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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>Design and Evaluation of Transition for TxDOT MASH Test Level 4 (Tl-4) Guardrail System</title>
      <link>https://trid.trb.org/View/2679057</link>
      <description><![CDATA[Researchers at the Texas A&M Transportation Institute (TTI) designed and tested a Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) compliant guardrail transition system (hereafter referred to as Transition) that enables transitioning and terminating the ends of the Texas Department of Transportation MASH TL-4 guardrail system with MASH-compliant guardrail end terminals. The researchers designed the Transition using finite element simulation analysis, details of which are presented in this report. The researchers performed vehicle impact simulations to improve the initial design concept of the Transition and developed the final design for full-scale crash testing. The researchers then constructed a test installation prototype and performed two full-scale crash tests that are also reported herein. The purpose of the tests was to assess the performance of the Transition according to the safety-performance evaluation guidelines included in the second edition of the American Association of State Highway and Transportation Officials MASH (1). The crash tests were performed in accordance with MASH TL-3 criteria, which require two crash tests: 1. MASH Test 3-20: An 1100C vehicle weighing 2,420 lb impacting the longitudinal barrier transition while traveling at 62 mi/h and 25 degrees. 2. MASH Test 3-21: A 2270P vehicle weighing 5,000 lb impacting the longitudinal barrier transition while traveling at 62 mi/h and 25 degrees. This report provides details of the Transition, the crash tests and results, and the performance assessment of the Transition for MASH TL-3 evaluation criteria for longitudinal barriers. The Transition met the MASH TL-3 performance criteria for longitudinal barriers.]]></description>
      <pubDate>Fri, 20 Mar 2026 09:27:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2679057</guid>
    </item>
    <item>
      <title>Development and Evaluation of Crashworthy Approach Guardrail Transition with Increased Span Length between Concrete Bridge Rail and First Transition Post – Phase I</title>
      <link>https://trid.trb.org/View/2675918</link>
      <description><![CDATA[This study developed and evaluated a 34-in.-tall Nebraska Department of Transportation (NDOT) thrie-beam approach guardrail transition (AGT) with an increased span between the concrete buttress end and the first transition post. The objective was to accommodate a wide range of common obstructions near bridge ends, including abutments, wing walls, drainage features, and utilities. A survey of NDOT districts identified critical obstruction geometries and informed design criteria. Most NDOT districts indicated that a maximum span of about 4 ft would be sufficient, and some preferred spans up to 6 ft. To accommodate a wider range of obstructions, the first transition post was set 8 ft-5 1/4 in. from the concrete buttress, more than twice the post spacing used in other MASH transitions. A validated LS-DYNA model of the standard 34 in. NDOT AGT system supported concept design screening under the Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3). The selected configuration used a double-tube design with HSS 4 in. × 4 in. × 1/4 in. members based on performance, handling weight, and connection demand. Simulations for MASH test designation nos. 3-21 and 3-20 showed stable vehicle behavior, acceptable occupant risk measures, and component stresses below yield and ultimate limits. Critical impact points were 89 in. upstream of the concrete buttress for MASH test designation no. 3-21 and 65 in. upstream of the concrete buttress for MASH test designation no. 3-20. Reverse direction and upstream impacts showed no significant pocketing or snag. Overall performance matched the standard NDOT 34-in. tall AGT system. The long-span design provides a crashworthy and practical option for non-ideal sites. Full-scale vehicle crash testing is required to confirm compliance and support FHWA eligibility.]]></description>
      <pubDate>Thu, 12 Mar 2026 08:48:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2675918</guid>
    </item>
    <item>
      <title>Probability-Based Pavement Asset Management in Ireland</title>
      <link>https://trid.trb.org/View/2655743</link>
