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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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    <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>A Data-Driven Framework for Predicting CDI and TDI from Mix Design Parameters using Interpretable Machine Learning</title>
      <link>https://trid.trb.org/View/2696184</link>
      <description><![CDATA[Workability and long-term performance of asphalt mixtures are vital for durable pavements. Conventional evaluation of Compaction Densification Index (CDI) and Traffic Densification Index (TDI) using Superpave Gyratory Compactor (SGC) data is labour-intensive and fails to capture nonlinear relationships among mix variables. Although machine learning (ML) has been increasingly applied in pavement engineering, most studies address single indices and lack interpretability. This study bridges that gap by developing an explainable ML framework to simultaneously predict CDI and TDI from key mix parameters aggregate gradation, nominal maximum aggregate size (NMAS), and binder type. A dataset of 151 samples, compiled from published studies and laboratory databases, was divided into 70% training and 30% testing subsets. Three ML models Decision Tree, Random Forest, and Multi-Layer Perceptron (MLP) were developed and compared. The MLP achieved the highest predictive accuracy for CDI (R² = 0.92), while the Decision Tree slightly outperformed others for TDI (R² = 0.50). The study further aims to interpret model predictions using SHAP (SHapley Additive exPlanations) to identify the influence of individual input variables such as gradation and NMAS on compaction behaviour. The proposed interpretable framework enables rapid and reliable estimation of densification indices, offering a practical tool for optimizing asphalt mix designs, minimizing laboratory effort, and enhancing pavement quality and service life, thereby supporting Sustainable Development Goal 9 (Industry, Innovation and Infrastructure), SDG 11 (Sustainable Cities and Communities), and SDG 12 (Responsible Consumption and Production).]]></description>
      <pubDate>Fri, 28 Aug 2026 08:35:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2696184</guid>
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    <item>
      <title>Analytical method considering P-Δ effect and soil densification effect of vertical load for the effect of asymmetric scour on pile lateral capacity in sand under combined loads</title>
      <link>https://trid.trb.org/View/2644044</link>
      <description><![CDATA[Scour reduces the lateral bearing capacity of pile foundations. However, scour is asymmetrical in reality, and ignoring this fact may lead to discrepancies between the pile foundation bearing capacity obtained and the actual bearing capacity. Under combined loads conditions, vertical loads not only produce P-Δ effect, but also alter the stiffness of the soil around the piles, resulting in soil densification and affecting the lateral bearing capacity of the piles. This paper modifies the ultimate soil resistance based on the asymmetric scour model and introduces a couple loading factor KVH to account for the soil densification effect caused by vertical load, thereby obtaining a modified p-y curve. Based on stress analysis, the differential equation of pile deflection is constructed, and a method is proposed to analyze the effect of asymmetric scour and combined loads coupling on the lateral bearing capacity of pile. The accuracy of the proposed analytical method is verified through existing research cases. Finally, this paper analyzes the influence of asymmetric scour on lateral bearing capacity, as well as the effects of asymmetric scour and combined loads on the P-Δ effect and soil consolidation effect. The results indicate that, compared with other scour parameters, passive scour depth has the greatest impact on the lateral bearing capacity of pile foundations. Asymmetric scour affects the P-Δ effect by influencing the lateral displacement of piles, while its impact on soil densification effect is achieved by influencing the ultimate soil resistance.]]></description>
      <pubDate>Fri, 13 Mar 2026 08:46:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2644044</guid>
    </item>
    <item>
      <title>Can Public Investment in Transport Influence Densification and Land Use? Evidence From the Tramway of Dijon (France)</title>
      <link>https://trid.trb.org/View/2633832</link>
      <description><![CDATA[Investment in public transport offers alternatives to reduce car dependency as well as many negative externalities associated with solo car usage. Yet, to be fully effective, public transport infrastructure must be able to facilitate economic activities and households’ concentration. By increasing building density around stations and corridors, transport land-use feedback cycle can be engaged. The paper aims to evaluate the existence and extent of the causal relationship between public investment and densification, leveraging the implementation of a tramway service in the metropole of Dijon (France). The analysis decomposes the impact by direction as well as by the distance to corridor and city center. The results suggest that investment in public transport systems can significantly affect population and/or employment densification patterns, but that success is largely linked to the political willingness to stimulate densification through facilitating private investment.]]></description>
