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    <title>Transport Research International Documentation (TRID)</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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>In Situ Monitoring and Numerical Studies on the Performance of Gentle Slopes to Preserve the Transportation Infrastructure in Northern Canada</title>
      <link>https://trid.trb.org/View/2596411</link>
      <description><![CDATA[Permafrost degradation occurs underneath the side slope due to snow accumulation, which prevents heat from being extracted from the ground in winter. This paper presents the in situ snow dynamics and thermal behavior of an airstrip in an area of continuous permafrost, in Nunavik, Quebec, Canada. The dynamic change of snow thickness around the embankment toe was measured in the field during 2014–2015. Thermistor strings were installed under the side slope and around the toe of the embankment. An empirical relationship between snowpack thickness and the freezing 𝘯-factor was proposed. The ground temperature data collected were used to calibrate a thermal conduction model, which was then used to develop the design chart for gentle slopes. The design chart was further validated using data from another experimental site at Tasiujaq airstrip in Nunavik, Canada. This work enhances the design capacity of gentle slopes to stabilize thaw-sensitive permafrost beneath the embankment shoulder.]]></description>
      <pubDate>Fri, 21 Nov 2025 17:09:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2596411</guid>
    </item>
    <item>
      <title>Derating as Thermal Protection for LED-Based Lighting
   Applications</title>
      <link>https://trid.trb.org/View/2608431</link>
      <description><![CDATA[This paper investigates the concept of derating in light-emitting diode                     (LED)–based automotive lighting systems, emphasizing its role in enhancing LED                     longevity, performance, and reliability under varying operating conditions.                     Derating is introduced from a general perspective and is modeled as an                     approximately linear function of the driving current with respect to the                     temperature measured by a negative temperature coefficient thermistor (NTC). The                     NTC serves as a temperature probe in this context. We demonstrate that poorly                     designed derating strategies can negatively impact luminous flux, lifespan, and                     overall system reliability. These theoretical insights are applied to a                     simplified lighting system, which is analyzed using both steady-state and                     transient computational fluid dynamics (CFD) simulations to illustrate the                     practical effects. It is shown that the distance between the NTC and the                     temperature-critical region primarily determines the slope of the derating                     curve, while having minimal influence on thermal protection on dynamic response.                     Finally, the precision of NTC-based temperature measurements defined by the                     thermistor specifications is briefly examined. It has an additional influence on                     the accuracy if the applied derating.]]></description>
      <pubDate>Tue, 14 Oct 2025 10:46:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2608431</guid>
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    <item>
      <title>Detection of Voids Underneath Concrete Pavements Using Infrared Thermography</title>
      <link>https://trid.trb.org/View/2439007</link>
      <description><![CDATA[This report describes preliminary theoretical and experimental investigations of a technique for void detection beneath concrete pavements. The technique is based upon use of infrared thermography and the hypothesis that the surface temperature of the pavement over the void is slightly different than the surface temperature of pavement in contact with the base material. Experimental investigations were conducted on a concrete slab 12 ft x 21 ft x 8 inches thick which was cast at Balcones Research Center. Three voids of known locations and dimensions were created beneath the slab. Thermistors were installed at various locations in the concrete slab and in the soil beneath the slab to monitor air, ground, and soil temperatures. An infrared scanning camera system was installed on a truck-mounted frame. Thermistor scans were conducted on five dates and an infrared scan was conducted on one date in late 1980. Results of the experimental studies show that thin voids can be detected by the infrared thermography technique. The technique is sensitive to environmental factors and needs additional investigation to determine optimum applications.]]></description>
      <pubDate>Sat, 12 Oct 2024 16:11:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2439007</guid>
    </item>
    <item>
