<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3ADcmthrurr%2A" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. 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>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Investigating the Performance of Snowplowable Reflective Pavement Markers in Illinois</title><link>http://pubsindex.trb.org/view/1759567</link><description><![CDATA[The Illinois Department of Transportation (IDOT) investigated the installation and performance of snowplowable reflective pavement markers (SRPMs) to determine optimum pavement marker solutions and policies for roadways in Illinois. The research evaluated the performance of five traditional cast-iron and two plastic SRPMs on test sections of both asphalt and concrete pavements. All five iron markers and one plastic marker had a traditional raised face for the reflective lens, and the other plastic marker was completely recessed in the pavement. Analysis included (1) comparisons of casting design, casting material, and groove design; (2) assessments on how each factor contributed to pavement marker performance; and (3) development of crash modification factors (CMFs) for quantifying any safety improvement from SRPM use. Due to a lack of crash data, the CMF development was limited to freeway sections with six or more lanes (combined directions). The results of the SRPM performance evaluation and CMF development were used to provide recommended updates to IDOT’s guidelines for the use of raised pavement markers and to IDOT’s raised reflective pavement marker inspection policy. This paper presents the SRPM performance assessment methods and results.]]></description><pubDate>Thu, 04 Feb 2021 10:57:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/1759567</guid></item><item><title>Effects of Pavement Marking Characteristics on Machine Vision Technology</title><link>http://pubsindex.trb.org/view/1438482</link><description><![CDATA[Machine vision systems are becoming more common with new vehicles. This technology can detect pavement markings to provide the driver various benefits such as lane departure warning and lane keeping assistance. In order to better understand the effects of pavement marking characteristics on the performance of machine vision systems, Potters Industries sponsored research to determine effects of pavement marking width, pavement marking color, and pavement marking retroreflectivity (dry and wet). The test equipment, protocol, and results are described below. This research offers the first-of-its-kind glimpse into the relationship between pavement markings characteristics and machine vision detection. While more work is clearly needed, this work should provide researchers, highway agencies, and vehicle manufacturers some general understanding that can lead to safer highways and more cost-effective pavement marking management practices.]]></description><pubDate>Wed, 08 Feb 2017 09:23:23 GMT</pubDate><guid>http://pubsindex.trb.org/view/1438482</guid></item><item><title>Road Markings Retroreflectivity Experimental Assessment: Observations on Rainfall, Dirt, Retroreflectometer Geometry and Minimum Requirements</title><link>http://pubsindex.trb.org/view/1393469</link><description><![CDATA[Horizontal markings retroreflectivity provides visibility for pavements during nighttime, which directly impacts road safety. Brazil employs international standards and minimum retroreflectivity requirements, which are partially adapted to the country conditions. In general, such adjustments reduced the security levels of these devices harming road safety. From the evaluation of three experimental sections (two urban avenues and one highway), with different markings and materials, for over two years, the Brazilian standard procedure and minimum retroreflectivity requirements were critically analyzed. Two handheld retroreflectometer with different geometries were applied enabling a correlation factor between 15 meter and 30 meter geometries. Also, the influence of rainfall and dirt accumulation on the markings performance was addressed. As expected, the thermoplastic markings outperformed those with acrylic paint. The abrasive effect of the tire-pavement interaction outwears the markings, reducing the number of retroreflective elements (glass beads); however, the combination of traffic and rainfall was positive for allowing a "natural" marking cleaning. The effect of dirt accumulation was as damaging as the abrasion caused by heavy vehicles. The analysis of retroreflectivity, obtained with different geometries, regarding national and international thresholds, showed that the retroreflectivity minimum levels applied in Brazil are inefficient, deserving, therefore, to be discussed in order to enhance road safety.]]