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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>
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    <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>FURTHER INVESTIGATION OF THE EFFECTIVENESS OF WARNING DEVICES AT RAIL-HIGHWAY GRADE CROSSINGS</title>
      <link>https://trid.trb.org/View/270818</link>
      <description><![CDATA[The main objective of the study was to analyze the national inventory of the U.S. Department of Transportation-Association of American Railroads and the accident files of the Federal Railroad Administration to develop measures of effectiveness for the following rail-highway grade-crossing upgrade stratifications: (a) passive systems to flashing lights on single track, (b) passive systems to gates on single and multiple track, and (c) flashing lights to gates on single and multiple track. Other objectives included determining the influence of crossing angle, train speed ratio, and train speed difference on the effectiveness of warning devices. Overall results confirmed effectiveness values developed previously (but with smaller data bases) for upgrades from passive systems to flashing lights (69 percent) and from passive systems to gates (84 percent). The only marked change from previous studies occurred in the flashing-lights-to-gates category; the effectiveness value determined in this study (72 percent) was higher than values obtained in previous work. Upgrades of warn- ing devices on single track had higher effectiveness values than those on multiple tracks. Variation in train speeds at grade crossings, as measured by the speed-ratio and speed-difference concepts, had no apparent influence on the effectiveness of warning devices. Additional detailed conclusions as well as recommendations for further study are also included in the paper.]]></description>
      <pubDate>Fri, 27 Aug 2004 21:59:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/270818</guid>
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    <item>
      <title>ACTIVE ADVANCE WARNING SIGNS AT HIGH-SPEED SIGNALIZED INTERSECTIONS: A SURVEY OF PRACTICE (ABRIDGMENT)</title>
      <link>https://trid.trb.org/View/270811</link>
      <description><![CDATA[A synthesis of current traffic engineering practice relative to accident countermeasures at high-speed signalized intersections is presented. The synthesis was prepared by using two main sources of information: a review of published and unpublished literature, and results of a questionnaire survey sent to practicing traffic engineers. Sixty-five state and local agency traffic engineers from all regions of the United States and Canada responded to the questionnaire. Physical environments known to cause problems at high-speed signalized intersections are described. The three most commonly used types of active advance warning devices are discussed along with quantitative and qualitative assessments of their effectiveness. The three types of devices are flashing RED SIGNAL AHEAD signs, PREPARE TO STOP WHEN FLASHING signs, and flashing strobe lights. Active devices are usually installed only as a last resort where conventional countermeasures have not proved to be effective. Although specific situations in which each type of device has been effective or in which its use should be avoided were identified, there is a need for guidelines to define the use, design, installation, and timing of active warning devices.]]></description>
      <pubDate>Fri, 27 Aug 2004 21:59:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/270811</guid>
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    <item>
      <title>ACCIDENT COUNTERMEASURES AT HIGH-SPEED SIGNALIZED INTERSECTIONS. PHASE 1. SYNTHESIS OF PRACTICE</title>
      <link>https://trid.trb.org/View/265957</link>
      <description><![CDATA[Physical environments known to cause problems at high-sped signalized intersections are described.  The three most commonly used types of active advance warning devices are discussed along wiht quantitative and qualitative assessments of their effectiveness.  The three types of devices are: (1) flashing RED SIGNAL AHEAD signs, (2) PREPARE TO STOP WHEN FLASHING signs and (3) flashing strobe lights.  Active devices are usually installed only as a last resort where conventional countermeasures have proven not to be effective.  While specific situations where each type of device has been effective or where its use should be avoided were identified, there is a need for guidelines to define the use, design, installation and timing of active warning devices. devices.]]></description>
      <pubDate>Fri, 27 Aug 2004 20:57:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/265957</guid>
