1、Designation: E 2176 01Standard Test Method forMeasuring the Coefficient of Retroreflected Luminance (RL)of Pavement Markings in a Standard Condition ofContinuous Wetting1This standard is issued under the fixed designation E 2176; the number immediately following the designation indicates the year of
2、original adoption 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 wetretroref
3、lective (RL) 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 of the
4、 wet retroreflectiveproperties (RL) of pavement markings utilizes a method ofcontinuously wetting the marking during measurement with theretroreflectometer (see Fig. 1).NOTE 1Test Method E 2177 may be used to describe the performanceof pavement markings in conditions of wetness after a period of rai
5、n.1.3 This test method specifies the use of portable or mobilereflectometers that can measure pavement markings per TestMethod E 1710.2The entrance and observation angles requiredof the retroreflectometer in this test method are commonlyreferred to as “30 meter geometry.”21.4 This test method is int
6、ended to be used for fieldmeasurement of pavement markings but may be used tomeasure the performance of materials on sample panels beforeplacing the marking material in the field.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespon
7、sibility 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.2. Referenced Documents2.1 ASTM Standards:D 6359 Specification for Minimum Retroreflectance ofNewly Applied Pavement Marking Using Porta
8、ble Hand-Operated Instruments3E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method4E 965 Test Method for Measuring Pavement MacrotextureDepth Using a Volumetric Technique3E 1710 Test Method for Measurement of RetroreflectivePavement Marking Materials with
9、 CEN-Prescribed Geom-etry Using a Portable Retroreflectometer5E 2177 Test Method for Measuring the Coefficient of Ret-roreflected Luminance (RL) of Pavement Markings in aStandard Condition of Wetness52.2 Other Standards:CENEN 1436 Road Marking MaterialsRoad MarkingPerformance for Road Users63. Termi
10、nology3.1 coeffcient of retroreflected luminance, RLthe ratio ofthe luminance, L, of a projected surface to the normal illumi-nance, E, at the surface on 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,
11、the unitscommonly used are millicandelas per square metre per lux(mcdm-2)/lx.3.2 conditions of continuous wettingthe test condition iscreated by artificially creating rain by using a rain simulatorsuch as a portable hand sprayer.1This test method is under the jurisdiction of ASTM Committee E12 on Co
12、lorand 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 Portable
13、Retroreflectometer.” 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 04.03.4Annua
14、l 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 Box
15、C700, West Conshohocken, PA 19428-2959, United States.3.3 external beam retroreflectometersretroreflectometersthat illuminate a measurement area outside of the instrumentsbody.3.4 internal beam retroreflectometersretroreflectometersthat illuminate a measurement area inside of the instrumentsbody.3.5
16、 mobile retroreflectometera retroreflectometer that hasbeen mounted to a vehicle for purposes of taking measure-ments while the vehicle is moving.3.6 portable retroreflectometeran instrument that can beused in the field or laboratory for measuring the coefficient ofretroreflected luminance, RL.3.7 R
17、L-RainThe retroreflectance value, RL, obtained whilethe marking is being continuously wetted during the measure-ment. See graph (Fig. 2). The value recorded is the average oftwo to three readings in the steady state area.4. Significance and Use4.1 The quality of the pavement marking is determined by
18、the coefficient of retroreflected luminance, RL, be it dry or wet,and depends on the materials used, age, and wear pattern.These conditions shall be observed and noted by the user.4.2 Under identical conditions of headlight illumination anddrivers viewing, larger values of RLcorrespond to higherleve
19、ls of visual performance at corresponding geometry.4.3 The pavement markings measured performance in con-ditions of continuous wetting may be used to characterize theperformance of the marking on the road as water is continu-ously falling on it and may be representative to a period of rain.This perf
20、ormance of the marking may be different than thatexperienced when the markings are just wet or damp.4.4 Retroreflectivity of pavement (road) markings degradeswith traffic wear and requires periodic measurement to ensurethat sufficient line visibility is provided to drivers. For examplesee Specificat
21、ion D 6359 for dry reflectivity requirements.4.5 For a given viewing distance, measurements of RLmadewith a retroreflectometer having a geometry corresponding tothat viewing distance are a good indicator of the visual rankingof the material measured.4.6 As specified by Test Method E 1710, the measur
22、ementgeometry of the instrument is based on a viewing distance of30 m, an eye height of 1.2 m and a headlight mounting heightof 0.65 m (see Appendix X1).4.7 Newly installed pavement markings may have a naturalsurface tension or release agents which prevent the wetting outof the product by rain/water
23、. This phenomenon produces aninterference when assessing the wet characteristics of a pave-ment marking. Attempt to measure markings with this surface“non-wetting” of the water may give higher values. Thiscondition is short lived and markings that have been on theroad for one month or more do not ex
24、hibit this non-wetting.4.8 It shall be the responsibility of the user to employ aninstrument having the specified observation and entranceangles.5. Apparatus5.1 RetroreflectometerPortable or Mobile:5.1.1 The retroreflectometer shall be an external beaminstrument and shall be designed and constructed
25、 so that straylight will not affect the reading.5.1.2 The retroreflectometer shall meet the requirements ofTest Method E 1710.5.2 Retroreflectometer SetupRain/Water Shield:5.2.1 The retroreflectometer, if necessary, shall be modifiedwith a rain/water shield to protect its lens from splatteringrain/w
26、ater during wet measurement.5.2.2 Adjust the shield such that it does not block theprojected light and diminish readings. Determine area ofmarking being illuminated with the projected light. Adjustshield so that it does not cover any of this area and thus preventcomplete wetting.5.3 Rain Simulator (