></description><pubDate>Thu, 24 Mar 2016 10:49:08 GMT</pubDate><guid>http://pubsindex.trb.org/view/1393469</guid></item><item><title>Enhancing Safety Performance of Rumble Strips Through the Use of Reflective Striping: An Empirical Study on U.S. 285 in New Mexico</title><link>http://pubsindex.trb.org/view/1394078</link><description><![CDATA[Although the transportation field has made significant progresses towards the improvements of the geometry of road alignments, stripe and marking elements, the safety features targeted toward driver error have plenty of constraints. Rumble strips and rumble stripes are relatively recent strategies that have been implemented and are aimed at aiding drivers that are experiencing fatigue on two lane and four lane rural roadways. This study examines the application, advantages, disadvantages, and the effects of rumble stripes on the overall traffic safety. Historical crash data of US 285 is analyzed as a case study to interpret safety performances of retroreflective rumble stripes. In addition, a survey of public opinions toward rumble stripes is conducted to evaluate public acceptance. The outcome of this study may be useful for better execution of traffic safety of rural roadways.]]></description><pubDate>Mon, 07 Mar 2016 10:19:42 GMT</pubDate><guid>http://pubsindex.trb.org/view/1394078</guid></item><item><title>Analysis of Nighttime Driving Behavior at Different Retroreflective Longitudinal Pavement Markings</title><link>http://pubsindex.trb.org/view/1393051</link><description><![CDATA[The purpose of this study was to assess the impact of different reflective longitudinal pavement markings on driving behavior under varying conditions at nighttime. A field experiment was carried out on a specifically prepared test track. Subjects were selected based on psychological pre-testing to ensure a homogenous test sample for three age groups. Nighttime test drives were carried out within three different marking conditions (non-reflective, standard reflective, wet reflective material) in three driving circumstances (dry, wet and wet &amp; rainy) with identical test vehicles. Driving performance was measured by means of speed choice and questionnaire data to collect drivers´ subjective comfort levels for each test condition. Results indicate that both reflective marking materials are perceived as more comfortable and guiding compared to the non-reflective marking. Applying reflective marking material showed a positive effect on the subjective comfort feeling of drivers, especially in adverse driving conditions. Regarding driving behavior by means of speed choice, subjects drove slowest in the non-reflective condition, faster under standard reflective marking condition, and slightly faster under the condition with advanced reflective material. It could be shown that both reflective longitudinal marking materials are perceived as more comfortable and guiding compared to the non-reflective marking. Furthermore, results suggest that these benefits outweigh the disadvantages (slightly higher speed choice) for drivers in general, but in particular for older drivers.]]></description><pubDate>Tue, 09 Feb 2016 09:18:04 GMT</pubDate><guid>http://pubsindex.trb.org/view/1393051</guid></item><item><title>Nighttime Safety and Pavement Marking Retroreflectivity on Two-Lane Highways: Revisited with North Carolina Data</title><link>http://pubsindex.trb.org/view/1339399</link><description><![CDATA[The relationship between pavement marking retroreflectivity and nighttime safety has been a topic of research for past decade or more but consistent findings have been elusive despite the intuitive nature of having bright markings. This paper builds from previous work that used Michigan retroreflectivity and crash data to demonstrate that pavement marking retroreflectivity relates to the nighttime safety on rural two-lane highways in a meaningful way. In this paper, new data from North Carolina were obtained and used. The North Carolina data were used to test the robustness of the statistical models derived from the Michigan data. Additional analyses were also explored and described in this paper. Using results from this paper, previous research, and state of the practice, recommendations and their implications are presented for safety-derived minimum retroreflectivity levels for pavement markings.]]