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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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      <link>https://trid.trb.org/</link>
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      <title>Impact of sidewall information on drivers’ visual load among different lanes: Traditional guiding facilities and decorated pattern</title>
      <link>https://trid.trb.org/View/2431761</link>
      <description><![CDATA[This research aims to: (i) compare the effects of different sidewall entrainment facilities on drivers’ visual behavior; (ii) compare the effects of the same sight entrainment facilities on drivers in different lanes; (iii) give recommendations for engineering applications based on the results of the study. The study designed four different scenes, each with symmetrically designed visual facilities on the both sidewalls of the tunnel, scene a represents a typical urban tunnel in China (horizontal stripes on sidewalls), scene b includes vertical stripes on sidewalls in addition to scene a, scene c introduces an LED-arch based on scene b, and scene d features a rhythmic pattern (Wave pattern on sidewalls). 30 participants, 21 men and 9 women, aged 21–54, drove the four scenes. Eye movement data of participants in each lane for different scenes were collected using an eye-tracking device. Visual performance indicators including fixation duration, number of fixations, saccade duration, and saccade amplitude were utilized to comprehensively evaluate drivers’ visual behavior. Factor analysis was employed to analyze the impact of different visual guiding facilities on drivers’ visual searching abilities. There is a significant effect of sidewall guiding facilities and lane location on drivers’ visual behavior and loading. Across scenes, drivers’ visual load is ranked as follows, from highest to lowest: scene a (baseline); scene b (horizontal stripes added to scene a); scene c (LED-arch added to scene b); scene d (Wave pattern). Furthermore, under the same scene, drivers’ visual load in each lane is ranked in descending order: Middle lane; Right lane; Left lane.  Due to the effect of the tunnel structure on the drivers’ visual field, drivers in the left lane have the highest visual load in any scenario compared to the other two lanes, which can be ameliorated but not eliminated. Traditional guiding facilities and decorated pattern both improve the visual behavior and reduce drivers’ visual load in urban tunnels, especially in scene c and scene d, but scene d should not be used for the entire length of the tunnel in order to prevent driver distraction. In engineering practice, scene c (LED-arch added to scene b) can be set up in general sections of urban tunnels, and decorated pattern can be added to fatigue reminder regions to alleviate driving fatigue.]]></description>
      <pubDate>Fri, 11 Oct 2024 09:32:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2431761</guid>
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    <item>
      <title>Traffic safety comprehensive evaluation of urban tunnel visual guiding system based on extension matter-element model: A case study in tunnel curves</title>
      <link>https://trid.trb.org/View/2431757</link>
      <description><![CDATA[The visual guiding system, as a tunnel traffic safety improvement method by using visual guiding facilities to actively guide driving safely, has been widely used in countries with many tunnels, in recent years. This paper aims to quantitatively study the comprehensive evaluation of traffic safety of the visual guiding system in tunnels, which has certain engineering application value and can provide support for the quantitative evaluation and optimal design of tunnel traffic safety. Based on the analysis of the relevant factors of urban tunnel traffic safety, a multi-factor comprehensive evaluation system with 5 upper-level indicators and 12 basic-level indicators was proposed. Considering the independent and incompatible indicators, a comprehensive evaluation method of traffic safety of the visual guiding system in urban tunnels was constructed by using the extension matter-element model. Taking the scene of 4 types of tunnel curves, such as no facilities, horizontal stripe, chevron alignment sign, and LED arch, as examples, the comprehensive evaluation of various schemes were carried out by using simulation tests. The traffic safety comprehensive evaluation system of visual guiding system in urban tunnels can be analyzed from five aspects: perception reaction, guidance ability, driver factor, driving task, and facility appearance. The results demonstrated significant the comprehensive evaluation result of the target level of scene 1 was L4, scene 2 was L3, scene 3 was L2, and scene 4 was L1. That is, the final results of the comprehensive evaluation of the four scenes were poor, medium, good, and very good, respectively.  In the scheme of visual guiding system for urban tunnel curves, the effectiveness of the three types of designs, from high to low, was the LED arch, chevron alignment sign, and horizontal stripe, and the safety of the scene without facilities was the lowest. Hence, setting the LED arch in the urban tunnel curve has a good effect in the aspects of guidance ability, sight distance, and sight zone, and is conducive to the driver’s perception reaction and driving task.]]></description>