      <description><![CDATA[This paper conducts an investigation into the application of Markov processes for optimizing the lifecycle management of pavements on the Irish national road network. Transition probability matrices (TPMs) are developed for a range of condition indicators, incorporating additional factors such as annual average daily traffic. The influence of these factors on the derived TPMs is illustrated. A methodology for updating the TPMs to facilitate consideration of the effects of incorporation of new materials, environmental management and/or of the effects of climate change and advance deterioration is considered. The research assesses the merits of employing homogeneous versus non-homogeneous Markov chains. The findings underscore the significant impact of probabilistic techniques in the domain of pavement asset management but considering budget allocation across the network for a specified time horizon.]]></description>
      <pubDate>Fri, 23 Jan 2026 09:20:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655743</guid>
    </item>
    <item>
      <title>Advanced Thermal Characterization of Styrene-Butadiene-Styrene (SBS)– Modified Asphalt Binders at Various SBS Contents and Long-Term Aging Levels</title>
      <link>https://trid.trb.org/View/2633002</link>
      <description><![CDATA[Styrene-butadiene-styrene (SBS) is an elastomeric copolymer that improves asphalt materials resistance to thermal and fatigue cracking. Different SBS-modified asphalt binders were evaluated by means of unmodulated and modulated differential scanning calorimetry (DSC) to determine their glass transition temperature (Tg), glass transition width (Tg,width), and the existence of crystallizable fractions in the base binders. Furthermore, to assess the impacts of different SBS content and long-term aging on asphalt binders’ thermal characteristics, this study used the thermogravimetric analysis (TGA) method in air and under nitrogen purge. This research aims to improve the understanding of the compatibility of SBS with various base binders and their impact on binder thermal characteristics at various aging levels. To be precise, this systematic study investigated SBS-modified binders at various SBS concentrations (0%, 2%, 4%), for three base binders across various pressure aging vessel conditioning at 20, 40, and 60?h. Additionally, these 27 binders were evaluated using Superpave performance grading (PG) standard tests and the Fourier-transfer infrared spectroscopy. Results suggest that long-term aging generally increases binder Tg, leading to stiffer binders, while the inclusion of higher SBS content was found to effectively lower Tg, thereby enhancing the flexibility and low-temperature performance of the binders. Additionally, SBS increases the Tg,width reflecting the increased heterogeneity of the multiphase modified binders. Although aging is expected to increase the Tg,width, the presence of higher SBS content helps stabilize the Tg,width across aging levels. Finally, the rate of maximum degradation from TGA was found to be useful for quantitative analysis of SBS after calibration.]]></description>
      <pubDate>Thu, 04 Dec 2025 11:36:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2633002</guid>
    </item>
    <item>
      <title>Impact of On-Road U.S. Vehicle Electrification and Lightweighting on Critical Materials Demand</title>
      <link>https://trid.trb.org/View/2521938</link>
      <description><![CDATA[This article reports on a study of the impact of vehicle electrification and lightweighting (material substitution) on the demand for critical materials in the United States.  The authors consider demand in two categories: light-duty vehicles (LDVs) and medium- and heavy-duty vehicles (MHDVs).  Results show that LDVs dominate the need for critical materials, despite the fact the MHDVs require more critical materials per vehicles.  Battery electric vehicles (BEV) need critical materials including cobalt, graphite, lithium, neodymium, and nickel; internal combustion engine vehicles (ICEV) use palladium and rhodium.  The authors note that lightweighting increases the total critical materials needed per vehicle (due to steel replacement with aluminum) but reduces the vehicle's mass, operational energy consumption, and reliance on high-concern battery-related critical materials. One section considers the implications of changing from nickel manganese cobalt to lithium iron phosphate battery chemistry.  The authors conclude by calling for improvements in battery material recycling and noncritical battery materials; lightweighting (and recyclability) of vehicle components; and reduction of critical material quantities required per vehicle in addition to the battery, such as electric motor downsizing or neodymium magnet material substitution.]]></description>
      <pubDate>Fri, 11 Jul 2025 10:00:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2521938</guid>
    </item>
    <item>
      <title>Crash Testing of South Dakota's Cable Guardrail to W-Beam Transition</title>
      <link>https://trid.trb.org/View/2522021</link>
