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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>Research in Progress (RIP)</title>
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      <link>https://rip.trb.org/</link>
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    <item>
      <title>Expansion of AASHTOWare ME Design Inputs</title>
      <link>https://rip.trb.org/View/1665877</link>
      <description><![CDATA[The Wisconsin Department of Transportation (WisDOT) designs pavements with the AASHTOWare Mechanistic Empirical (ME) and AASHTO 1972 methodologies. WisDOT engineers would like to increase usage of the ME design methodology but require additional high-level inputs to increase confidence in pavement structure designs. The ME design methodology can be completed using different material input levels (Levels 1 through 3). Level 1 inputs are preferred because they are determined from laboratory testing instead of material assumptions. Reliable hot mix asphalt (HMA) material inputs are particularly challenging to obtain because of the wide range of expected material properties and the required testing equipment. Ideally, a catalog of material properties from HMA facilities throughout Wisconsin would be available to WisDOT designers to provide accurate estimates, however a catalog of material properties does not yet exist. Therefore, there is a need to create a strategic collection and testing plan of HMA material properties to populate higher level inputs for ME design methodology.
Researchers will be asked to create a test matrix to represent material properties of Wisconsin mixtures and execute the approved testing plan. A similar study was completed through the 0092-08-06 WHRP project, but WisDOT material specification changes have resulted in production of mixtures that cannot be adequately represented by those testing results. To avoid this obstacle in the future, researchers will also be asked to develop a strategic testing plan to verify and update future material properties.
The primary objective of this research is to update HMA material inputs for the Level 1 ME design methodology and compare them with current WisDOT inputs. Based on this comparison, researchers are expected to recommend a sampling strategy to verify/update HMA material inputs with time. Secondarily, researchers are expected to compare the AASHTO 1972 design method layer coefficients with ME design material inputs. This comparison should consider how the surface layer properties contribute to the overall design structure using each methodology and recommend a new structural coefficient for HMA materials, if warranted.]]></description>
      <pubDate>Mon, 11 Nov 2019 17:54:47 GMT</pubDate>
      <guid>https://rip.trb.org/View/1665877</guid>
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      <title>Data Collection for Local Calibration of the AASHTOWare Pavement ME Design Performance Models for Mississippi</title>
      <link>https://rip.trb.org/View/1508229</link>
      <description><![CDATA[The Mechanistic-Empirical Pavement Design Guide (MEPDG) method for designing pavement structures utilizes mechanistic materials properties combined with other inputs to predict pavement performance using user inputs. Pavement performance models are used for this prediction of pavement performance. The pavement performance models are based upon national predictive models that are likely not applicable to Mississippi. This research project is designed to provide the required information for the calibration of these performance models for Mississippi materials and conditions. A number of test pavement sections will be visited, evaluated, sampled, and tested. Following these activities site reports will be prepared for each individual site that provides the information required for this calibration of the pavement performance models to local conditions.]]></description>
      <pubDate>Mon, 09 Apr 2018 13:50:04 GMT</pubDate>
      <guid>https://rip.trb.org/View/1508229</guid>
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    <item>
      <title>The Influence of Subgrade Soils Susceptible to Shrink/Swell and/or Frost Heave on Pavement Performance</title>
      <link>https://rip.trb.org/View/1466752</link>
      <description><![CDATA[Expansive clay soils that are susceptible to shrink and swell, and silty soils that are susceptible to frost heave are found in many parts of the United States. At these locations, these soils serve as the subgrade of the pavement structure. The AASHTOWare Pavement Mechanistic-Empirical (ME) Design (formerly DARWin-ME) and the AASHTO Mechanistic-Empirical Pavement Design Guide Manual of Practice (MEPDG) provide a methodology for the analysis and performance prediction of new and rehabilitated pavements. Although the performance of these pavements is known to be closely related to properties of the subgrade, the performance predicted by this methodology does not adequately consider the influence of subgrade soils susceptible to shrink/swell and/or frost heave on pavement performance. There is a need to evaluate the procedures contained in the Pavement ME Design and identify or develop enhancements (in the form of modified or new models) to ensure that the procedures appropriately account for the influence of these types of subgrade soils on the performance of new and rehabilitated pavements. Incorporating these enhancements into the Pavement ME Design procedures will allow an improved analysis and design of pavement structures.
