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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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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>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Impacts of Emergency Vehicle Marking Characteristics and Wearable Lights on Driver Responses</title>
      <link>https://trid.trb.org/View/2452717</link>
      <description><![CDATA[Retroreflective markings provide important visual information to drivers about emergency vehicles and the incidents at which they are working. A stationary outdoor field study to investigate the impacts of emergency vehicle marking color, retroreflectivity level, and spatial patterns on drivers’ ability to see nearby emergency responders was carried out. The study also examined the impacts of a wearable flashing light-emitting diode (LED) light. Based on the results, agencies should use materials with higher levels of retroreflectivity carefully, especially when they will be covering large-area vehicle surfaces. Limiting the maximum retroreflectivity level to no greater than American Society for Testing and Materials Type III may help lessen negative impacts of bright reflective materials on drivers’ ability to see emergency responders. As long as the average reflectivity of different color combinations is similar to that of red and yellow reflective markings, chevron patterns with those color combinations will not reduce emergency responder visibility. Outline patterns of reflective markings on vehicles performed similarly at night to patterns covering most of the vehicle surface. The effectiveness of using high-retroreflectivity materials in an outline pattern in combination with lower- (or non-) retroreflectivity materials elsewhere on the surface should be studied. Wearable flashing LED lights can make emergency responders easier to see at night, provided they do not increase glare to approaching drivers.]]></description>
      <pubDate>Fri, 15 Nov 2024 09:48:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2452717</guid>
    </item>
    <item>
      <title>Can retroreflective rings enhance drivers’ safety perception of spatial right-of-way in freeway tunnels? A simulation exploration</title>
      <link>https://trid.trb.org/View/2445562</link>
      <description><![CDATA[In order to investigate whether retroreflective rings can enhance drivers’ perception of spatial right-of-way in freeway tunnels, this paper explores a simulation test. The characteristics of spatial right-of-way in tunnels are elucidated, and a comparative test is conducted using commonly used delineators and raised pavement markers against retroreflective rings to enhance the perception of spatial right-of-way. The test employs the perception of lateral deviation and longitudinal distance as indicators to reflect the lateral and longitudinal right-of-way. Video scenarios, incorporating different facilities and spacing, are created using 3Ds Max software following the design standards of freeway tunnels. The indicators of Stimulation of Subjectively Equal Distance (SSED), lateral deviation, and perception reaction time (PRT) are chosen to assess the effects of different facilities on drivers under varying spacing conditions. Fifty-two participants, divided into two groups of novice drivers and experienced drivers, underwent perception testing in a simulated driving environment. The results indicate that drivers exhibit the highest overestimation of longitudinal distance and the longest PRT of lateral deviation in the absence of facilities. Installing retroreflective rings with a spacing of 50–200 m significantly mitigates the overestimation of longitudinal distance, while reducing the PRT of lateral deviation. On the other hand, setting up delineators and raised pavement markers with a spacing of 6–12 m significantly reduces the PRT of lateral deviation, while there is no significant enhancement to the perception of longitudinal distance. A spacing of 200 m for retroreflective rings and 10 m for delineators and raised pavement markers in the straight section is recommended as a safer and more economical setting scheme. The combination of these facilities can enhance drivers’ safety perception of spatial right-of-way in freeway tunnels, facilitating rapid perception, correct judgment, and timely decision-making for the safe passage of vehicles.]]></description>
      <pubDate>Fri, 08 Nov 2024 15:49:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2445562</guid>
    </item>
    <item>
      <title>Demonstrations of Retroreflectivity Help Road Users Appreciate Retroreflective Markings</title>
      <link>https://trid.trb.org/View/2314424</link>
      <description><![CDATA[Retroreflective surfaces reflect light back towards the source of the illumination. All road users benefit from retroreflective markings in the roadway environment, as their use is required on road signs, on lane delineators, and on large trailers. Although a large body of evidence indicates that retroreflective markings can greatly enhance the conspicuity of pedestrians and bicyclists, these road users are largely unaware of strategies to enhance their own conspicuity at night. Here, 47 observers in an online study predicted how bright three stimuli would appear during a demo designed to highlight retroreflectivity. They did not expect a retroreflective swatch to be any brighter than the diffuse reflector. Their brightness predictions were consistently too high for specular and diffuse reflectors, but not for a retroreflector. This indicates that the observers failed to recognize and appreciate the special optical characteristics of retroreflectors. Educational interventions could be particularly useful in this domain.]]></description>