      <description><![CDATA[A cable guardrail to W-beam transition system, used by the South Dakota Department of Transportation, was crash tested to determine whether the system meets current safety standards. The three-strand cable guardrail with reduced post spacing was attached to a standard W-beam guardrail which incorporated a breakaway cable terminal (BCT) on the upstream end. Three full-scale crash tests were successfully performed according to the Test Level 3 requirements specified in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. Two tests - one using a small car and one with a pickup truck - were used to evaluate the potential for vehicle snagging in the region where the cable guardrail transitions into the W-beam guardrail. One additional pickup truck crash test was performed to evaluate the potential for snagging and pocketing when the pickup impacts the cable guardrail upstream of the BCT terminal and deflects the cable guardrail such that the pickup contacts the terminal in a critical manner. The South Dakota cable guardrail to W-beam transition successfully met current safety standards and is recommended for use along the National Highway System.]]></description>
      <pubDate>Tue, 25 Mar 2025 12:28:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2522021</guid>
    </item>
    <item>
      <title>Determination of optimum limestone filler content in asphalt mastic by dielectric spectroscopy</title>
      <link>https://trid.trb.org/View/2470658</link>
      <description><![CDATA[The rheological and dielectric characteristics of asphalt mastics with different ratios of limestone filler were analyzed and compared with each other for road pavement applications. The dielectric properties of asphalt mastics are studied as a function of frequency (0,1–106 Hz) at different temperatures ((-)40°C-40°C). The glass transition temperature and the relaxation behaviour were determined by Vogel–Fulcher-Tamman and Cole–Cole equations, respectively. The free volume fraction was calculated by the Dolittle equation. The filler ratio dependence of the dielectric properties was attributed to the variation of the void fraction. This result was related to the glass transition temperature and ductility. The sample with 6?wt% limestone filler showed the highest dielectric constant value among all samples for all temperatures due to the excellent adhesion between binder and filler. Consequently, it was determined to be the optimum value to design hot mix asphalt for use in territories with high-temperature differences.]]></description>
      <pubDate>Mon, 27 Jan 2025 15:39:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2470658</guid>
    </item>
    <item>
      <title>Study on the Relationship between Water Accumulation and Linear Shape in the Ultra-High Transition Section of Expressway</title>
      <link>https://trid.trb.org/View/2475342</link>
      <description><![CDATA[Due to the existence of zero slope section, the outer lanes of the flat curve ultra-high transition section of the expressway often become waterlogged sections and accident-prone sections on rainy days, and the number of traffic accidents shows an increasing trend with the increase of lanes. Based on the calculation model of pavement water film thickness of HintCAD software, this paper explored the relationship between the water accumulation on the road surface and highway longitudinal slope, ultra-high gradient rate, and pavement width in the combination of ultra-high transition section and straight slope section of the expressway and established the corresponding functional regression model. Then the paper further proposes the traffic safety measures for expressway traffic on rainy days to reduce the possibility of water accumulation on the road surface of the flat curve ultra-high transition section to improve the safety capacity and service level of the expressway.]]></description>
      <pubDate>Mon, 23 Dec 2024 10:36:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2475342</guid>
    </item>
    <item>
      <title>Modeling as a Source of Innovation in Design Railway</title>
      <link>https://trid.trb.org/View/1972916</link>
      <description><![CDATA[Nowadays in the field of railway lines designing and construction it is forbidden by normative base to combine transition curves in plane and vertical curves in profile. The purpose of the research is to prove groundlessness and inadmissibility of this prohibition by means of the analysis in the program complex “Universal Mechanism”. Consider more rational design a railways in using biclotoide curves, combine transition curves in plane and vertical curves in profile. It is necessary to consider abolition of the requirement about presence “clean” circular curve between transition curves by biclotoide curves. This analysis confirms the admissibility of such a combination. Accordingly, the combination of transition curves in plane and vertical curves in profile leads to reducing of interaction forces in the “wheel-rail” system, increasing of the motion smoothness, improving of the track stability.]]></description>
