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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=PHNlYXJjaD48cGFyYW1zPjxwYXJhbSBuYW1lPSJzdWJqZWN0bG9naWMiIHZhbHVlPSJvciIgLz48cGFyYW0gbmFtZT0idGVybXNsb2dpYyIgdmFsdWU9Im9yIiAvPjxwYXJhbSBuYW1lPSJsb2NhdGlvbiIgdmFsdWU9IjAiIC8+PC9wYXJhbXM+PGZpbHRlcnM+PGZpbHRlciBmaWVsZD0ia2V5d29yZHMiIHZhbHVlPSImcXVvdDtNaXgmcXVvdDsgYW5kICZxdW90O2Rlc2lnbiZxdW90OyBhbmQgJnF1b3Q7Zmxvd2FibGUmcXVvdDsgYW5kICZxdW90O2ZpbGwmcXVvdDsiIG9yaWdpbmFsX3ZhbHVlPSJNaXggZGVzaWduIGZvciBmbG93YWJsZSBmaWxsIiAvPjwvZmlsdGVycz48cmFuZ2VzIC8+PHNvcnRzPjxzb3J0IGZpZWxkPSJwdWJsaXNoZWQiIG9yZGVyPSJkZXNjIiAvPjwvc29ydHM+PHBlcnNpc3RzPjxwZXJzaXN0IG5hbWU9InJhbmdldHlwZSIgdmFsdWU9InB1Ymxpc2hlZGRhdGUiIC8+PC9wZXJzaXN0cz48L3NlYXJjaD4=" 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>
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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>Use of Whole Tires and Fly Ash in Earth Retaining Structures</title>
      <link>https://trid.trb.org/View/2567183</link>
      <description><![CDATA[Finding secondary applications for used automobile tires has become a major issue because of the unique problems associated with their disposal. The vast majority of these secondary applications involve the use of waste tires in shredded form. Examples include Tire Derived Fuel (TDF) that recover energy through combustion of shredded tires, crumb rubber as a modifier for asphalt binder and asphalt concrete mix, and shredded tire as a lightweight fill material. This research examined the potential use of whole waste tires in the construction of earth retaining structures. Several retaining wall designs that incorporate waste tires as a basic structural unit are proposed. The proposed retaining wall designs involve the use of whole waste tires in a number of different forms. They are (1) whole tires filled with gravel or low strength flowable filler, (2) tires bales that are produced by compressing as many as 100 automobile tires to form a 30 in. x 50 in. x 60 in. blocks and (3) tire bales encapsulated in a concrete casing to produce 4 ft x 4 ft x 8 ft blocks called Eco-Bloc®. The proposed designs include gravity retaining walls as well as mechanically stabilized earth (MSE) retaining walls. Necessary analyses have been performed to ensure adequate factor of safety against internal failure as well as external failure of the retaining wall systems. The internal stability conditions that were considered included the following: (a) rupture of the reinforcement, (b) reinforcement pullout and (c) bulging of the wall. The external stability conditions included: (a) sliding, (b) bearing failure, (c) overturning, and (d) global rotational stability. The analyses have been repeated for a range of wall heights, wall batter and backfill material properties to produce design charts.]]></description>
      <pubDate>Mon, 18 Aug 2025 16:30:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2567183</guid>
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    <item>
      <title>Development of insulating backfill materials produced from the ternary mixtures of red mud, fly ash and preformed foam</title>
      <link>https://trid.trb.org/View/2420300</link>
      <description><![CDATA[Many public utility lines to transport power, water, natural gas, water, sewer, and communication are placed beneath trafficable areas. However, insufficient or inadequate backfill induces sudden subsidence, damage, or pothole on the road. This study aims to develop lightweight controlled low-strength materials (CLSM) with low thermal conductivity using the ternary mixtures of red mud to replace aggregate sand, high carbon fly ash, and preformed foam. Changes in flow consistency, air void characteristics, bulk unit weight, unconfined compressive strength (UCS), and thermal conductivity (k) of the tested materials with varying red mud contents were investigated as a function of the foam volume ratio (FVR). The results demonstrate that the UCS and k of tested materials decreased with increasing FVR due the decrease in unit weight, and a greater UCS but smaller k was observed at a given FVR with increasing red mud content because the inclusion of red mud in the lightweight CLSM mix design helps improve the stability of air bubbles and achieve uniform distribution of air voids. In addition, the red mud can act as a NaOH supplier, leading to the developed material had additional strength gain from the alkali activation. Thus, the developed insulating backfill material showed 43 % decrease in k while maintaining UCS similar to non-foam CLSM without red mud.]]></description>
