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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>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Framing Camera Time-resolved Laser Induced Incandescence Measurements in a Rich Quench Lean Combustor</title>
      <link>https://trid.trb.org/View/2730842</link>
      <description><![CDATA[Determining the size of soot particles in dynamic turbulent flames is critical for optimizing injector and combustor designs. In this work, we demonstrate the first use of a gigahertz-rate framing camera for planar time-resolved laser-induced incandescence (TiRe-LII) measurements in a rich quench lean (RQL) combustion system with Jet A fuel. In this method, the framing camera is able to capture the background luminosity, prompt LII signal, and temporal incandescence decay at up to 40 MHz. This enables shorter time constant fits than any prior 2D TiRe-LII experiments, enhancing confidence in soot particle size and soot volume fraction estimates. Measurements are performed at a preheat temperature of 600 K, pressures ranging from 59 to 120 psig, and equivalence ratios from 0.26 to 0.29. Initial results show clear soot volume fraction and particle size changes with pressure and equivalence ratio.]]></description>
      <pubDate>Wed, 22 Jul 2026 09:06:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2730842</guid>
    </item>
    <item>
      <title>Unveiling the role of size characteristics of recycled rubber-polyethylene elastomers on polymer-asphalt interaction and asphalt rheology</title>
      <link>https://trid.trb.org/View/2721197</link>
      <description><![CDATA[Upcycling waste tires and recycled polyethylene (rPE) into asphalt offers a sustainable solution. However, poor compatibility between crumb rubber (CR), rPE and asphalt limits practical application. Accordingly, the size characteristics of modifiers is critical to polymer-asphalt interaction and the resulting rheological behavior, yet remains insufficiently understood in rubber-polyethylene elastomers. In this study, CR and rPE were extruded and cryogenically pulverized to obtain the thermo-mechanical rubber-polyethylene elastomers (TRPE) and micronized elastomers (mRPE). The microphase interaction, phase separation, and rheological behavior of modified asphalt were evaluated. The results indicate that TRPE already establishes a relatively well-dispersed polymeric phase in asphalt, while further micronization improves microstructural uniformity and reduces the softening point difference to 0.8 ℃. Rheological analysis reveals a progressive enhancement in polymer-asphalt interaction of TRPE modified asphalt (TRPEA) and mRPE modified asphalt (mRPEA), as evidenced by a reduction in rheological interaction index (h value) from 0.87 to 0.14. The results show that the Cole-Cole plots are insufficient to distinguish the compatibility of TRPEA and mRPEA under the specific test conditions. Due to the dissolution of large elastic particles, TRPEA and mRPEA exhibit a pronounced shift toward viscous behavior. Moreover, mRPEA shows improved deformation resistance at high temperature and highest fatigue life with 5.66×106 at 2.5% strain. Overall, this work provides valuable insights in optimizing waste-derived modifiers for sustainable pavement materials.]]></description>
      <pubDate>Thu, 09 Jul 2026 13:32:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2721197</guid>
    </item>
    <item>
      <title>Quantifying size effects on particle breakage strength and energy of red-bed soft and hard rock waste materials: Experiments, simulations, and model correction</title>
      <link>https://trid.trb.org/View/2676298</link>
      <description><![CDATA[Accurately predicting the breakage strength and energy of red-bed soft–hard rock waste materials (RB-SHWM) across different particle size (d) ranges is critical for evaluating gradation evolution and controlling breakage-induced risks in road engineering fills. In this study, single-particle breakage (SPB) tests (216 groups in total) and discrete element method (DEM) simulations were conducted on hard red-bed sandstone (HRS) and soft red-bed mudstone (SRS) particles to elucidate particle-size scale effects and to establish a correction model applicable to very large particle sizes. The results indicate that the post-breakage particle-size distribution exhibits clear fractal characteristics; under mixed particle-group conditions, the final fractal dimensions of SRS and HRS are 2.53 and 2.45, respectively. For a given particle size, both the breakage strength and energy of HRS are consistently higher than those of SRS. As the particle size increases from 4.75–9.5 mm to 19–37.5 mm, the average breakage strength of SRS and HRS decreases by 38.51% and 43.30%, respectively, whereas the crushing energy increases by factors of 9.18 and 8.04, respectively. Conventional strength and energy prediction models developed based on fractal theory show excellent agreement with experimental results within the normal particle-size range (R² = 0.99). DEM simulations can stably reproduce the experimental peak response for d < 60 mm, with relative errors in peak strength ranging from 3.04% to 6.56%. However, when the particle size enters the