      <pubDate>Fri, 11 Oct 2024 09:32:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2431757</guid>
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    <item>
      <title>Multistate Analysis Investigating Roadway Characteristics that Affect Driver Yielding at LED-Embedded Pedestrian- and School-Crossing Signs</title>
      <link>https://trid.trb.org/View/1938271</link>
      <description><![CDATA[To address public health concerns about rising pedestrian–vehicle crashes, traffic agencies are seeking options to reduce the number and severity of crashes. For established pedestrian-crossing locations, an increasingly common traffic-control treatment is the pedestrian- or school-crossing warning sign with light-emitting diodes (LEDs) embedded in the borders (called LED-Em in this paper). The LED-Em treatment, a system that includes LEDs embedded in warning signs and pedestrian push buttons, is pedestrian activated, so the LEDs only flash when a pedestrian is attempting to cross the street. For this analysis, researchers considered more than 7,000 drivers involved in more than 3,200 staged pedestrian crossings at 53 sites. The average driver-yielding rates at those sites were analyzed, using analysis of covariance models to assess the effects of various roadway characteristic variables as well as traffic-control device characteristic variables. The statistical analysis showed that the posted speed limit and the vehicle volume at the time of the crossing influenced a driver’s decision to yield to a pedestrian attempting to cross a street when an LED-Em treatment was present. Higher posted speed limits and higher vehicle volumes were associated with lower driver yielding.]]></description>
      <pubDate>Wed, 06 Apr 2022 10:26:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1938271</guid>
    </item>
    <item>
      <title>Improving the safety of distracted pedestrians with in-ground flashing lights. A railway crossing field study</title>
      <link>https://trid.trb.org/View/1850053</link>
      <description><![CDATA[Current signage at intersections is designed for attentive pedestrians who are looking ahead. Such signage may not be sufficient when distracted by smartphones. Illuminated in-ground LED lights at crossings are an innovative solution to alert distracted pedestrians.  The authors conducted a field study at a railway crossing equipped with in-ground lights to assess whether distracted pedestrians (N = 34, Mean age 33.6 ± 8.6 years) could detect these lights and how this impacted on their visual scanning and crossing behavior. This involved a 2 × 3 repeated measures design exploring the impact of the presence (treatment) or absence (control) of in-ground lights (treatment) at a crossing, and a distractor task presented through a mobile device (none, visual, and audio) on eye movements recorded using an eye tracker, and verbal reporting of when participants detected the lights.  Participants engaged in the distraction tasks as evidenced by their accuracy and reaction times in all conditions. With both the audio and visual distraction tasks, participants looked at the in-ground LEDs and detected their activation as accurately as when not distracted (95%). While most participants detected the lights at their activation, visual distraction resulted in 10% of the detections occurring as participants entered the rail corridor, suggesting effectiveness in gaining pedestrians’ attention. Further, participants were significantly less likely to check for trains when visually distracted (70%), a 10% reduction compared to the no or audio distractor conditions (80% and 78% respectively). The introduction of the in-ground lights resulted in appropriate scanning of the rail tracks (77% and 78% for the visual and auditory distractor tasks respectively) similar to that of non-distracted participants for the crossing without lights (80%).  The findings indicate that illuminated in-ground lights could be useful in attracting the attention of distracted pedestrians at railway level crossings, and possibly at other road intersections. Illuminated in-ground lights can be installed at rail and road intersections with known pedestrian distraction as a countermeasure. Further research is necessary to understand their long-term effects.]]></description>
      <pubDate>Thu, 27 May 2021 12:37:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1850053</guid>
    </item>
    <item>
      <title>Determining Cost-Effective Policy for Visibility of Overhead Guide Signs on Highways</title>
      <link>https://trid.trb.org/View/1662260</link>
      <description><![CDATA[Overhead guide sign visibility on highway, can be achieved either by illumination or by using retroreflective sheeting. Two surveys were sent to all U.S. departments of transportation, to determine the states’ policies for increasing overhead guide sign visibility. Results showed that 57% of states currently illuminate guide signs, and the most used retroreflective sheeting by states that do not illuminate signs is Diamond Grade for legend and High Intensity for background. Based on cost analysis, the LED light source and the High Intensity (types III and IV) retroreflective sheeting are the most cost-effective methods for increasing guide signs visibility.]]></description>