></description><pubDate>Tue, 10 Mar 2015 07:50:32 GMT</pubDate><guid>http://pubsindex.trb.org/view/1339399</guid></item><item><title>Automatic Recognition of Patterns and Words on Road Markings Based on Laser Reflectance Information</title><link>http://pubsindex.trb.org/view/1288864</link><description><![CDATA[Road surface markings provide guidance and information to drivers, promote road safety, and ensure the smooth flow of traffic. Most previous studies in this area focused on the detection and recognition of lane lines with very limited prior work on the recognition of lane center road markings. This paper focuses on the development of algorithm for automatically detecting and recognizing road markings of patterns and word messages at traffic lane center. Road markings of Chinese characters are first studied. In addition, a method for identifying the completeness of road markings is also presented. Authors propose an approach to extract road marking features based on the derivation of a binary matrix image transformed from laser reflectance collected from a top down roadway view laser scanner. The results of case studies on asphalt pavement (city streets) show that the approach can detect and recognize lane center road markings with a significant success rate. The average success rate is 96.06%, including 94.05% Chinese character road markings and 97.73% success of direction arrows and others. From the case studies, it was also noted that a significant portion of road markings have relatively low completeness. Further studies will focus on increasing survey speed, detecting other highway classes containing different Chinese characters and road markings such as icon, increasing detection rate, conducting study on various pavement condition, and developing a decision making strategy for road marking maintenance.]]></description><pubDate>Thu, 27 Feb 2014 09:06:23 GMT</pubDate><guid>http://pubsindex.trb.org/view/1288864</guid></item><item><title>Traffic control: Devices and Delineation</title><link>http://pubsindex.trb.org/view/1177857</link><description></description><pubDate>Fri, 24 Aug 2012 01:40:13 GMT</pubDate><guid>http://pubsindex.trb.org/view/1177857</guid></item><item><title>Characteristics of Calibration Standard for Mobile Retroreflectometer Unit</title><link>http://pubsindex.trb.org/view/881558</link><description><![CDATA[In 2004, the Florida Department of Transportation (FDOT) acquired a Mobile Retroreflectometer Unit (MRU) to safely collect and process pavement marking retroreflectivity for a Pavement Marking Management System (PMMS). The goal of the program is the transition from site specific handheld retroreflectometers and subjective visual surveys to a continuous and high speed data collection methodology. MRU technology is still relatively new and previous studies have shown it is critical to understand the operations of the device for valid test results. Crucial to the valid results is the calibration step, which is used to standardize the MRU response to a known retroreflectivity sample. Current calibration procedures typically require use of a short section of pavement line marking, often referred to as a beaded stripe, with a known retroreflectivity value as the MRU calibration standard. The beaded stripe has the advantage of being similar to the typical material measured by the MRU, but is inherently non-uniform due to a non-homogeneous pattern of glass bead placement and size. The non-uniformity of the glass beads creates the potential for issues with accuracy and repeatability of the calibration step. Ceramic blocks, which are used as the calibration standard for handheld retroreflectometers, have demonstrated a spatially uniform retroreflectivity response. This paper compares MRU calibration with the beaded stripe to that of a ceramic block, in part to show an alternative calibration standard. Initial testing has shown comparable calibration results when using a ceramic block versus the beaded line stripe. The study also attempts to validate the laboratory test results by conducting field experiments, comparing both the beaded calibration stripe and the ceramic block calibration methodologies.]]></description><pubDate>Fri, 13 Mar 2009 06:36:18 GMT</pubDate><guid>http://pubsindex.trb.org/view/881558</guid></item><item><title>Evaluation of Road-Sign Geometry Parameter Space Using Exact Roadway Geometry Output Computer Model</title><link>http://pubsindex.trb.org/view/848121</link><description><![CDATA[Most reflective sheeting specifications were developed when glass-bead retroreflectors were the norm. Micro-prismatic retroreflective sheeting is now become wide-spread and specifications are being revised to accommodate this newer technology.  Microprismatic retroreflective sheeting is not as rotationally symmetric as glass-bead sheeting and so greater care in performance specifications is needed.  