      <pubDate>Fri, 01 Nov 2024 08:50:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1972916</guid>
    </item>
    <item>
      <title>Approach Guardrail Transition Retrofit to Existing Buttresses &amp; Bridge Rails</title>
      <link>https://trid.trb.org/View/2433879</link>
      <description><![CDATA[The Nebraska Department of Transportation (NDOT) frequently applies roadway overlays to the surface of bridges to extend the bridge’s lifespan. To minimize repair costs, NDOT does not desire to replace or alter any bridge rails with adequate structural capacity and height. Bridge rails installed to National Cooperative Highway Research Program (NCHRP) Report 350 or Manual for Assessing Safety Hardware (MASH) standards are likely to remain in place, though their effective heights would be reduced by the overlay. This creates a problem of attaching new, 31-in. tall approach guardrail transitions (AGTs) to existing concrete bridge rails and buttresses (after an overlay) that were not designed for such connections and the resulting system may not be crashworthy to current safety standards. The objective of this project was to develop retrofit options for attachment of thrie-beam AGT systems to existing NDOT bridge railings and buttresses. The project began with a review of existing bridge railings and end buttresses used by NDOT to identify issues related to connection hardware alignment and crash safety performance. Retrofit options were then developed to address these issues while adhering to established design criteria. A new connector plate assembly was designed to facilitate the attachment of the thrie-beam terminal connector to these bridge railings and buttresses. Additionally, three retrofit concepts, including concrete fill, a steel assembly, and a curb, were considered to mitigate concerns related to vehicle snag below the thrie beam. These selected retrofit concepts were evaluated through a combination of structural analysis and computer simulated crash tests. All simulations of the AGT attached to these buttresses through these retrofit concepts met MASH Test Level 3 (TL-3) safety performance criteria.]]></description>
      <pubDate>Mon, 30 Sep 2024 17:21:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2433879</guid>
    </item>
    <item>
      <title>Development of MASH Computer Simulated Steel Bridge Rail and Transition Details</title>
      <link>https://trid.trb.org/View/2420001</link>
      <description><![CDATA[The predominate bridge rail and approach guardrail transition (AGT) systems used among the New England states include details for 2-bar, 3-bar and 4-bar designs which were developed and tested under previous crash test standards (i.e., American Association of State Highway and Transportation Officials Guide Specifications for Bridge Railings Performance Level 2 (AASHTO GSBR PL2) and National Cooperative Highway Research Program (NCHRP) Report 350). These basic designs are currently being implemented among various participating states using slight variations in design details, such as spacing between tube rails and curb height. The objectives of this study were to (1) conduct a detailed review of each State’s Standards to identify differences in design details and to recommend dimensional and material specifications to ensure consistency among the States and (2) to evaluate the crash performance of the New England Transportation Consortium (NETC) bridge rail and transition designs using finite element analysis (FEA) to determine if these systems comply with current test standards of the Manual for Assessing Safety Hardware (MASH).]]></description>
      <pubDate>Mon, 26 Aug 2024 14:45:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2420001</guid>
    </item>
    <item>
      <title>Analysis on Mechanical Performances of High-Speed Railway Transition Curves</title>
      <link>https://trid.trb.org/View/2203453</link>
      <description><![CDATA[Whether the type of high-speed railway transition curves is suitable or not affects a train's running stability and passengers' comfort directly. The lateral change of acceleration (LCA) plays an important role in determining the transition curve parameters. Based on vehicle movement dynamics, the motions with positive or negative acceleration are taken into account to deduce the equation of lateral change of the vehicle acceleration. The LCA of several common transition curves were compared in five different motion models. The results show that the LCA which considers motion with positive or negative acceleration can be used for the optimization of high-speed railway transition curves as a theoretical basis.]]></description>
      <pubDate>Sat, 15 Jun 2024 16:42:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2203453</guid>
    </item>
    <item>