      <title>Ground Temperatures across the Old and New Roads at Mile 130, Richardson Highway during 1954–62</title>
      <link>https://trid.trb.org/View/2160463</link>
      <description><![CDATA[Year-round studies of the geothermal impacts of road construction in a "warm" (–1 to –2°C) permafrost area were undertaken during 1954–1962 at six road sections across the Richardson and Glenn Highways, in the vicinity of Glennallen, Alaska. The most extensive studies were at Richardson Highway Mile 130 where nine 6.1-m vertical thermistor cables were installed beneath the newly constructed road, beneath a 40-year-old roadway, and in undisturbed areas. The cables, installed beneath the centerlines, shoulders, and the adjacent ditches of the highways, as well as beneath undisturbed areas, provided weekly temperature measurements at 13 depths. A tenth cable, with thermistors at 0.3-m spacing, was installed horizontally at a depth of 1.2-m across the new road. The mean annual ground temperatures in the ice-rich lacustrine silty clays in the Glennallen area appeared to approximate –1.2°C, about 1.8°C warmer than the mean annual air temperatures. The seasonal amplitudes of temperature changes were greatest beneath the centerline of the new road; increasing the depth of seasonal thaw from 1.87 m, versus about 0.7 m in the undisturbed areas, in 1954 to 3.0 m in 1957. The old road centerline and ditch then had similar depths of thaw, about 4.9 m, after almost 40 years of light usage. This suggests that differential settlement in the new roadway would continue until at least an additional 1.8-m-depth of thaw had been completed. While the permafrost at the 6.1-m depth beneath the centerline of the new road was warming, the permafrost at the same depth beneath the old, abandoned road was cooling slightly during the study period.]]></description>
      <pubDate>Wed, 26 Apr 2023 09:18:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2160463</guid>
    </item>
    <item>
      <title>Ten-Year Review of Monitoring System on I-35W Saint Anthony Falls Bridge</title>
      <link>https://trid.trb.org/View/1728192</link>
      <description><![CDATA[The I-35W St. Anthony Falls bridge was highly instrumented with over 500 sensors to verify design assumptions, serve as a testbed to examine bridge sensing techniques, and evaluate the effectiveness of different bridge monitoring strategies. The instrumentation deployed on the bridge to investigate the structural behavior included vibrating wire strain gages (VWSGs), thermistors, fiber optic sensors (SOFO), resistance strain gages, linear potentiometers, accelerometers, and corrosion monitoring sensors. This report documented the successes and challenges of the monitoring program over the first ten years of the bridge’s life. In particular, the effectiveness of different strain measurement techniques and sensor distributions were addressed. Previous investigations of temperature-dependent and time-dependent behavior were also expanded with the larger data set to better understand the behavior of post-tensioned concrete box girder structures with the potential to impact future designs.]]></description>
      <pubDate>Wed, 19 Aug 2020 17:30:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1728192</guid>
    </item>
    <item>
      <title>The Determination of Heat Transfer Coefficient on Water-ice Surface in a Free Convection</title>
      <link>https://trid.trb.org/View/1722229</link>
      <description><![CDATA[In ice ridges consolidation, the convective heat flux term comes critical due to the larger contact areas and surface temperature differences compare with those from level ice. In this paper, a submerging experiment was designed to determine the heat transfer coefficient (h) between fresh ice and fresh water in a free convection. A thermistor string was used to measure temperature changes while ice growth was recorded by photograph. To study the factor, the tests were carried on different ice thickness (4.9cm to 20.5cm) and initial temperatures (-20°C and -32°C). The result shows that the h exponential increased with temperature difference from 0.3 W/m²K to 175 W/m²K. On the other hand, the variation of initial thickness and temperature was not a direct influence for h. For convective heat transfer, the boundary layer condition is central for understanding the convection between ice surface and water flowing past it. From the governing equation, the water flow in a free convection is caused by density difference, which is driven by the thermal expansion. A large temperature difference between surface and environmental water creates a thicker boundary layer, which leads to a higher h.]]></description>
      <pubDate>Wed, 29 Jul 2020 16:09:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/1722229</guid>
    </item>
    <item>
      <title>Investigation on the heat extraction capacity of the heat drain for thermal stabilization of embankments on thaw sensitive permafrost</title>
      <link>https://trid.trb.org/View/1714199</link>
