1、Designation: E1709 09E1709 16Standard Test Method forMeasurement of Retroreflective Signs Using a PortableRetroreflectometer at a 0.2 Degree Observation Angle1This standard is issued under the fixed designation E1709; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case 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 measurement of the retroreflective properties o
3、f sign materials such as traffic signs and symbols(vertical surfaces) using a portable retroreflectometer that can be used in the field. The portable retroreflectometer is a hand-heldinstrument with a defined standard geometry that can be placed in contact with sign material to measure the retrorefl
4、ection in astandard geometry. The measurements can be compared to minimum requirements to determine the need for replacement. Entranceand observation angles specified in this test method are those used currently in the United States and may differ from the anglesused elsewhere in the world.1.2 This
5、test method is intended to be used for the field measurement of traffic signs but may be used to measure theperformance of materials before placing the sign in the field or before placing the sign material on the sign face.1.3 This test method covers measurements at a 0.2 degree observation angle. S
6、ee Test Method E2540 for measurements at a0.5 degree observation angle.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and to determine
7、 the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D4956 Specification for Retroreflective Sheeting for Traffic ControlE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE284 Terminology of AppearanceE691 Practice for Conducting
8、 an Interlaboratory Study to Determine the Precision of a Test MethodE808 Practice for Describing RetroreflectionE809 Practice for Measuring Photometric Characteristics of RetroreflectorsE810 Test Method for Coefficient of Retroreflection of Retroreflective Sheeting Utilizing the Coplanar GeometryE2
9、540 Test Method for Measurement of Retroreflective Signs Using a Portable Retroreflectometer at a 0.5 Degree ObservationAngle3. Terminology3.1 The terminology used in this test method generally agrees with that used in Terminology E284.3.2 DefinitionsThe delimiting phrase “in retroreflection” applie
10、s to each of the following definitions when used outside thecontext of this or other retroreflection standards.3.2.1 annular geometry, nthe portable instrument retroreflection collection method where an annular area 0.1 degrees widearound the illumination axis collects the retroreflected energy at a
11、n angle to the center of the annular area corresponding to aspecific observation angle.3.2.2 coeffcient of retroreflection, RA, nof a plane retroreflecting surface, the ratio of the coefficient of luminous intensity (RI)of a plane retroreflecting surface to its area (A), expressed in candelas per lu
12、x per square metre (cd lx1 m2).1 This test method is under the jurisdiction ofASTM Committee E12 on Color andAppearance and is the direct responsibility of Subcommittee E12.10 on Retroreflection.Current edition approved July 1, 2009July 1, 2016. Published February 2010November 2016. Originally appro
13、ved in 1995. Last previous edition approved in 20082009as E1709 08.E1709 09. DOI: 10.1520/E1709-09.10.1520/E1709-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to t
14、he standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes a
15、ccurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United
16、States13.2.3 datum axis, na designated half-line from the retroreflector center perpendicular to the retroreflector axis.3.2.4 entrance angle, , nthe angle between the illumination axis and the retroreflector axis.3.2.5 entrance half-plane, nthe half plane that originates on the line of the illumina
17、tion axis and contains the retroreflectoraxis.3.2.6 instrument standard, nworking standard used to calibrate the portable retroreflectometer.3.2.7 observation angle, , nthe angle between the illumination axis and the observation axis.3.2.8 observation half-plane, nthe half plane that originates on t
18、he line of the illumination axis and contains the observationaxis.3.2.9 orientation angle, s, nthe angle in a plane perpendicular to the retroreflector axis from the entrance half-plane to thedatum axis, measured counter-clockwise from the viewpoint of the source.3.2.10 portable retroreflectometer,
19、na hand-held instrument that can be used in the field or in the laboratory for measurementof retroreflectance.3.2.10.1 DiscussionIn this test method, “portable retroreflectometer” refers to a hand-held instrument that can be placed in contact with sign materialto measure the retroreflection in a sta
20、ndard geometry.3.2.11 presentation angle, , nthe dihedral angle from the entrance half-plane to the observation half-plane, measuredcounter-clockwise from the viewpoint of the source.3.2.12 retroreflection, na reflection in which the reflected rays are returned preferentially in directions close to
21、the oppositeof the direction of the incident rays, this property being maintained over wide variations of the direction of the incident rays.3.2.13 rotation angle, , nthe angle in a plane perpendicular to the retroreflector axis from the observation half-plane to thedatum axis, measured counter-cloc