      <title>Effects of Transition Curves and Superelevation on the Critical States of Truck Rollovers on Sharp Curves</title>
      <link>https://trid.trb.org/View/2362017</link>
      <description><![CDATA[Sharp curves are vulnerable sections for rollover accidents. This study was conducted to investigate the effects of transition curve and superelevation on the critical speed and critical braking distance of truck rollovers. Using different transition types (spiral, Bloss and Grabowski curve) and different superelevation values (6%, 120 m transition length and 8%, 160 m) as variables, experiments of constant speed driving and hard braking were simulated and conducted by Trucksim. Conclusions regarding the influence of these road design factors on the stability of vehicles were then proposed. Grabowski curve allowed for the maximum critical rollover speed. The difference in critical rollover speed between different transition types was only determined by the length of the transition section. Simply extending the length of the transition section increased the critical rollover speed of spiral curve, at the same time decreasing the critical speed of Bloss and Grabowski curve. Hard braking experiments showed completely different characteristics. As the initial speed increased, only spiral curve became safer. Increasing superelevation made the braking behaviour of the vehicle more dangerous and fraught with uncertainties due to different target speed, starting curvature and changing superelevation. Based on these findings, a number of useful recommendations for drivers and road designers were put forward.]]></description>
      <pubDate>Wed, 24 Apr 2024 09:34:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2362017</guid>
    </item>
    <item>
      <title>Elucidating the Polycyclic Aromatic Hydrocarbons Involved in Soot Inception</title>
      <link>https://trid.trb.org/View/2353870</link>
      <description><![CDATA[Polycyclic aromatic hydrocarbons (PAHs) are the main precursors to soot particles in combustion systems. A lack of direct experimental evidence has led to controversial theoretical explanations for the transition from gas-phase species to organic soot clusters. This work focuses on sampling infant soot particles from well-defined flames followed by analysis using state-of-the-art mass spectrometry. The authors found that PAH molecules present in soot particles are all stabilomers. Kinetic Monte Carlo simulations and thermodynamic stability calculations further identify the detected PAHs as peri-condensed and without aliphatic chains. Van der Waals forces can easily link PAHs of such size and shape to form PAH dimers and larger clusters under the specified flame conditions. The results provide direct experimental evidence that soot inception is initiated by a physical process under typical flame conditions. This work improves our understanding of aerosol particulates, which has implications for their environmental and climate change impacts.]]></description>
      <pubDate>Wed, 17 Apr 2024 09:29:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2353870</guid>
    </item>
    <item>
      <title>Probabilistic characterisation of transition points in three-stage permanent deformation curves using Bayesian inference approach</title>
      <link>https://trid.trb.org/View/2310491</link>
      <description><![CDATA[Multiple specimens are tested to evaluate their rutting propensity by applying static and dynamic creep loads until a three-stage permanent deformation curve is obtained. This three-stage curve consists of two transition points, i.e. one from the primary to the secondary stage and the other one from the secondary to the tertiary stage of deformation. Due to replication, these transition points behave like random variables rather than deterministic. This stochasticity in the transition points is characterised by the Probabilistic -Stress-Number of cycles (P-S-N) approach. A power law model is used to describe the trajectory of transition points with respect to the input stress level. The probabilistic nature of these power law parameters is characterised by the Bayesian approach rather than the classical approach because the latter considers distribution parameters to be constant and does not reflect the replicate stochasticity. Posterior distributions are determined based on data translated likelihood method. Based on the posterior distributions of the data sets, obtained power law trajectories at various reliability levels, ranging from highest to lowest, are constructed. One advantage of this approach is its capability to extrapolate secondary transition points (Flow number or Flow time) when they cannot be readily obtained under desired testing conditions.]]></description>
      <pubDate>Mon, 04 Mar 2024 14:29:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2310491</guid>
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