      <pubDate>Wed, 25 Sep 2024 09:22:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2420300</guid>
    </item>
    <item>
      <title>Engineering Properties of Cementless Alkali Activated CLSM Using Ferrochrome Slag</title>
      <link>https://trid.trb.org/View/2085907</link>
      <description><![CDATA[This manuscript aims to utilize industrial wastes, i.e., ferrochrome slag (FS), ground granulated blast furnace slag, and fly ash to prepare alkali activated cementless controlled low strength material (CLSM). The physical properties, i.e., flowability, bleeding, unit weight, and mechanical properties such as strength, durability, and settlement were assessed for different CLSM mix designs and compared with cement-based FS-CLSM. The alkali activated FS-based CLSM achieved adequate flowability and unit weight with a strength value of 1.72 to 10.44 MPa for different CLSM mix propotions, with a California bearing ratio (CBR) value of 328% to make the CLSM mix a feasible pavement material. The study concludes that a high molar ratio of potassium hydroxide (KOH) accelerates the alkali activation process which helps in the formation of alkaline alumino/calcium silicate hydrates to bind the FS and produce CLSM with adequate strength. The high durability and low levels of toxic metals in the leachate cause the FS-based CLSM environment to be acceptable. Furthermore, life cycle analysis was carried out to investigate the effects of the FS-based CLSM on the ecosystem and human health.]]></description>
      <pubDate>Tue, 24 Jan 2023 09:31:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2085907</guid>
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    <item>
      <title>Use of Rice Husk Ash (RHA) in Flowable Fill Concrete Mix Material [supporting dataset]</title>
      <link>https://trid.trb.org/View/1861033</link>
      <description><![CDATA[Corresponding data set for Tran-SET Project No. 18CASU03. Abstract of the final report is stated below for reference:  "In the way of finding sustainable development, the flowable fill is a relatively new construction technology. Flowable fill is a self-compacting material, which has been developed in recent years. Flowable fill has been used for different applications such as backfilling walls, sewer trenches, bridge abutments, conduit trenches, pile excavations, and retaining walls. This study examines the potential uses of Rice Husk Ash (RHA) as a sustainable cementitious material (SCM) in the preparation of flowable fill concrete. RHA is an agricultural by-product of the rice milling process. This study has evaluated the usage of RHA in producing low strength and self-consolidating flowable fill concrete (FFC). Two different RHA samples (600 µm and 150 µm) in two different percentages (40%, and 60%, by the weight) of an Ordinary Portland Cement (OPC) have been used to prepare flowable fill mixtures. The evaluation processes of these FFC mixtures include determination of strength, flowability, unit weight, and air content in the laboratory. Test results showed that the FFC mixtures made with coarse RHA particles resulted in lower strength property compared to the regular FFC. On the other hand, the medium fine RHA particle was found to be effective in increasing the strength properties. Furthermore, a field demonstration has been conducted in this study to evaluate the workability, placement, and in-service performance of RHA modified FFC. Findings of this study will help the transportation and construction agencies in using RHA as a cost-effective construction material."]]></description>
      <pubDate>Wed, 07 Jul 2021 09:31:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1861033</guid>
    </item>
    <item>
      <title>Statistical models to develop optimised controlled low-strength materials with wastepaper sludge ash</title>
      <link>https://trid.trb.org/View/1848926</link>
      <description><![CDATA[This study aims to create robust controlled low-strength material (CLSM) mixes of wastepaper sludge ash (WSA) binders and recycled fine aggregates (RFAs). A factorial design was carried out to mathematically model the effect of three main mix design parameters on the plastic and hardened properties of wastepaper sludge ash CLSM (WSA-CLSM) mixtures. The criteria were the ratio of water to cementitious materials (w/cm), the proportion of WSA replacement content, and the total cementitious material (cm) content. Flowability, bleeding, segregation, initial stiffening time, densities, water absorption, and unconfined compressive strength were the derived statistical models' responses. With the intention of extracting the statistical models, twenty mixes were prepared, and ten mixes were used to validate the precision of the produced models. The models are valid for mixtures of 2.53 to 2.73 w/cm, 50 to 100% of WSA (by total cm content) and 160 to 200 kg/m3 of total cm content. The regression methods were synthesised and analysed by classifying the key factors and their correlations to measure their properties in terms of the impacts of w/cm, WSA% and total cm content. Three optimum WSA-CLSM mixtures with significant positive desirability were formulated and tested using the established models. Robust WSA-CLSMs that meet the Department of Transportations (DOTs) specifications for CLSM backfill material classifications may be developed.]]