      <description><![CDATA[Construction of transportation infrastructure often results in permafrost degradation and climate warming amplifies this phenomenon. Heat drains, based on wintertime natural convection, are a new mitigation technique designed to limit or avoid the thawing of permafrost. In winter, heat extraction is enhanced by the buoyancy-driven convection of the pore-air due to unstable air density in the heat drain. To monitor the efficiency of this technique, a heat drain was constructed in the shoulder of the Tasiujaq airstrip in Northern Quebec, Canada, in the summer of 2007. Thermistors were installed beneath the side slopes to measure ground temperatures. A good thermal performance was observed resulting in thermal stabilization of the underlying permafrost. A thermal model was developed based on the Tasiujaq experimental site characteristics and conditions. The model was also calibrated to the field data collected at Tasiujaq. A set of design charts were developed through the model and were successfully validated using the measured data from Salluit, Northern Quebec, Canada, where a heat drain was installed in 2012.]]></description>
      <pubDate>Thu, 23 Jul 2020 16:16:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1714199</guid>
    </item>
    <item>
      <title>Approach to Model Thermistor Based AC Compressor Cut-OFF/Cut-IN Phenomenon in 1D Simulation of Mobile Air Conditioning</title>
      <link>https://trid.trb.org/View/1578845</link>
      <description><![CDATA[This paper documents the approach followed to simulate the physical phenomenon of thermistor based AC compressor Cut-OFF/Cut-IN (AC compressor cycling) in 1-Dimensional Computer Aided Engineering (1D CAE) to enable Mobile Air Conditioning (MAC) performance prediction at different ambient conditions. Thermistor based AC compressor cycling logic is incorporated in MAC systems to prevent ice formation at evaporator core and liquid refrigerant flow to AC compressor. Currently, during MAC system performance simulation over a transient drive cycle, the 1D models are able to predict cabin cooldown performance for severe ambient conditions (>40°C, high solar load) with >95% accuracy, as in these cases AC compressor cycling due to thermistor doesn’t occur at higher ambient. In case of moderate/low ambient conditions (~20-40°C, moderate/low solar load), AC compressor cycling takes place and the simulation model is able to predict the cabin cooldown performance only till first event of compressor Cut-OFF in line with physical test. Hence, to predict cabin cool-down performance with AC compressor cycling, it is necessary to model the same phenomenon in 1D CAE.         To model the phenomenon described above, a logic to control AC compressor cycling operation based on evaporator air outlet temperature and lumped masses to model evaporator thermal inertia are incorporated in transient MAC performance simulation model using 1D software KULI. Accuracy of >95% in average cabin temperature prediction has been achieved at moderate ambient condition after incorporating AC compressor cycling model, which confirms the robustness of the simulation model. Frequency of AC compressor cycling phenomenon (i.e. number of cycling events in a minute) in the proposed simulation model is observed to be higher as compared to real world physical test which affects the prediction of AC compressor power consumption, further work is required to address this gap. The present work can be extended to determine optimum thermistor location through 1D CAE, thereby eliminating the need of physical testing for the same.       ]]></description>
      <pubDate>Wed, 01 May 2019 09:31:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1578845</guid>
    </item>
    <item>
      <title>Changes in Temperature Distribution in a Geosynthetic Reinforced Soil Abutment and Their Effect on Measured Strain</title>
      <link>https://trid.trb.org/View/1559679</link>
      <description><![CDATA[This paper investigates temperature changes in the abutment of a geosynthetic reinforced soil integrated bridge system (GRS-IBS). A GRS-IBS structure is a type of bridge construction that uses geosynthetic reinforced soil (GRS) abutments to support prefabricated bridge structural members. GRS abutments are composed of high quality granular soil and closely spaced geosynthetic layers; the close spacing of the reinforcement increases the confinement and stiffness of the compacted aggregate, resulting in a strong and internally-supported abutment system for the bridge superstructure. Thermal expansion and contraction behavior of the bridge and abutment plays a role in the long-term behavior of GRS-IBS structures over the course of many seasons and years of service. This paper examines seasonal heating and cooling behavior within a typical GRS bridge abutment, using temperature data collected from an array of thermistors installed in a GRS-IBS constructed in the state of Delaware in the U.S. In order to monitor the temperature changes in the abutment of the constructed GRS-IBS, thermistors were installed on the fabric in the GRS abutments and changes in the abutment temperature were continuously measured using these embedded thermistors over 3 years of in-service operation. Measured results showed that the changes in the abutment temperature follow the same trend as the air temperature and are proportional to the elevation and the distance from the facing wall. To illustrate this behavior, temperature distribution contours in the abutment on different days and months over the course of a year are presented. Finally the effect of temperature change on measured strain readings for the GRS abutment is explained and some recommendations are made for minimizing its effect or correcting for its effect in future field studies of this type.]]