      <pubDate>Mon, 22 Dec 2025 17:03:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2633832</guid>
    </item>
    <item>
      <title>Characterization of the permanent deformation in the primary stage of creep of asphalt mixtures</title>
      <link>https://trid.trb.org/View/2582172</link>
      <description><![CDATA[The primary stage of deformation in creep of asphalt concrete involves both densification mechanisms and shear flow. The mechanical behaviour at this stage is generally nonlinear. In this study, the deformation in the primary stage was characterised by conducting creep and recovery tests with the creep time specifically chosen such that it coincides with the transition from the primary to the secondary stage of deformation. In this way, creep and recovery tests were conducted on three different asphalt mixtures at three different temperatures. The results highlight the nonlinearity of the mechanical behaviour. Notably, the extent of increase in strain during the ramp-up of stress was found to be several times higher than the recovery during the ramp-down. A visco-elasto-plastic model was used to describe the experimental results. The results show that permanent deformation mechanisms other than shear flow, such as densification, dominate this stage.]]></description>
      <pubDate>Fri, 24 Oct 2025 16:53:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2582172</guid>
    </item>
    <item>
      <title>Densification behavior of warm stone mastic asphalt with construction and demolition waste aggregate under repeated compressive loading</title>
      <link>https://trid.trb.org/View/2597962</link>
      <description><![CDATA[Construction and demolition waste (CDW) aggregate is generally characterized by lower mechanical strength compared to conventional natural aggregates. Surprisingly, research has shown that asphalt mixtures incorporating CDW aggregates exhibit improved stability, resilient modulus, and resistance to rutting. This study examines the underlying mechanisms responsible for this behavior by evaluating the post-compaction behavior of the mixtures under repetitive loading using Densification Index (Di) and Consolidation Index (Ki). The two unique indices provide a novel approach for linking material-level responses to macro-scale mechanical performance. The results show that the mixtures demonstrate significant densification and consolidation under cyclic loading, with Di increasing from 1.10 to 1.40 and Ki increasing from 4.1 to 8.4. In addition, replacing 30 % of the natural aggregate with CDW aggregates resulted in a Stability of 10.6 kN, a resilient modulus of 2099 MPa when tested at 25°C, a creep stiffness modulus of 22.34 MPa, and a Tensile strength ratio (TSR) of 82 %. However, at 40 % and 50 % CDW aggregate replacement, decreased moisture resistance was observed, with TSR values of 73 % and 64 %, respectively. Mediation statistical analysis confirmed that densification has a significant influence on dynamic stiffness. This research provides a foundation for the performance-based design of recycled asphalt pavements, targeting both structural longevity and environmental benefits.]]></description>
      <pubDate>Thu, 23 Oct 2025 09:23:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2597962</guid>
    </item>
    <item>
      <title>Durability evaluation and microstructure optimization of spray concrete for undersea tunnel: Role of hydrophobic agent and densifying material</title>
      <link>https://trid.trb.org/View/2541380</link>
      <description><![CDATA[The durability of spray concrete structures as permanent rock support in the undersea tunnel is a matter of continuing concern because of long service-life deign and severe environment. This study aims to evaluate the erosion resistance and enhancement mechanism of spray concrete modified with densifying materials and hydrophobic agent under the attack of sulfate, chloride and magnesium ions. Compressive strength, water absorption, chloride permeability, chloride and sulfate ions profiles, and leaching depth were adopted for assessing durability of the spray concrete exposed to the corrosive solution made of multiple ions. Besides, air-bubble parameters and micro-computed tomography (micro-CT) scanning, XRD and thermogravimetric (TG), SEM and contact angle were utilized to characterize microstructure, mineralogy and hydrophobicity of the concrete specimens. The results indicated the inclusion of a densifying material or hydrophobic agent into the spray concrete slowed down the degradation process, reduced the leaching depth, and decreased the loss rate of compressive strength and water absorption. Simultaneously, there was a significant improvement in chloride permeability and resistance to ion ingress. Notably, both the densifying material and hydrophobic agent demonstrated mechanisms involving portlandite consumption and pore refinement to inhibit the formation of ettringite and the degradation of portlandite induced by leaching. It is important to note that the effect of hydrophobic modification was more pronounced than that of porosity refinement in enhancing the resistance of the spray concrete to corrosive solutions.]]></description>
      <pubDate>Thu, 15 May 2025 08:26:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/2541380</guid>
    </item>
    <item>
