Minimum In-Service Retroreflectivity of Pavement Markings

2000 ◽  
Vol 1715 (1) ◽  
pp. 60-70 ◽  
Author(s):  
Helmut T. Zwahlen ◽  
Thomas Schnell
Keyword(s):  
Field Experiments ◽  
Single Point ◽  
Luminance Contrast ◽  
Population Based ◽  
Time Of Day ◽  
Observation Angle ◽  
Contrast Threshold ◽  
Entrance Angle ◽  
Pavement Markings ◽  
Pavement Marking

Minimum in-service retroreflectivity values for pavement markings are presented based on visibility computations performed with the CARVE (Computer-Aided Road-Marking Visibility Evaluator) computer model. CARVE accurately computes all geometric and photometric relationships for each headlamp separately; applies the human visual luminance contrast threshold database from Blackwell (Part III, 1946) adjusted by a field factor function that has been obtained from a number of pavement marking visibility field experiments; and provides retroreflectivity values for the pavement markings for any selected single-point geometry (e.g., ASTM 30-m geometry, observation angle = 1.05°, entrance angle = 88.7°). Based on the CARVE computation results, a set of in-service pavement marking retroreflectivity values are derived for fully marked, dark, straight, and dry roads using paint-and-beads pavement markings. The derived minimum retroreflectivity values for fully marked roads without raised pavement markers (RPMs) are highly speed dependent, because the computations are based on a constant minimum preview time of 3.65 s (3.0 s true preview and 0.65 s for eye-fixation duration). A separate set of minimum retroreflectivity values, based on a constant preview time of 2.0 s, is provided for fully marked roads with RPMs in good working order. It was found that the minimum retroreflectivity requirements for pavement markings could be substantially relaxed if RPMs (in good photometric working condition) were used. The proposed minimum retroreflectivity values are based on a 62-year-old driver (about the 85th percentile of the licensed driver population, about the 95th per-centile of the nighttime driver population based on trip frequency data as a function of the time of day).

Laboratory-Based Retroreflectivity Assessment of Raised Retroreflective Pavement Markers

2017 ◽  
Vol 2612 (1) ◽  
pp. 113-120 ◽  
Author(s):  
Adam M. Pike
Keyword(s):  
Quantitative Evaluation ◽  
Visual Inspection ◽  
Observation Angle ◽  
Entrance Angle ◽  
Charge Coupled Device ◽  
Measurement Systems ◽  
Pavement Markings ◽  
Performance Requirements ◽  
Pavement Marking ◽  
Standard Marker

Pavement markings are often supplemented with raised retroreflective pavement markers (RRPMs) to provide increased visibility, especially in wet nighttime conditions. To provide adequate visibility, highway agencies need to replace their markings and markers before they reach inadequate levels of performance. Currently, there are no quantitative visibility performance requirements for in-service RRPMs. Most markers are replaced on the basis of visual inspection or predetermined replacement schedules. This paper presents an initial investigation into the impacts of different measurement systems and different geometries on the quantitative evaluation of the visibility of RRPMs. A key question was how the different measurement geometries affected the retroreflective performance of RRPMs. The research found that when the observation angle was held at 0.2° and the entrance angle increased, the coefficient of luminous intensity also increased. This finding was true for every color and brand of marker for the geometries tested. There was a notable drop in performance when the evaluation geometry was changed from pavement marker geometry to pavement marking geometry. When the photometric range was used, the pavement marking geometry resulted in data that were 7.8% of the values from the standard marker geometry. Charge-coupled device photometer measurements resulted in pavement marking geometry results that were on average 6.7% of the value of the RRPM geometry. These values being close indicated that the two measurement types were comparable and that the markers could consistently be evaluated at the two distinct geometries.

scholarly journals Using ADAS to Future-Proof Roads—Comparison of Fog Line Detection from an In-Vehicle Camera and Mobile Retroreflectometer

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1737
Author(s):  
Ane Dalsnes Storsæter ◽  
Kelly Pitera ◽  
Edward McCormack
Keyword(s):  
Warning System ◽  
Management Systems ◽  
Warning Systems ◽  
Lane Departure Warning ◽  
Automated Driving ◽  
Pavement Markings ◽  
Lighting Conditions ◽  
Lane Marking ◽  
Lane Departure ◽  
Pavement Marking

