1、Designation: E 2177 01Standard Test Method forMeasuring the Coefficient of Retroreflected Luminance (RL)of Pavement Markings in a Standard Condition of Wetness1This standard is issued under the fixed designation E 2177; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the wetretroreflective (R
3、L) properties of horizontal pavement markingmaterials, such as traffic stripes and road surface symbols,using a portable or mobile retroreflectometer that can be placedon or before the road marking to measure the retroreflection atthe prescribed geometry.1.2 This method of measuring the wet retroref
4、lective prop-erties (RL) of pavement markings measures the wet retroreflec-tivity in a standard condition of wetness (see Fig. 1).1.2.1 DiscussionThis test condition typically exists (1)after a rainfall has ended and the pavement markings are stillwet or (2) as the markings are wet from dew or humid
5、ity.1.3 Retroreflective performance obtained with this test inconditions of wetness does not necessarily relate to howmarkings perform in conditions of rain, that is, as markings arebeing rained upon.NOTE 1Test Method E 2176 defines a method to use to measure theperformance of pavement markings in c
6、onditions of simulated rain.1.4 This test method specifies the use of portable or mobilereflectometers that can measure pavement markings in accor-dance with Test Method E 1710.2The entrance and observationangles required of the retroreflectometer in this test method arecommonly referred to as “30 m
7、eter geometry.”21.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use
8、.2. Referenced Documents2.1 ASTM Standards:D 6359 Specification for Minimum Retroreflectance ofNewly Applied Pavement Marking Using Portable Hand-Operated Instruments3E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method4E 965 Test Method for Measuring Pav
9、ement MacrotextureDepth Using a Volumetric Technique5E 1710 Test Method for Measurement of RetroreflectivePavement Marking Materials with CEN-Prescribed Geom-etry Using a Portable Retroreflectometer5E 2176 Test Method for Measuring the Coefficient of Ret-roreflected Luminance (RL) of Pavement Markin
10、gs in aStandard Condition of Continuous Wetting52.2 Other Standard:CENEN 1436 Road Marking MaterialsRoad MarkingPerformance for Road Users63. Terminology3.1 coeffcient of retroreflected luminance, RLthe ratio ofthe luminance, L, of a projected surface to the normal illumi-nance, E, at the surface on
11、 a plane normal to the incident light,expressed in candelas per square metre per lux (cdm-2)/lx.Because of the low luminance of pavement markings, the unitscommonly used are millicandelas per square metre per lux(mcdm-2)/lx.3.2 condition of wetnessthe test condition is created byliberally wetting th
12、e road marking and waiting a certain timeperiod after wetting for water to run off.3.2.1 DiscussionSimilar conditions exist when roadmarkings are wet or damp such as typically found after a rainhas ended or from dew and high humidity.1This test method is under the jurisdiction of ASTM Committee E12
13、on Colorand Appearance and is the direct responsibility of Subcommittee E12.10 onRetroreflection.Current edition approved Dec. 10, 2001. Published February 2002.2Reference ASTM E 1710 “Standard Test Method for Measurement of Retrore-flective Pavement Markings with CEN-Prescribed Geometry Using a Por
14、tableRetroreflectometer.” The standard measurement condition is intended to representthe angles corresponding to a distance of 30 m for the driver of a passenger car withan eye height of 1.2 m and a headlight height of 0.65 m above the road. SeeAppendix X1.3Annual Book of ASTM Standards, Vol 04.03.4
15、Annual Book of ASTM Standards, Vol 14.02.5Annual Book of ASTM Standards, Vol 06.01.6Available from European Committee for Standardization, Central Secretarial(CEN), rue de Stassart 36, B1050, Brussels, Belgium.FIG. 1 Illustration of Measurement1Copyright ASTM International, 100 Barr Harbor Drive, PO
16、 Box C700, West Conshohocken, PA 19428-2959, United States.3.3 mobile retroreflectometera retroreflectometer that hasbeen mounted to a vehicle for purposes of taking measure-ments while the vehicle is moving.3.4 portable retroreflectometeran instrument that can beused in the field or laboratory for
17、measuring the coefficient ofretroreflected luminance, RL.3.5 “recovery method” or “bucket method”alternativenames commonly used to describe this test method for achiev-ing measurements in condition of wetness.3.6 RL-wetthe retroreflectance value, RL, obtained 45 safter wetting. (See Fig. 2.)4. Signi
18、ficance and Use4.1 The nighttime performance of pavement markings isdetermined by the coefficient of retroreflected luminance, RL,be it dry or wet, and depends on the materials used, age, andwear pattern. These conditions shall be observed and noted bythe user.4.2 Under the same conditions of headli