></description>
      <pubDate>Thu, 24 Jun 2021 16:43:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1848926</guid>
    </item>
    <item>
      <title>High-Fidelity Model Development for Pavement Repair Performance</title>
      <link>https://trid.trb.org/View/1759154</link>
      <description><![CDATA[The Air Force Civil Engineer Center (AFCEC) is conducting research to develop pavement repair capabilities that minimize disruptions to military airfield operations. This work includes the investigation of hot-mix asphalt and rapid-setting flowable fill repair technologies. Pavement repairs pose unique challenges in terms of equipment availability, operational limitations, time available for construction, geometric boundaries and constructability. Initial traffic loadings may be applied within two hours of the repair completion. Consequently, materials degrade quickly, restricting their operational life. High-fidelity modeling and simulation can provide a mechanistic understanding of failure modes and causes of material degradation during aircraft wheel loading. Validated models can provide a tool for predicting the response of a wide variety of repair configurations as well as material and design concepts. Optimized repair designs will save costs and improve performance during operations. A phased research project is underway to systematically perform the testing and validation needed for model development. Models include nonlinear finite element analysis (FEA) and transient heat transfer analysis. Phase 1 has been completed and covers the first generation of a FEA model for a full-scale pavement repair. Experiments supporting this effort include nonlinear materials characterization testing as well as two full-scale experiments to validate the models. The first was a well-instrumented thermal test that measured through-thickness temperatures at various locations, and the second measured stress and strain levels during F-15E load cart traffic. This paper provides an outline for the modeling project and a detailed overview of the two full-scale validation tests performed.]]></description>
      <pubDate>Thu, 04 Feb 2021 16:48:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1759154</guid>
    </item>
    <item>
      <title>Investigation into the freeze–thaw durability of semi-flexible pavement mixtures</title>
      <link>https://trid.trb.org/View/1746864</link>
      <description><![CDATA[Semi-flexible pavement (SFP) is made of a composite material that consists of porous asphalt concrete (PA) filled with highly flowable grouting material. At present, most researches on SFP focuses on the materials design and pavement performance characterisation, and very limit effort has been made on evaluating its freeze–thaw durability, which limits the application of SFP in cold regions. The present paper was to fill this gap. In the study, two SFP mixes made with a given PA but two different grouting materials (early-strength (ES) and high-strength (HS) grouting materials) were evaluated. ASTM C666 freeze–thaw durability tests were performed not only on the SFP mixes but also on each of SFP component (PA, ES and HS grouting materials), where relative dynamic modulus and mass loss of the tested samples were measured. In addition, indirect tensile strength of the samples was also tested, and the stiffness and strain–stress behaviour of the samples were evaluated. The results indicate that the order of the freeze–thaw resistance of the individual components was the PA matrix < ES grouting material (4.9 MPa at 3 h and 25.4 MPa at 28 days) ≪ HS grouting material (82.4 MPa at 28 days). The relative dynamic elastic modulus and strain–stress behaviours of SFP-ES samples were very similarly to those of PA, indicating the loss of integrity of the composite during freeze–thaw cycling. Differently, relative dynamic elastic modulus and strain–stress behaviours of SFP-HS samples were close to those of HS grouting material, indicating that enhanced freeze–thaw resistance of a SFP mix can be achieved by incorporating a high strength grouting material into a PA matrix.]]></description>