      <title>Densification and Drainage Effects of Stone Columns on Mitigating the Uplift of a Shield Tunnel Induced by Soil Liquefaction</title>
      <link>https://trid.trb.org/View/2529691</link>
      <description><![CDATA[After sand liquefaction, buried underground structures may float, leading to structural damage. Therefore, implementing effective reinforcement measures to control sand liquefaction and soil deformation is crucial. Stone columns are widely used to reinforce liquefiable sites, enhancing their resistance to liquefaction. In this study, we investigated the mitigation effect of stone columns on the uplift of a shield tunnel induced by soil liquefaction using a high-fidelity numerical method. The liquefiable sand was modeled using a plastic model for large postliquefaction shear deformation of sand (CycLiq). A dynamic centrifuge model test on stone column–improved liquefiable ground was simulated using this model. The results demonstrate that the constitutive model and analysis method effectively reproduce the liquefaction behavior of stone column–reinforced ground under seismic loading, accurately reflecting the time histories of excess pore pressure ratio and acceleration. Subsequently, numerical simulations were employed to analyze the liquefaction resistance of saturated sand strata and the response of a shield tunnel before and after reinforcement with stone columns. Additionally, the effects of densification and drainage of the stone columns were separately studied. The results show that, after installing stone columns, the excess pore pressure ratio at each measurement point significantly decreased, eliminating liquefaction and mitigating the uplift of the tunnel. The drainage effect of the stone columns emerged as the primary mechanism for dissipating excess pore pressure and reducing tunnel uplift. Furthermore, the densification effect of stone columns effectively reduces soil settlement, particularly pronounced around the stone columns, i.e., at a distance of three times the diameter of the stone column.]]></description>
      <pubDate>Thu, 01 May 2025 09:37:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2529691</guid>
    </item>
    <item>
      <title>Experimental Research and Application of Small-Strain Soil Hardening Model Parameters in a Major Project in Hangzhou</title>
      <link>https://trid.trb.org/View/2395106</link>
      <description><![CDATA[According to current research, the small-strain soil hardening model (HSS model) is being used more and more widely because it can consider the small-strain characteristics of soil, making the corresponding numerical analysis results more accurate. At present, research into the test value of HSS model parameters of soil mass is mainly concentrated in Shanghai. Given the limits of the test conditions, there has been notably insufficient research into the value of small-strain parameters. Considering the regional differences of soil parameters, this paper, based on an actual project, conducts the HSS model parameter test value study on the main soil layers in the west of Hangzhou, focusing on the value study of small-strain parameters. The corresponding results are used for numerical analysis. The research shows that, compared with the Mohr–Coulomb model, the numerical analysis results using the HSS model are obviously closer to the measured data, and the prediction of the lateral deformation and its change law of the diaphragm wall is obviously more accurate. At the same time, when other HSS model parameters are unchanged, the numerical results using in situ small-strain parameters are closer to the measured results than using indoor small-strain parameters, and the corresponding deformation prediction accuracy is higher. The research results provide valuable references for determining HSS model parameters and engineering applications in the western area of Hangzhou.]]></description>
      <pubDate>Tue, 25 Jun 2024 10:33:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2395106</guid>
    </item>
    <item>
      <title>Liquefaction Mitigation by Vibro Stone Columns for Hamner Bridge Project</title>
      <link>https://trid.trb.org/View/2377768</link>
      <description><![CDATA[The planned bridge approach embankment located at the Hamner Avenue Bridge over the Santa Ana River in Norco, CA, is located in a high-risk seismic area. The embankment will be constructed on fill overlying young alluvial river deposits. Under the site design earthquake of magnitude 7.7 and peak ground surface acceleration of 0.57 g, the embankment site will be liquefied and potentially trigger lateral spreading. Treatment by Vibro Replacement Stone Columns was adopted to mitigate the site liquefaction and lateral spreading hazards below the planned embankment retaining wall footprint. To densify the liquefiable sands, the specialty geotechnical contractor performed liquefaction analysis and determined the stone column replacement ratio and treatment based on the soil fines content and pre-treatment cone penetration test (CPT) tip resistance. The contractor used a real time data acquisition system to monitor and record the stone column installation, including the vibrator penetration depth, electric current, and air pressure, which allowed the contractor and engineer to interpolate stone column diameter as a function of depth. This system provided a reliable field quality control record to the design engineer and the client. As part of the project QA/QC process, 20 post-treatment CPTs were performed and analyzed, which confirmed all the design densification criteria achieved. This paper discusses the project design, construction, and quality controls. The soil densification effectiveness was evaluated statistically by the comparison of the pre- and post-CPTs as a function the CPT Ic values.]]></description>