19、ght illumination anddrivers viewing, larger values of RLcorrespond to higherlevels of visual performance at corresponding geometry.4.3 The pavement markings measured performance in thestandard condition of wetness is used to characterize theperformance of the marking on the road when wet.4.4 Newly i
20、nstalled pavement markings may have a naturalsurface tension or release agents that prevent wetting of theproduct by water. The water will tend to “bead up” on themarking. This “non wetting” condition is usually short lived.Pavement markings that have been on the road for one monthprior to testing u
21、sually do not exhibit this non-wetting phe-nomenon. (WarningThis phenomenon produces an interfer-ence when assessing the wet characteristics of a pavementmarking. Attempts to measure markings with this surface“non-wetting” or “beading” of the water may give highervalues.)4.5 The retroreflectivity, R
22、L, of pavement (road) markingsdegrades with traffic wear and requires periodic measurementto ensure that sufficient line visibility is provided to drivers.For example see Specification D 6359 for dry retroreflectivityrequirements.4.6 For a given viewing distance, measurements of RLmadewith a retrore
23、flectometer having a geometry corresponding tothat viewing distance are a good indicator of the visual rankingof the material measured.4.7 As specified by Test Method E 1710, the measurementgeometry of the instrument is based on a viewing distance of30 m, an eye height of 1.2 m and a headlight mount
24、ing heightof 0.65 m (see Appendix X1).4.8 It shall be the responsibility of the user to employ aninstrument having the specified observation and entranceangles.5. Apparatus5.1 Portable or Mobile RetroreflectometerThe reflecto-meter must comply with Test Method E 1710.5.2 Stopwatch or Watch, with sec
25、ond hand.5.3 Water, for wetting the pavement marking.5.3.1 A portable hand sprayer (garden sprayer) may be usedto wet the pavement marking to create the wet condition. Theportable hand sprayer shall have an adjustable nozzle. A batteryoperated unit works well.5.3.2 Alternatively a bucket may be used
26、 to create the wetcondition by pouring the water over the marking. Approxi-mately 2 to 5 L of water are needed.5.3.3 The water shall be clean tap water.6. Sampling6.1 The number of readings to be taken at each test locationand the spacing between test locations shall be specified by theuser.6.2 It i
27、s common to take less frequent measurements thanone would do when assessing dry retroreflectance.6.3 Measurements for each line type shall be averaged for afinal result.7. Calibration and Precautions7.1 The portable or mobile retroreflectometer shall be cali-brated (standardized) using the instructi
28、ons from the instru-ment manufacturer. A reference or working standard is usedand is supplied with the instrument.7.2 Transporting the portable reflectometer from an airconditioned area to the test site may result in fogging of mirrorsin the instrument. If there is any doubt concerning thecalibratio
29、n or if the readings of a reference or working standardare not constant, allow the instrument to reach ambientconditions and recalibrate with the reference or workingstandard.7.3 Verification must be made that there is no moisture onthe instruments lens when the instrument is being used for wetreadi
30、ngs. Sometimes the reflectometers lens will become“fogged over” in high temperatures due to water evaporation.When roads are hot one can pre-cool the road with water beforeapplying the test method to prevent the reflectometer fromfogging.7.4 Calibration RecheckIf the subsequent readings on therefere
31、nce standard deviate by more than 5 % from the initialone, re-calibration shall be performed. If the readings on thereference standard deviate by more than 10 % from the initialone, recalibrate and, in addition, re-measure previous measure-ments.FIG. 2 Definition of RL-WetE21770128. General Procedur
32、e8.1 Both a dry and a wet measurement are usually taken inorder to characterize the performance of the marking. The drymeasurement establishes the effectiveness of the marking in adry condition plus acts as a bench mark for the marking towhich the wet performance can be compared. However, the drymea
33、surement is optional per this test method.8.2 Measuring Dry or Wet Retroreflectance (RL) of Mark-ings:8.2.1 Use the manufacturers instructions for calibration andoperation of the retroreflectometer.8.2.2 Locate the area of the pavement marking to bemeasured.8.2.3 Place the retroreflectometer squarel
34、y on or in front ofthe pavement marking material with the illumination in thedirection of travel. Ensure that the illuminated measurementarea of the retroreflectometer fits within the width of the stripe,and take a measurement.8.3 Measuring Retroreflectance (RL) in a Standard Condi-tion of Wetness:8