      <pubDate>Thu, 02 Apr 2020 09:43:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1662260</guid>
    </item>
    <item>
      <title>Effective Light Source for Illuminating Overhead Guide Signs and Improving Roadway Safety</title>
      <link>https://trid.trb.org/View/1662219</link>
      <description><![CDATA[Driver safety is considered an important issue to departments of transportation. One way to increase highway safety is to improve the visibility of overhead guide signs for drivers. Visibility improving methods include the use of sign illumination or retroreflective sheeting materials. This paper focuses on sign illumination by comparing five light sources including high pressure sodium (HPS), metal halide (MH), mercury vapor (MV), induction lighting, and light emitting diode (LED). A laboratory experiment was conducted to compare effective light distribution of each light source and a cost analysis was performed to compare initial, maintenance, and operating cost components of the light sources. Results of the light distribution experiment indicated that HPS was the optimum light source followed by MH, induction lighting, MV, and LED. Induction lighting is a promising lighting technology which features good efficiency and long life. According to cost analysis, induction lighting was the most effective source, followed by the LED, HPS, MV, and MH. Of the five light sources considered, induction lighting provided the best overall performance when considering initial cost, operating cost, expected maintenance, and sign illuminance. Environmentally, LED does not contain mercury, and for those agencies that prefer using sources that are friendlier with the environment, the LED can be their best choice.]]></description>
      <pubDate>Thu, 02 Apr 2020 09:43:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1662219</guid>
    </item>
    <item>
      <title>Illuminated Sign Conspicuity: What Factors Make a Sign Noticeable and Legible?</title>
      <link>https://trid.trb.org/View/1627390</link>
      <description><![CDATA[This document focuses on maximizing the conspicuity of illuminated signs. It begins with a literature review looking at the conspicuity and legibility of: typographic and symbolic characteristics; photometric, colorimetric and temporal characteristics; and environmental characteristics. Next two human factors laboratory studies evaluated (1) sign legibility, character aspect ratio of text, and luminance and (2) visual comfort, conspicuity, and sign luminance. Field measurement of luminance using an illuminance meter is outlined and the report concludes with preliminary guidelines for illuminated sign design.]]></description>
      <pubDate>Mon, 19 Aug 2019 11:01:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1627390</guid>
    </item>
    <item>
      <title>Driving Simulator Study on the Influence of Digital Illuminated Billboards Near Pedestrian Crossings</title>
      <link>https://trid.trb.org/View/1540586</link>
      <description><![CDATA[To evaluate the effect of display time and distance of digital illuminated billboards near a pedestrian crossing on glance and driving behavior. Several functional characteristics and placement conditions of digital billboards influence glance and driving behavior. Forty-one participants drove seven different routes (3.8–5.2 km) in a driving simulator. The authors performed a repeated measures ANOVA with presence of billboard, display time of the message (3 s, 6 s and 15 s), distance from a pedestrian crossing (41 m and 65 m) and road environment (transition road to a built-up area and retail zone) as the manipulated conditions in a randomized order. Shorter display times and retail zone resulted in a significantly higher number of eye glances towards the digital billboard. Participants reported a significantly higher mental workload and a lower estimation of personal driving performance in the presence of a digital billboard. Scenarios with a digital billboard resulted in a somewhat higher approaching speed towards the pedestrian crossing with the minimum approaching speed reached closer to the crossing. The first time a pedestrian crossed the road, reaction time to the crossing pedestrian was higher in presence of the digital billboard (this was not tested statistically). The presence of a digital billboard, especially with short display time, leads to visual distraction, which has a negative impact on driving behavior and traffic safety.]]></description>
      <pubDate>Mon, 24 Sep 2018 10:05:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1540586</guid>
    </item>
    <item>
      <title>Safety Assessment of Backlit Pedestrian Crossing Sign on Stopping Characteristics at Unsignalized Intersection</title>
      <link>https://trid.trb.org/View/1437617</link>