></description>
      <pubDate>Tue, 20 Nov 2018 10:24:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1559679</guid>
    </item>
    <item>
      <title>Monitoring the Thermal and Mechanical Behaviours of Puvirnituq Airstrip, Nunavik, Northern Quebec</title>
      <link>https://trid.trb.org/View/1274564</link>
      <description><![CDATA[The Puvirnituq airstrip has an important embankment that fills a valley composed of saline fine-grained sediment. Subsidence has been observed at this location of the runway. The Puvirnituq airstrip was extended in 2009. During the construction work, a convective embankment and a berm with ventilation system were constructed. A small creek was also diverted. The embankment and the natural ground were instrumented in order to monitor the thermal and mechanical behaviours of the Puvirnituq airstrip. This paper summarizes the observations made during the first two monitoring years. A decrease of the active layer thickness was observed on three of the four thermistor strings. Indications of convective movement in the embankment have also been observed.]]></description>
      <pubDate>Tue, 03 Dec 2013 09:10:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1274564</guid>
    </item>
    <item>
      <title>A Synthesis of Practical and Appropriate Instrumentation Use for Accelerated Pavement Testing in the United States</title>
      <link>https://trid.trb.org/View/896097</link>
      <description><![CDATA[Pavement testing facilities can be utilized to help with the integration of the new Mechanistic-Empirical Pavement Design Guide (MEPDG). One way test facilities are doing this is by embedding instrumentation, such as strain gauges and pressure plates, in pavement structures to measure pavement responses under loading. As new facilities are being constructed or reconstructed, it is important that the instrumentation chosen for research at the facility is appropriate and reliable. Accelerated Pavement Testing (APT) facilities have come together through the Consortium of Accelerated Pavement Testers to help develop practical and appropriate instrumentation uses based on positive and negative experiences at various facilities. Using this insight, a facility undergoing redesign or a new facility might be able to answer some of the following questions before designing its instrumentation scheme. What types of strain gauges are appropriate for what we are trying to determine? What gauges are other facilities using so our results might be comparable to theirs? If a facility were determining whether thermistors are advantageous over thermocouples, it would be important to realize it is difficult to install thermistors horizontally pre-construction; however, these instruments can be installed post-construction vertically in the pavement. The difficulty with this scenario is determining the tip depth of the device. Using experiences from other successful APT facilities to bolster success at other facilities will only increase the amount of valuable findings and help make APTs more profitable.]]></description>
      <pubDate>Thu, 23 Jul 2009 09:41:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/896097</guid>
    </item>
    <item>
      <title>Using Advanced Road Weather Information Systems (ARWIS) to Control Load Restrictions on Gravel and Surface Treated Highways - Phase 1</title>
      <link>https://trid.trb.org/View/890582</link>
      <description><![CDATA[The economic impacts of the cyclic nature of Canadian weather provides a dilemma for engineers. Pavement damage occurs during the spring thaw period. To mitigate pavement damage, spring load restrictions (SLR) are applied over a certain time frame. Unfortunately, these restrictions impact the transportation industry negatively as the amount of goods that is permitted to be transported is reduced. Therefore, the economic impact of SLR is significant. Conversely, there is possibly an opportunity to employ Winter Weight Premiums (WWP) which enable for heavier loads on the infrastructure.  