    </item>
    <item>
      <title>CHILD PEDESTRIAN-CAR CRASHES NEAR SCHOOLS ARE A SMALL PERCENTAGE OF TOTAL CHILD PEDESTRIAN CRASHES IN PHILADELPHIA</title>
      <link>https://trid.trb.org/View/541908</link>
      <description><![CDATA[An analysis was conducted of 2,167 pedestrian-car crashes reported by the Philadelphia Police Department in 1994.  Age, sex, location, type and severity of injury, and neighborhood of victim and driver were taken directly from the police reports. The pedestrian's actions were coded into 43 categories using the description in the police report.  The unique aspect of this research is that the "distance to the nearest school" was measured and included in the database.  The impetus to create this database was a politician's demand that School 15 mph (24 kph) flasher signs be installed at the over 500 schools in Philadelphia.  Only three schools in Philadelphia had school flashers when these data were collected in 1994.  Most schools had School Crossing signs and School 15 mph (24 kph) speed limit signs where appropriate.  There were about 600 school crossing guards in 1994.  The data indicate that few children are injured by cars near schools during opening, recess, and closing times. More children are injured en route to or from school, but not near the school.  A greater number are injured while playing after returning home from school than are injured during the trip to or from school combined.  Thus, an implementation of in-school child traffic safety education, installation of new strong yellow-green School Crossing signs, and targeted and advertised enforcement of motor vehicle laws would be better responses to child traffic safety than the wholesale installation of flashing school speed limit signs.  The data also confirm that dart-outs, other nonintersection crossings, traffic signals, and playing in the street are the principal crash types for children.  Philadelphia has a very high rate of unlicensed, unregistered, and uninsured drivers (estimated at over 40%).  Enforcement is lax, and the traffic court dismisses most moving violation cases.  Children deserve to be made safer 24 hours a day, 365 days a year.  Flashers cannot do that because only a small percentage of crashes occur near schools during school hours and because flashers are ineffective in reducing speeds and car-pedestrian crashes near schools.]]></description>
      <pubDate>Mon, 07 Dec 1998 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/541908</guid>
    </item>
    <item>
      <title>PROCESSING OF FLASHING DISPLAYS BY YOUNGER AND OLDER DRIVERS</title>
      <link>https://trid.trb.org/View/466000</link>
      <description><![CDATA[Two groups of subjects participated in this experiment: twelve older drivers with a mean age of 69, and twelve younger drivers with a mean age of 25. Subjects had to perform a two-alternative, forced-choice task, which involved responding to an arrow pointing either left or right. The response time was measured for different arrow presentation modes (steady vs. flashing tail) and distracting conditions (present or absent). The results strongly suggest that flashing does not lead to an automatic processing of the stimulus information, and therefore flashing is not of any particular benefit for the elderly drivers. Although flashing of the arrow tail can enhance the salience of the arrow, the observer still must integrate features of the arrow in a controlled manner. Therefore, age-related slowing is expected, as can be seen in the results of this experiment.]]></description>
      <pubDate>Tue, 09 Dec 1997 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/466000</guid>
    </item>
    <item>
      <title>COUNTY'S TRAFFIC CONTROL ENTERS THE 21ST CENTURY</title>
      <link>https://trid.trb.org/View/470877</link>
      <description><![CDATA[The Engineering Department for Burlington County, New Jersey has installed a computerized internal closed loop traffic control system that interconnects 19 traffic control signals in Burlington, Hainesport, Westampton and Mount Holly townships, and Burlington City. The project goal is to reduce traffic delays, congestion and vehicle emissions, improve safety, monitor signal failures, improve maintenance operations, and collect traffic volume data. The county expects to expand the system to all of its 200 signaling devices consisting of traffic control signals, school speed limit flashers, intersection control beacons, and stop sign flashers.]]></description>
      <pubDate>Thu, 13 Feb 1997 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/470877</guid>
    </item>
    <item>