Under NCHRP Project 01-59, &ldquo;Proposed Enhancements to Pavement ME Design: Improved Consideration of the Influence of Subgrade Soils Susceptible to Shrink/Swell and/or Frost Heave on Pavement Performance,&rdquo; Arizona State University was asked to propose enhancements, as needed, to the Pavement ME Design procedures to better reflect the influence of subgrade soils susceptible to shrink/swell and/or frost heave on pavement performance. The research team (1) evaluated the adequacy of Pavement ME Design models to predict the influence of subgrade soils susceptible to shrink/swell and/or frost heave on the in-service pavement performance for a range of relevant factors (e.g., material, environment, and traffic conditions), (2) proposed a plan to improve the predictive ability of Pavement ME Design by modifying the models contained in the Pavement ME Design and/or developing new models, (3) proposed enhancements (in the form of modified or new models) to Pavement ME Design to better reflect the influence of subgrade soils susceptible to shrink/swell and/or frost heave on pavement performance, (4) identified issues affecting implementation of the proposed enhancements, and (5) prepared draft language for consideration by AASHTO to incorporate the research results in the next update of the AASHTO MEPDG.
In addition to the conduct of research that documents the entire research effort published as NCHRP Research Report 1096: Subgrade Soil Susceptibility to Shrink/Swell and Frost Heave, supplemental information for each corresponding chapter (Appendices 1-13) are available here and on the TRB website at www.trb.org.]]></description>
      <pubDate>Fri, 12 May 2017 09:46:24 GMT</pubDate>
      <guid>https://rip.trb.org/View/1466752</guid>
    </item>
    <item>
      <title>PPRC14 SPE 5.08: Document PaveM Traffic Updating Processes</title>
      <link>https://rip.trb.org/View/1441834</link>
      <description><![CDATA[This task documents processes for updating traffic used in PaveM and in bridge and pavement design and implement them in PaveM. The study will also characterize truck traffic with unregulated loads for mechanistic empirical (ME) design for state highways near heavy load facilities.]]></description>
      <pubDate>Wed, 04 Jan 2017 10:53:57 GMT</pubDate>
      <guid>https://rip.trb.org/View/1441834</guid>
    </item>
    <item>
      <title>PPRC14 SPE 4.53: Validation of Greenhouse Gas Emissions from Pavement Deflection</title>
      <link>https://rip.trb.org/View/1441820</link>
      <description><![CDATA[The task will be amended to complete the funding of the field test validations.  The field tests are very sensitive and will require more accurate measurements.  The field validation will be the means to assess which of the proposed deflection models capture the physics properly.  Follow up to 13/14 project to review mechanistic algorithms from Massachusetts Institute of Technology (MIT) and other research centers to calculate viscoelastic energy dissipation from vehicle operation for different pavement types, climate regions and vehicle types.  Perform field validation of fuel economy differences, compare results with models, and then perform comprehensive assessment for state network implementation. Task objectives are as follows: (1) Develop user and system functional requirements; (2) Design and implementation of new system architecture; (3) Design and implementation of an ME compute engine; (4) Design and implementation of a web-based user interface (UI); (5). Perform system integration of CalME v3.0; (6) Perform testing; (7) Provide user support for CalME v2.0; and (8) Develop user and system documentation.]]></description>
      <pubDate>Wed, 04 Jan 2017 10:53:29 GMT</pubDate>
      <guid>https://rip.trb.org/View/1441820</guid>
    </item>
    <item>
      <title>PPRC14 SPE 3.31: Improved ME Design Algorithms and Reliability Approach</title>
      <link>https://rip.trb.org/View/1441809</link>
      <description><![CDATA[The objective of this project is to improve the ability/reliability of California Department of Transportation (Caltrans) and national Mechanistic-Empirical (M-E) procedures to predict pavement distresses.  Update/add algorithms for asphalt fatigue cracking, thermal reflection cracking, top-down cracking, full-depth reclamation and raveling. Address asphalt recovery between truck loadings, and the interaction of truck traffic loading and temperature for asphalt surfaced pavement. Address upcoming changes in  American Association of State Highway and Transportation Officials (AASHTO) test methods for asphalt fatigue cracking and translation of data from repeated shear to the new Asphalt Material Performance Tester (AMPT) equipment. Improve roughness progression algorithms for asphalt and concrete. Update calibration of Mechanistic-Empirical Pavement Design Guide (MEPDG) models for jointed plain concrete (JPC) transverse cracking and faulting using new condition survey data. Complete study investigating range of coefficient of thermal expansion (CTE) values.]]></description>
