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    <title>Transport Research International Documentation (TRID)</title>
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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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      <title>Recognition of Road Surface Conditions With a 82–98 GHz Total Power Dual-Polarized Radiometer on a Vehicle</title>
      <link>https://trid.trb.org/View/2512179</link>
      <description><![CDATA[This paper presents field-measurements of road surfaces in different conditions using a dual-polarized radiometer installed on a moving vehicle. The radiometer measures the surfaces emissivity in both vertical and horizontal polarizations between 82 - 93 GHz, with a 47° angle of incidence. The tested surfaces include dry and wet asphalt, asphalt covered with thin/thick ice and packed/unpacked snow patches. The measured surface emissivity varies between the surfaces (dry, snow, liquid water, or ice) because of differences in the dielectric properties of the materials and roughness’s. Using field measurements, the authors compare the emissivity of the surfaces and show that the corresponding emissivity of each road condition is distinct and well-defined. Polarimetric radiometer measurements can thus be used to identify road-surface conditions in outdoor environment.]]></description>
      <pubDate>Fri, 13 Jun 2025 14:56:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2512179</guid>
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    <item>
      <title>Detecting Fouled Ballast Using Forward-Looking Infrared Radiometer (FlIR) Technology</title>
      <link>https://trid.trb.org/View/2447239</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>Wed, 20 Nov 2024 13:08:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2447239</guid>
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    <item>
      <title>Use of an L-band radiometer for proximal moisture measurement in road construction</title>
      <link>https://trid.trb.org/View/2050351</link>
      <description><![CDATA[The moisture content level during compaction plays a crucial role in the performance of road pavements. Current state-of-the-art methods involve manually taking small samples from a few isolated locations, making it difficult to monitor the spatial variation in moisture content along the entire construction corridor during compaction in an economically feasible manner. Therefore, finding an easy and effective method to measure soil moisture is a matter of importance. In agricultural applications, L-band passive microwave has proven to be the most accurate method for measuring soil moisture, with current satellites having a spatial resolution of approximately 40 km, which however is too coarse for road construction. Nevertheless, this technology can be deployed closer to the ground, to the point that a spatial resolution of less than 10 m is possible to achieve. Consequently, this study demonstrates the effectiveness of an L-band passive microwave radiometer for measuring soil moisture in the context of optimum compaction for road construction materials. An L-band radiometer called ELBARA-III was used to measure near-surface soil moisture in a 4.5 m x 7.5 m x 0.3 m test-bed having a sand subgrade and then an unbound granular material (UGM) sub base/ base. The moisture content of the material was measured using traditional techniques such as taking thermogravimetric physical samples at targeted locations at 50 mm depth to validate the results. The results demonstrated that the L-band microwave radiometer can provide an accuracy of 5% volumetric moisture content (VMC) or 3% gravimetric moisture content (GMC) for sand subgrade and 2% VMC or 1% GMC for UGM sub base/ base. An incidence angle of 0° using dual or single (horizontal or vertical) polarization was found to be the most effective configuration since it is less affected by surface roughness and is recommended for use in further field testing.]]></description>
      <pubDate>Fri, 23 Dec 2022 14:07:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2050351</guid>
    </item>
    <item>
      <title>A Real-Time Monitoring Method for Civil Aircraft Take-Off and Landing Based on Synthetic Aperture Microwave Radiation Technology</title>
      <link>https://trid.trb.org/View/1971052</link>