35、.3.1 Take a hand sprayer and wet the area of the markingto be measured and the adjacent surrounding area (road surfaceand marking) for 30 s. Verify that the marking and adjacentarea are completely flooded. Or pour 2 to 5 litres of clean waterfrom a bucket. Slowly pour the water over the area of them
36、arking to be measured plus the immediate surrounding area.The water is poured evenly along the test surface so that themeasuring field and its surrounding area is momentarilyflooded by a crest of water (see Fig. 3).8.3.2 Measure the coefficient of retroreflected luminance,RL, of the wetted marking 4
37、5 6 5 s after completion ofspraying or pouring the water on the marking as described in8.3.1 (see Fig. 3).8.4 RecordsRecord the dry and wet measurements inmillicandelas per square metre per lux, (mcdm-2)/lx. Move tonext measurement location which is separated sufficiently toprovide meaningful data a
38、nd repeat procedures in 8.2 and 8.3.9. Test Report9.1 Include the following in the test report.9.1.1 Test date.9.1.2 Average of the readings taken per line or markingexpressed in millicandelas per square metre per lux(mcdm-2)/lx. The average of the readings shall be reportedfor wet and for dry condi
39、tions and for each traffic direction ofinterest.9.1.3 Readings for centerlines shall be taken for eachdirection of traffic. Readings for centerlines, edge lines, skiplines, etc.9.1.4 Geographical location of the test site. Global position-ing system (GPS) location or distance from the nearestpermane
40、nt site identification, such as a mileage marker orcrossroad.9.1.5 Identification of the pavement marking materialtested: type, color, age, and the location on road (edge line, firstline, second line, centerline, etc.).9.1.6 Identification of the instrument used, value and date ofcalibration of the
41、reference standard panel used.9.1.7 Remarks concerning the overall condition of the line,such as rubber skid marks, carryover of asphalt, snowplowdamage, and other factors that may affect the retroreflectionmeasurement.9.1.8 Ambient temperature and other weather conditions.9.1.9 Description of roadw
42、ay slope and general drainagewhere measurement is made (that is, puddles on marking dueto low spot in road, water drained due to road incline, etc.)9.1.10 Description of road surface and road texture, that is,portland concrete cement (PCC) (broomed, brushed, worn),bituminous, chip seal, etcNOTE 2Pav
43、ement texture may be identified and quantified by TestMethod E 965.10. Factors That May Influence Measurements10.1 There are factors that may cause measurement vari-ability when taking readings in the field. Some of these are:10.1.1 Slight changes in the position of the reflectometer onor in front o
44、f the traffic line may yield different readings.10.1.2 The magnitude of the wet measurement obtainedmay sometimes be dependent upon how well the water drains9off from9 the marking. Steep inclines will allow the water torun off quickly and lead to higher values. Conversely, low areasor dips will allo
45、w the water to puddle and will give lowervalues.11. Precision and Bias11.1 The precision and bias is based on three separatestudies, and their results can be found in Tables 1 and 2. Thetables show the repeatability for two instrument types and fortwo levels of wet performance. One level of wet perf
46、ormanceis shown in Table 1 for values less than 100 (mcdm-2)/lx andthe other level is shown in Table 2 for values greater than 100(mcdm-2)/lx. The calculations and results follow PracticeE 691.11.2 In each study, the wet reflective measurement wasperformed by wetting the marking, waiting 45 s for th
47、e waterFIG. 3 Illustration of MeasurementTABLE 1 Repeatability in Conditions of Wetnessfor Values ofWet Performance Under 100 (mcdm-2)/lxNOTE 1Individual readings range from 0 to 103 (mcdm-2)/lx.n Range ofValuesMeanValuePooledSt. Dev.Coef. ofVariation95 % C.I.2.8 (St. Dev.)Study 1Instrument A 24 0 t
48、o 36 7.5 0.8 29.9 % 62.2Study 2Instrument A 17 4 to 98 52 4.2 22.7 % 612E2177013to drain and then taking the measurement. For each study, 2-3replicate readings were obtained by simply triggering theinstruments a second or third time without moving the instru-ment (within 5 s). The wetting of the mar
49、kings was done usinga sprayer. The instruments were calibrated before the studieswere conducted.11.3 A reproducibility study (between instruments) has notbeen completed. However, in Table 2 for values of wetperformance above 100 (mcdm-2)/lx, study #1 gives acomparison of two instruments (A1 and A2).12. Keywords12.1 dry retroreflection; mobile retroreflectometers; pave-ment markings; portable retroreflectometer; retroreflection inwet conditionsAPPENDIX(Nonmandatory Information)X1. EXAMPLES OF PAVEMENT MARKING MEASURING SYSTEMSX1.1 The ent