      <title>COMPARATIVE STUDY OF ADVANCE WARNING SIGNS AT HIGH SPEED SIGNALIZED INTERSECTIONS</title>
      <link>https://trid.trb.org/View/452615</link>
      <description><![CDATA[The effects of two dynamic signs that begin to flash a few seconds before the onset of the yellow interval and a static sign that flashes all the time were examined at rural, high-speed signalized intersections.  The dynamic signs included (a) a PTSWF (prepare to stop when flashing) sign, and (b) an FSSA (flashing symbolic signal ahead) sign with green, yellow, and red circles.  The static sign was a CFSSA (continuously flashing symbolic signal ahead) sign with the three circles. The effects of these signs on vehicular speeds at different segments of the intersection approach including the dilemma zone were analyzed as were the vehicle conflict rates and the responses from the drivers' surveys.  The study revealed that the PTSWF and FSSA signs generally have similar effects on driver behavior.  It is advantageous to consider the CFSSA sign before using the PTSWF sign because the PTSWF and FSSA signs have a few undesirable effects on vehicular speeds, unlike the CFSSA sign.  The use of a PTSWF sign at a tangent approach to a high-speed signalized intersection is discouraged.]]></description>
      <pubDate>Tue, 12 Dec 1995 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/452615</guid>
    </item>
    <item>
      <title>HIGHWAY EVALUATION OF MAINTENANCE WORK ZONE SAFETY DEVICES</title>
      <link>https://trid.trb.org/View/409564</link>
      <description><![CDATA[Open highway testing is the evaluation of a device operated or used under actual highway conditions by State maintenance forces. Open highway testing was performed on devices in actual maintenance work zones. The following devices were tested: Portable Speed Bump; Flashing Stop/Slow Paddle; Infrared and Ultrasonic Intrusion Alarms; Queue-Length Detection Alarm; Direction Indicator Barricade; Opposing Traffic Lane Divider; Remote Driven Vehicle. This paper summarizes observational procedures, results, and recommended implementation strategies for each device.]]></description>
      <pubDate>Thu, 08 Sep 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/409564</guid>
    </item>
    <item>
      <title>A HYPEREFFECTIVE VISUAL SIGNAL FOR NIGHT DRIVING WARNING DEVICE</title>
      <link>https://trid.trb.org/View/111050</link>
      <description><![CDATA[THE ENHANCEMENT OF RETINAL SENSITIVITY IS DISCUSSED IN RELATION TO HUMAN PERCEPTION. THE TWO CONTRAST PARAMETERS- LUMINANCE AND TIME-ARE INDEPENDENTLY SUPERIMPOSED ON THE RATE OF ITERATION OR REPETITION. THE INTERACTION OF THESE TWO PARAMETERS OF VISUAL PERCEPTION WERE MEASURED, AND THE PRELIMINARY RESULTS OF THESE MEASUREMENTS ARE PRESENTED.]]></description>
      <pubDate>Fri, 08 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/111050</guid>
    </item>
    <item>
      <title>REDUNDANT USE OF LUMINANCE AND FLASHING WITH SHAPE AND COLOR AS HIGHLIGHTING CODES IN SYMBOLIC DISPLAYS</title>
      <link>https://trid.trb.org/View/378576</link>
      <description><![CDATA[Three visual search experiments evaluated the benefits and distracting effects of using luminance and flashing to highlight subclasses of symbols coded by shape and color.  The details are given of the study and of the experiments.  In each of the experiments, the search times for nonhighlighted target subclasses were not affected by the presence of brighter and flashing targets.  The failure of the initial experiment to find a significant performance improvement caused by increasing the symbol luminance suggested that a larger luminance increase was necessary for this code to be effective.  The overall results suggest that using luminance and flashing to highlight subclasses of color- and shape-coded symbols can reduce search times for these subclasses without producing a distraction effect by way of a concomitant increase in the seach times for unhighlighted symbols.]]></description>
      <pubDate>Wed, 28 Jul 1993 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/378576</guid>
    </item>
    <item>
      <title>SHRP DEVELOPS THREE NEW SAFETY DEVICES</title>
      <link>https://trid.trb.org/View/372614</link>
      <description><![CDATA[This article describes three new traffic safety devices produced by the Strategic Highway Research Program. The infrared intrusion alarm works by sounding a loud (120-decible) siren whenever a vehicle strays into a work zone, giving maintenance workers four to seven seconds warning to clear the work area and protect their safety. The new flashing stop/slow paddle developed by SHRP has two high-intensity, quartz halogen lamps that drivers can see from as much as 1,000 feet away. If cars don't appear to be slowing, the flagger operates the lights by pressing a button on the side of the paddle pole. The portable speed bump, made of neoprene rubber, 10 feet long and weighing just 75 lbs., can easily unfold from the back of a pickup, along with work-zone warning signs.]]></description>
