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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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    <item>
      <title>Portable microwave radiometer for assessing moisture content in construction of road subgrade and aggregate layers</title>
      <link>https://trid.trb.org/View/2768598</link>
      <description><![CDATA[Recent field trials have demonstrated the practical use and application of portable L-band microwave radiometers for measuring and mapping subgrade moisture content for road construction. Trials were conducted in Logroño A68 highway and Valdebebas Formula 1 track sites in Spain during 2024 and 2025. The radiometer was operated in parallel with a nuclear densimeter (nuclear moisture-density gauge) over natural soil and aggregates. The results of measurements in Logroño showed R2 correlation of 0.92 and 0.86 between nuclear gauge calculated volumetric water content and radiometer retrieved soil dielectric, for natural soil and transported material, respectively. An additional 35 nuclear gauge measurements taken at the Valdebebas site showed R2 values of 0.83, 0.66, 0.69 and Mean Absolute Errors of 0.32%, 0.92%, and 2.13% gravimetric moisture content for materials treated with cement concentrations of 2%, 3.5%, and 4% respectively. L-band radiometers have been known to be sensitive to soil moisture in the upper 5-15 cm of soil. The portable radiometer produced by TerraRad Tech AG (Switzerland) provides dual polarization brightness temperatures, and calculated soil dielectric and volumetric moisture content, from a compact and transportable sensor. Timely and non-intrusive radiometer measurements, and interpolated moisture maps with meter-scale resolution are expected to improve current quality assessment capabilities for civil works, and can reduce operational construction and maintenance costs by reducing moisture-related failures.]]></description>
      <pubDate>Wed, 16 Sep 2026 16:15:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2768598</guid>
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    <item>
      <title>Leveraging Existing Traffic Signal Assets to Obtain Quality Traffic Counts: A Guide</title>
      <link>https://trid.trb.org/View/2582398</link>
      <description><![CDATA[The scope of this guide is to provide transportation agencies with information about extracting motorized and non-motorized traffic volume data from existing signal assets. For completeness, the guide covers both commonly used signal assets and less commonly used but promising types of signal equipment. The guide is organized as follows: Chapter 1—Introduction;  Chapter 2—Inductive Loop Detectors; Chapter 3—Video-Based Systems; Chapter 4—Microwave Radar Sensors; Chapter 5—Light Detection and Ranging (LiDAR) Sensors; Chapter 6—Infrared Sensors; Chapter 7—Magnetic Sensors; Chapter 8—Ultrasonic Sensors; Chapter 9—Other Technologies; and Chapter 10—Data Management. For each type of equipment, the guide offers information about its operation, strengths, weaknesses, count accuracy, cost, and recommended practices for improving the accuracy of traffic volume data. Each chapter provides information on how the respective technology applies to motorized and non-motorized traffic so that users focused on a specific mode can easily find the relevant details. For clarity, the strengths and weaknesses of each technology are presented for both traffic modes combined, as well as separately for motorized and non-motorized traffic where distinctions exist. Additionally, recommendations specific to non-motorized traffic are provided separately to highlight key considerations for accurate data collection. The guide also provides recommendations for obtaining, storing, transmitting, and managing count data for traffic monitoring purposes in Chapter 10.]]></description>
      <pubDate>Wed, 30 Jul 2025 16:56:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2582398</guid>
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    <item>
      <title>CAAP Final Report: Holistic Electromagnetic and Ultrasonic NDE Techniques for Plastic
Pipeline Aging and Degradation Characterization</title>
      <link>https://trid.trb.org/View/2536195</link>