      <description><![CDATA[Traffic engineers regularly choose LED illuminated signs in order to improve safety at locations identified as high risk for crashes. Recent studies have shown that these signs have characteristics that make them more visible and legible than the conventional signs. LED signs are commonly used at stop-controlled intersections, particularly for the actual STOP sign. Investigations have been conducted into the effectiveness of different treatments -including back lit LED (BLS) STOP signs, and their impacts on gap selection and stopping patterns. However, there is yet to be an understanding of the complete adequacy of these remedies on traffic operations and road safety, especially on regulatory or warning signs other than STOP signs. This research study has selected pedestrian crossing BLS to quantify the amelioration of traffic safety at stop-controlled intersections (SCI) in low visibility settings. This two-pronged study includes a pairwise comparison of surrogate crash measurements and a conflict analysis of an intersection. Replication of field observations were possible with the help of calibration and validation of a micro simulation model in order to conduct conflict analysis. The results from both analyses support the previous studies' on BLS signs safety impacts and indicated safer driving behavior characterizes with the countermeasure - less chance of violation of the traffic sign under hazardous condition when a BLS is present. The number of conflicts has dropped as well under such scenarios. Thus, this research may represent a point of reference for engineers in adjusting or considering BLS pedestrian crossings and suggests a method to assess such treatments.]]></description>
      <pubDate>Mon, 30 Jan 2017 09:54:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1437617</guid>
    </item>
    <item>
      <title>Recommended Guidelines for Nighttime Overhead Sign Visibility</title>
      <link>https://trid.trb.org/View/1438859</link>
      <description><![CDATA[Guidelines for the provision of effective nighttime performance of overhead signs were developed. Relevant policies and guidelines with regard to sign lighting currently provide little useful information to determine when sign lighting is needed, and the reference material available to practitioners is out of date. Two complementary nighttime visibility studies were conducted, which were designed to produce results useful in developing updated guidelines for overhead sign visibility. The first was conducted on a closed course and investigated the legibility distances of three sign legend and background configurations under various sign lighting treatments. The second was conducted on the open road. It investigated the effects of sign luminance and visual complexity on the distance at which a driver can read overhead signs during a recognition task. The combined findings were used to develop revised guidelines designed to provide adequate nighttime visibility of overhead signs. The proposed guidelines are based on the needs of nighttime motorists and have been formatted specifically for AASHTO’s Roadway Lighting Design Guide, which is being updated. The revised chapter on roadway sign lighting was provided to the AASHTO task force responsible for revisions. The guidelines include a list of recommended retroreflective sheeting materials that can be used to meet nighttime driver needs for specific complexity levels.]]></description>
      <pubDate>Thu, 29 Dec 2016 15:53:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1438859</guid>
    </item>
    <item>
      <title>Evaluation of Overhead Guide Sign Sheeting Materials to Increase Visibility and Safety for Drivers</title>
      <link>https://trid.trb.org/View/1407535</link>
      <description><![CDATA[Overhead guide sign visibility must increase to improve driver safety on roadways. Two methods increase overhead guide sign visibility: sign illumination and use of retroreflective sheeting materials. This paper compares three types of retroreflective sheeting: Engineering Grade (type I), Diamond Grade (type XI), and High Intensity (type IV). A field experiment was conducted at night using licensed drivers to determine the optimum retroreflective sheeting material that increases sign visibility and legibility. Results showed that, of the three types of retroreflective sheeting, Diamond Grade (type XI) sheeting requires minimum illuminance to be visible, followed by High Intensity (type IV) sheeting. Cost analysis, including labor, maintenance, and material cost components of the three retroreflective sheeting materials, showed that High Intensity (type IV) could increase sign visibility and legibility at night for Departments of Transportation with limited budgets, consequently increasing driver safety on roadways.]]></description>
      <pubDate>Thu, 26 May 2016 14:50:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1407535</guid>
    </item>
    <item>
      <title>Investigating Safety of Different Treatments at Stop Controlled Intersection Using Driver Behavior Analyses</title>
      <link>https://trid.trb.org/View/1394414</link>