Pavement markings are used to convey positioning information to both humans and automated driving systems. As automated driving is increasingly being adopted to support safety, it is important to understand how successfully sensor systems can interpret these markings. In this effort, an in-vehicle lane departure warning system was compared to data collected simultaneously from an externally mounted mobile retroreflectometer. The test, performed over 200 km of driving on three different routes in variable lighting conditions and road classes found that, depending on conditions, the retroreflectometer could predict whether the car’s lane departure systems would detect markings in 92% to 98% of cases. The test demonstrated that automated driving systems can be used to monitor the state of pavement markings and can provide input on how to design and maintain road infrastructure to support automated driving features. Since data about the condition of lane marking from multiple lane departure warning systems (crowd-sourced data) can provide input into the pavement marking management systems operated by many road owners, these findings also indicate that these automated driving sensors have an important role in enhancing the maintenance of pavement markings.

scholarly journals Developing Pavement Marking Management Systems: A Theoretical Model Framework Based on the Experiences of the US Transportation Agencies

2021 ◽  
Vol 6 (2) ◽  
pp. 18
Author(s):  
Alireza Sassani ◽  
Omar Smadi ◽  
Neal Hawkins
Keyword(s):  
Asset Management ◽  
Management Practices ◽  
Relevant Literature ◽  
Building Blocks ◽  
Management Systems ◽  
Model Framework ◽  
Pavement Markings ◽  
The Us ◽  
Pavement Marking ◽  
Transportation Agencies

Pavement markings are essential elements of transportation infrastructure with critical impacts on safety and mobility. They provide road users with the necessary information to adjust driving behavior or make calculated decisions about commuting. The visibility of pavement markings for drivers can be the boundary between a safe trip and a disastrous accident. Consequently, transportation agencies at the local or national levels allocate sizeable budgets to upkeep the pavement markings under their jurisdiction. Infrastructure asset management systems (IAMS) are often biased toward high-capital-cost assets such as pavements and bridges, not providing structured asset management (AM) plans for low-cost assets such as pavement markings. However, recent advances in transportation asset management (TAM) have promoted an integrated approach involving the pavement marking management system (PMMS). A PMMS brings all data items and processes under a comprehensive AM plan and enables managing pavement markings more efficiently. Pavement marking operations depend on location, conditions, and AM policies, highly diversifying the pavement marking management practices among agencies and making it difficult to create a holistic image of the system. Most of the available resources for pavement marking management focus on practices instead of strategies. Therefore, there is a lack of comprehensive guidelines and model frameworks for developing PMMS. This study utilizes the existing body of knowledge to build a guideline for developing and implementing PMMS. First, by adapting the core AM concepts to pavement marking management, a model framework for PMMS is created, and the building blocks and elements of the framework are introduced. Then, the caveats and practical points in PMMS implementation are discussed based on the US transportation agencies’ experiences and the relevant literature. This guideline is aspired to facilitate PMMS development for the agencies and pave the way for future pavement marking management tools and databases.

scholarly journals Influence of Land Cover and Soil Moisture on the Horizontal Distribution of Sensible and Latent Heat Fluxes in Southeast Kansas during IHOP_2002 and CASES-97

2007 ◽  
Vol 8 (1) ◽  
pp. 68-87 ◽  
Author(s):  
Margaret A. LeMone ◽  
Fei Chen ◽  
Joseph G. Alfieri ◽  
Mukul Tewari ◽  
Bart Geerts ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Latent Heat ◽  
Land Surface ◽  
Field Experiments ◽  
Time Of Day ◽  
Horizontal Distribution ◽  
Heat Fluxes ◽  
Surface Model ◽  
Green Vegetation ◽  
The Impact

Abstract Analyses of daytime fair-weather aircraft and surface-flux tower data from the May–June 2002 International H2O Project (IHOP_2002) and the April–May 1997 Cooperative Atmosphere Surface Exchange Study (CASES-97) are used to document the role of vegetation, soil moisture, and terrain in determining the horizontal variability of latent heat LE and sensible heat H along a 46-km flight track in southeast Kansas. Combining the two field experiments clearly reveals the strong influence of vegetation cover, with H maxima over sparse/dormant vegetation, and H minima over green vegetation; and, to a lesser extent, LE maxima over green vegetation, and LE minima over sparse/dormant vegetation. If the small number of cases is producing the correct trend, other effects of vegetation and the impact of soil moisture emerge through examining the slope ΔxyLE/ΔxyH for the best-fit straight line for plots of time-averaged LE as a function of time-averaged H over the area. Based on the surface energy balance, H + LE = Rnet − Gsfc, where Rnet is the net radiation and Gsfc is the flux into the soil; Rnet − Gsfc ∼ constant over the area implies an approximately −1 slope. Right after rainfall, H and LE vary too little horizontally to define a slope. After sufficient drying to produce enough horizontal variation to define a slope, a steep (∼−2) slope emerges. The slope becomes shallower and better defined with time as H and LE horizontal variability increases. Similarly, the slope becomes more negative with moister soils. In addition, the slope can change with time of day due to phase differences in H and LE. These trends are based on land surface model (LSM) runs and observations collected under nearly clear skies; the vegetation is unstressed for the days examined. LSM runs suggest terrain may also play a role, but observational support is weak.

