1、Designation: E1696 15Standard Test Method forField Measurement of Raised Retroreflective PavementMarkers Using a Portable Retroreflectometer1This standard is issued under the fixed designation E1696; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the retrore-flective properties of raised retr
3、oreflective pavement markers ata prescribed geometry, by means of a portable retroreflecto-meter that can be used in the field. The measurements can becompared to minimum requirements to determine the need forreplacement.1.2 The observation angle specified for retroreflectometersin this test method
4、is that currently specified for raisedpavement markers in the United States and may differ from theangles used elsewhere. For other jurisdictions, replace theobservations angle specified herein with the observation anglespecified by the pertinent agency.1.3 This test method is intended to be used fo
5、r fieldmeasurement of raised retroreflective pavement markers butmay also be used to measure the performance of new markersbefore they are placed in the field.1.4 This test method covers measurements of raised pave-ment markers mounted on a road surface or mounted insnow-plowable metal castings.1.5
6、The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 The 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-pr
7、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use2. Referenced Documents2.1 ASTM Standards:2E284 Terminology of AppearanceE808 Practice for Describing RetroreflectionE809 Practice for Measuring Photometric Characteristics ofRetroreflectors3. Ter
8、minology3.1 The terms and definitions in Terminology E284 areapplicable to this test method. Some terms particular toretroreflection are defined and illustrated in Practice E808.3.2 Definitions:3.2.1 The delimiting phrase “in retroreflection” applies toeach of the following definitions when used out
9、side the contextof this or other retroreflection standards.3.2.2 coeffcient of luminous intensity, RI, nof aretroreflector, ratio of the luminous intensity (I) of the retrore-flector in the direction of observation to the illuminance (E|nt)at the retroreflector on a plane perpendicular to the direct
10、ion ofincident light, expressed in candelas per lux (cdlx1).3.2.2.1 DiscussionWhen values are low, the coefficient of(retroreflected) luminous intensity may be given in millican-delas per lux (mcdlx1). RI=(I/E|nt).3.2.3 portable retroreflectometera hand-held instrumentthat can be used in the field o
11、r in the laboratory for measure-ment of retroreflectance.3.2.3.1 DiscussionIn this test method, “portable retrore-flectometer” refers to a hand-held instrument that can be placedover a raised retroreflective pavement marker to measure thecoefficient of luminous intensity with a prescribed geometry.3
12、.2.4 instrument standard, na working standard used tostandardize the portable retroreflectometer.1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.10 onRetroreflection.Current edition approved Dec. 1, 2015. P
13、ublished January 2016. Originallyapproved in 1995. Last previous edition approved in 2004 as E1696 04 which waswithdrawn January 2013 and reinstated in December 2015. DOI: 10.1520/E1696-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
14、eastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 This test method involves the
15、 use of commercial por-table retroreflectometers for determining the coefficient ofluminous intensity of pavement markers.4.2 Entrance angle component 1shall be between 2 and0; entrance angle component 2shall be 0 6 2.4.3 Unless otherwise specified by the user, the observationangle shall be 0.2 6 0.