      <description><![CDATA[According to the strategic highway safety plans (SHSP) (American Association of State Highway and Transportation Officials (AASHTO) 2005), evaluating the impact on the performance of highway safety is required for any new safety device or treatment. Deployment of backlit LED illuminated STOP signs (BLS) has been proposed recently to improve safety at locations with known history or potential collision risk. While these signs are expected to affect traffic operations and road safety, the effects of such treatments are not yet fully understood. This research study investigates the effects of BLS on ameliorating traffic safety at stop-controlled intersections (SCI). This study benchmarked BLS with three other STOP signs with enhanced conspicuity properties at low visibility ambiance. An unbiased experiment was design in order to make a pairwise comparison of surrogate crash measures. A procedure for calibration and validation of a micro-simulation model was carried out to replicate the field observation. The number of conflicts at SCI with different treatment was estimated for rear-end and crossing movements. Overall the study demonstrated the usefulness of all four treatments while the LED and BLS having the highest impact on vehicle speed and compliance to the control device. Thus this research may represent a point of reference for engineers in adjusting or consideration of these type of treatment at hot spot SCIs.]]></description>
      <pubDate>Thu, 10 Mar 2016 16:07:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/1394414</guid>
    </item>
    <item>
      <title>Development and Verification of Dynamic Road Signs for Next-Generation ITS</title>
      <link>https://trid.trb.org/View/1254947</link>
      <description><![CDATA[This study aims at securing original technology to provide traffic information, utilizing the road surface by grafting LED and optical technology highly recognized in terms of energy efficiency onto ITS, thereby developing next-generation ITS service. To attain study objectives, the direction of research development, including application contents, was established. As a result of the study, it turned out that the original technology was successfully secured, but improvement of detailed technologies (LCD size & optical lens, etc.) and modification of relevant law/system is required.]]></description>
      <pubDate>Thu, 18 Jul 2013 13:52:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1254947</guid>
    </item>
    <item>
      <title>Use of Electroluminescence Technology for Highway Signage</title>
      <link>https://trid.trb.org/View/1127035</link>
      <description><![CDATA[Laboratory work will be combined with reviews of highway signage protocols, requirements, and potential applications that will lead to prototype design requirements for a typical highway sign. The sign should have the potential to improve safety for the motoring public and produce energy savings for the transportation industry. The prototype design will be prepared in anticipation of accelerated environmental exposure experiments and will also address legibility criteria under various inclement weather scenarios. Upon completion, the highway sign, including sensor instrumentation for inclement weather monitoring, will be placed along a highway in West Virginia and will be evaluated for weather sustaining availability over the winter season.]]></description>
      <pubDate>Wed, 25 Jan 2012 14:23:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1127035</guid>
    </item>
    <item>
      <title>Roundabouts and Other Traffic Calming Initiatives for Downtown Safety Village of Great Neck Plaza, NY</title>
      <link>https://trid.trb.org/View/923800</link>
      <description><![CDATA[The Village of Great Neck Plaza, a suburban incorporated village located on Long Island, NY, has embarked on a comprehensive program to improve pedestrian safety through traffic calming initiatives. The Village is densely populated containing approximately 90 multiple-family apartment buildings, forty-five office buildings, a Central Business District with 260 boutique stores, two senior independent living facilities, a nursing home, three parks and the Great Neck station of the Long Island Rail Road, which serves as a transportation hub for the entire Great neck peninsula. As a result, this small community, only one-third of an acre in size, is subject to gridlock conditions in the area adjacent to the train station and commercial district, speeding vehicles approaching the Village on wide arterial streets and pedestrian safety problems associated with busy city centers. The over-65 population in the Village is increasing, and this age group now comprises over 30% of the population and growing each year. This paper will address the traffic calming initiatives completed by the Village and those underway to address vehicular and pedestrian safety, including a modern roundabout, illuminated pedestrian crossing signs, electronic speed awareness devices, countdown type pedestrian signals, enhanced crosswalks, and a road diet. This program has been funded primarily by the New York State Department of Transportation through its Local Safe Streets and Traffic Calming grants. It will discuss the techniques employed and ways in which constrained municipal budgets can be leveraged to benefit the safety of pedestrians who walk the Village streets.]]></description>
      <pubDate>Fri, 30 Jul 2010 08:28:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/923800</guid>
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