The intent of this report is to summarize the results of Phase 1, a one year project which involved a literature review of current SLR policies and practices. It also included the installation of two pilot sites in Northwestern and Northeastern Ontario. Under this project, the sensors or thermister strings The primary goal of the instrumentation was to provide real time frost penetration data and relate that to the ARWIS data. The thermister strings were also designed and constructed in a manner that they can be related to current on-going activities and analysis in Quebec and various parts of Northern Canada. A preliminary analysis of data acquired from the Northeast Region study site and surrounding ARWIS data has been performed based on models from Quebec, Manitoba and Minnesota. Initial future steps, including both short- and long-term are described. The immediate future will be focused on data acquisition and ensuring proper functionality of the equipment prior to the spring thaw. Long-term modelling will be performed as data is collected from each site. The ultimate deliverable is to provide the Ministry a means of accurately assessing and applying SLR to the required facilities while mitigating both pavement damage and economic hardships to the transportation industry.]]></description>
      <pubDate>Thu, 18 Jun 2009 09:21:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/890582</guid>
    </item>
    <item>
      <title>COMPACTION OF BITUMINOUS PAVEMENTS</title>
      <link>https://trid.trb.org/View/39377</link>
      <description><![CDATA[For satisfactory compaction at the lowest cost, the compactibility of bituminous mixtures for different cooling rates and rolling processes must be known, and a quick means of determining the degree of compaction must be available. The nuclear method subjects the pavement to gamma radiation, the amounts absorbed and back-scattered being a measure of density. The instrument tested has a probe containing isotope cs 137, back scatter being detected by GM tubes. Agreement between paraffin and nuclear methods was good, standard deviation being 0.02-0.03 g/cm3. For efficient utilisation of equipment, time available for compaction must be known. This is the interval between stability and stiffness of the asphalt. Lower limit depends on compactibility, rolling process and cooling process. In field tests the temperature was measured by thermistors placed in the pavement. Good agreement was obtained between field results and theoretical analysis. Field tests in 1965 with variable rolling parameters resulted in the following rolling programme: 1. Rolling to start as soon as possible by 2 static rollers in tandem, 2. At least 8 and preferably 12 passes, 3. Speed of approx. 5 km/h. Average degree of compaction was 97-100%, standard deviation 1%. Resistance to wear by studs was improved by 30%. /TRRL/]]></description>
      <pubDate>Tue, 15 Jul 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/39377</guid>
    </item>
    <item>
      <title>IN-SITU THERMAL CONDUCTIVITY MEASUREMENTS</title>
      <link>https://trid.trb.org/View/731587</link>
      <description><![CDATA[This report describes a method for using commercially available thermistors to make in-situ thermal conductivity measurements with commonly available electronic equipment. The emphasis is on use of a single thermistor to measure thermal conductivities of soils and building insulations. Calibration techniques are explained and examples provided. Limitations on this technique are discussed, including material grain size, amount of material needed for a valid measurement, and temperature stability necessary. Specific examples of the use of this technique are provided for both soil measurements and building material measurements. Data analysis is discussed, including a statistical approach to finding the thermal conductivity in large volumes of material.]]></description>
      <pubDate>Tue, 22 Apr 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/731587</guid>
    </item>
    <item>
      <title>STABILIZATION OF EMBANKMENT SLOPE WITH GEOFOAM</title>
      <link>https://trid.trb.org/View/674336</link>
      <description><![CDATA[A case history is presented describing the use of expanded polystyrene (EPS) geofoam blocks to treat an unstable roadway embankment slope involving clayey soils.  The selection of the geofoam treatment was based upon its ability to be constructed and have the least impact on both the environment and adjacent homeowners.  The site subsurface conditions, engineering properties of EPS, design analysis, and construction phases are reviewed.  Potential traffic safety problems associated with differential icing of roadways caused by the presence of geofoam blocks beneath the pavements were minimized by using a thicker subbase layer in the geofoam-treated area.  Data from an instrumentation program consisting of an inclinometer, extensometers, and thermistors are presented.  Pavement temperature readings collected from areas with and without geofoam treatment are compared to investigate potential differential icing on the roadway.]]></description>
      <pubDate>Fri, 05 Jan 2001 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/674336</guid>
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