      <description><![CDATA[It is important to monitor the take-off and landing of civil aircraft using passive detection methods. Due to the strict aircraft safety requirements and the electromagnetic environment around an airport, using too many active detection methods should be avoided. Using an aircraft’s microwave radiation signal detection is very advantageous because it does not actively emit signals and has a strong cloud penetration, suitable for all-weather observation. This paper introduces a synthetic aperture microwave radiation system for monitoring the take-off and landing of civil aircraft, which is characterized by real-time two-dimensional imaging, and the image refresh rate can reach 10 ms, which meets the high refresh rate requirements for aircraft imaging. Applicable system parameters and antenna array distribution scheme and imaging algorithm are given. Then the paper focuses on the error analysis and correction method of the system. The correction method is simple and fast, which avoids the disadvantage that the error needs to be corrected regularly in the laboratory environment, and is suitable for airport application. Finally, the simulation and experimental results show that this technology can be used for real-time monitoring of civil aircraft during take-off and landing, and it is a practical means to assisting landing.]]></description>
      <pubDate>Tue, 21 Jun 2022 14:26:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1971052</guid>
    </item>
    <item>
      <title>Development of Accurate Ice Observation Technologies for Arctic Oil and Gas Developments and Verification by Field Campaigns</title>
      <link>https://trid.trb.org/View/1722751</link>
      <description><![CDATA[Arctic is one of the most important areas for the future oil and gas development. However presence of ice is a serious hazard for safe, efficient and sustainable developments. The authors developed accurate ice observation technologies and verified their functions by field campaigns in Japan and Greenland. The “EM-BIRD” (airborne Electro-Magnetic induction sensor of ice thickness) was improved by installing a portable microwave radiometer (PMR) and a laser scanner for observing more comprehensive information including snow depth and surface geometry of ice. The authors developed the on-board pulse-doppler ice radar and the parametric sub-bottom profiler which are capable of measuring motions and distributions of sea ice, and gouging depth by massive ice features with high accuracy. The authors also developed ice database system containing satellite remote-sensing and field data measured by the developed sensors for the operability analysis of arctic facilities.]]></description>
      <pubDate>Wed, 22 Jul 2020 15:52:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/1722751</guid>
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    <item>
      <title>Application of Forward Looking Infrared Radiometer (FLIR) Technology for Detecting Early Stages of Fouled Ballast</title>
      <link>https://trid.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://trid.trb.org/View/1602483</guid>
    </item>
    <item>
      <title>Infrared Experiment on a Road Wheel During an FMVSS-109 Type Compliance Test</title>
      <link>https://trid.trb.org/View/1505977</link>
      <description><![CDATA[The work described in this report was performed to determine the relationship between an automobile tire's thermal performance and tire failure. This work was coordinated by the Transportation Systems Center (TSC), Electromechanical Branch as a part of the nondestructive Automobile Tire Testing Program sponsored by the National Highway Traffic Safety Administration, Research Institute. The experiment was conducted at Ogden Technology, a compliance center testing retread tires in Long Island, New York. TSC designed the experiment and provided coordination, technical assistance, data analysis and evaluation during the experiment. The purpose of this report is to describe the instrumentation and the data collection techniques used rather than to cite results of the first experiments, although some preliminary thermal data proved to be interesting.]]></description>
      <pubDate>Sun, 29 Apr 2018 19:16:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1505977</guid>
    </item>
    <item>
      <title>Radiant Heat Attenuation by Clothing and Human Tolerance to Radiant Heat: Field Experiments with LNG fires</title>
      <link>https://trid.trb.org/View/1485506</link>
      <description><![CDATA[A series of tests involving the exposing mannequins clothed with normal civilian clothing to a 10 ft x 10 ft liquefied natural gas (LNG) pool fire was conducted. Both single layer clothing and double layer clothing were used. The radiant heat flux incident outside the clothing and incident on the skin covered by clothing were measured using wide-angle radiometers, for durations of 100 s to 200 s (per test). The levels of heat flux incident on the clothing were close to 5 kW/m². The magnitude of the attenuation factor (AF) (ratio of the outside radiant heat flux to that on the skin) was calculated. It is seen that AF varies between 2 and higher for ordinary cotton and polyester clothing (of thickness 0.286 mm to 1.347 mm). Values as high as 6 have been measured for clothes of thickness 1.347 mm. Tests similar to the above were