      <pubDate>Wed, 31 Jan 2024 14:16:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2314424</guid>
    </item>
    <item>
      <title>Barrier Striping for the Reduction of Accidents</title>
      <link>https://trid.trb.org/View/2255816</link>
      <description><![CDATA[The Traffic Safety Division (TRF) of Texas Department of Transportation (TxDOT) drafted a special specification (SS) for the vertical application of a retroreflective solid stripe on concrete barriers, approximately six (6) inches below the barrier's top. During the phase of new product approval, this SS describes an application similar to three (3) locations already installed on Texas roadways in previous years. Barrier striping increases motorist awareness of the roadway's edge and the barrier itself, particularly in low-visibility conditions (i.e., heavy rain and snow). These existing implementation sites have not been formally evaluated. Furthermore, the short-term effectiveness of the treatments has not been investigated; therefore, there is a need for long-term and short-term safety effectiveness evaluation of these treatments. The research teams will collect before-and-after collision data from Crash Record Information System (CRIS) and near-collision data from connected vehicle data vendor (e.g., Wejo) to evaluate the effectiveness of vertical application of a retroreflective solid stripe on concrete barriers. Furthermore, the research teams will install these treatments at six (6) high crash locations with different barrier types including, but not limited to concrete barriers and metal beam guard fences to evaluate their short-term effectiveness using non-traditional safety evaluation approaches. The research teams will utilize the findings to update the drafted SS for the future use across the state and beyond.]]></description>
      <pubDate>Wed, 27 Sep 2023 13:43:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2255816</guid>
    </item>
    <item>
      <title>Establishment of a metric to characterize retroreflector properties using a consumer-grade colour camera</title>
      <link>https://trid.trb.org/View/2137523</link>
      <description><![CDATA[The coefficients of retroreflection and chromaticity coordinates are critical metrics for determining the quality of a retroreflector. However, conventional retroreflection measurement techniques rely heavily on the night-time colour, size and characteristics of the sample being measured. This complicates the measurement process and leads to deviations in the test results. In addition, chromaticity cannot be determined using this approach. Therefore, it is necessary to improve the measurement accuracy, simplify the measurement process and achieve the measurement of the traffic sign RA and chromaticity coordinates simultaneously. In this study, an improved method for retroreflector characterization using imaging was proposed. This allowed for the measurement of the coefficients of retroreflection and the chromaticity coordinates simultaneously, and only a white standard sample was required for calibration. The primary components of the proposed system included a lighting projector, a receiver, two motorized rotational stages, a retroreflective sample holder and customized software that using scaling factors to convert a digital signal into sample retroreflection coefficients and retroreflective chromaticity coordinates. The experimental results indicated that the raw data output from the camera exhibited a positive correlation relationship with the luminous flux from the surface of the retroreflector. The maximum measurement errors for the retroreflection and chromaticity were -12.2 cd/(lx·m²) and -2.09%, respectively. This method was inexpensive and convenient, used a commercially available digital camera, could help to identify defects in retroreflection and chromaticity for retroreflective sheeting and led to increased accessibility for the quality control of retroreflective sheeting.]]></description>
      <pubDate>Tue, 23 May 2023 10:12:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2137523</guid>
    </item>
    <item>
      <title>Influence of the tunnel retro-reflective arch in freeway tunnels on driving behavior: A driving simulator study</title>
      <link>https://trid.trb.org/View/1970155</link>
      <description><![CDATA[In this study, a driving simulator experiment was conducted to investigate the influence of tunnel retro-reflective arch (TA) on driving behavior, through the employment and analysis of TAs with disparate spacing alternatives (no TAs, TAs with a spacing of 200 m, and TAs with a spacing of 300 m) and tunnel lengths (800 m, 1800 m, 3500 m, and 5800 m). The performances of a total of 32 drivers were collected and assessed. The tunnels and TAs were accurately replicated in the driving simulator. On the basis of the experimental data, four behavioral variables, namely, average speed, the standard deviation of speed, the standard deviation of acceleration, and lateral position were obtained. A series of linear mixed models with random effects were estimated to reveal the contributing factors of driving behavior subjected to TAs variation. The results demonstrate that drivers showed significantly higher consciousness of speed control and lower mental stress, coupled with less risky driving behavior, under the condition of TAs in long and extra-long tunnels. Furthermore, drivers are more comfortable subjected to TAs with a spacing of 300 m.]]></description>