      <pubDate>Thu, 19 Nov 2020 14:22:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1746864</guid>
    </item>
    <item>
      <title>Use of Rice Husk Ash (RHA) in Flowable Fill Concrete Mix Material</title>
      <link>https://trid.trb.org/View/1659514</link>
      <description><![CDATA[In the way of finding sustainable development, the flowable fill is a relatively new construction technology. Flowable fill is a self-compacting material, which has been developed in recent years. Flowable fill has been used for different applications such as backfilling walls, sewer trenches, bridge abutments, conduit trenches, pile excavations, and retaining walls. This study examines the potential uses of Rice Husk Ash (RHA) as a sustainable cementitious material (SCM) in the preparation of flowable fill concrete. RHA is an agricultural by-product of the rice milling process. This study has evaluated the usage of RHA in producing low strength and self-consolidating flowable fill concrete (FFC). Two different RHA samples (600 µm and 150 µm) in two different percentages (40%, and 60%, by the weight) of an Ordinary Portland Cement (OPC) have been used to prepare flowable fill mixtures. The evaluation processes of these FFC mixtures include determination of strength, flowability, unit weight, and air content in the laboratory. Test results showed that the FFC mixtures made with coarse RHA particles resulted in lower strength property compared to the regular FFC. On the other hand, the medium fine RHA particle was found to be effective in increasing the strength properties. Furthermore, a field demonstration has been conducted in this study to evaluate the workability, placement, and in-service performance of RHA modified FFC. Findings of this study will help the transportation and construction agencies in using RHA as a cost-effective construction material.]]></description>
      <pubDate>Mon, 28 Oct 2019 10:26:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1659514</guid>
    </item>
    <item>
      <title>Evaluation of Mechanical Response of an Industry-Scale Flexible Pavement System</title>
      <link>https://trid.trb.org/View/1572388</link>
      <description><![CDATA[Through its design life, the performance of asphalt pavement is decided by the mechanical response in key locations. Measured strains in the surface layer and at the top of the subgrade are used to predict distress and plan rehabilitation, making them of great interest. This paper explains typical gauge configurations and evaluates novel methods of mechanical measurement, focusing on vibrating wire technology. These gauges were tested by constructing and installing them in a lane of asphalt concrete 200’ long, split into six sections with varying base and surface properties. High-temperature models of strain gauges, which are designed for Portland cement concrete with a high heat of hydration, were installed at the bottom of the hot-mix asphalt concrete layer. The gauges were connected to data loggers and calibrated, recording strain data as well as temperature data from each gauge’s onboard thermistor. Application of loading using a passenger vehicle of known axle weights facilitates the comparison of the mechanical response of pavement sections using different layer configurations and materials. Mainly, the effect of flowable fill as a base material was compared with the conventional, granular base material. It was concluded that the rigidity of flowable fill base resulted in a significantly lower vertical deflection at the top of the subgrade which leads to better performance of flexible pavements.]]></description>
      <pubDate>Sat, 02 Mar 2019 15:41:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1572388</guid>
    </item>
    <item>
      <title>Laboratory investigation of using foam grout as micro-trench backfilling material in cold regions</title>
      <link>https://trid.trb.org/View/1563645</link>
