, and aging effects</title>
      <link>https://trid.trb.org/View/2685344</link>
      <description><![CDATA[Archie's cementation exponent (m) is a critical parameter for the resistivity-based characterization of marine sediments, as it enables the accurate estimation of porosity or void ratio profiles essential for offshore foundation design. However, its quantification remains challenging due to the complex anisotropic fabric of natural clays. This study investigated directional electrical behavior by combining laboratory experiments, ridge regression modeling, and field validation. Results on representative commercial clays (three kaolins and four bentonites) demonstrate that m is primarily governed by intrinsic index properties, with a log-linear model achieving high predictive accuracy (RMAE <7%). Validation using seabed clays from South Korea revealed that intrinsic properties alone are insufficient for natural deposits. This study identified that particle size distribution significantly enhances pore-path complexity; thus, incorporating gradation-related parameters in the model reduced the RMAE for remolded field samples to 8.6%. Furthermore, a time-dependent aging correction factor was introduced to account for long-term fabric development, reducing RMAE for undisturbed specimens from 40.7% to 18.6%. Finally, this study established that electrical anisotropy (λe) is a robust geophysical metric for assessing sample disturbance, with λe ranging 1.22-1.34 identified for boundary between intact and disturbed fabric. This framework supports reliable resistivity-based characterization for critical offshore infrastructure design.]]></description>
      <pubDate>Fri, 27 Mar 2026 10:14:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2685344</guid>
    </item>
    <item>
      <title>Sales forecast of new energy vehicles in China based on multi-source information fusion and link prediction</title>
      <link>https://trid.trb.org/View/2682323</link>
      <description><![CDATA[This study develops an integrated forecasting framework that leverages multi-source information fusion to improve predictions of new energy vehicle (NEV) sales in China. The dataset incorporates historical sales records, key influencing factors, and unstructured Baidu Index (BI) data. Our framework first applies complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) combined with sample entropy (SE) reconstruction. This procedure decomposes the original sequences into high-, medium-, and low-frequency components, yielding data that are more regular and informative while retaining underlying dynamics. Forecasting is then conducted through a structured combination of methods tailored to each frequency band. High-frequency components are modeled by converting the time series into directed visibility graphs (DVGs) and performing prediction as a link-prediction task on the resulting complex networks, implemented using a particle-swarm-optimized support vector regression (PSO-SVR) model. Medium- and low-frequency components are predicted using backpropagation neural networks (BPNN) and Lasso regression, respectively. Empirical evaluations show that integrating multi-source information, CEEMDAN-SE decomposition, DVG-based modeling, and frequency-specific predictors substantially improves forecasting accuracy compared with benchmark approaches. The findings show the potential evolution of China's NEV market and highlight the drivers of sales dynamics, providing evidence to inform policy formulation and sectoral strategic planning.]]></description>
      <pubDate>Thu, 26 Mar 2026 09:05:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2682323</guid>
    </item>
    <item>
      <title>Multiscale and multidimensional analysis of coarse aggregate morphological characteristics for road-used steel slag</title>
      <link>https://trid.trb.org/View/2648714</link>
      <description><![CDATA[Steel slag has emerged as a promising coarse aggregate for pavement construction, offering a pathway toward green and sustainable infrastructure. However, insufficient multi-scale particle morphology characterization limits the accurate matching between material properties and pavement functional requirements, restricting its efficient utilization. This study investigates the aggregate morphological characteristics and develops a refined multidimensional evaluation framework encompassing macroscopic, mesoscopic, and microscopic scales. Two-dimensional analysis and three-dimensional scanning were employed to quantify morphological parameters of three steel slags, with basalt and limestone as references. Seven digital indices were used to access particle shape. Surface texture was characterized using orientation distribution, arithmetic mean roughness, fractal dimension, and SEM images, while pore structure using mercury intrusion porosimetry. Furthermore, grey relational analysis quantified the association degree between digital morphological parameters and empirical performance metrics. Results indicate strong correlations between the indicators. Steel slag exhibits the shape index of 1.1 – 1.3, shape factor of 0.04 – 0.07, aspect ratio of 1.0 – 1.6, flatness ratio of 1.5 – 1.8, polygonal perimeter ratio of 0.6 – 0.7, elliptical perimeter ratio of 1.02 – 1.12, and sphericity of 0.45 – 0.85, reflecting a balance between angularity and flowability. The orientation entropy of three steel slags is 6.33 % – 6.47 % higher than that of basalt, with values of 4.1546, 4.1526, and 4.1490, indicating more complex textures. Distinct morphology supports function-oriented applications of different steel slags. Basic oxygen furnace slag, with favorable morphology, texture, low porosity, and stable performance, is suitable for high-skid-resistance pavements. Open-hearth furnace slag, featuring coarse texture and abundant mesopores and micropores, also demonstrates strong skid-resistance potential. Electric arc furnace slag, with the highest porosity of up to 10.22 %, is recommended for drainage or noise-reducing pavements. This study clarifies the relationship between multi-scale particle characteristics and pavement functionality, providing theoretical support for non-destructive evaluation and function-driven application of steel slag in various pavements.]]></description>