      <description><![CDATA[Plasticizer loss in pipelines occurs gradually over time as a result of diffusion and evaporation. It can go unnoticed with conventional nondestructive evaluation (NDE) techniques as it occurs uniformly in a pipeline. Plasticizer loss results in brittleness and sudden failure subjecting the surroundings to hazard. The proposed method will involve the development of flexible microwave probe that can conform to any curvature and gauge the extent of plasticizer loss. Operating on the principle of change in dielectric property in close vicinity (near field), even the slight variation in the dielectric properties will be gauged accurately. This allows the early prediction of plasticizer loss. Experiments will be conducted to correlate the dielectric change as a function of frequency to the plasticizer loss along the thickness of the pipe. The probe will be mounted on an endoscopic scanning type hardware to provide a visual output of the scanned surface indicating plasticizer loss and other defects. Additional processing capability will be developed to the hardware to classify the plasticizer loss with other defects. The classification will further be ascertained with a higher probability of detection using additional results from the non-linear ultrasonic measurement, and with the quantification and minimization of uncertainty parameters in the measurements like liftoff and noise. Such capabilities impart operator independence to the diagnostic system that provides with intuitive scans. In addition, methodologies for NDE uncertainty quantification and inspection optimization will be proposed. The uncertainty of NDE measurement will be quantified using Gaussian process and Kolmogorov–Smirnov testing. The inspection optimization will be performed using mechanical analysis and Markov Decision Process modeling to advise the optimal location and planning of NDE inspection.]]></description>
      <pubDate>Wed, 23 Apr 2025 10:18:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2536195</guid>
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    <item>
      <title>Non-Nuclear Moisture Content and Density Determination</title>
      <link>https://trid.trb.org/View/2470497</link>
      <description><![CDATA[Adequate soil compaction is important for the stability and safety of structures and transportation infrastructure. Thus, methods utilized to obtain properties that control the quality of compaction in the field are essential to ensure proper construction. The most common method to measure these properties in the field is the Nuclear Density Gauge. Moisture content and density results are obtained using the Nuclear Density Gauge in one to four minutes. However, this method requires specialized training and strict storage requirements in addition to licensing and certification, due to the radioactive nature of the device. A photogrammetry-based method to determine total density and total unit weight soil properties by volume estimation combined with separate soil weight measurements is presented herein. This method includes a photogrammetric analysis, using the Photomodeler software, on photographs obtained from an uncalibrated regular mobile phone camera. To validate this method, the images were obtained of a circular excavation dug in compacted soil. The image acquisition process took less than five minutes. The Photomodeler processing time took approximately 15 minutes to develop a three-dimensional model and volume of the excavated hole. The results obtained with this analysis method were compared with in-situ results obtained from the Troxler nuclear density gauge, sand cone, and the Humboldt electrical density gauge. Based on the obtained results, the photogrammetric method is capable of providing similar results to the nuclear density gauge and the sand cone (within four pcf for total unit weight). The HydroMix HM-08 microwave sensor was deployed as an alternative testing method to determine the water content of the soil. The soil moisture content of different types of unsaturated soils including sand, clay, and base coarse was measured using this sensor. This sensor allowed for the instant (within 5 seconds) measurement of soil moisture content of loose and compacted soil.]]></description>
      <pubDate>Mon, 30 Dec 2024 09:57:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2470497</guid>
    </item>
    <item>
      <title>Concrete pavement with microwave heating enhancement functional layer for efficient de-icing: Design and case study</title>
      <link>https://trid.trb.org/View/2162672</link>
      <description><![CDATA[As traditional de-icing methods, such as applying road de-icing salt and mechanical methods, are inefficient and cause environmental pollution, a concrete pavement structure with a microwave heating enhancement functional layer (MHEFL) is proposed in this study. First, microwave heating (MH) test of magnetite with different particle sizes was performed and the mechanical strength of microwave-absorbing concrete (MAC) was tested to determine the limestone replacement particle size. Then, MH tests were performed to investigate the influence of ice covering on the heating ability of MAC and to study the temperature distribution at different depths. The results indicated that, when magnetite was used to replace limestone, magnetite particle sizes in the range of 16.0–19.0 mm improved the mechanical strength and MH rate. Water producted by ice degraded the heating performance of MAC; therefore, the critical de-icing period for eliminating this influence was determined to be 60–120 s. The optimal thickness of the functional layer was determined to be 3 cm. Finally, the pavement for microwave de-icing test was paved; field results indicated that the de-icing rate of the MHEFL pavement was increased by 60%, and the microwave leakage intensity of 2.710 W/cm2 satisfied the safety requirements. The results of this study indicated that the application of an MHEFL for road de-icing is effective and environment friendly as it dispenses with the need for using the de-icing salt.]]></description>