27、Water Sprayer):5.3.1 The rain maker (simulator) shall bea8L(2gal)minimum capacity, adjustable nozzle garden sprayer. The rateof water spray should be approximately 0.8 L/min. A batteryoperated sprayer performs the best since the battery allows aconstant rate/volume of water spray.5.3.2 Clean tap wat
28、er shall be used.5.4 Wetting Agent:5.4.1 DiscussionThe use of a wetting agent as explainedherein is not a standard test procedure. However, the use of awetting agent may be a practical way to estimate the perfor-mance of newly installed markings.5.4.2 In that newly installed pavement markings may ha
29、ve anatural surface tension or release agents which prevent thewetting out of the product by rain/water, a practical method canbe used to estimate the performance of newly placed markings.The addition of a small amount of soap or surfactant to thewater in the sprayer eliminates this interference wit
30、houtdamage to the installed line or sample panel. Recommendedsolution mixtures are: (a) 0.10 % by volume liquid soapsolution; and (b) a fluorocarbon surfactant solution, 1 mL in8L.NOTE 2Pavement markings that have been installed on the road forone month prior to testing usually do not exhibit this n
31、on-wettingphenomena. When testing new markings using the soap/surfactant agentsabove, visually examine the appearance of the marking as the water isapplied. The water should not form small beads of water on top of themarking. If small beads are formed, increase the soap/surfactant levelslightly and
32、retry.FIG. 2 Definition of RL-RainE21760126. 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 Because of the unique nature of this test procedure, it iscommon to take less frequent measurements than one would
33、 dowhen assessing dry retroreflectance.6.3 Measurements for each line type shall be averaged for afinal result.7. Calibration7.1 The portable or mobile retroreflectometer shall be cali-brated (standardized) using the instructions from the instru-ment manufacturer. A reference or working standard is
34、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 thecalibration or if the readings of a reference or working standardare not constant, a
35、llow the instrument to reach ambientconditions and recalibrate with the reference or workingstandard.7.3 Verification must be made that there is no moisture onthe reflectometers lens when the instrument is being used forwet readings. Adjust the water protective shield as necessary.7.4 Calibration Re
36、checkIf the subsequent readings on thereference 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.8. General
37、 Procedure8.1 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, t
38、he drymeasurement is optional per this test method.8.2 Measuring Dry Retroreflectance: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 squarely on the pavemen
39、tmarking material with the illumination in the direction oftravel. Ensure that the illuminated measurement area of theretroreflectometer fits within the width of the stripe, and take ameasurement.8.3 Measuring Wet Retroreflectance:8.3.1 If necessary, use a shield to prevent water splatter ontothe le
40、ns of the retroreflectometer.8.3.2 Position and adjust the water spray with the nozzlesuch that it provides an even spray covering the whole area tobe measured. Typically the spray area is approximately a20 6 2 in. circle. Open the nozzle until the water rate isapproximately 0.8 6 0.2 L/min. The pre
41、ssure in the tank shallbe maintained such that the flow does not noticeably diminish.Do not fill the sprayer too full of water so that one cannot keepa constant pressure. A range of14 to34 full works well. Thespraying height shall be 0.45 6 0.15 m (18 6 6 in.) above themarking.NOTE 3The most consist
42、ent spraying of the water has been foundwhen using a battery operated portable sprayer. With this type of sprayer,the water rate is constant and the volume level in the tank does not effectthe spray rate.8.3.3 With the retroreflectometer in place, a reading shall betaken initially in the dry conditi
43、on. (This is optional.)8.3.4 With the retroreflectometer still in place, the waterspray is turned on, and the area of the marking to be measuredand adjacent area (road) is wetted for 1015 s.8.3.5 Hold the water spray over the area of the marking tobe measured and take a measurement. Continue to take
44、measurements approximately every 10 s thereafter until littlechange in the values or a steady state occurs. This usually takesabout 30 s to obtain a steady state value.NOTE 4During the measurement process, the values obtained usuallystart high and will become lower until the steady state condition o
45、ccurs.8.3.6 Record the measurements in millicandelas per squaremetre per lux, (mcdm-2)/lx. Move to next measurementlocation which is separated sufficiently to provide meaningfuldata and repeat procedures 8.2 and 8.3.NOTE 5Verification must be made that there is no moisture on the lenswhen the instru
46、ment is being used for wet readings. Care must be takenwhen removing the moisture drops that a water smear is not left on thelens.8.4 Measuring Wet Reflectance Using a Wetting Agent:8.4.1 DiscussionThe use of a wetting agent as explainedherein is not a standard test procedure. However, the use of aw
47、etting agent may be a practical way to estimate the perfor-mance of newly installed markings.8.4.2 In order to wet out newly applied markings or toovercome release agents that may be present, a soap orsurfactant may be added to the water spray to overcome thistype of interference.8.4.3 After the sur
48、factant or soap has been added to thespray tank, the line is measured as in 8.3.NOTE 6Caution should be taken that bubbles are not created in theapplied soap/water mixture as the bubbles act as interference.9. Test Report9.1 Include the following in the test report.9.1.1 Test date.9.1.2 Average of t
49、he readings taken per line or markingexpressed in millicandelas per square metre per lux. The average of the readings shall be reported for wet and fordry conditions and for each traffic direction of interest.9.1.3 Readings for centerlines shall be taken for eachdirection of traffic. Readings for centerlines, edge lines, skiplines, etc., shall be averaged separately.9.1.4 Geographical location of the test site. Global position-ing system (GPS) location or distance from the nearestpermanent site identification, such as a mileage marker orcrossroad.E2176