22、kwise from the viewpoint of the source.3.3 Definitions of entrance angle components 1 and 2, as well as other geometrical terms undefined in this test method, maybe found in Practice E808.4. Summary of Test Method4.1 This test method involves the use of commercial portable retroreflectometers for de
23、termining the retroreflectivity ofhighway signing materials.4.2 The entrance angle shall be 4.4.3 The observation angle shall be 0.2.4.4 The portable retroreflectometer uses an instrument standard for calibration.4.5 After calibration, the retroreflectometer is placed in contact with the sign to be
24、tested, ensuring that only the desired portionof the sign is within the measurement area of the instrument.4.6 The reading displayed by the retroreflectometer is recorded. The retroreflectometer is then moved to another position on thesign, and this value is recorded. A minimum of four readings shal
25、l be taken and averaged for each retroreflective color or materialon the sign to be tested.5. Significance and Use5.1 Measurements made by this test method are related to the night time brightness of retroreflective traffic signs approximatelyfacing the driver of a mid-sized automobile equipped with
26、 tungsten filament headlights at about 200 m distance.5.2 Retroreflective material used on traffic signs degrades with time and requires periodic measurement to ensure that theperformance of the retroflection provides adequate safety to the driver.5.3 The quality of the sign as to material used, age
27、, and wear pattern will have an effect on the coefficient of retroreflection.These conditions need to be observed and noted by the user.5.4 This test method is not intended for use for the measurement of signs when the instrument entrance and observation anglesdiffer from those specified herein.6. A
28、pparatusNOTE 1Paragraphs 6.1 and 6.2 are primarily addressing field considerations, while paragraphs 6.3 through 6.5 address typical lab settingconsiderations.E1709 1626.1 Portable RetroreflectometerThe retroreflectometer shall be portable, with the capability of being placed at variouslocations on
29、the signs. The retroreflectometer shall be constructed so that placement on the sign will preclude stray light (daylight)from entering the measurement area of the instrument and affecting the reading.6.2 Instrument Standard, or standards of desired color(s) and material(s).6.3 Light Source Requireme
30、nts:6.3.1 The projection optics shall be such that the illuminance at any point over the measurement area shall be within 10 % ofthe average illuminance.6.3.2 The aperture angle of the source as determined from the center of the measurement area shall be not greater than 0.1.6.4 Receiver Requirement
31、s:6.4.1 The receiver shall have sufficient sensitivity and range to accommodate coefficient of retroreflection values from 0.1 to1999.9 cd lx1 m2.6.4.2 The combined spectral distribution of the light source and the spectral responsivity of the receiver shall match thecombined spectral distribution o
32、f CIE Illuminant A and the V() spectral luminous efficiency function according to the followingcriterion: For any choice of plano-parallel colored absorptive filter mounted in front of a white retroreflective sample, the ratio ofthe RA measured with the filter to the RA measured without the filter s
33、hall be within 10 % of the Illuminant A luminoustransmittance of an air space pair of two such filters.6.4.3 The instrument may be either a “point instrument” or an “annular instrument,” depending on the shape of the receiveraperture (see Fig. 1). Point and annular instruments make geometrically dif
34、ferent measurements of RA, which may produce valuesdiffering on the order of 10 %. Both measurements are valid for most purposes, but the user should learn the type of instrumentfrom its specifications sheet and be aware of certain differences in operation and interpretation. For both instrument typ
35、es, the “up”position of the instrument shall be known. Both types of instruments may make additional measurements at observation anglesother than the 0.5 degree of this specification and combine the measurement at two or more different observation angles if thereadings at the different observation a
36、ngles are reported separately.6.4.3.1 The point instrument makes an RA measurement virtually identical to an RA measurement made on a range instrumentfollowing the procedure of Test Method E810. The 4 entrance angle would be set on a range instrument by setting 1=4; 2=0.This may be called “-4 entran
37、ce angle.” The rotation angle () for the point instrument is determined by the angular position ofthe instrument on the sign face. Assuming the retroreflectors datum axis to be upward, the rotation angle equals 0 when theinstrument is upright. Clockwise rotation of the instrument on the sign face in
38、creases the rotation angle.6.4.3.2 For the point instrument the “up” marking shall be opposite the entrance half-plane. It shall be in the observationhalf-plane (see Fig. 2).6.4.3.3 The annular instrument makes an RA measurement similar to an average of a large number of RA measurements on arange in
39、strument with presentation angle () varying between 180 and +180. For the 4 entrance angle the range instrumentwould include the 1 and 2 settings indicated in Table 1. There is no definite rotation angle () for the annular instrument. Allvalues from 180 to +180 are included in the measurement.6.4.3.