This paper analyzes a range of retroreflective geometries that will occur on the road through the use of the ERGO (Exact Roadway Geometry Output) program. Using this approach, the roadway geometry parameter space can be mapped and reasonable limits and testing may be applied to retroreflective sheeting.]]></description><pubDate>Tue, 03 Jun 2008 07:32:16 GMT</pubDate><guid>http://pubsindex.trb.org/view/848121</guid></item><item><title>Calibration Standards for Mobile Retroreflectometer Units</title><link>http://pubsindex.trb.org/view/848760</link><description><![CDATA[To better quantify the retroreflectance of longitudinal pavement markings throughout the state, the Florida Department of Transportation (FDOT) acquired the Mobile Retroreflectometer Unit (MRU) which has the potential benefit of fast, safe, and unbiased measurements of retroreflectivity as compared to traditional evaluation techniques such as handheld units or visual inspections.  Current MRU calibration standards requires that the equipment be calibrated using a beaded line stripe that has been verified by a handheld retroreflectometer.  By its very nature, this type of striping is inherently non-uniform as the beads are dispersed in a non-homogeneous pattern.  This non-uniformity of retroreflectance results in issues with performing accurate, repeatable calibrations. Issues with the non-uniformity are further exacerbated by oscillations of the MRU laser light.  Test results showed that the standard deviation of the retroreflectivity of the beaded line stripe was greater than 12% of the reading.  In comparison, a ceramic block calibration standard had a retroreflectivity standard deviation of less than 0.5% of the rated value.  Further tests showed that more repeatable calibrations and more stable readings were also achieved through use of the ceramic block.  As a result, it is the view of the authors that the ceramic block is more suitable for use as an MRU calibration device.]]></description><pubDate>Fri, 29 Feb 2008 07:41:27 GMT</pubDate><guid>http://pubsindex.trb.org/view/848760</guid></item><item><title>Retroreflectivity and Life Cycle Study of Waterborne Paint Pavement Markings: Case Study for the State of Maryland</title><link>http://pubsindex.trb.org/view/848773</link><description><![CDATA[Pavement markings on highways are often taken for granted by motorists and only noticed when they fail to do their job.  Highway administrators, on the other hand, are tasked with understanding the materials that are used to create the pavement markings.  The objectives of this research are to gain an understanding of the relationship between measured retroreflectivity and exposure to elements including length of exposure, traffic, rain and snow.  The weather exposure relationships from this study are unique and represent a new set of information regarding retroreflectivity duration.  In order to pursue this research, eight sites were selected in geographically diverse parts of the state of Maryland.   The relationship between waterborne paint pavement markings¡¯ retroreflectivity and exposure variables were estimated using multivariate regression techniques.  The resulting predicted retroreflectivity measures are compared to the thresholds of each paint type for different speed limits.  This comparison yields a service life for different pavement marking types under different exposure conditions.  As results, the inclusion of precipitation and snowfall leads to a better fit with the data and better predicted retroreflectivity service life expectancy.  The R-Squares were roughly double those of most previous studies. In addition, we are able to show how different pavement marking colors have different service life durations under different climatic and traffic conditions.  The inclusion of weather variables combined with the more sophisticated regression analysis allows us to present these service life durations.]]></description><pubDate>Fri, 29 Feb 2008 07:41:27 GMT</pubDate><guid>http://pubsindex.trb.org/view/848773</guid></item><item><title>Evaluating the Retroreflectivity of Pavement Marking Materials Under Continuous Wetting Conditions</title><link>http://pubsindex.trb.org/view/801767</link><description><![CDATA[Wet weather performance of pavement markings has received increased emphasis with the availability of new products designed specifically to improve nighttime visibility in wet weather conditions. Procedures for measuring the performance of these and standard marking materials are found in ASTM E1710, E2176, and E2177, which describe retroreflectivity measurement in dry, continuous wetting, and recovery conditions, respectively. Research comparing the retroreflectivity values measured for 