      <pubDate>Wed, 28 Jun 2023 16:29:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2162672</guid>
    </item>
    <item>
      <title>Intelligent Control of Microwave Heating Temperature for Smart City Road Deicer Considering Ambient Temperature</title>
      <link>https://trid.trb.org/View/2129415</link>
      <description><![CDATA[Snow in winter can make roads into ice, thus hindering people’s normal life travel. Therefore, in order to realize the quick deicing of roads in winter, an intelligent control method of microwave heating temperature for road deicers is proposed. The intelligent control system of microwave heating temperature was designed by analyzing the influence of ambient temperature on deicing efficiency. In terms of hardware, the structure of the microwave circuit control system is constructed by using a microwave generation system to realize the heating of ice and the measurement of temperature. Simulation results show that the method has a good effect on temperature control and improves deicing efficiency.]]></description>
      <pubDate>Wed, 26 Apr 2023 16:46:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2129415</guid>
    </item>
    <item>
      <title>Investigation of Cold Start Capability of a Briggs and Stratton Engine Using Jet A Fuel and Microwave Plasma Ignition</title>
      <link>https://trid.trb.org/View/1818029</link>
      <description><![CDATA[There is a growing interest in improving engine versatility through the capacity to run on more than one fuel. To aid in this effort, the research presented in this paper investigated a novel system using microwave plasma ignition designed with the goal of allowing standard gasoline engines to run on non-standard fuels. The fuel used was Jet A. The test engine was a Briggs and Stratton single cylinder engine outfitted with an aftermarket fuel injection system and the microwave plasma ignition system. The tests performed were to determine the cold-start temperature limit, the lowest temperature at which the engine could be repeatedly started, using microwave plasma ignition with a conventional spark plug as a reference. A detailed system outline is presented, as well as results and conclusions. Recommendations for further research are also suggested.]]></description>
      <pubDate>Mon, 24 Oct 2022 10:22:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1818029</guid>
    </item>
    <item>
      <title>Accuracy of In-Situ Water-to-Cement Meters for Concrete</title>
      <link>https://trid.trb.org/View/1652529</link>
      <description><![CDATA[Concrete’s water to cementitious (w/cm) ratio is the most important indicator of the overall strength and durability of the structure. A method to determine the w/cm ratio on-site is important and needed for quality assurance and quality control. There are currently limited standardized techniques for the measurement of w/cm on-site and those techniques can be very time consuming. A developed in-situ microwave moisture meter exists that relies on the difference in the dielectric constant of concrete from that of water to estimate the w/cm ratio. In this report, the accuracy and precision of the meter is studied. Several paste, mortar, and concrete mixes with known w/cm ratios as well as aggregates with known moisture contents were measured with the Cementometerᵀᴹ device. An AASHTO T318-02 microwave test was also performed in comparison to the Cementometerᵀᴹ on known w/cm values. Statistical methods included a t-test determining the accuracy of the device.For precision, linear regression analysis, absolute difference, and sum of squared error calculations were made between the Cementometerᵀᴹ predicted w/cm and actual w/cm contents of the mixtures. Overall, the Cementometerᵀᴹ device was found to precisely measure moisture levels in aggregates, but in concrete none of the modes were precise (all R² values were less than 0.065) nor accurate (p-value less than 0.044). On the other hand, the in-lab AASHTO microwave method produced statistically precise (R² of 0.62 or more) and accurate (p-value of 0.91) readings; and thus the in-lab AASHTO T318-02 method is recommended over the in-situ Cementometerᵀᴹ for w/cm ratio determination.]]></description>
      <pubDate>Tue, 24 Sep 2019 14:53:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/1652529</guid>
    </item>
    <item>
      <title>Use of Hi-resolution data for evaluating accuracy of traffic volume counts collected by microwave sensors</title>
      <link>https://trid.trb.org/View/1485627</link>