very large scale (d ≥ 60 mm), prediction deviations from traditional models increase markedly. To address this limitation, corrected models are proposed to capture the nonlinear evolution characterized by attenuated strength degradation and decelerated energy growth. Their reliability and extensibility are validated through independent numerical simulations, supplementary experiments, and comparisons with published datasets, with overall prediction errors maintained within an acceptable range. The key contribution of this work lies in proposing and validating engineering-scale predictive equations for single-particle breakage strength and breakage energy in soft–hard mixed granular fill systems, together with correction forms for very large particle sizes. These equations provide a quantitative tool that can be directly embedded into numerical simulations and engineering analyses to support gradation evolution assessment and breakage evaluation of mixed fills.]]></description>
      <pubDate>Wed, 17 Jun 2026 12:23:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2676298</guid>
    </item>
    <item>
      <title>Enhancing Granular Surface Material Performance Using California Bearing Ratio and Repeated Load Triaxial Tests</title>
      <link>https://trid.trb.org/View/2678494</link>
      <description><![CDATA[Granular-surfaced roads are prone to significant wear and damage due to heavy agricultural traffic and freeze-thaw cycles, which tend to increase maintenance costs and safety risks. While previous studies have explored the role of particle size distribution in influencing properties like resilient modulus (MR) and California Bearing Ratio (CBR) of surfacing aggregates, limited research has focused on quantifying the effects of gradation on the mechanical performance of such roads. The present study addresses this gap by analyzing laboratory tests, including soaked CBR, MR, and plastic strain (εp), combined with statistical analysis to assess the impact of gradation variations. The gradation of the tested materials was parametrized using a two-parameter sigmoidal model to enable optimization based on values of soaked CBR, MR, and plastic strain. Two specimen sets were analyzed: one with six mixtures of virgin quarry aggregates and another with six mixtures of virgin aggregates blended with existing roadway surface materials. The findings show that incorporating existing surface materials into the virgin materials enhances the strength and stiffness while significantly influencing the optimum gradation parameters. This research presents an approach involving gradation analysis, experimental testing, and statistical modeling to identify the optimal gradation. By adopting this systematic process, engineers and practitioners can develop cost-effective solutions for constructing and rehabilitating granular-surfaced roads, ultimately enhancing their durability and performance while reducing long-term maintenance demands.]]></description>
      <pubDate>Fri, 12 Jun 2026 15:59:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2678494</guid>
    </item>
    <item>
      <title>Investigation Into the Mechanical Behavior of Track-Bed Materials with Different Grain Size Distributions of Coarse Grains</title>
      <link>https://trid.trb.org/View/2113131</link>
      <description><![CDATA[In French ancient railway substructure, the interpenetration of ballast and subgrade soils formed a new layer, namely interlayer. Along the depth, a decreasing trend of ballast content was identified in field investigation. In this study, the effect of Cu of coarse grains on the mechanical behaviors of interlayer soils was investigated by carrying out monotonic triaxial tests. Five volumetric contents of coarse grains fv (5, 10, 20, 35, and 45%) and three Cu values were considered. Also, X-ray μCT scans were performed on representative samples to visualize the grain distributions. Results show that: (a) at each Cu value, from the variation trend of qmax with fv, a characteristic volumetric content of coarse grains fv-cha was identified, defining two soil fabrics (namely fine-fine contact structure and grain-grain contact structure). When Cu decreased, fv-cha increased since fewer grain contacts were developed at smaller Cu; (b) in the case of grain-grain contact structure, the decrease of Cu increased the maximum deviator stress qmax, friction angle, Poisson’s ratio and dilatancy angle, since more large grains were involved at smaller Cu; (c) in the case of fine-fine contact structure, the Cu decreasing led to decreases in qmax, friction angle, Poisson’s ratio and dilatancy angle due to smaller quantity of coarse grains; (d) for two soil fabrics, the variations of Young’s modulus and cohesion with Cu shared the same pattern: the smaller the Cu, the larger Young’s modulus and the cohesion.]]></description>
      <pubDate>Thu, 28 May 2026 17:09:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113131</guid>
    </item>
    <item>
      <title>Experimental Study on the Impact Force and Dynamic Evolution of Landslide-Debris Flows at the Portal Section of Mountain Tunnels</title>
      <link>https://trid.trb.org/View/2703731</link>
