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    <title>Research in Progress (RIP)</title>
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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>
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      <title>Research in Progress (RIP)</title>
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    <item>
      <title>Continuous and Rapid Detection Methods for Segregation in Asphalt Mixture Paving</title>
      <link>https://rip.trb.org/View/2734857</link>
      <description><![CDATA[Segregation in asphalt mixtures, where coarse aggregates become separated from fine aggregates, leads to non-uniform pavement surfaces with reduced density and durability. This deficiency significantly impacts the performance of asphalt pavements, often resulting in premature failures such as raveling, cracking, and potholes. Identification of segregation during or immediately after asphalt paving operations is crucial for mitigating these potential issues, ensuring higher-quality, longer lasting, and more durable pavements while minimizing future repair needs.

Historically, segregation detection has relied on visual inspection methods or density measurements, which are both time-consuming and susceptible to errors. Recent advances in real-time monitoring and continuous inspection technologies, such as infrared imaging, Ground Penetrating Radar (GPR), continuous density and macrotexture measurement, and machine learning-driven analysis present opportunities for detecting segregation as it occurs. These innovations promise to improve the detection process, allowing for more immediate interventions that preserve pavement quality and minimize costs.

Segregation is a leading cause of premature asphalt pavement failure. Thermal, density, and gradation inconsistencies create weak areas in pavements that deteriorate faster and cost more to maintain. The purpose of this study is to explore, identify, and validate advanced technologies for detecting and quantifying segregation in asphalt pavements both during and immediately following paving operations. The focus will be on the development and implementation of continuous, real-time detection methods that facilitate immediate corrective actions and improve the overall quality and longevity of pavements.
]]></description>
      <pubDate>Thu, 23 Jul 2026 07:25:06 GMT</pubDate>
      <guid>https://rip.trb.org/View/2734857</guid>
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      <title>Use of a Monocular Head-Worn Display (HWD) With and Without an Enhanced Flight Vision System (EFVS) to Conduct Lower-than-Standard Approach and Landing Minima Flight Operations</title>
      <link>https://rip.trb.org/View/2533787</link>
      <description><![CDATA[When flying a Special Authorization Category I (SA CAT I) instrument landing system (ILS) approach, pilots may use a Head-Up Display (HUD), which presents flight symbology on a transparent screen so that the pilot can view primary flight information while looking out the window, along the flightpath. Pilots can also use an Enhanced Flight Vision System (EFVS) on a HUD during this operation, which provides a real-time sensor image of the forward view to enhance runway awareness when transitioning to visual flight references.  The Head-Worn Display (HWD) is an emerging technology in civil aviation that is designed to provide the benefits of a HUD; however, the unique optical and physical characteristics of the HWD may change the existing levels of pilot performance and workload during SA CAT I operations flown with a HUD. When flying with a monocular HWD, binocular rivalry occurs, which may impact pilot performance and workload. This raises questions about whether pilot performance and workload are significantly impacted during manual SA CAT I flight operations where the pilot flying (PF) uses a monocular HWD with and without an EFVS. To address this concern, a study was carried out in which 11 pilot crews, made up of 22 Airline Transport Pilot (ATP) Captains, flew manual SA CAT I approach, landing, and rollout scenarios in a Boeing 737 Level D-equivalent flight simulator with a HUD and monocular HWD, with and without an EFVS, and in day and night ambient lighting conditions. Pilots rated their workload during each scenario using the National Aeronautics and Space Administration Task Load Index (NASA-TLX). The findings of the study suggest that a monocular HWD may not have a significant negative impact on a pilot’s ability to manage most aspects of the flightpath during an SA CAT I operation; however, the monocular HWD elevated pilot workload. The monocular HWD also caused increased glideslope deviation during the instrument segment and increased deviation from the runway centerline during rollout. However, these increases were small, and may not translate to operational significance. While the use of an EFVS did not impact any aspects of pilot performance or workload, pilots reported that it enhanced their awareness of the runway environment when transitioning from instrument to visual flight references; however, it was reported to be a hindrance when transitioning to flare, landing, and rollout regardless of whether it was implemented on a HUD or a monocular HWD. ]]></description>
      <pubDate>Tue, 01 Apr 2025 14:13:05 GMT</pubDate>
      <guid>https://rip.trb.org/View/2533787</guid>
    </item>
    <item>
      <title>Evaluation of Infrared Technology (Pave IR) and GPR for Uniformity Measurements During Asphalt Placement</title>
      <link>https://rip.trb.org/View/1877374</link>