      <description><![CDATA[Over the past few years, the Utah Department of Transportation has developed the signal performance metrics (SPMs) system to evaluate the performance of signalized intersections dynamically. This system currently provides data summaries for several performance measures, one of them being turning movement counts collected by microwave sensors. As this system became public, there was a need to evaluate the accuracy of the data placed on the SPMs. A large-scale data collection was carried out to meet this need. Vehicles in the Hi-resolution data from microwave sensors were matched with the vehicles by ground-truth volume count data. Matching vehicles from the microwave sensor data and the ground-truth data manually collected required significant effort. A spreadsheet-based data analysis procedure was developed to carry out the task. A mixed model analysis of variance was used to analyze the effects of the factors considered on turning volume count accuracy. The analysis found that approach volume level and number of approach lanes would have significant effect on the accuracy of turning volume counts but the location of the sensors did not significantly affect the accuracy of turning volume counts. In addition, it was found that the location of lanes in relation to the sensor did not significantly affect the accuracy of lane-by-lane volume counts. This indicated that accuracy analysis could be performed by using total approach volumes without comparing specific turning counts, that is, left-turn, through and right-turn movements. In general, the accuracy of approach volume counts collected by microwave sensors were within the margin of error that traffic engineers could accept. The procedure taken to perform the analysis and a summary of accuracy of volume counts for the factor combinations considered are presented in this paper.]]></description>
      <pubDate>Mon, 23 Oct 2017 13:38:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1485627</guid>
    </item>
    <item>
      <title>Airborne weather radar concept for measuring water surface backscattering signature and sea wind at circular flight</title>
      <link>https://trid.trb.org/View/1441128</link>
      <description><![CDATA[A concept for measuring water surface backscattering signature and wind over sea using airborne weather radar is discussed. The radar operates in the ground-mapping mode as a scatterometer, in addition to its meteorological and navigation application. An aircraft circular flight is used under such measurement. Recommendations to perform measurement of the water surface backscattering signature along with a sea wind retrieval algorithm are proposed. A simulation study of wind vector estimation is performed. The results obtained show that airborne weather radar can provide reasonable sea wind vector retrieval accuracy.]]></description>
      <pubDate>Tue, 03 Jan 2017 12:50:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1441128</guid>
    </item>
    <item>
      <title>Laboratory Investigation on Microwave Deicing Function of Micro Surfacing Asphalt Mixtures Reinforced by Carbon Fiber</title>
      <link>https://trid.trb.org/View/1409451</link>
      <description><![CDATA[Traffic accidents occur frequently during snowfall and freezing rain in winter. Therefore, it is desirable that snow and ice be removed effectively and rapidly without using chemical salt or mechanical devices. In this paper, the influences of carbon fiber with different contents on mechanical properties, microwave reflectivity, and microwave deicing time of micro surfacing asphalt mixtures were investigated. The results indicate the percentage of carbon fiber has significant influences on the mechanical properties of the mixtures. The flexural strength of the mixtures with 0.75 % carbon fiber was 1.5 times and the compressive strength with 0.45 % was 1.3 times higher than those of the mixtures without carbon fiber. At the percentage of 0.45, the minimum reflectivity was reached as –13.5?dB in the frequency range of 2.3–2.6?GHz. The carbon fiber addition can evidently enhance the ability of the mixtures to absorb the microwave. The deicing time keeps decreasing as the carbon fiber percentage increases from 0.15 % until 0.45 %; then increases gradually and rises sharply until 0.75 %. The minimum deicing time reaches 55?s for the mixtures with 0.45 % carbon fiber. The lower the microwave reflectivity is, the shorter the deicing time. The thickness of ice is also found to be an important factor affecting the deicing time of the mixtures. The mixtures with around 15?mm thick ice obtain the shortest deicing time.]]></description>
      <pubDate>Tue, 28 Jun 2016 16:22:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1409451</guid>
    </item>
    <item>
      <title>How Accurate Are Turning Volume Counts Collected by Microwave Sensors?</title>
      <link>https://trid.trb.org/View/1412390</link>