      <description><![CDATA[As transport networks continue to improve, more tunnels are being commissioned. The complex topography and geological conditions of certain mountainous regions have led to the construction of road and railway tunnels that must pass through geologically sensitive zones which are prone to landslide-debris flows at tunnel entrances during operation. This study, based on real engineering cases, combines scale-model tests and numerical simulations to examine the maximum impact force and dynamic behavior of landslide-debris flow at tunnel entrances in mountainous areas. The main findings are as follows. (1) Laboratory model tests were used to quantitatively analyze how particle gradation, flume inclination, and source volume influence impact force, and particle gradation was identified as the most significant factor. (2) A three-dimensional physical model of landslide-debris flow was developed, based on the physical and mechanical properties of landslide-debris-flow particles and their size distribution obtained from testing. This model simulated the entire process, from the initiation of landslide-debris flows to their attenuation, revealing the evolution of flow depth and velocity during impact. (3) The debris flow accumulates from east to west, reaching a maximum depth of about 12 m at the tunnel entrance, posing a considerable threat. The impact process can be divided into three stages: 0–6 s of initial acceleration, 6–13 s of slow acceleration, and 13–23 s of deceleration and cessation of accumulation. Because particle size substantially influences the impact behavior of debris flows, we recommend adopting a tiered protection system that classifies and designs countermeasures according to particle-size composition.]]></description>
      <pubDate>Sat, 16 May 2026 12:15:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2703731</guid>
    </item>
    <item>
      <title>High-Cycle Fatigue Behavior and Fracture Mechanism of Q370qD Bridge Steel Subjected to Different Stress Levels</title>
      <link>https://trid.trb.org/View/2674992</link>
      <description><![CDATA[In engineering practice, fatigue failure is the primary failure mode of bridge steel, which is a brittle fracture without obvious symptoms. This work characterizes the microstructure of Q370qD steel before and after fatigue testing using a series of characterization techniques, including optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electron back-scatter diffraction (EBSD). The fatigue fracture mechanism of Q370qD steel at different stress levels is further investigated. Results indicate that the fatigue strength of the S-N curve (97.7% guarantee rate) at N = 2 × 10⁶ is 245 MPa for naturally linear fitting and 197 MPa for fixed-slope linear fitting. The initial microstructure is characterized by uniformly distributed Fe-C dendritic eutectic phases with the dendrite spacing of approximately 10.63 μm. The microstructure analysis near the fracture surface indicates that grain size and the percentage of low-angle grain boundaries significantly affect fatigue performance. The deformation band can drastically reduce the energy needed for crack initiation and provide a low-resistance path for crack propagation. Small-sized grains can hinder dislocation motion and delay crack initiation. In addition, crack initiation is dominant in high-cycle fatigue. Average kernel average misorientation (Ave. KAM) is a statistical representation of the overall dislocation structure and has a weak effect on fatigue performance. Consequently, the correlation between microfactors affecting fatigue performance can be expressed as deformation band > grain size > Ave. KAM. As the stress level increases, the {100} texture evolves from two pole density peaks, which deviate 45° from normal direction (ND) toward transverse direction (TD), to three pole density peaks extending along the loading direction. For the {111} texture, the pole density peaks parallel to ND gradually dismiss, and the other two pole density peaks that deviate 45° from ND to TD are retained. This study provides strong data support for the high-cycle fatigue behavior and fracture mechanism of bridge steel from the perspective of microstructure.]]></description>
      <pubDate>Fri, 15 May 2026 09:18:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2674992</guid>
    </item>
    <item>
      <title>Effect of Sand Grading and Proportion on the Performance of Cement Asphalt Mortar for High-Speed Rail Slab Track Systems</title>
      <link>https://trid.trb.org/View/2701133</link>
      <description><![CDATA[Sand makes up about 40% of cement asphalt mortar (CAM) used in non-ballast tracks for high-speed rail infrastructure, playing a crucial role on the performance of CAM. This study investigates the influence of sand gradation (quantified using fineness modulus [FM]), and sand-to-cementitious component ratio (S/CC) on key CAM parameters, including flow time, working time, material separation, compressive strength, elastic modulus, and shrinkage. Multiple gradations and S/CC ratios were evaluated to establish combinations that achieve the required flow time (16–28 s), a minimum 30 min working time, minimize material separation, and ensure desired mechanical performance. Results indicate that coarser gradations improve workability but increase material separation, whereas finer gradations reduce separation but prolong flow time. An FM of 1.6, with particles passing 1.18 mm sieve ensure desired flow time and homogeneity of CAM. An S/CC ratio of 2 maintained good workability, reduced shrinkage and deformation, and improved compressive strength and modulus. These findings offer insights for CAM mix design particularly with reference to sand gradation and proportion selection.]]></description>
