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    <title>Research in Progress (RIP)</title>
    <link>https://rip.trb.org/</link>
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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>Research in Progress (RIP)</title>
      <url>https://rip.trb.org/Images/PageHeader-wTitle-RIP.jpg</url>
      <link>https://rip.trb.org/</link>
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    <item>
      <title>2504 Evaluating Pavement Friction using Dynamic Friction Tester (DFT)</title>
      <link>https://rip.trb.org/View/2786776</link>
      <description><![CDATA[ODOT has taken significant steps toward implementing a balanced mix design (BMD) approach, which evaluates asphalt mixtures based on performance characteristics including rutting and cracking. One critical performance measure is friction. Current ODOT specifications require aggregates to satisfy certain criteria, such as insoluble residue limits, to help ensure adequate polishing resistance. However, the insoluble residue test and other tests such as the L.A. abrasion and Micro Deval are intended to assess the aggregate properties and may not fully represent the overall friction resistance of the asphalt mixture. Overall pavement friction is also influenced by factors such as aggregate gradation, surface texture, aggregate blending, and mixture design. This project will investigate the use of the Dynamic Friction Test (DFT) along with the three-wheel polisher (TWP) device to assess friction resistance of asphalt mixes in Oklahoma. To accomplish this, the laboratory and field friction performance of Oklahoma asphalt mixtures will be evaluated by examining the effects of mixture type, aggregate source, RAP content, and binder type. Asphalt mixtures containing recycled asphalt pavement (RAP) will be tested to determine the frictional contribution of RAP aggregates, since ODOT specifications assume zero insoluble residue for RAP materials. The correlation between insoluble residue and DFT friction values will be investigated for different traffic levels to establish whether current insoluble residue limits are appropriate. Preliminary threshold friction values will be proposed for ODOT asphalt mixtures for incorporation into the BMD provisional specification.]]></description>
      <pubDate>Wed, 07 Oct 2026 11:19:27 GMT</pubDate>
      <guid>https://rip.trb.org/View/2786776</guid>
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    <item>
      <title>Evaluation of Traffic Speed Deflection Devices (TSDD) for Collecting, Reporting, and Utilizing Pavement Network and Project Level Structural Data in Utah</title>
      <link>https://rip.trb.org/View/2784729</link>
      <description><![CDATA[Evaluate the potential of Traffic Speed Deflection Devices (TSDD) for collecting, reporting, and utilizing pavement network and project level structural data in Utah.]]></description>
      <pubDate>Wed, 30 Sep 2026 19:13:13 GMT</pubDate>
      <guid>https://rip.trb.org/View/2784729</guid>
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      <title>Advancing the Extended T-FAST Test for Assessing ASR Risk in Hardened Concrete</title>
      <link>https://rip.trb.org/View/2784610</link>
      <description><![CDATA[Alkali-Silica Reaction (ASR) remains a significant durability concern for concrete infrastructure and continues to present challenges for transportation agencies. Existing ASR test methods often involve the tradeoff between speed and reliability. Accelerated methods can produce false positives and false negatives, while more reliable expansion-based methods may require several months or years to complete. Research project RP#2024-11 evaluated an extended version of the T-FAST test (Turner-Fairbank Alkali Silica Reaction (ASR) Aggregate Susceptibility Test) by AASHTO TP144, for quantifying ASR risk in hardened concrete. Significant progress has been made through the evaluation of aggregates with known reactivity, development of and experimental database, and assessment of variables affecting the Reactivity Index (RI), including curing conditions, immersion solutions, and use of fly ash and silica fume for ASR mitigation. As the research progressed, several new variables were identified that were not included in the original scope but are important for continued validation of the method. This Technical Transfer project will further advance the Extended T-FAST method by: (i) incorporating additional aggregates with documented reactivity; (ii) evaluating interactions between fine and coarse aggregates; (iii) refining the RI classification framework using classification algorithms; and (iv) supporting the statistical analysis needed to develop a standardized test procedure.​]]></description>
      <pubDate>Wed, 30 Sep 2026 10:32:25 GMT</pubDate>
      <guid>https://rip.trb.org/View/2784610</guid>
    </item>
    <item>
      <title>Effects of Sand Equivalent and Fractured Face Percentage on Concrete Strength</title>
      <link>https://rip.trb.org/View/2780488</link>
      <description><![CDATA[This project will evaluate the effects of sand equivalent values and fractured face percentages on the performance of concrete used in transportation infrastructure. The study will use laboratory testing to examine how aggregate quality affects concrete strength and overall performance. The project will also compare sand equivalent and methylene blue testing methods and assess whether current aggregate specifications could be modified to reduce costs while maintaining concrete quality. The results will be used to develop recommendations for potential updates to the Idaho Transportation Department's (ITD's) aggregate material specifications.