conducted to determine the attenuation factor when a single or multiple sheets of newspaper are interposed in front (about 5 cm) of the radiometer. Single sheet newspapers reduce the heat flux to the radiometer by a factor of about 5 at a heat flux level of 5 kW/m². Double sheets reduce the heat flux intensity by a factor of almost 8! The magnitude of the AF for newspaper sheets depends on the magnitude of the heat flux and thickness. It decreases linearly with increasing heat flux values and increases linearly with increase in thickness. The author exposed himself, in normal civilian clothing (of full sleeve cotton/polyester shirt and jean pants) to the radiant heat flux from the LNG fire at levels of 4 7 kW/m² and higher for tens of seconds; Occasionally, as high as 7 kW/m² for durations of several seconds. He did not suffer any injury, burns or skin blisters for exposure times ranging from 25 s to 97 s at average heat flux values of 4 kW/m² to 5 kW/m². The incident heat flux on the author was measured by a handheld radiometer with a display and later by wide-angle radiometers (whose output was recorded on a computer) strapped on to him. The results indicated that he could withstand the regulatory criterion of 5 kW/m² for 30 seconds without suffering any damage or burns. Temperature measured on the skin of the author covered by the clothing did not rise above the normal body temperature even after 200 s of exposure to an average heat flux of 4 kW/m². .]]></description>
      <pubDate>Wed, 25 Oct 2017 14:40:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1485506</guid>
    </item>
    <item>
      <title>Comparison of Potential Temperature Gradient Estimates from Various Temperature Profile Data Sources</title>
      <link>https://trid.trb.org/View/1458097</link>
      <description><![CDATA[From July through September 2015, concurrent and collocated measurements of temperature profiles from two passive radiometers and a RADAR-RASS (Radio Acoustic Sounding System) were made at a site near the ocean just to the west of Los Angeles International Airport (LAX). In addition, temperature profiles for this same time period from National Oceanic and Atmospheric Administration's (NOAA’s) Rapid Refresh (RAP) hourly-updated assimilation/modeling system were collected. The motivation for this data collection effort was the idea that intercomparisons of data obtained from various temperature profiling sources could be used to characterize the variability of potential temperature gradient (PTG) values. The observed scatter of PTG intercomparisons can be used as a practical way of quantifying the variability in measurements of PTG at 250m. This information is important for understanding the variability of aircraft wake vortex data as well as for providing bounds on the variability of the environmental data used for wake modeling. The authors determined that PTG measurements derived from various sources are mostly consistent and indicate an uncertainty in the measurement of PTG of about one degC/100m. This implies that it may not be possible to measure PTG to much better than a tolerance of that amount. Fast-time model results demonstrated that a one degC/100m variation in PTG can result in uncertainties of 50 m²/sec for vortex circulation and 50m for descent distance.]]></description>
      <pubDate>Mon, 27 Mar 2017 09:30:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1458097</guid>
    </item>
    <item>
      <title>Airborne Forward-Looking Interferometer for the Detection of Terminal-Area Hazards</title>
      <link>https://trid.trb.org/View/1312216</link>
      <description><![CDATA[The Forward Looking Interferometer (FLI) program was a multi-year cooperative research effort to investigate the use of imaging radiometers with high spectral resolution, using both modeling/simulation and field experiments, along with sophisticated data analysis techniques that were originally developed for analysis of data from space-based radiometers and hyperspectral imagers. This investigation has advanced the state of knowledge in this technical area, and the FLI program developed a greatly improved understanding of the radiometric signal strength of aviation hazards in a wide range of scenarios, in addition to a much better understanding of the real-world functionality requirements for hazard detection instruments. The project conducted field experiments on three hazards (turbulence, runway conditions, and wake vortices) and  analytical studies on several others including volcanic ash, reduced visibility conditions, in flight icing conditions, and volcanic ash.]]></description>
      <pubDate>Mon, 30 Jun 2014 09:41:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1312216</guid>
    </item>
    <item>
      <title>An Optimum Multisensor Approach for Detailed Engineering Soils Mapping, Volume I : Progress Report</title>