      <pubDate>Tue, 12 May 2026 16:57:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2701133</guid>
    </item>
    <item>
      <title>Characterization Of Sediment Loads and Size Distribution in Nebraska Roadway Runoff</title>
      <link>https://trid.trb.org/View/2686245</link>
      <description><![CDATA[The Nebraska Department of Transportation (NDOT) must manage sediment, and pollutant loads from roadway runoff to meet stormwater regulations. The SAFL Baffle, a hydrodynamic separator used by NDOT, depends on reliable estimates of total suspended solids (TSS) and particle size distribution (PSD). However, limited data exists for Nebraska roadways. In this study stormwater runoff was monitored at four NDOT-maintained sites, two in Lincoln and two in Beatrice, over 1.5 years to characterize TSS and PSD and to evaluate SAFL Baffle performance using the SHSAM model. Results showed large variability across sites and seasons. Median TSS ranged from 158 to 580 mg/L, and median particle size (d50) from 16 to 322 μm. Finer particles dominated at most sites, likely due to runoff from gravel or exposed soils off the roadway and especially outside of the NDOT right of way. Higher TSS in spring was observed and reflected low vegetation cover and winter sediment buildup. SHSAM modeling showed that the SAFL Baffle alone may not achieve 80 percent TSS removal, as it is less effective for fine particles. However, if off-site sediment loads are credited toward compliance, performance goals could be met. The study highlights the need for local sediment data and for accounting for off-site sources in NDOT stormwater design.]]></description>
      <pubDate>Thu, 09 Apr 2026 11:37:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2686245</guid>
    </item>
    <item>
      <title>Friction and Texture Analysis of 3D-Printed Samples</title>
      <link>https://trid.trb.org/View/2666113</link>
      <description><![CDATA[This study investigates the influence of surface texture and contact area size on frictional performance using laboratory samples fabricated through 3D printing and sandpaper-based surfaces. Measurements were conducted under both wet and dry conditions using the British Pendulum Tester. Results confirmed that contact area size significantly impacts friction values, whereas surface pattern arrangements have a less pronounced effect. In tests with sandpaper surfaces, the highest PTV values were observed for intermediate grain sizes (58.5–78 μm), contrary to expectations of a monotonic increase with coarser grains. Asphalt samples analyzed through 3D scanning and texture evaluation showed no clear correlation between average roughness (Sa) or projected contact area and PTV values, suggesting a need for finer evaluation depths. These findings emphasize the importance of combining macrotexture and microtexture assessments in optimizing pavement designs for improved skid resistance.]]></description>
      <pubDate>Mon, 23 Mar 2026 15:15:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2666113</guid>
    </item>
    <item>
      <title>DEM investigation on granular soil arching with emphasis on particle size distribution effect</title>
      <link>https://trid.trb.org/View/2644134</link>
      <description><![CDATA[Soil arching is a common load transfer mechanism in geotechnical engineering, which is significantly influenced by soil particle size distribution (PSD). Existing studies have not fully understood the PSD effect, specifically the mean particle size (d50) and coefficient of uniformity (Cu), on the arching evolution and critical height. To this end, this study tries to investigate the PSD effect on the evolution of soil arching using the discrete element method. A series of two-dimensional trapdoor tests were simulated on eight specimens with varying d50 and Cu. The macroscopic responses and microscopic mechanisms were systematically analyzed. Simulations reveal that an increase in d50 or Cu leads to a reduction in the critical arching height. This indicates that coarser and better-graded granular soils promote a more rapid development of soil arching effect, thereby enhancing the initial load-transfer efficiency. At the microscopic level, specimens with larger d50 develop stronger yet sparser force chains and exhibit greater normal contact force anisotropy, while specimens with higher Cu form denser contact networks with larger coordination numbers, resulting in more stable force transmission. The findings of this study strongly suggest that PSD significantly controls the soil arching development process through its governing role in fabric formation and force chain structure. Besides, the implications of this study offer direct relevance for optimizing backfill material design in geotechnical practices, notably in pile-supported embankments and underground excavation projects.]]></description>