      <pubDate>Tue, 21 Jun 2022 10:31:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1970155</guid>
    </item>
    <item>
      <title>Division of Operations Research On-Call Task #2 - Evaluation of the Effects of Wind Loads on Flexible
Backplates</title>
      <link>https://trid.trb.org/View/1903447</link>
      <description><![CDATA[Retroreflective backplates for traffic signals have a proven record of reducing traffic accidents and, currently, all new traffic signals are designed with backplates. While including backplates in the design of new signals and support structures is straightforward, adding backplates to existing signals can be problematic as doing so increases wind loads on the signals and the supporting structures, possibly to the extent that the existing structure is not adequate. This report describes a research project centering on an examination of pertinent design standards, specifications, and typical practice, to determine if broad recommendations could be made regarding whether the addition of backplates to existing signals would be acceptable or would render existing support structures inadequate for the increased wind loads. The University of Cincinnati research team, in concert with Kittelson and Associates, Inc., performed analyses of representative mast-arm and span-wire signal support structures and was able to identify areas where standard design procedures sometimes result in conservative designs. Additionally, the research team evaluated a commercially available flexible backplate design that can potentially reduce wind loads associated with the addition of retroreflective backplates to new or existing signals. Based on these analyses, a procedure for evaluating existing signs support structures for the increased wind loads due to the addition of rigid or flexible backplates is proposed.]]></description>
      <pubDate>Thu, 20 Jan 2022 12:14:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1903447</guid>
    </item>
    <item>
      <title>Surveying the Effectiveness of Methods for Enhancing the Visibility of Snowplows in Texas</title>
      <link>https://trid.trb.org/View/1856994</link>
      <description><![CDATA[Effective visibility methods are crucial for the safe operation of snowplows. Despite modern devices and methods, snowplow crashes cause economic and casualty losses. According to the National Climatic Data Center (NCDC) database, the number of heavy snow events was more than 25% of all winter weather events over the past decade in Texas. The objective of this research is to survey the effectiveness of the current snowplow visibility methods in Texas. Fifteen TxDOT districts (covering nearly all of north Texas) responded to the survey. The survey results brought forward an accurate representation of the effectiveness of warning lights, message signs, retroreflective markings, rear airfoils, and smart snowplow systems—the snowplow visibility methods in Texas. This research led to recommending warning lights and retroreflective markings to be used in specific colors and locations to increase the visibility of snowplows. On the other hand, rear airfoils were not recommended as they had not increased the conspicuity of the vehicles effectively. These recommendations guide TxDOT to implement more effective snowplow visibility methods.]]></description>
      <pubDate>Fri, 23 Jul 2021 15:26:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1856994</guid>
    </item>
    <item>
      <title>Evaluation of tunnel retro-reflective arch in an extra-long tunnel based on the matter-element extension method</title>
      <link>https://trid.trb.org/View/1756959</link>
      <description><![CDATA[Traffic safety devices are one of the most important tools used to improve safety in tunnels. The tunnel retro-reflective arch (TA) plays a crucial role in stimulating drivers, relieving visual stress, and improving safety. However, determining the TA spacing mostly relies on experience and relevant standards are lacking. The aim of this research was to evaluate the degree of influence of the TA on driver behavior, visual aspects, and psychology in different zones (overall tunnel, curved segment, and middle segment) of extra-long tunnels. To test the influence of TAs, four scenarios were constructed, including three alternatives with different TA spacings (200, 300, and 400 m), and one no-arch design as a control alternative. Based on a driving simulator, the evaluation indicators related to driving safety, smoothness, and handling stability were selected and analyzed. The authors acquired data every 50 m as an analytical unit. The results show that the TA significantly affects driver behavior, visual aspects, and psychology. According to the matter-element model result, setting the TA spacing to 300 m in curved segment and in the tunnel overall is the best option. In the middle segment, the setting spacing of 400 m is ideal.]]></description>
      <pubDate>Mon, 11 Jan 2021 11:08:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1756959</guid>
    </item>
    <item>
      <title>Driver Understanding of Red Retroreflective Raised Pavement Markers</title>
      <link>https://trid.trb.org/View/1722802</link>