16、01.4.4 The observation half plane shall be vertical. Rotationangle shall be 0 (see Fig. 1 and Fig. 2).4.5 The aperture angles of the source and of the receivershall each be 0.1 with a tolerance of 60.04 on the sum of thetwo aperture angles.4.6 The aperture angle of an individual retroreflective ele-
17、ment shall be 0.02 max (see Practice E809). For a portablephotometer this aperture angle can be achieved by interposinga collimating lens in the illumination and observation axes.4.7 A portable standard shall be used for standardization.4.8 After standardization place the retroreflectometer di-rectl
18、y over the marker to be tested making sure that theroad-axis marking on the retroreflectometer is parallel to thelane line of the road.4.9 The reading displayed by the retroreflectometer is re-corded. The retroreflectometer is removed from the marker,then replaced and the reading recorded again. If
19、the differencein readings is greater than 10 %, the process is to be repeateda third time.5. Significance and Use5.1 Measurements of RImade by this test method, with the0.2 observation angle, are related to visual observation ofraised retroreflective pavement markers at distances of ap-proximately 2
20、20 m (720 ft) for cars or approximately 440 m(1440 ft) for trucks when illuminated by tungsten filament lightsources such as car headlights.5.2 There are some castings that block vehicle illuminationof a portion of the marker mounted within it. In this case,measured RIcan be significantly lower than
21、 when the markeris photometered outside the casting, but will correspond to thevisual observation.5.3 The test method is not applicable to raised pavementmarkers mounted in depressions cut into the pavement.5.4 The coefficient of luminous intensity of raised retrore-flective pavement markers degrade
22、s with traffic wear andrequires periodic measurement to ensure that sufficient visibil-ity is provided to the driver.5.5 The quality of the pavement markers as to materialsused, age and wear pattern, will have an effect on thecoefficient of (retroreflected) luminous intensity. These condi-tions need
23、 to be observed and noted by the user.6. Apparatus6.1 Portable Retroreflectometer:6.1.1 The retroreflectometer shall be portable with thecapability of being positioned over markers installed on theroadway surface.6.1.2 The retroreflectometer shall be constructed so thatplacement on the road will pre
24、clude any stray light fromentering the area being tested under daylight conditions.6.1.3 The retroreflectometer shall be constructed so that itcan be placed over the marker with the illumination axisapproximately parallel to the road surface.6.1.4 The combined spectral distribution of the light sour
25、ceand the spectral responsivity of the receiver shall match thecombined spectral distribution of CIE Standard Illuminant Aand the V() photopic spectral luminous efficacy functionaccording to the following two criteria for all 0between 470nm and 640 nm:0.9,1(5360830expSS 2 025D2DS!R!(5360830A!V!(5360
26、830expSS 2 025D2DA!V!(5360830S!R!2,1.1and also1(56701000S!R!(53601000S!R!2,0.02where:S() = instrument illumination spectral power distribution,R() = instrument spectral responsivity,A() = CIE Standard Illuminant A, andV() = CIE photopic luminous efficacy function.FIG. 1 Position of Marker for Photom
27、etryE1696 152The 0shall be chosen at 5 nm intervals and the summationsshall be at 5 nm intervals.NOTE 1A user can partially verify the instrument spectral correctionby making a pair of RImeasurements on a crystal-white unmetallizedlarge-prism retroreflector, one measurement with and one measurementw
28、ithout a calibrated absorptive filter interposed. For relevance, the filterscolors should resemble some retroreflective markers color. The filtershould be mounted with approximately 1 downward tilt to avoid specularreflection into the receiver. The transmittance of the filter (in air) must besquared
29、 and a value for luminous transmittance of CIE illuminant Acalculated. The ratio of the two RImeasurements should match theluminous transmittance value to within approximately 10 %. The verifi-cation can be repeated for several colors of interest.NOTE 2The second criterion can alternatively be met b
30、y means of afilter test. A 3 mm thick Schott RG-665 filter glass shall be mounted infront of a crystal-white unmetallized large-prism retroreflector, the RImeasured, and the value divided by the RImeasured without the filter. Theratio shall be less than 2 %. The filter should be mounted with approxi
31、-mately 1 downward tilt to avoid specular reflection into the receiver.6.1.5 When using a standard similar in color, material, andtype to the sample, measured RIshall not deviate by more than10 % from measurements made on a laboratory photometerconforming to Practice E809 with observation angle, ,as
32、specified and 1= 2= = 0.6.1.6 If, for convenience, the user chooses to use a whitestandard for all markers, a correction factor shall be applied tothe readings obtained with the white standard. To determine thecorrection factor, (1) standardize the instrument using a whitestandard; (2) without chang