      <description><![CDATA[This project will evaluate implementation of infrared (IR) imaging — recently proposed by the SHRP2 program — for temperature uniformity measurements on new hot-mix asphalt (HMA) layers. Uniformity of HMA materials is critical to the durability and performance of asphalt. Segregation and inadequate and non-uniform density continue to be major construction-related problems around the U.S., adversely impacting pavement service life. Commonly used quality control testing procedures only provide limited information on the overall uniformity of HMA. Acquiring information that is real-time, non-destructive, and which covers the full pavement width for thermal uniformity will help improve HMA quality. Kentucky Transportation Cabinet (KTC) will also evaluate a ground penetrating radar (GPR) rolling density device.  ]]></description>
      <pubDate>Wed, 08 Sep 2021 11:04:06 GMT</pubDate>
      <guid>https://rip.trb.org/View/1877374</guid>
    </item>
    <item>
      <title>Application of Forward Looking Infrared Radiometer (FLIR) Technology for Detecting Early Stages of Fouled Ballast</title>
      <link>https://rip.trb.org/View/1602483</link>
      <description><![CDATA[The feasibility and limitations of Forward Looking Infrared Radiometer (FLIR) Aerial Technology for detecting fouled ballasts is studied in this project. The method is intended to provide an efficient and ready-to-use approach that can help the railroads detect fouled ballasts in their early stages.  Ballast fouling commonly occurs as a result of fine particles clogging off water passage through them.  Subsequently, this results in trapped water that often results in poor foundation strength, rotting of the ties, and other ill effects.  
This study includes a novel approach to evaluate the railway ballast fouling by using thermal imaging techniques. A simple setup for implementing ballast fouling of different amounts have been implemented in the lab.  For the purpose of laboratory testing, the camera is set up in stationary and moving configurations.  The thermal characteristics of clean and fouled ballasts are studied using FLIR cameras that can be used onboard rolling stock, Hyrail trucks, or drones. Laboratory tests are primarily performed to measure the surface temperature changing rate of clean and fouled ballasts in response to ambient temperature changes. 
The test results indicate that clean and fouled ballasts have different thermal characteristics. In particular, different thermal patterns are obtained during naturally-occurring daily temperature change.  The test results also indicate that the FLIR cameras can be used on a moving platform for quick scanning of thermal images of the ballasts that could be used for assessing the early stage of fouling.
]]></description>
      <pubDate>Sat, 27 Apr 2019 19:11:29 GMT</pubDate>
      <guid>https://rip.trb.org/View/1602483</guid>
    </item>
    <item>
      <title>Reducing Uncertainties in Snow Fence Design: Development of Methods for Estimation of Snow Drifting and the Snow Relocation Coefficient TR-760</title>
      <link>https://rip.trb.org/View/1550862</link>
      <description><![CDATA[The current measurement protocols for snowfall and snowdrift quantification and evaluation of the design of snow fence efficiency are incomplete, costly, and are practically of unknown (presumably quite low) accuracy. Most of the pitfalls of measurement approaches are related to the fact that the measurements are acquired with intrusive instruments, i.e., snow bags, snow traps, and snow boards. Data acquisition performed with these type of instruments also requires extended exposure to adverse, frigid, and windy conditions that pose a significant risk for personnel safety and health.
The main objective of the present study is to assemble, test, and deploy a set of new technologies to support the design and evaluation of snow fence performance using non-intrusive measurement technologies based on imaging of the movement of the snow drift and of the accumulation of the snow at fences. Specifically, the objectives proposed for this study addresses three critical aspects of snow fence design that are needed by IDOT winter maintenance designers: (Objective 1) Estimation of local snowfall; (Objective 2) Mapping of the snow volumes accumulated at fences; (Objective 3) Estimation of snow drifting and SRC. The proposed research consists of field investigations that leverage surveying methods tested in previous studies of this research team for IDOT (Constantinescu and Muste, 2015; Tsai et al., 2017). These projects were focused on evaluation of the efficiency of various types of structural snow fences. Several observing protocols for informing the qualitative and quantitative analyses were also developed through those studies. Consequently, the outcomes of the prior research also included development of customized instruments and protocols for assessing variables used in the evaluation of the snow fence design. The tasks will be conducted at two experimental sites tested in the previous studies, i.e., Site 1: Williams on Hwy 20, and, Site 2: Shueyville on US 218.]]></description>
      <pubDate>Wed, 26 Sep 2018 15:46:51 GMT</pubDate>
      <guid>https://rip.trb.org/View/1550862</guid>
    </item>
    <item>
      <title>Exploration and Evaluation of High-Resolution Imagery for Environmental Assessment</title>
      <link>https://rip.trb.org/View/1504843</link>
      <description><![CDATA[The goal of this project is to assess potential and develop protocols for the use of high-resolution LiDAR and multi-spectral imagery to evaluate environmental characteristics of Iowa DOT (DOT) project areas. Specifically, the research team will evaluate how LiDAR and multi-spectral imagery can support the assessment of design alternatives, and if these data could help DOT staff select alternatives earlier and with less fieldwork required. 