18 different marking samples in 14 measurement conditions is described. Each sample was measured according to the three ASTM procedures, plus an additional 11 rates of continuous wetting. In addition, analysis was done of 20 years of Texas rainfall data to gain an understanding of the relationships between actual rainfall rates and the rates specified in E2176. Findings indicate that while the allowable rainfall rate in E2176 ranges from 6 to 14 in./h, 88% of rainfall events produced maximum rates less than 0.75 in./h. A wide variability was found in the retroreflectivity values of materials as a function of the wet condition. For most markings, the retroreflectivity level decreases as the rainfall rate increases, but changes in retroreflectivity were not consistent for the different samples. Also, an analysis of the effect of cross slope on wet retroreflectivity measurements indicated that it has a major impact on the measured values. Findings suggest that the range of conditions permitted by E2176 brings into question the ability to use this procedure to compare material retroreflectivity in a standardized manner.]]></description><pubDate>Wed, 25 Apr 2007 08:09:26 GMT</pubDate><guid>http://pubsindex.trb.org/view/801767</guid></item><item><title>Evaluation of Visibility of Pavement Markings in Wet-Night Rainy Conditions and Appropriateness of Associated Measurement Techniques</title><link>http://pubsindex.trb.org/view/801551</link><description><![CDATA[Researchers evaluated the performance of 18 different pavement markings in a wet-night condition to obtain a better understanding of how a wide range of markings perform under such conditions and how their performance can be assessed.  Three metrics were obtained and analyzed: 1) retroreflectivity measurements, 2) dynamic detection distance measurements, and 3) luminance measurements.  The retroreflectivity measurements were made under a variety of conditions including dry, wet recovery, and 12 levels of continuous wetting ranging from 0.28 inches per hour to over 20 inches per hour.  Detection distance measurements were made in a dynamic setting in which 30 research participants drove through a rain tunnel that was calibrated to produce realistic rainfall rates (0.28 and 0.87 inches per hour).  Finally, the luminance of the markings was measured at 30-meter geometry under realistic rainfall rates.  The relationships between the measured detection The results indicate the weakness of ASTM E2176 and provide recommendations for further study.]]></description><pubDate>Tue, 24 Apr 2007 07:19:39 GMT</pubDate><guid>http://pubsindex.trb.org/view/801551</guid></item><item><title>Pedestrian Conspicuity at Night: How Much Biological Motion Is Enough?</title><link>http://pubsindex.trb.org/view/777563</link><description><![CDATA[This paper describes how inadequate conspicuity has been shown to be a key causal factor in nighttime vehicle-pedestrian collisions. Although earlier research has shown that positioning reflective markers to depict biological motion can dramatically enhance pedestrian conspicuity at night, the mechanisms responsible for this effect remain unclear. In order to determine the effects that the number of reflective elements and natural pedestrian motion have on pedestrian conspicuity, this paper conducted an experiment in open-road conditions. 120 participants were driven along a residential route at night and pressed a button to indicate that a pedestrian was present. Pedestrians, who either stood still or walked in place, were positioned to the right of the roadway and wore either black clothing or black clothing plus 304 cm2 of retroreflective material in one of four different configurations. The mean response distance for the vest condition (23.8 m) was not significantly different from the mean response to the black condition (30.6 m). When pedestrians walked in place, all conditions with markings on the extremities became significantly more conspicuous, with response distances ranging from 88.9 m (ankles) to 113.5 m (biological motion). Although the advantages of marking the extremities were reduced when the pedestrians were standing still, the biological motion configuration (63.2 m) remained significantly more conspicuous than the other conditions. Marking just the ankles was effective only when the pedestrian was walking. These results confirm the conspicuity benefit of placing reflective markings on the major joints of pedestrians and indicate that both form perception and motion perception contribute to this benefit.]]></description><pubDate>Wed, 28 Jun 2006 08:47:44 GMT</pubDate><guid>http://pubsindex.trb.org/view/777563</guid></item></channel></rss>