      <pubDate>Fri, 16 Apr 1993 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/372614</guid>
    </item>
    <item>
      <title>SOLAR POWERED FLASHING BEACONS</title>
      <link>https://trid.trb.org/View/366363</link>
      <description><![CDATA[Article discussing the successful use of a solar powered flashing beacon in a school zone by the City of Vacaville, California.]]></description>
      <pubDate>Fri, 31 Jul 1992 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/366363</guid>
    </item>
    <item>
      <title>EFFECTIVENESS OF TRAFFIC CONTROL DEVICES IN REDUCING ACCIDENT RATES AT URBAN WORK ZONES</title>
      <link>https://trid.trb.org/View/353915</link>
      <description><![CDATA[This article describes a study in which the effectiveness of traffic control devices used in urban work zones was evaluated using data for sites located in Virginia. Regression models were developed relating work-zone accident rates with prior accident rates and types of control devices used. These regression models were developed for both two-lane and multi-lane highways. The traffic control devices evaluated were those used at the sites selected but include most of the devices commonly used at urban work zones (barricades, cones, flashing arrows, static signs, flagmen and temporary pavement markings). Use of advance warning signs was not considered in this study. Results indicate that the accident rate during periods of maintenance and rehabilitation work for multi-lane highways is highly dependent on the accident rate just prior to the work period.]]></description>
      <pubDate>Tue, 30 Apr 1991 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/353915</guid>
    </item>
    <item>
      <title>TECHNICAL NOTE NO. 3. SHOULD THE FLASHING MAN BE RED OR GREEN</title>
      <link>https://trid.trb.org/View/282927</link>
      <description><![CDATA[A study is reported of the color of pedestrian flashing singals and their flash rates.  Two groups, the elderly and children, were shown photographs and asked to say what was the exact message conveyed by the flashing red.  Another coding dimension for pedestrians, the rate at which the signal flashes was also studied.  The results of the tests are tabulated and discussed.  The results indicate that the intended message associated with the flashing signal, "you may complete your crossing, but do not commence to cross," was judged to be conveyed more effectively by the red signal rather than the green signal.  This corresponded with subjects' overwhelming preference for the red signal.  Also, the slowest flash rate was judged less effective than the others in conveying the desired method.]]></description>
      <pubDate>Sun, 31 Jul 1988 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/282927</guid>
    </item>
    <item>
      <title>DRIVER RESPONSE IN ACTIVE ADVANCED WARNING SIGNS AT HIGH-SPEED SIGNALIZED INTERSECTIONS. FINAL REPORT</title>
      <link>https://trid.trb.org/View/273837</link>
      <description><![CDATA[This research was conducted on the FHWA highway driving simulator (HYSIM) using 60 test subjects to examine driver responses to active advanced warning systems (AAWS) at high-speed signalized intersections.  Measures of effectiveness included identification distance, reaction time, vehicle approach speed, and vehicle lateral placement measured on the HYSIM.  Driver preferences were obtained from an interview following the driving test.  The AAWS's examined were "PREPARE TO STOP WHEN FLASHING" with flashing beacons using both a diamond-shape sign, and a rectangular sign mounted both on an overhead structure and ground-mounted on the roadside.  Also a symbolic signal ahead sign with flashing lights and a "RED SIGNAL AHEAD" sign with the "RED" flashing, were candidate test signs. The standard "SIGNAL AHEAD" and the symbolic signal ahead signs were also displayed.  The results indicated the symbolic signal ahead sign with flashing beacons had the greatest identification distance among all the test signs and was preferred by most drivers.  No differences could be detected between ground-mounted versus overhead signs.  All the active advance warning signs were superior to the standard passive warning signs.]]></description>
      <pubDate>Sat, 31 Jan 1987 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/273837</guid>
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