In addition to capturing normal land survey and engineering data concurrently, which is invaluable to the design and project development process, the team will augment this data with high-resolution remotely obtained data. This will allow the team to assess the extent to which the following can be completed using such imagery: (a) wetland spatial extent and vegetation characterization; (b) stream channel morphology
determination (depth, width, center-line location); and (c) tree assessment (tree stand density and health, individual tree heights, diameter and health).

In addition to land survey data for engineering purposes, the DOT also believes this remote sensed data (in the form of high resolution multi-spectral orthoimagery and LiDAR) will provide ancillary benefit that will allow potential threatened and endangered species habitat to be identified early as well as an Archaeological Landform and Architectural Building/Setting Assessment to be investigated further
through correlation of field collected data. While these additional assessments are not part of this proposal, the images and data gathered in this project will be available for future investigation.

Current DOT methods for environmental assessment require a significant amount of manual and on-site work, driving up the costs and time associated with these phases of projects. This project will determine what savings might be realized through use of high-resolution imagery and what the break-even point for this type of data collection might be in terms of the size of the study area. Specifically, the team intends to evaluate the use of three types of imagery at approximately a 15-50 cm spatial resolution: standard (near infrared) LiDAR elevation and terrain data, multi spectral color (blue, green, red, and near infrared) reflectance data, and narrow-band green LiDAR imagery which penetrates into water surfaces and gives information relevant to topography under shallow water.]]></description>
      <pubDate>Fri, 09 Mar 2018 14:18:09 GMT</pubDate>
      <guid>https://rip.trb.org/View/1504843</guid>
    </item>
    <item>
      <title>Novel Integrated Nondestructive Testing Methodology for Detection and Evaluation of Corrosion in Cement-Based Materials</title>
      <link>https://rip.trb.org/View/1314838</link>
      <description><![CDATA[The integration of thermography/infrared (IR) and ultrasonic test (UT) methods has been successfully demonstrated by others. By vibrating a material via UT, heat is generated at the location of flaws. Subsequently, this heat is imaged using an IR camera. The work proposed here suggests a similar yet unique approach through the integration of microwave methods with IR/thermography, an established nondestructive testing (NDT) technique. The combination of microwave and IR NDT may offer a substantial improvement to traditional thermographic techniques. First, microwaves can be used to selectively and locally heat an area of interest, as opposed to heating the entire sample (and risking heat damage). Furthermore, thermography has an issue with speed, as heat transfer can be quite slow. Using microwaves to selectively heat a localized area will improve the speed of the method by 50%, as microwave heating is instantaneous. Preliminary results have shown the combination of microwave and IR methods as a promising technique for detection of surface cracks and corrosion in metals. This project will build upon these preliminary results to development a new technique to detect and evaluate the presence of corrosion in cement-based materials, which is of critical importance to the nation's transportation infrastructure.]]></description>
      <pubDate>Thu, 03 Jul 2014 01:01:14 GMT</pubDate>
      <guid>https://rip.trb.org/View/1314838</guid>
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