      <description><![CDATA[In the United States, the use of red retroreflective raised pavement markers (RRPMs) has been traditionally reserved to mark wrong way direction on one-way roadways. There are some agencies such as the State of Hawaii and surrounding U.S. territories that use red RRPMs on undivided highways to mark wrong way direction on two-way roadways (the red RRPMs are installed on the far edge line). This application is used in areas with frequent tourists from left-hand drive countries. The red RRPMs are used to remind the tourists that they are driving in the United States, which is a right-hand drive country. When traveling in the correct direction on these undivided highways, the red RRPMs are visible during nighttime conditions. This has raised concerns regarding current practices and drivers’ understanding of the red RRPMs. This study investigated drivers’ understanding of red RRPMs as traditionally used (i.e., to mark wrong way direction on one-way highways) and as used in unique applications (such as described above). A survey was administered to almost 200 participants. This survey featured five different roadway configurations, each with four different marking patterns. Survey participants were asked several questions aimed at determining their understanding of the markings and markers while watching the video on the laptop computers. Three participant groups were targeted for the surveys: drivers from left-hand drive countries, drivers from Hawaii, and drivers from right-hand drive countries. The findings of the survey show that drivers do not become confused when red RRPMs are used on undivided highways. Furthermore, the understanding rate of drivers from left-hand drive countries was always improved when supplemental red RRPMs were included on undivided highways. The findings also show that red RRPMs do little to help drivers understand that they are traveling the wrong direction on one-way divided highways. In areas where driver confusion may be a problem, the findings show that directional pavement marking arrows provide much better means of communication to all drivers. Based on these findings, it has been recommended that the Manual of Uniform Traffic Control Devices (MUTCD) language be reworded to allow for red RRPMs on undivided highways. However, additional emphasis should be provided such that directional pavement marking arrows are used in locations where driver confusion regarding direction of travel may be a concern.]]></description>
      <pubDate>Mon, 27 Jul 2020 17:04:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1722802</guid>
    </item>
    <item>
      <title>Development and implementation of retro-reflective elements for automatic accessories and places of planned points</title>
      <link>https://trid.trb.org/View/1690385</link>
      <description><![CDATA[For the first time, it was proposed to develop an optimal design of a circular reflector, to modernize the equipment for the production of a special cutting tool, and to work out the technology of formation with its use of the matrixes of the originals of the retro-reflective elements, and the technology of galvanic cultivation of precision working matrix dies.]]></description>
      <pubDate>Thu, 23 Apr 2020 15:58:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1690385</guid>
    </item>
    <item>
      <title>Identification of Exit Taxiways (Retroreflective Markers Only)</title>
      <link>https://trid.trb.org/View/1646527</link>
      <description><![CDATA[The purpose of the exit taxiway lighting is to enable the pilot to expeditiously exit from the runway to a taxiway. There is evidence that this has not been satisfactorily accomplished by the present lighting for short-radius exit taxiways. This report evaluated the use of surface retroreflective markers for identifying short-radius exit taxiways at night. The markers are intended for locations where the cost of inset centerline lighting cannot be justified. The results indicate that there was an improvement in the pilot's ability to identify the exit taxiway associated with the exit-taxiway retroreflectors. The results also show that the retroreflectors should be placed on an arc from near the runway centerline to the taxiway centerline using a cord spacing of 12.5 feet (4 meters).]]></description>
      <pubDate>Mon, 26 Aug 2019 15:43:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/1646527</guid>
    </item>
    <item>
      <title>Examining Correlations Between Motorcyclist’s Conspicuity, Apparel Related Factors and Injury Severity Score: Evidence from New Motorcycle Crash Causation Study</title>
      <link>https://trid.trb.org/View/1632722</link>
      <description><![CDATA[Motorcyclists are vulnerable road users at a particularly high risk of serious injury or death when involved in a crash. In order to evaluate key risk factors in motorcycle crashes, this study quantifies how different “policy-sensitive” factors correlate with injury severity, while controlling for rider and crash specific factors as well as other observed/unobserved factors. The study analyzes data from 321 motorcycle injury crashes from a comprehensive US DOT FHWA’s Motorcycle Crash Causation Study (MCCS). These were all non-fatal injury crashes that are representative of the vast majority (82%) of motorcycle crashes. An anatomical injury severity scoring system, termed as Injury Severity Score (ISS), is analyzed providing an overall score by accounting for the possibility of multiple injuries to different body parts of a rider. An ISS ranges from 1 to 75, averaging at 10.32 for this sample (above 9 is considered serious injury), with a spike at 1 (very minor injury). Preliminary cross-tabulation analysis mapped ISS to the Abbreviated Injury Scale (AIS) injury classification and examined the strength of associations between the two. While the study finds a strong correlation between AIS and ISS classification (Kendall’s tau of 0.911), significant contrasts are observed in that, when compared to ISS, AIS tends to underestimate the severity of an injury sustained