]]></description>
      <pubDate>Mon, 21 Sep 2026 15:55:54 GMT</pubDate>
      <guid>https://rip.trb.org/View/2780488</guid>
    </item>
    <item>
      <title>Advancing Pavement Design Inputs Through Improved R-Value Predictions</title>
      <link>https://rip.trb.org/View/2780407</link>
      <description><![CDATA[The objective of this research is to develop improved R-value prediction equations that enhance accuracy while remaining practical for Arizona Department of Transportation (ADOT) pavement design use. To achieve this objective, the project will: 
(1) Collect and compile available ADOT soil and R-value datasets from different Arizona regions, including measured R-values, soil classification, index properties, gradation data, project location, material source, and other routinely available laboratory or field information. (2) Perform regression and statistical analyses to evaluate the accuracy of the current ADOT R-value correlation and identify soil parameters that can improve prediction performance for Arizona materials. (3) Develop and validate enhanced R-value prediction equations using practical input parameters such as PI, percent passing the No. 200 sieve, gradation indices, USCS classification, and regional soil information where appropriate.
(4) Provide implementation recommendations for ADOT, including recommended equations, input requirements, limitations, example calculations, and a simple calculation tool for use by Pavement Design and Geotechnical staff.]]></description>
      <pubDate>Fri, 18 Sep 2026 17:07:19 GMT</pubDate>
      <guid>https://rip.trb.org/View/2780407</guid>
    </item>
    <item>
      <title>Quantifying the Impact of Pavement Smoothness</title>
      <link>https://rip.trb.org/View/2780399</link>
      <description><![CDATA[Pavement smoothness affects the lifespan of Arizona’s state highway network, the frequency of roadway maintenance and preservation projects needed to maintain it, and the cost to individuals of operating vehicles on it. Quantifying the impact of pavement smoothness specifications on pavement service life, vehicle operating costs, and emissions will help Arizona Department of Transportation (ADOT) determine appropriate smoothness standards for roadway construction and rehabilitation. For instance, pavements with a lower score on the International Roughness Index (IRI) typically require less maintenance and have a longer service life. Pavements with high IRI values can lead to increased overall vehicle maintenance costs for motorists, as rough roads cause tires and suspension systems to deteriorate at a faster rate and vehicles to consume more fuel. 
This study will estimate how changes to ADOT’s pavement surface smoothness specifications might extend pavement service life, delay the emergence of maintenance and rehabilitation (M&R) treatment triggers, and reduce vehicle operating costs for individual users. ADOT may use the findings of this study to modify smoothness specifications, producing statewide cost savings due to the increases in service life of pavements and reduced or deferred M&R activities. The results of this study may also be used to update project cost estimates and estimate user-cost savings.  
]]></description>
      <pubDate>Fri, 18 Sep 2026 16:35:41 GMT</pubDate>
      <guid>https://rip.trb.org/View/2780399</guid>
    </item>
    <item>
      <title>Evaluating the Cracking Characterizations of Stone Matrix Asphalt (SMA) Mixtures</title>
      <link>https://rip.trb.org/View/2780398</link>
      <description><![CDATA[The primary objective of this research study is to evaluate the cracking characteristics of Arizona stone matrix asphalt (SMA) mixtures and use the findings to develop more accurate and reliable testing protocols, ultimately enhancing SMA pavement performance and durability. 