      <description><![CDATA[Micro-trenching, an innovative method for fiber optic cables installation, involves creating a narrow trench in the road pavement to place a cable or conduit; the trench is normally narrower than 40 mm wide and shallower than 300 mm deep, depending on the size of the used conduit and trencher. After cutting the pavement, the next step is cleaning the area and placing the cable or conduit inside the trench, followed by backfilling. The quality of the backfilling plays an important role in both the sustainability of the installed cable or conduit and the cut pavement; using unsuitable materials or improperly installing cable or conduit can significantly decrease pavement life. The trench dimensions are very small, so for a successful procedure the backfilling material should be self-compacted and flowable enough to penetrate and completely fill the whole trench depth. As it has been investigated before, using traditional backfilling material such as play sand is not appropriate for Canadian cold regions; hence, it is recommended to stabilize the conduit inside the pavement’s granular layer using a material similar to a cement grout. Alternatively, foam grout is a mixture of cement, water, and pre-formed foam; the foam considerably reduces the density of the blend by adding air, which consists of more than 25% of the mix. As a result, using this foam grout technology reduces the amount of cement required significantly and could be a cost effective solution for backfilling. The objective of this paper is to assess foam grout as a backfilling material for micro-trenching in cold climates. For this purpose, foam grout samples were prepared in a laboratory and their compressive strengths before and after several freeze and thaw cycles were investigated. Different mix-proportioning ratios were also studied in an attempt to create a more reliable method and assess variations in compressive strength and cost along with density.]]></description>
      <pubDate>Tue, 16 Oct 2018 14:05:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1563645</guid>
    </item>
    <item>
      <title>Performance-Based Procedure for the Definition of Controlled Low-Strength Mixtures</title>
      <link>https://trid.trb.org/View/1371927</link>
      <description><![CDATA[Controlled low-strength material (CLSM) is a self-consolidating cementitious material used as backfill in narrow trenches. The high content of aggregates and water in CLSM leads to a special behavior that is closer to soil than concrete. Consequently, mixture proportioning methodologies for conventional concrete do not apply to CLSM. The objective of this paper is to propose a new methodology to achieve the optimal composition that fulfills the flowability and compressive strength requirements of the material. Instead of computing the aggregate or the cement separately, all solid particles in the mixture are considered concurrently to estimate the water content in terms of water-to-solid ratio (W/S). In this way, the compressive strength can be modified without compromising the desired flowability. An example application is presented and an experimental program is conducted to validate this philosophy. The results confirm that the methodology proposed provides compositions that satisfy the main requirements of CLSM, thus representing a contribution to the use of more economical and adequate materials.]]></description>
      <pubDate>Fri, 23 Oct 2015 09:28:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/1371927</guid>
    </item>
    <item>
      <title>Relative Proportioning Method for Controlled Low-strength Material</title>
      <link>https://trid.trb.org/View/1352327</link>
      <description><![CDATA[Controlled low-strength material (CLSM) mixture design remains a trial-and-error process. A new approach using relative proportioning of the constituent materials instead of prescribed mass contents is proposed. Relative proportions allow for independent adjustments that enable unbiased estimation of their effects on CLSM properties. For the CLSM mixtures studied, a central composite experimental design was defined using three relative proportions: volumetric paste percentage (VPP), water-cementitious material ratio (W/CM), and portland cement-total cementitious materials ratio (OPC/CM). Second-order response models for slump flow, subsidence, and 28-day compressive strength were obtained for different sets of constituents, including virgin and recycled concrete fine aggregates and two fly ash sources. Slump flow and subsidence were most affected by the VPP and W/CM, respectively, whereas strength was explained by the combined effect of the W/CM and OPC/CM. The W/OPC ratio was not a reliable predictor of CLSM strength.]]></description>
      <pubDate>Thu, 28 May 2015 09:23:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1352327</guid>
    </item>
    <item>
      <title>Design of Sustainable High-Volume Pavements Using Controlled Low-Strength Material from Native Soil</title>
      <link>https://trid.trb.org/View/1338127</link>