      <pubDate>Wed, 25 Feb 2026 09:05:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2644134</guid>
    </item>
    <item>
      <title>Suggested Test Procedure for Ultrasonic Disaggregation of Clay Forming Materials - Grain Size Distribution</title>
      <link>https://trid.trb.org/View/2658092</link>
      <description><![CDATA[The procedure described is applicable to clay forming materials such as hardened clay soils, hard pan, shales, etc. It presents a method of preparing a sample of the material so that the grain size distribution can be determined under the most critical conditions.]]></description>
      <pubDate>Thu, 12 Feb 2026 08:53:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2658092</guid>
    </item>
    <item>
      <title>Optimisation of gradation based on fractal dimension for large-size graded crushed stone</title>
      <link>https://trid.trb.org/View/2618001</link>
      <description><![CDATA[To improve the mechanical properties of large particle size graded crushed stone mixture and obtain the optimal grading. By using different design methods to obtain the grading of large particle size graded crushed stone, the maximum dry density test, CBR penetration test, static pressure test, and cyclic repeated compaction test were conducted on the large particle size graded crushed stone samples. Finally, fractal theory was introduced to quantitatively calculate the grading of large particle size graded crushed stone, and the fractal dimension of large particle size graded crushed stone was obtained. The relationship between the fractal dimension of large particle size graded crushed stone and density, CBR value, compressive strength, and deformation resistance was analyzed through grey correlation analysis. The experimental results show that large particle size graded crushed stone has better skeleton performance than conventional graded crushed stone; The density, CBR value, compressive strength, and deformation resistance of large-sized graded crushed stone are related to the grading. The skeleton dense grading ratio has stronger mechanical properties compared to the suspended dense grading and skeleton interlocking grading. And the optimal fractal dimension for the optimal configuration should be between 2.59−2.61.]]></description>
      <pubDate>Mon, 09 Feb 2026 13:55:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2618001</guid>
    </item>
    <item>
      <title>Sound absorption characteristics of rubberised porous asphalt mixture</title>
      <link>https://trid.trb.org/View/2618015</link>
      <description><![CDATA[Traffic noise pollution has increased the demand for low-noise pavements. Improving the sound absorption performance of asphalt mixtures is crucial for reducing tyre-pavement noise. This study investigates the sound absorption characteristics of rubberised porous asphalt mixtures (RPAM) at macro- and micro-scales, focusing on the effect of rubber particles. The results indicated that there was a significant correlation between the maximum aggregate size, rubber particle content and the sound absorption performance of RPAM. Furthermore, the pore characteristics of RPAM with different maximum aggregate sizes and rubber particle contents were extracted by X-ray CT scanning and 3D reconstruction techniques, and the impact on sound absorption performance was investigated. The grey correlation analysis showed that pore characteristic parameters including throat length and coordination number had a more significant impact on the sound absorption performance. Reducing the maximum aggregate size and rubber particle content can increase these parameters, thereby improving the sound absorption performance.]]></description>
      <pubDate>Mon, 09 Feb 2026 13:55:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2618015</guid>
    </item>
    <item>
      <title>Development of a Prediction Model of Soot Particle Size Distribution Applicable to Design Calculations of Internal Combustion Engines</title>
      <link>https://trid.trb.org/View/2630448</link>
      <description><![CDATA[In previous work, we proposed a soot prediction model that can predict the particle size distribution and is applicable to design calculations of internal combustion engines. The model was validated for experimental results measured using burner stabilized stagnation flames and a DISI engine for iso-octane/n-heptane/toluene blended fuels. In this study, the model was extended to a 5-component gasoline surrogate composed of iso-octane/n-heptane/toluene/iso-pentane/1,2,4-trimethylbenzene, which reproduces the sooting characteristics of gasoline. The proposed model was validated against the experimental results measured on a DISI engine. As a result, it was shown that the proposed model can reproduce the particle formation characteristics with changes in fuel injection timing, coolant temperature, fuel injection pressure, and intake port configuration.]]></description>
      <pubDate>Thu, 05 Feb 2026 11:52:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2630448</guid>
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