]]></description>
      <pubDate>Fri, 18 Sep 2026 16:31:44 GMT</pubDate>
      <guid>https://rip.trb.org/View/2780398</guid>
    </item>
    <item>
      <title>Fiber Reinforcement in Concrete Pavement</title>
      <link>https://rip.trb.org/View/2780393</link>
      <description><![CDATA[This research identified the major gaps in the analysis and design of fiber reinforced concrete (FRC) pavements and gathered various structural-mechanics methods and solutions to various FRC-based concrete application that include: fatigue, tension stiffening, shrinkage cracking, multiple parallel cracking distribution, toughening of hybrid systems by fibers, development of tensile stress distribution across the thickness of a slab, and the moment-curvature response of a section, limit analysis of plates, as well as the load-deflection response of a slab.]]></description>
      <pubDate>Fri, 18 Sep 2026 16:13:55 GMT</pubDate>
      <guid>https://rip.trb.org/View/2780393</guid>
    </item>
    <item>
      <title>Liquid Nitrogen-Cooled Concrete</title>
      <link>https://rip.trb.org/View/2778088</link>
      <description><![CDATA[Placing concrete in warm weather can accelerate cement hydration and moisture evaporation, reducing workability and long-term strength. One method to rapidly cool concrete in warm weather is to use liquid nitrogen, which lowers a mix’s temperature without adding water or ice or altering the design. This project’s goal is to review current industry practices and assess the effectiveness of using liquid nitrogen to cool concrete in warm weather. Researchers will identify key considerations and recommended practices for the use of liquid nitrogen to cool concrete in Illinois Department of Transportation projects. Effectively using liquid nitrogen to cool concrete will allow construction personnel to pour concrete for longer, uninterrupted periods, improving its consistency and quality.]]></description>
      <pubDate>Wed, 16 Sep 2026 11:01:26 GMT</pubDate>
      <guid>https://rip.trb.org/View/2778088</guid>
    </item>
    <item>
      <title>Develop Enhanced Quality Assurance Methods for Full-Depth Reclamation Construction</title>
      <link>https://rip.trb.org/View/2778041</link>
      <description><![CDATA[Full depth reclamation (FDR) with emulsified or foamed asphalt can rapidly renew a pavement with significant time and cost savings compared to major reconstruction while providing a durable, high modulus, moisture-resistant base. While most FDR asphalt projects are performing well, improvements are needed in construction startup operations, moisture control, and better relations of acceptance testing to field performance. The research team will assess existing FDR quality assurance frameworks, identify technological advancements, and develop new test methods and protocols to ensure FDR layers achieve their intended performance. The research team will develop more comprehensive and reliable testing coverage for moisture content control to reduce the risk of premature distress under early traffic. The research team will identify, develop, and pilot acceptance test methods that better correlate to long-term pavement performance. The research team will identify improvements to guidance resources to promote more successful FDR project startups. The research team will use the results from this project to develop new test procedures, update construction specifications, and update FDR construction guidelines.]]></description>
      <pubDate>Mon, 14 Sep 2026 16:22:41 GMT</pubDate>
      <guid>https://rip.trb.org/View/2778041</guid>
    </item>
    <item>
      <title>Developing a Pavement Performance Model for Effective Pavement Management of Wyoming County Roads, Phase I</title>
      <link>https://rip.trb.org/View/2777829</link>
      <description><![CDATA[As pavements progressively age and deteriorate over time, it becomes necessary for agencies to allocate substantial financial resources to sustain their pavement network in a condition deemed acceptable. A significant number of county roads were constructed decades ago and have received on-demand maintenance, resulting in suboptimal overall road conditions for Wyoming counties. Therefore, since 2014, the Wyoming Technology Transfer Center, in association with Wyoming Department of Transportation (WYDOT), has been collecting county road pavement performance data in Wyoming to make informed management decisions in the future. The pavement data collected includes rut depth, cracking, roughness, and other associated data such as route, direction, mile post, road width, length, district, county, and speed. Local governmental entities are responsible for the management of county roads, relying on their engineering expertise and judgment, without the implementation of a county-specific Pavement Management System (PMS). Also, different vendors have collected this data over time. There exists a need to check the consistency, quality, and continuity of this data from vendors. This study addresses this gap and plans to develop a pavement performance model from the collected data for county roads. Overall, this study is divided into two phases. Phase I of the research will review the data collected from different vendors for consistency, check quality, and continuity. Thereafter, the study will examine the existing pavement performance deterioration model for county roads. Finally, Phase II of this research plans to develop a new county pavement deterioration model and performance index, along with decision trees for pavement management. This research will help aid decision-makers in making better choices by allocating the funding appropriately with preventive treatment, minor and major rehabilitation to ensure good quality county roads. Finally, the outcome of this research can be used by policymakers to implement the best practices of PMS in Wyoming counties.]]></description>
      <pubDate>Mon, 14 Sep 2026 14:14:50 GMT</pubDate>
      <guid>https://rip.trb.org/View/2777829</guid>
    </item>
    <item>
      <title>Agentic AI for ASTM-Aligned Pavement Assessment Framework</title>
      <link>https://rip.trb.org/View/2777810</link>
      <description><![CDATA[This project proposes an agentic artificial intelligence (AI) framework for pavement assessment that brings together multimodal deep learning, depth-aware evidence, and standards-aligned reasoning within a single workflow. Although recent automated methods have improved distress detection, segmentation, and severity labeling, they still function largely as isolated tasks and therefore do not support the broader engineering reasoning required for maintenance decision-making. As a result, an important gap remains between model prediction and practical pavement assessment. Building on prior advances in pavement condition index estimation, dense captioning, and annotation-efficient segmentation, the proposed framework will detect and classify pavement distress, estimate severity and depth-related condition indicators, identify the appropriate ASTM-aligned assessment pathway, and generate clear engineering-oriented reports. In this way, the project connects perception, interpretation, pathway selection, and reporting in a coordinated system. Ultimately, it aims to move pavement AI beyond passive prediction toward a more interpretable, scalable, and decision-ready tool for transportation practice.]]></description>
      <pubDate>Mon, 14 Sep 2026 14:03:26 GMT</pubDate>
      <guid>https://rip.trb.org/View/2777810</guid>
    </item>
    <item>
      <title>Development of a Regional Model for Pavement Design for Local Low-Volume Road Conditions</title>
      <link>https://rip.trb.org/View/2689388</link>
      <description><![CDATA[The United States has thousands of miles of low volume roadways that are located in a variety of climate zones and underutilized socioeconomic areas; most of them inhabited by traditionally underserved rural and urban communities. The Departments of Transportation have designed and constructed resilient long-life pavements in these areas, which has resulted in improving mobility of people and goods. These pavements have lower life cycle and user costs, saving agencies millions of dollars in maintenance and rehabilitation and minimizing traffic disruption for the life of the pavement. 