      <description><![CDATA[Long-term performance and durability of a pavement structure built on expansive soils are mainly dependent on the effective stabilization of the subgrade and the compaction techniques adopted during construction. Recent studies proved that the self-compacting, controlled low-strength materials acted as an effective bedding material for pipelines. A major portion of highways and low-volume traffic intersections are underlain by pipelines and other culvert structures. In this research study, an attempt was made to investigate the effectiveness of controlled low-strength material (CLSM) as a pavement subgrade material. For this study, CLSM mix designs were investigated by using native high-plasticity soil and Type 1 portland cement. From these mix designs, two high-performing mixes were selected on the basis of their setting time, flowability, and density. A series of resilient modulus tests and durability tests was conducted on the samples cast in the laboratory. Alternate wetting–drying cycles were conducted on laboratory cast specimens to address the long-term stability of the proposed mixtures. These test results were analyzed. A sustainable mix design is recommended for the design of high-traffic pavement roads. It was observed that Mix Design 2, with 10% cement, showed significant improvement in terms of strength and durability and thereby showed promise as a subgrade material for high-volume roads.]]></description>
      <pubDate>Sat, 17 Jan 2015 17:28:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1338127</guid>
    </item>
    <item>
      <title>User Guideline for Foundry Sand in Green Infrastructure Construction</title>
      <link>https://trid.trb.org/View/1316009</link>
      <description><![CDATA[Foundry sand is high-quality uniform silica sand that is used to make molds and cores for ferrous and nonferrous metal castings. The metal casting industry annually uses an estimated 100 million tons of foundry sand for production. Over time, foundry sands physically degrade until they are no longer suitable for molds. Consequently, 9 to 10 million tons of sand is discarded each year. However, the discarded foundry sands have remarkably consistent composition and are typically considered a higher quality material than typical bank run or natural sands used in construction. Recycling of foundry sand can save energy, reduce the need to mine virgin materials, and may reduce costs for both producers and end users. Use of foundry sand as a fine aggregate in construction applications offers project managers the ability to enhance green sustainable construction by reducing their carbon footprint, while also qualifying for Leadership in Energy and Environmental Design (LEED) credits. This paper provides a comprehensive overview of the engineering and construction properties of foundry sand for use in Portland cement and concrete, hot mix asphalt, road subbase layers, embankments, and flowable fill. Recent studies addressing environmental concerns of using foundry sand, an industrial by-product, as a construction material are reviewed. Some case studies are presented to demonstrate successful applications of foundry sand. With the goal of advancing use of foundry sand in construction application, references to resources and tools, such as web-based training and a foundry locator map module, are made available]]></description>
      <pubDate>Tue, 29 Jul 2014 08:56:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1316009</guid>
    </item>
    <item>
      <title>Flow and Strength Characteristics of CLSM Using Ground Granulated Blast Furnace Slag</title>
      <link>https://trid.trb.org/View/1308773</link>
      <description><![CDATA[Controlled low strength material (CLSM), as defined by the American Concrete Institute (ACI) Committee, is a self-flowing cementitious material consisting typically of portland cement, fine aggregates, supplementary cementing materials, and water. In this present experimental study, industrial by-product, namely, ground-granulated blast-furnace slag, is used as a constituent material in CLSM. Mixture proportions were developed for CLSM containing the industrial by-product (GGBS) and were tested in the laboratory for ﬂow and unconfined compressive strength properties. The cardinal aim is to analyze the experimental data generated to formulate a phenomenological model to arrive at the combinations of the ingredients to produce CLSM to meet the desired flow and strength. An independent set of data is generated to examine the validity of the phenomenological approach.]]></description>
      <pubDate>Wed, 28 May 2014 15:20:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1308773</guid>
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