      <description><![CDATA[The Utah Department of Transportation (UDOT) has recently developed the Signal Performance Metrics System (SPMS) to evaluate the performance of signalized intersections dynamically. This system currently provides data summaries for several performance measures, one of them being turning movement volume counts. As this system became public, there was a need to evaluate the accuracy of the data collected by microwave sensors for the SPMS. UDOT considered first that sensor position, number of approach lanes, and volume level would affect the accuracy. Later, speed limit was added as another factor. Data were collected manually and compared with volume count data reported by the system. A mixed model analysis of variance was employed to analyze the effect of each factor on the accuracy of traffic volume counts. The volume level and number of approach lanes factors were found to have a statistically significant effect on the accuracy of traffic volume counts by microwave sensors.]]></description>
      <pubDate>Tue, 28 Jun 2016 16:22:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/1412390</guid>
    </item>
    <item>
      <title>Evaluate and Develop Innovative Pavement Repair and Patching: Taconite-Based Repair Options</title>
      <link>https://trid.trb.org/View/1398199</link>
      <description><![CDATA[In support of a broader Minnesota Department of Transportation (MnDOT) effort to evaluate current practices, materials, and policies for pavement patching and repair for both asphalt and concrete pavements, the University of Minnesota Duluth Natural Resources Research Institute (NRRI) conducted additional evaluation, refinement, field testing, and performance monitoring of two taconite-related approaches to pavement repair that rely on mixes/techniques that contain (or are enhanced by) taconite mining byproducts and co-products. The first taconite-related approach to pavement repair uses a rigid pavement/pothole repair compound formulation developed and patented by NRRI that is fast-setting, taconite-based, and contains no petroleum or Portland cement. Depending on the formulation, the repair compound can be water-activated or activated by a chemical solution. A water-activated formulation referred to as Rapid Patch was the focus of the investigation. The second taconite-related approach to pavement repair employs a high-power (50kW), vehicle-based (truck-mounted) microwave system for in-place pothole/pavement repair/recycling in which magnetite and/or magnetite-containing aggregate (taconite rock) can enhance microwave absorption and therefore the system’s performance. The two repair alternatives evaluated during this project merit further development and consideration, as the field performance of both suggests they have long-term potential for more widespread use. Based on feedback from maintenance personnel who used and/or observed both repair alternatives during the project, both alternatives would benefit from operational modifications that would reduce the deployment time required to complete a repair and increase the number of repairs that can be accomplished during a single shift. Doing so would likely lead to greater acceptance and more widespread use.]]></description>
      <pubDate>Mon, 29 Feb 2016 16:54:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1398199</guid>
    </item>
    <item>
      <title>Holographical Microwave Imaging of Corroded Steel Bars in Concrete</title>
      <link>https://trid.trb.org/View/1343921</link>
      <description><![CDATA[Corrosion assessment of embedded steel in concrete structures is generally performed by electrochemical methods that are not fully nondestructive because the device requires connection to the steel. For practical applications, the development of a truly nondestructive technique for the detection of corrosion is desirable. This paper presents an experimental study of a wideband microwave three-dimensional synthetic aperture radar imaging technique applied to reinforced concrete specimens subjected to corrosion. Two orthogonal wave polarization directions were used for this purpose. Two-dimensional microwave image slices were analyzed and compared with the actual loss of steel measured during the destructive testing. As expected, the results indicated that higher-frequency images have higher spatial resolution, while the signal penetration became more limited at these frequencies. Though the relatively high moisture content significantly increased the dissipative properties against electromagnetic propagation, the technique was capable of differentiating between corroded and non-corroded steel bars.]]></description>
      <pubDate>Fri, 27 Feb 2015 10:03:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1343921</guid>
    </item>
    <item>
      <title>Novel Integrated Nondestructive Testing Methodology for Detection and Evaluation of Corrosion in Cement-Based Materials</title>
      <link>https://trid.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://trid.trb.org/View/1314838</guid>
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