      <link>https://trid.trb.org/View/1219186</link>
      <description><![CDATA[This research study investigated the potential of available types of remote sensing systems for the evaluation of soils and soil conditions for the purpose of developing an optimum multisensor approach for detailed engineering soils mapping. Other objectives of the study were: (l) to investigate the value of quantitative measurements on aerial photography and imagery for assistance in interpretation; and (2) to perform a limited study to determine which parameters would be of value to measure at the time of flights. Three test sites were selected which contained a variety of land forms and soil units. A total of nine flight programs were obtained over the test sites during the period from May 1965 to June I966. Coverage was obtained with various types of aerial films (color, color -infrared, color negative, black-and-white panchromatic and black-and-white infrared), a multiband camera, a radar sensor (K-band), infrared sensors (far infrared), and a multichannel sensor (ultraviolet through far infrared). All of these types were not obtained in any one flight program, but generally several combinations were obtained at one time. Daytime and nighttime imagery were also obtained during one flight. The field investigations included field radiometer readings (taken during last two flight programs), soil moisture content measurements, and resistivity surveys . Ground photographs were taken during aerial flights to record the conditions existing at flight time. Meteorological data were also collected during flights . The resistivity surveys were performed to add to the existing information known about the test areas . The remainder of the data were used to help evaluate the influence of various parameters on the data collected. Quantitative aspects of the project included performing continuous scans with reflection and transmission densitometers, to determine if typical density patterns existed for various land forms . Attempts were also made to prepare isotonal maps. Densitometers were used to prepare normalized response curves from multichannel data. A system was also developed which determines the Munsell color notation on aerial photographs based on densitometer readings with four filters. Based on this color measuring system a method was developed to prepare isochromal maps (maps showing areas of uniform colors). Major conclusions obtained in this study include: (l) the optimum multisensor system for detailed engineering soils mapping is a multichannel sensor (minimum of seven bands in ultraviolet through far infrared) obtained simultaneously with medium scale color aerial photography; (2) alternate systems depending on availability of equipment and security restrictions are color and color-infrared photography and infrared imagery obtained simultaneously, or color and  photography obtained simultaneously; (3) spectral response curves obtained by normalizing multichannel data has great, potential for differentiating between various soils and soil conditions automatically; (k) typical patterns for various land forms are not obtained by densitometric scans - influence of various parameters results in more variations within land forms than between them; (5) the technique of determining Munsell notations by means of densitometer readings is a simple, rapid method whose accuracy (for the intended purpose) is commensurate with other color measuring systems; and (6) field measurements found to be of greatest value in evaluating the photography and imagery include field radiometer readings, ground photographs taken at. the time of flight and meteorological data.]]></description>
      <pubDate>Fri, 16 Nov 2012 08:54:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1219186</guid>
    </item>
    <item>
      <title>Analysis and Measurement of Water Emissivity for the Monitoring of Road Surface State</title>
      <link>https://trid.trb.org/View/1127411</link>
      <description><![CDATA[A traffic accident is caused by bad weather conditions like rain fall, snow or ice cover of road surface status. The microwave radiometer measures the natural thermal radiation from the terrestrial atmosphere and the road surface and it can detect the status of road by the measurement of emissivity. There are several reasons to use microwaves for remote sensing of road surface compared with IR or a visible camera. The most important reasons are their capability to penetrate clouds, fog, and rain with small attenuation. Additionally, microwave remote sensing is not dependent on the sun as source of illumination. The information observed by visible and infrared radiation mainly determines the molecular resonance in the surface layer of the soil, whereas the information observed by microwaves determines geometric and bulk-dielectric properties of the surface or volume studied. In this paper, the theoretical analysis of water emissivity and dielectric characteristics are investigated to monitor the water layer on the road surface. Theoretical calculation of water emissivity is  derived and the result is validated by the experiment in indoor and outdoor.]]></description>