      <pubDate>Wed, 04 Jan 2017 10:53:09 GMT</pubDate>
      <guid>https://rip.trb.org/View/1441809</guid>
    </item>
    <item>
      <title>PPRC14 SPE 3.30: Standard Materials Library and Guidance</title>
      <link>https://rip.trb.org/View/1441808</link>
      <description><![CDATA[The objective of this project is to test and include additional regional materials in the California Department of Transportaiton (Caltrans) mechanistic-empirical (M-E) Standard Materials Library, including base, subbase and new recycled materials.  Implement procedures to simplify the selection of material types for ME design by district designers, and develop guidance for asphalt mix designers to meet performance related mix design requirements. This study is a continuation of Task 2356. Specific objectives include: (1) laboratory testing; (2) field testing; (3) materials selection guidance; (4) performance based mix design guidance; and (5) project report.]]></description>
      <pubDate>Wed, 04 Jan 2017 10:53:07 GMT</pubDate>
      <guid>https://rip.trb.org/View/1441808</guid>
    </item>
    <item>
      <title>Accelerated Performance Testing on the 2012 NCAT Pavement Test Track</title>
      <link>https://rip.trb.org/View/1336363</link>
      <description><![CDATA[The objectives of this research project will be: (1) Constructing 200 ft test sections on the existing 1.7-mile National Center for Asphalt Technology (NCAT) test oval that are representative of in-service roadways; (2) Applying accelerated performance truck traffic in the 2 years following construction; (3)  Assessing/comparing the functional and structural field performance of trafficked sections on a regular basis via surface and subsurface measures; (4) Validating/calibrating new &amp; existing mechanistic-empirical (M-E) approaches to pavement analysis and design using pavement surface condition, pavement load response, precise traffic and environmental logging, and cumulative damage; (5) Determining the life cycle cost of various pavement preservation alternatives in a highly controlled experiment that will provide state Departments of Transportation (DOTs) with the financial foundation to begin to build a decision tree for their own maintenance program; (6) Correlating field results with laboratory data for both mechanistic and preservation applications; and (7) Answering practical questions posed by research sponsors through formal (i.e., reports and technical papers) and informal (e.g., one-on-one responses to sponsor inquiries) technology transfer.]]></description>
      <pubDate>Mon, 29 Dec 2014 01:00:41 GMT</pubDate>
      <guid>https://rip.trb.org/View/1336363</guid>
    </item>
    <item>
      <title>Laboratory Evaluation of Hot Mix Asphalt (HMA) in Delaware</title>
      <link>https://rip.trb.org/View/1230369</link>
      <description><![CDATA[Pavement design approach is slowly moving towards the mechanistic design approach from the traditional pavement design. One of the drawbacks of traditional pavement design is that it does not take into consideration the effect of changing load types in the design. Hence the mechanistic design approach has an edge over the traditional pavement design in this aspect. The mechanistic design approach also helps in improved characterization and utilization of available materials, better prediction of performance, and improved definition of existing pavement layer properties as well as the accommodation of environmental and aging effects. The success of the mechanistic design approach is dependent on understanding the behavior of the material properties. Of all the material properties, resilient modulus is the most important of all because it helps in better characterization of the stress-strain relationship of the material. The advantages of resilient modulus is that it is: (1) used to define fundamental material properties,(2) used in constitutive models, (3) used to predict stress, strain, and displacement, (4) used to develop performance models, (5) used in current American Association of State Highway and Transportation Officials (AASHTO) pavement design guide and&amp;nbsp;(6) used in the mechanistic design approach. The focus of this research is to evaluate the resilient modulus of several mixtures from the Delaware Department of Transportation (DelDOT). Hence the goal is to develop quantitative models of Resilient Modulus of Delaware Hot Mix Asphalt (HMA). This research will help to increase the understanding of the behavior of construction materials that are used in Delaware and also provide a database of resilient moduli for further analysis and refinement of pavement design and evaluation. The resilient modulus test carried out in this research uses aspects of AASHTO and American Society for Testing and Materials (ASTM) test methods for determining the resilient modulus of bituminous mixtures by indirect tension.]]></description>
      <pubDate>Thu, 03 Jan 2013 13:59:00 GMT</pubDate>
      <guid>https://rip.trb.org/View/1230369</guid>
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