scholarly journals FLUAZIFOP-P-BUTYL EFFICACY AS A FUNCTION OF APPLICATION TIME AND HERBICIDE DOSE

2017 ◽  
Vol 35 (0) ◽  
Author(s):  
L.F. CIESLIK ◽  
R.A. VIDAL ◽  
A.B. MACHADO ◽  
M.M. TREZZI
Keyword(s):  
Relative Humidity ◽  
Common Bean ◽  
Weed Control ◽  
Air Temperature ◽  
Field Experiments ◽  
Time Of Day ◽  
Leaf Angle ◽  
Herbicide Application ◽  
The Common ◽  
Bean Crop

ABSTRACT Grass weeds are common in summer crops and strongly decreases the grain yield of the common bean crop. The time of herbicide application influences the variability of environmental conditions and affects the product performance. The objectives of this work were to identify the time of fluazifop-p-butyl (fluazifop) application which gives best grass weed control in the common bean crop and to elucidate the environmental variables most important for the efficacy of this herbicide. Field experiments were conducted involving five application times (2 a.m., 6 a.m., 11 a.m., 4 p.m. and 9 p.m.) and five doses of fluazifop (80, 110, 140, 170 and 200 g ha-1), with additional no-herbicide control. At the time of the herbicide application it was determined the air temperature, relative humidity, the photosynthetically active radiation (PAR) and the leaf angle, whereas the weed control and the dry mass of the weed Urochloa plantaginea was assessed at 20 days after treatment (DAT). Efficacy on grass control with fluazifop was dependent on the herbicide dose and on the time of day that the product was applied. Spray at early morning hours (6 a.m.) showed better efficacy on weed control in relation to periods during warmer conditions of the day (11 a.m. and 4 p.m.). Nocturnal fluazifop application had better weed control when compared to herbicide sprayed in the afternoon. The air temperature, relative humidity and PAR were correlated to weed leaf angle, which correlated the most with fluazifop performance.

scholarly journals Evaluating the genetic variability of rubber hybrid progenies of the two crosses PB260 x RO44/71 and PB260 x RO62/54 by RAPD technique

2019 ◽  
Vol 2 (3) ◽  
pp. 36-43
Author(s):  
Thien Minh Nguyen ◽  
Tien Thi My Pham
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Genetic Similarity ◽  
Field Experiments ◽  
Agronomic Traits ◽  
Genetic Relationships ◽  
Genetic Material ◽  
Population Based ◽  
Shannon Index ◽  
Polymorphic Bands

The agronomic values of this population have been evaluated in the field experiments based on their phenotypic performance of agronomic traits, but the genetic variability of this population needs to be evaluated via techniques based on genetic material - DNA. In this study, the genetic variability in the investigated population of 71 hybrids and their parents was evaluated by RAPD technique, using eight selected arbitrarily primers; Genetic parameters and dendrogram expressing the genetic relationships among the investigated population were analyzed by GenALEx 6.1, Popgene 1.31 and NTSYSpc 2.1 softwares. Eight primers were used to generate the amplify products on each individual in the investigated population. From 74 genotypes, a total of 109 fragments were generated, among which, there were 89 polymorphic bands representing 81.65% with an average of 11 polymorphic bands/primer. Genetic similarity coefficient among the investigated population, based on DICE coefficient, ranged from 0.560 (LH05/0822 and PB260) to 0.991 (LH05/0781 and LH05/0841) with an average of 0,796, meaning that the genetic distance among ranged from 0.009 to 0.440 with an average of 0.231. The Shannon index and mean heterozygosity values were 0.328 and 0,176, respectively. This indicated that the progenies of the two investigated crosses possessed a relatively high range of genetic variability. The analysis of molecular variance (AMOVA) showed that genetic variation within population represented 62%, while genetic variation among two different crosses contributes 38% to the total genetic variability. Dendrogram based on DICE’s genetic similarity using UPGMA method showed that the hybrids divide into two major genetic groups (0.75), but the crosses were scattered independently of the hybrid.

scholarly journals The Chromosome 9p21 CVD- and T2D-Associated Regions in a Norwegian Population (The HUNT2 Survey)

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Øyvind Helgeland ◽  
Jens K. Hertel ◽  
Anders Molven ◽  
Helge Ræder ◽  
Carl G. P. Platou ◽  
...  
Keyword(s):  
Single Point ◽  
Strong Association ◽  
Population Based ◽  
Risk Haplotype ◽  
Cross Sectional ◽  
Chromosome 9P21 ◽  
Snp Association ◽  
Risk Variants ◽  
Norwegian Population