      <pubDate>Tue, 28 May 2024 09:25:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2377768</guid>
    </item>
    <item>
      <title>Creating inequality in access to public transit? Densification, gentrification, and displacement</title>
      <link>https://trid.trb.org/View/2362032</link>
      <description><![CDATA[Densification is a key concept in contemporary urban planning. Yet, there are widespread concerns about densification causing displacement and gentrification. This paper examines densification around train stations—a prevalent form of transit-oriented development (TOD) in cities with established public transit systems—in the Canton of Zurich, Switzerland. We assess the effects of densification around train stations on the socioeconomic population composition in these areas and investigate three different potential displacement effects. Leveraging 1.8 million linked person-housing unit observations for all individuals within our study perimeter, we provide a more nuanced understanding of densification’s effects on the population composition and displacement than prior research. Our findings reveal that even though densification increases the absolute number of low-income residents, it primarily benefits middle- and high-income households. Specifically, there is a decline in the share of low-income residents, attributed to the influx of younger high-income individuals. Moreover, incumbent low-income residents experience an increased risk of direct displacement due to housing demolitions. These outcomes highlight the limitations of TOD strategies in mitigating persistent socioeconomic disparities in public transit access, emphasizing the need for more comprehensive measures to address the challenges of equitable housing and public transit accessibility.]]></description>
      <pubDate>Thu, 18 Apr 2024 17:07:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/2362032</guid>
    </item>
    <item>
      <title>Ineffective built environment interventions: How to reduce driving in American suburbs?</title>
      <link>https://trid.trb.org/View/2307320</link>
      <description><![CDATA[Designing effective built environment policies to reduce auto use is key to promoting sustainable transportation in suburban areas. However, most studies on the association between the built environment and auto use focus on the entire region rather than suburban areas. In addition, previous studies often ignore the possible nonlinear association between them. Applying Gradient Boosting Decision Trees to the data in the Twin Cities, USA, this study explores the nonlinear relationships between built environment attributes and driving distance in suburban areas and illustrates how the relationships differ from those in urban areas. The results show that suburban residents are less sensitive to the built environment than urban residents. More importantly, built environment policies that work in urban areas might be infertile in suburban areas. Although many studies have advocated population densification and mixed-use development for driving mitigation, this study suggests that these policies are ineffective in suburban areas. Instead, promoting job accessibility and densifying intersection density are promising to reduce auto use in suburban areas. Densifying transit stops has a small but nontrivial contribution to mitigating auto use.]]></description>
      <pubDate>Fri, 26 Jan 2024 10:02:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2307320</guid>
    </item>
    <item>
      <title>Densification behavior of asphalt mixture and its relation with particle dynamic responses during gyratory compaction</title>
      <link>https://trid.trb.org/View/2146777</link>
      <description><![CDATA[Compaction of asphalt mixture is a critical step of the pavement construction, which determines the performance and durability for asphalt pavement. The densification behavior of asphalt mixture is complicated and its workability is prone to be affected by the material composition and construction conditions. Knowing the compaction process is of great significance for improving the pavement construction quality. This study aims to investigate the densification behavior of asphalt mixture in the compaction process and its correlation with dynamic responses of the built-in Smart Aggregate. Through Los Angeles abrasion tests and aggregate imaging measurement system, 40 kinds of coarse aggregates with different morphologies were prepared and employed to carry out gyratory compaction tests for asphalt mixtures. The height decline and density growth of the mixtures were concerned in different compaction stages. Meanwhile, the Smart Aggregate was embedded in the mixture to capture the particle dynamic responses, which were further correlated to the densification behavior of the mixture. The results show that material factors have the significant influence on the compaction process after the mixture has been compacted to the P1 at which the height change is less than 1 mm. The gyratory compaction process can be divided into different stages of 0∼P1, P1∼P0.1, P0.1∼P0 according to the change in mixture height, and every gyration would enable the percentage of maximum theoretical specific gravity (Gmm) increase with 1.46 %, 0.3 %, 0.11 % in the corresponding stage. After the threshold point P0, the increment of compaction degree after per gyration is less than 0.05 %. AC and SMA-13 mixtures would achieve the 95.5 %∼97.4 % of Gmm when they are compacted to locking point of P0. Asphalt mixture height is highly related to the relative rotation of the embedded Smart Aggregate. Change in the mixture height can be characterized by the variation of particle relative rotation, which could be further adopted to determine the locking state of asphalt mixture compaction in real-time.]]></description>