      <pubDate>Wed, 25 Mar 2026 11:45:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2648714</guid>
    </item>
    <item>
      <title>Investigation of particle migration and drainage behavior in railway ballast induced by multiphase flow using a coupled VOF-DEM approach</title>
      <link>https://trid.trb.org/View/2647977</link>
      <description><![CDATA[Railway ballast is a crucial component of rail tracks and plays a vital role in various functions, with drainage being one of the most important for maintaining the track’s operation ability. Over time, ballast degradation and accumulation of foreign materials result in fouling, which blocks the interstitial spaces and flow passage between ballasts, thereby significantly reducing drainage efficiency. To investigate the interaction between fouling and fluid flow and its effect on fine particle migration and drainage, a coupled discrete element method (DEM) and computational fluid dynamics (CFD) model capable of solving multiphase fluid flow is developed, aiming to advance the understanding of the relevant transport behavior. The discrete (particle) and the continuous (water and air) phases are resolved using a Lagrangian and a Eulerian approach, respectively. Then, the model is employed to investigate multiphase fluid flow that washes away fouled materials through the ballast aggregate for different parameters, including fouling index, fouling profile, cohesive energy density (CED) between particles, and shoulder cleaning. This parametric simulation offers comprehensive insights into the interplay between the multiphase flow and fine particles within ballast at different conditions. Moreover, the particle distribution and their migrations over time are quantitatively evaluated using the Local Fouling Index. It is evident from the analysis that particle migration greatly depends on the parameters under consideration, with the CED value being the most important factor. Additionally, the comparison of the water table height demonstrates that shoulder cleaning is an effective means of improving drainage efficiency.]]></description>
      <pubDate>Tue, 24 Mar 2026 09:09:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647977</guid>
    </item>
    <item>
      <title>Influence of geogrid stabilization on ballast breakage under monotonic triaxial loading</title>
      <link>https://trid.trb.org/View/2647976</link>
      <description><![CDATA[Railway ballast particle breakage leads to fines generation, increases fouling, reduces drainage capacity, and ultimately weakens track performance. While geogrids are known to stabilize ballast by limiting particle movement and redistributing contact stresses, their effectiveness in reducing breakage, particularly at different ballast depths, remains unclear. This study employs a large-scale monotonic triaxial testing framework to evaluate particle breakage in clean ballast, with and without geogrid stabilization, under both loose and compacted density conditions. Each specimen was divided into four vertical zones: Top, Top-Mid, Bottom-Mid, and Bottom, and particle size groups were color-coated to enable breakage tracking. The results show that geogrid-stabilized specimens exhibited greater strength and stiffness in both density conditions. For loose ballast, geogrid inclusion reduced total particle breakage by approximately 27%, with the most significant reduction occurring in the middle zones. In contrast, for compacted ballast, the total breakage remained nearly unchanged with geogrid use; however, breakage was more evenly distributed across all zones, with noticeable reductions in the Top and Top-Mid zones. Corner breakage dominated in the middle zones, and splitting breakage near the top and bottom. Marsal’s breakage (Bg) index proved most sensitive for zone-by-zone evaluation. The findings highlight the benefit of geogrids in mitigating ballast degradation and emphasize the importance of zone-specific analysis under varying density conditions. The proposed monotonic triaxial framework provides a mechanistic baseline for future cyclic triaxial studies, where repetitive loading will further clarify long-term stress redistribution, particle migration, and cumulative breakage under realistic railway service conditions.]]></description>
      <pubDate>Tue, 24 Mar 2026 09:09:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647976</guid>
    </item>
    <item>
      <title>The Behaviour of Ballasted Track Foundations: Track Drainage and Geosynthetic Reinforcement</title>
      <link>https://trid.trb.org/View/2191986</link>
      <description><![CDATA[Ballasted Rail tracks are widely used throughout the world due to its resiliency to the repeated wheel loads, low construction cost and ease of maintenance. However, the ballast layer needs periodic maintenance due to its deformation and degradation associated with particle breakage and fouling. A proper understanding of the contamination due to various types of fines and its implications on track drainage is a pre-requisite for effective implementation of track maintenance operations. A new parameter Void Contaminant Index (VCI) can accurately assess the contamination as it includes the effect of void ratio, specific gravity and gradation of ballast and fouling material. A series of constant head hydraulic conductivity tests using a specially designed large-scale permeability apparatus were performed on fresh ballast mixed with different proportions of fines to study the relationship between the percentage of fouling and drainage characteristics. A field trial is conducted on an instrumented track at Bulli, NSW Australia, to study the benefits of a geocomposite layer installed at the ballast-capping interface, and to evaluate the performance of recycled ballast in comparison to traditionally uniform fresh ballast. It is found that recycled ballast can be effectively reused if reinforced with a geocomposite. The geocomposite can effectively reduce vertical and lateral deformations of the ballast with obvious implications on improved track stability thereby reducing maintenance costs.]]></description>
      <pubDate>Mon, 23 Mar 2026 15:24:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2191986</guid>
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