In this project, the researchers will conduct a calibration process to region specific local (rural versus urban) and environmental conditions, policies, and materials that will allow for the development of state-of-the-art technology to improve design methods and construction procedures for low volume roads.  The use of locally available recycled materials including the existing pavement structure and chip seal surfacing will be given high priority in these methods along with the inclusion of local environmental factors and pavement preservation factors as well as equity and environmental justice related policy matters.
]]></description>
      <pubDate>Thu, 10 Sep 2026 11:03:44 GMT</pubDate>
      <guid>https://rip.trb.org/View/2689388</guid>
    </item>
    <item>
      <title>Investigating the Efficacy and Variability of the Bar Linear Shrinkage Test for Aggregates </title>
      <link>https://rip.trb.org/View/2775953</link>
      <description><![CDATA[Aggregate is a widely used construction material in the Virginia Department of Transportation (VDOT) construction projects. Its quality is governed by many properties, including gradation, soundness, and Atterberg limits. Specifically, VDOT sets specification requirements for both the plasticity index (PI) and liquid limit (LL). These limits are determined by Atterberg limit tests. The requirements for PI and LL aim to limit or eliminate contaminants like active clay in aggregate, which negatively impact performance.

The fines in aggregates are typically non-plastic (NP) or marginally plastic, which creates challenges when determining PI and LL using conventional test methods—for example, materials may slide on the Casagrande cup or may not roll into 1/8-inch threads. A bar linear shrinkage (BLS) test, which measures the shrinkage limit of fine materials, is proposed as a surrogate test for these properties. The BLS test is simple, repeatable, and sensitive to the presence of active clay particles.
Materials with a range of properties will be tested in the laboratory to evaluate the effectiveness of the BLS test in distinguishing low-PI materials across the acceptance range for aggregate materials and to standardize the test method for VDOT use. The study will also include an interlaboratory evaluation to quantify repeatability and reproducibility, ensuring the BLS test can be reliably incorporated into routine VDOT quality‑assurance operations.]]></description>
      <pubDate>Thu, 10 Sep 2026 09:53:10 GMT</pubDate>
      <guid>https://rip.trb.org/View/2775953</guid>
    </item>
    <item>
      <title>Performance Evaluation of Intermediate and Base Asphalt Mixtures in Virginia</title>
      <link>https://rip.trb.org/View/2775952</link>
      <description><![CDATA[The Virginia Department of Transportation (VDOT) has implemented a balanced mix design (BMD) specification for the design and acceptance of dense-graded asphalt surface mixtures (SM) with A and D designations. The BMD specification incorporates performance tests and corresponding criteria to screen out potentially poor-performing mixtures by balancing their cracking and rutting resistances during mix design. Since the BMD specification is applicable to SMs, it does not address potential deficiencies of the underlying asphalt layers such as asphalt intermediate mixtures (IMs) and base mixtures (BMs). 

The IM and BM layers correspond to most of the material used in the asphalt concrete pavement and, thus, have a key role in the pavement structural capacity. Nonetheless, IMs and BMs are not often included in routine maintenance schedules. Besides, changes in the mix design and in-place density requirements for BMs starting in 2026 may lead to changes in BMs expected performance, potentially affecting the decision-making during pavement design. Collectively, these factors highlight the need to design and produce good-performing IMs and BMs.

The goal of this study is to benchmark the performance of IMs and BMs with respect to fatigue cracking and rutting resistances and evaluate mix design strategies to potentially improve the performance of BMs, such as incorporating the recycled binder availability (RBA) concept during mix design. The scope of work will include analyzing VDOT's mix design, production, and in-place density data, performing laboratory tests (index-based and fundamental), and conduct pavement performance simulations. 

Better understanding the performance of these mixtures will not only contribute to the design and production of structurally sound pavements but will also support a succesful and responsible BMD implementation for SMs.
]]></description>
      <pubDate>Thu, 10 Sep 2026 09:45:29 GMT</pubDate>
      <guid>https://rip.trb.org/View/2775952</guid>
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