Background.Two adjacent regions upstreamCDKN2Bon chromosome 9p21 have been associated with type 2 diabetes (T2D) and progression of cardiovascular disease (CVD). The precise location and number of risk variants have not been completely delineated and a possible synergistic relationship between the adjacent regions is not fully addressed. By a population based cross-sectional case-control design, we genotyped 18 SNPs upstream ofCDKN2Btagging 138 kb in and around two LD-blocks associated with CVD and T2D and investigated associations with T2D, angina pectoris (AP), myocardial infarction (MI), coronary heart disease (CHD; AP or AMI), and stroke using 5,564 subjects from HUNT2.Results.Single point and haplotype analysis showed evidence for only one common T2D risk haplotype (rs10757282∣rs10811661: OR = 1.19,P=2.0×10-3) in the region. We confirmed the strong association between SNPs in the 60 kb CVD region with AP, MI, and CHD(P<0.01). Conditioning on the lead SNPs in the region, we observed two suggestive independent single SNP association signals for MI,rs2065501  (P=0.03)andrs3217986  (P=0.04).Conclusions.We confirmed the association of known variants within the 9p21 interval with T2D and CHD. Our results further suggest that additional CHD susceptibility variants exist in this region.

Development and Implementation of a Pavement Marking Management System in Florida

2018 ◽  
Vol 2672 (12) ◽  
pp. 209-219
Author(s):  
Bouzid Choubane ◽  
Joshua Sevearance ◽  
Charles Holzschuher ◽  
James Fletcher ◽  
Chieh (Ross) Wang
Keyword(s):  
Management System ◽  
Handheld Devices ◽  
Department Of Transportation ◽  
Pavement Markings ◽  
Lighting Conditions ◽  
Florida Department ◽  
Roadway Safety ◽  
Application Techniques ◽  
Effective Use ◽  
Pavement Marking

The visibility of pavement markings is an important aspect of a safe transportation system as the markings convey vital roadway warnings and guidance information to the traveling public. Therefore, it is beneficial to maintain acceptable visibility levels of markings on pavements under all weather and lighting conditions. To ensure the intended in-service visibility level is adequately maintained, the reflectivity must be monitored and quantified accordingly. Historically, visibility or retroreflectivity of in-service pavement markings has been measured with handheld devices and visual inspections. However, visual surveys are considered subjective and the handheld measurements are tedious and potentially hazardous. Consequently, the Florida Department of Transportation (FDOT) has focused on the use of a non-contact technology capable of assessing pavement markings continuously at highway speeds with improved safety and efficiency. The use of mobile technology for measuring reflectivity has allowed FDOT to develop and, subsequently, implement a Pavement Marking Management System (PMMS) to improve the safety and nighttime visibility of its roadways. Implementation of such a system provides an efficient and less subjective methodology to identify conditions that are detrimental to roadway safety, and strategize mitigating solutions including the selection of appropriate materials and application techniques. The system will ultimately result in an effective use of state funds while ensuring the safety of the traveling public. This paper presents a description of the Florida Pavement Markings Management System and its subsequent implementation including FDOT’s effort to ensure the quality, consistency, repeatability, and accessibility of statewide pavement marking retroreflectivity data.

Neurophysiological Contributions to Luminance and Chromatic Mechanisms in a Hyperacuity Task

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 339-339
Author(s):  
L Rüttiger ◽  
B B Lee
Keyword(s):  
Detection Threshold ◽  
Luminance Contrast ◽  
Contrast Threshold ◽  
Psychophysical Data ◽  
Spatial Mechanisms ◽  
Cone Cells

We recently reported (paper presented at ARVO 1997) psychophysical evidence as to contributions of luminance and chromatic mechanism in a hyperacuity task, namely detection of small displacements. Achromatic or chromatic (430, 550, 690 nm) edges were presented on white or chromatic (550 nm) backgrounds, and displacement thresholds measured as a function of luminance contrast. Above 3% (achromatic detection threshold), all conditions yielded nearly identical contrast/threshold curves; we believe a luminance mechanism to be responsible. In chromatic conditions, below 3% contrast, large (>100 s arc) displacements were detectable; presumably chromatic mechanisms are responsible. We have now carried out equivalent physiological experiments. Data were consistent with cells of the magnocellular (MC) pathway underlying the luminance mechanism. Opponent S-cone or parvocellular (PC) cells became responsive to displacements in the chromatic conditions. S-cone cells were very responsive to the 430 nm edge, and responded at low contrasts matching the psychophysical thresholds. L, M-cone opponent cells were responsive to the 690 nm edge, but less so than was expected from the psychophysical data. Our data suggest MC-cells underlie a luminance hyperacuity mechanism. Additional factors (eg cell numerosity) may have to be considered for chromatic spatial mechanisms.

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