      <pubDate>Mon, 30 Jan 2012 07:09:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1127411</guid>
    </item>
    <item>
      <title>Sakura - An Airborne Infrared Imaging Camera for the Detection of Volcanic Ash and Sulphur Dioxide Gas (Abstract Only)</title>
      <link>https://trid.trb.org/View/756618</link>
      <description><![CDATA[CSIRO Atmospheric Research has been examining the utilization of infrared radiometers for the discrimination and detection of airborne volcanic ash since the early 1990s.  The goal has been the development of a forward looking infrared camera system that commercial jet aircraft could use.  Airborne trials and simulations at Sakurajima volcano in Japan suggest that volcanic ash can be detected by infrared radiometry.  Other more recent studies suggest that sulfur dioxide gas can also be detected.  The system is being improved to offer indications of other atmospheric hazards, such as low level wind shear, severe weather, clear-air turbulence and desert dust outbreaks.  The author describes the basic operation of the infrared airborne camera (named "Sakura"), suggests possible modes of operation, and demonstrates the overall performance of the system.]]></description>
      <pubDate>Tue, 14 Jun 2005 12:52:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/756618</guid>
    </item>
    <item>
      <title>MILLIMETER-WAVE PASSIVE IMAGING SYSTEM FOR SURVEY AND OBSTACLE DETECTION IN ITS</title>
      <link>https://trid.trb.org/View/700463</link>
      <description><![CDATA[There is a recognized need to develop improved systems for survey and obstacle detection offering characteristics such as day, night and adverse weather capabilities, acceptable operating range and adequate spatial resolution. Passive infrared (IR) systems can perform well at night. They are also able to penetrate smoke and haze to a far greater distance than visible systems, but have difficulties when trying to detect through clouds, fog and light rain, since these attenuate strongly infrared radiation. In contrast, millimeter-wave imaging systems suffer little attenuation in either cloudy or foggy conditions, especially around the 35 GHz, 94 GHz and 140 GHz frequency band. This paper presents the development of a low cost one-channel radiometric system working around 52 GHz. The authors have chosen to use a noise-added radiometer with low energy consumption. Four important points are discussed in this paper. First, the radiometric visibility gives the investigation volume for different weather conditions. The computation of such volumes shows a real interest for the radiometric technique. Secondly, a new calibration method, based on a modulated noise diode source, followed by a real-time Kalman filter processing is validated on a 4 GHz radiometer. Thirdly the millimeter-wave radiometer in the 51 GHz - 55 GHz band is described. The authors present also the low-noise amplifier (LNA) that will be used in the final project of the imaging system working in the 94 GHz band. Finally the image processing, based on a deconvolution process and followed by a regularization of the temperature improves the spatial resolution and optimizes the radiometer matrix located in the focal plane of a Fresnel lens.]]></description>
      <pubDate>Thu, 29 Apr 2004 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/700463</guid>
    </item>
    <item>
      <title>LITHOLOGICAL DISCRIMINATION AND STRUCTURAL TRENDS IN W-RWANDA (AFRICA) ON IMAGES OF AIRBORNE RADIOMETRIC AND AEROMAGNETIC SURVEYS, COREGISTERED TO A LANDSAT TM SCENE</title>
      <link>https://trid.trb.org/View/359974</link>
      <description><![CDATA[Processing and interpretation of an airborne gamma-ray and aeromagnetic survey, combined with Thematic Mapper imagery, enabled the successful discrimination of lithological units and their geological and structural interpretation in a complex area where weathering and a dense vegetation cover make traditional mapping extremely difficult. The visual inspection of RGB color composites reveals the differentiation of the area into distinct color domains, each of which has been related to existing geologic units. The aeromagnetic data not only reveal superficial structures, but also show deeper structural detail inside the tectonometamorphic complexes of the area, adding weight to existing hypotheses on the evolution of the Kibaran orogeny.]]></description>
      <pubDate>Sun, 30 Nov 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/359974</guid>
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