33、ing the instrument settings, note thereading for a selected prephotometered standard similar incolor, material, and type to the markers to be tested; and (3)divide the known retroreflectance of the selected prephotom-etered standard by the reading noted in (2). Multiply allreadings obtained for mark
34、ers of a particular color, material,and type by the correction factor obtained for that color,material, and type.6.1.7 For the convenience of the user, a road-axis markingshould be placed on the instrument to permit it to be alignedwith the direction of traffic.6.2 Light Source Requirements:6.2.1 Th
35、e projection optics shall be such that the illumi-nance over the entire test area shall be within 10 % of theaverage illuminance.6.2.2 The source shall be regulated such that the illumina-tion of the test area does not change by more than 61 % for theduration of the test.6.2.3 For measurement of sur
36、face mounted markers, thelower edge of the illumination shall be no more than 1 mmabove ground level at the distance of the markers leadingedge.6.2.4 For measurement of markers in castings, the loweredge of the illumination shall be within 60.5 mm of groundlevel at the distance where the marker lens
37、 intersects theground level.6.3 Receiver Requirements:6.3.1 The receiver shall have sufficient sensitivity and rangeto accommodate coefficient of luminous intensity values ex-pected in use, typically 1 to 1999 mcdlx1.6.3.2 The receiver response shall not vary more than 62%for the duration of the tes
38、t.6.4 Measurement Geometry:6.4.1 The light source and receiver shall be at opticalinfinity to ensure that the angular aperture of an individualretroreflecting element shall be not more than 0.02.6.4.2 The light source and receiver shall be separated fromeach other by a center to center distance corr
39、esponding to 0.26 0.01 observation angle.7. Procedure7.1 Turn on the retroreflectometer and allow it to reachequilibrium.7.2 With the retroreflectometer positioned on the roadsurface near the markers to be tested, adjust the retroreflecto-meter zero knob for reading of 0 6 2 in the least significant
40、figure. For laboratory use the retroflectometer shall be zeroedon the same non-retroreflective surface on which the marker isto be positioned for test.7.3 At approximately the same location on the road wherethe retroflectometer was adjusted for zero, place an instrumentstandard similar in color, mat
41、erial, and type to the marker beingtested and having a known and relatively constant retroreflec-tivity. The instrument standard shall be checked on a laboratoryphotometer (see Practice E809) at regular intervals, and thestandard value shall be adjusted.7.4 Position the retroflectometer over the ins
42、trument stan-dard and turn on the instrument. After warm up for the timerecommended by the manufacturer, typically 15 s, set theinstrument gain so that the meter shows the value of theinstrument standard.FIG. 2 Angles and Apertures for Collimating Type Portable Retroreflectometer for Raised Retroref
43、lective Pavement MarkersE1696 1537.5 Place the retroflectometer over the marker to be pho-tometered making sure that there are no impediments to seatingthe instrument on the roadway surface. Record the value of themeasurement in mcdlx1.7.6 Remove the retroreflectometer, reposition the retrore-flecto
44、meter over the marker, and again record the reading. Ifthe two readings differ by more than 10 %, again remove andreposition the retroreflectometer and take a third reading.7.7 Wipe the surface of the marker with a soft rag very wetwith detergent and water using care not to abrade the markersurface.
45、 Dry thoroughly by patting with a paper towel.7.8 Repeat 7.6 and 7.7 and record readings for the markersafter cleaning.8. Report8.1 Report the following information:8.1.1 The test date,8.1.2 The marker location including distance from thenearest permanent site identification such as a mileage marker
46、or crossroad,8.1.3 The identification of the instrument used,8.1.4 The average reading before cleaning and averagereading after cleaning. The readings will be the coefficient ofluminous intensity in millicandelas per lux (mcd/lx),8.1.5 Remarks as to condition of the marker such aspercentage of area
47、undamaged, and8.1.6 The value and date of standardization and identifica-tion of the reference standard used.9. Sources of Error9.1 There are many factors that cause high variability whentaking readings in the field.9.1.1 Retroreflectometers with differing entrance angles,observation angles, or angu
48、lar apertures, or combinationthereof will give different readings.9.1.2 Retroreflectometers lacking a collimating lens toeliminate the effects of size of the retroreflecting element willgive different readings and are not recommended (see 4.6).9.1.3 Slight differences in the seating of the retrorefl
49、ecto-meter around the marker may give different readings.9.1.4 Differences in the cleanliness of the marker will causedifferences in reading. For instance, a marker photometeredshortly after a rain will read higher than the same markerphotometered after a long dry spell.10. Precision and Bias10.1 These data are under development.11. Keywords11.1 portable retroreflectometers; raised retroreflectivepavement markers; retroreflectionASTM International takes no position respecting the validity of any p