by a rider. For modeling, fixed and random parameter Tobit modeling frameworks were used in a corner-solution setting to account for the left-tail spike in the distribution of ISS and to account for unobserved heterogeneity. The developed random parameters Tobit framework additionally accounts for the interactive effects of key risk factors, allowing for possible correlations among random parameters. A correlated random parameter Tobit model significantly out-performed the uncorrelated random parameter Tobit and fixed parameter Tobit models. While controlling for various other factors, the authors found that motorcycle-specific shoes and retroreflective upper body clothing correlate with lower ISS on-average by 5.94 and 1.88 units respectively. Riders with only partial helmet coverage on-average sustained more severe injuries, whereas, riders with acceptable helmet fit had lower ISS Methodologically, not only do the individual effects of several key risk factors vary significantly across observations in the form of random parameters, but the interactions between unobserved factors characterizing random parameters significantly influence the injury severity score as well. The implications of the findings are discussed.]]></description>
      <pubDate>Wed, 17 Jul 2019 11:36:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1632722</guid>
    </item>
    <item>
      <title>Effectiveness of retro-reflective tape at the rear of heavy trucks to increase visibility and reduce rear-end collisions</title>
      <link>https://trid.trb.org/View/1581167</link>
      <description><![CDATA[The purpose of this study is to compare the visibility of various colors and patterns of retroreflective tapes and evaluate the effect of human and environmental factors on the detection of distance, perception-reaction time, and heart rate while driving behind heavy trucks with different patterns of retroreflective tapes. The Kitami Institute of Technology Driving Simulator (KITDS) was used for the experiment throughout this study. BACS Advance (TAOS Institute) is another piece of equipment used to measure heart rate and used to determine the driver's level of stress. Five patterns of retroreflective tape designs were evaluated and compared. The results of the study clearly show that the most visible retroreflective tape pattern is the fully outlined alternating red and yellow retroreflective tape following Regulation No.48 from UNECE, in comparison to the other patterns tested. Gender, driver age, the speed of the following vehicles, tape width, tape pattern, lighting conditions, and weather conditions significantly affect the detection distance. Driver age significantly affects the perception-reaction time. The perception-reaction time is significantly longer for drivers behind trucks with no retroreflective tape at the rear-end. Therefore, the selection of the most effective color and pattern of retroreflective tape is very important in order to increase the visibility of heavy trucks and reduce the chances of rear-end truck collisions, particularly at nighttime or in conditions with limited visibility. This study strongly recommends that countries which have not implemented regulations concerning the placement of retroreflective tape on the rear of large trucks, or have implemented the regulation but not in accordance with UNECE Regulation No.48, should consider revising their regulation to improve the visibility of large trucks.]]></description>
      <pubDate>Wed, 20 Mar 2019 10:39:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/1581167</guid>
    </item>
    <item>
      <title>Evaluating Retroreflectivity Assessment Techniques for In-Service Raised Retroreflective Pavement Markers</title>
      <link>https://trid.trb.org/View/1494948</link>
      <description><![CDATA[Raised Retroreflective Pavement Markers (RRPMs) are traffic control devices placed on the road to enhance nighttime visibility by reflecting light from the headlights of vehicles back to the drivers. This helps delineate the roadways, making the lanes easier to identify for drivers, especially in wet-night conditions.This paper will explore how two devices, portable and mobile retroreflectometers, measure retroreflectivity levels of in-service markers. Mobile retroreflectometers are designed to measure pavement markings. One of the goals of this paper is to see how well RRPMs can be measured by the mobile retroreflectometer and to compare those mobile results with those of the standard portable RRPM retroreflectometer. If a strong correlation is found between the two systems then the mobile retroreflectometer could be used as a means of evaluating the quality of in-service markers. In addition, the paper explorers RRPM retroreflectivity in a condition of continuous wetting in a controlled lab setting. Mobile and portable retroreflectivity values were collected at several field sites with various types of RRPMs. Different settings were used on the mobile retroreflectometer to optimize the system for marker evaluation. After examining the data from both devices, it was found that no correlation existed. Even though the devices measure different values, with different units, it was anticipated that some form of correlation would exist. RRPM retroreflectivity values, when measured with the portable device, decreased initially when subjected to a continuous wetting environment, but then increased as the water flowed off of the face of the markers.]]></description>
      <pubDate>Thu, 25 Jan 2018 09:32:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1494948</guid>
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