      <pubDate>Wed, 24 May 2023 09:06:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2146777</guid>
    </item>
    <item>
      <title>Numerical Study of the Influence of Foundation Soil on the Deformation Behavior of Geosynthetic Reinforced Soil-Integrated Bridge System under Service Load Conditions</title>
      <link>https://trid.trb.org/View/2141998</link>
      <description><![CDATA[The geosynthetic reinforced soil-integrated bridge system (GRS-IBS) is becoming widely used for transportation infrastructure. Most of the reported GRS-IBS case histories were constructed on relatively stiff foundation soil layer, and all showed good service performance. This paper presents a numerical study of the deformation behavior of GRS-IBS under service load conditions, with the objective of evaluating the influence of foundation soil conditions. Numerical simulations were conducted using the finite difference program FLAC for GRS-IBS constructed on granular foundation soils with different densities. The granular foundation soil and backfill soil were characterized using a nonlinear elasto-plastic model that incorporates the Duncan-Chang hyperbolic relationship and the Mohr-Coulomb failure criterion. Foundation soil parameters were selected according to data reported in the literature, and the soil stiffness and strength increase with increasing density. Geogrid reinforcements were characterized using linearly elastic-plastic cable elements. Various interfaces were included to simulate the interaction between different components. Simulation results indicate that increasing the foundation soil stiffness and strength effectively reduce facing displacements, bridge seat settlements, and foundation soil settlements, but also produce larger vertical compressions of the GRS abutment. Results provide insights for the application of GRS-IBS for different granular foundation soil conditions.]]></description>
      <pubDate>Mon, 17 Apr 2023 09:00:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2141998</guid>
    </item>
    <item>
      <title>Vibrations and Ground Deformations Due to Road Compaction</title>
      <link>https://trid.trb.org/View/2134832</link>
      <description><![CDATA[The following project objectives will be accomplished using numerical modeling approaches and data collected from real project sites in Florida: (1) To develop a prediction method of the amount of dynamic ground deformations and vibrations caused by road compaction and their variation along an influence zone. (2) To understand the mechanisms of near-field and far-field ground deformations during road compaction and determine the critical distance from near-field to far-field ground deformation zones. This applied to primarily medium-dense sands and silty sand conditions. (3) To investigate relationships among four major components that are ground deformations, ground vibrations (i.e., PPV), input energy, and distance from the source of road compaction. Affecting parameters such as soil strength and stiffness, type of road compaction equipment, relative density of the soil, and characteristics of the energy source will be considered in the correlation development. Field data and numerical modeling will be used to develop the correlations of those major components. (4) To develop a ground deformation chart arising from road compaction (or correlation or equation) as a function of PPV, relative density of the soil, distance from the source, soil shear strain, and/or input energy.]]></description>
      <pubDate>Tue, 07 Mar 2023 08:51:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2134832</guid>
    </item>
    <item>
      <title>A Report on a Static and Dynamic Pile Test in Pocatello, Idaho</title>
      <link>https://trid.trb.org/View/2008869</link>
      <description><![CDATA[Dynamic tests were made on three piles at a site located about 15 miles west of Pocatello, Idaho. A complete static load test was available for only one of these piles (Pile No. 11). The results of the tests on the piles which were not statically load tested are presented in the detailed portion of this report. The test pile was a 16-inch diameter cast-in-place concrete pipe pile with a 3/8-inch wall thickness. It was driven, with a closed end, through seven feet of sand and gravel and 20 to 30 feet of medium stiff silty clay into a loose sand. It was expected that the bearing capacity of the sand could be improved by densification during the driving of this displacement type pile. All tests were performed prior to filling the pile with concrete.]]></description>
      <pubDate>Wed, 09 Nov 2022 17:50:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2008869</guid>
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