40、4 For the annular instrument the “up” marking shall be opposite the entrance half-plane (see Fig. 2).FIG. 1 Annular and Point Aperture Instrument AnglesE1709 1636.4.3.5 For both instrument types, the orientation angle (s) is determined by the angular position of the instrument on the signface. It is
41、 the rotation angle () rather than the orientation angle (s) which primarily affects retroreflection of signs measured atthe small 4 entrance angle.6.4.3.6 Rotationally insensitive sheetings, such as glass bead sheetings, have RA values that are nearly independent of therotation angle. Accordingly,
42、the point and annular instruments will make practically identical measurements of RA for signs madewith such sheetings.6.4.3.7 Most prismatic retroreflectors are rotationally sensitive, having RA values that vary significantly with rotation angle (),even at small entrance angles. The difference of R
43、A measurements made with the two types of instrument on prismatic signs maybecome as great as 25 % in extreme cases, but is generally on the order of 10 %. Neither the magnitude nor the direction ofdifference can be predicted for unknown samples. Thus, critical comparison of prismatic sign RA values
44、 measured by instrumentsof the two types is not recommended.6.4.3.8 A point instrument can gage the variation of RA with rotation angle by placing it with different angular positions uponthe sign face. RA variation of 5 % for 5 rotation is not unusual. Accordingly, repeatable RA measurement of prism
45、atic signs witha point instrument, requires care in angular positioning.6.4.3.9 An annular instrument cannot gage the variation of RA with rotation angle. Accordingly, repeatable RA measurement ofprismatic signs with an annular instrument does not require care in angular positioning. Positioning to
46、within 615 is sufficient.6.4.4 The aperture angle of the receiver as determined from the measurement area shall be not greater than 0.1. The apertureangle of the receiver is measured from inner to outer ring limits for annular receivers (see Fig. 1).NOTE 1For each instrument type, the illumination b
47、eam is 4 downward For the point instrument, receiver is above source.FIG. 2 Upright Optical SchematicsTABLE 1 Laboratory Emulation of Annular Instrument Geometry 1 2 0.2 3.86 1.03 1650.2 3.47 2.00 1500.2 2.83 2.83 1350.2 2.00 3.46 1200.2 1.04 3.86 1050.2 0.00 4.00 900.2 1.04 3.86 750.2 2.00 3.46 600
48、.2 2.83 2.83 450.2 3.47 2.00 300.2 3.86 1.03 150.2 4.00 0.00 00.2 3.86 1.03 150.2 3.47 2.00 300.2 2.83 2.83 450.2 2.00 3.46 600.2 1.04 3.86 750.2 0.00 4.00 900.2 1.04 3.86 1050.2 2.00 3.46 1200.2 2.83 2.83 1350.2 3.47 2.00 1500.2 3.86 1.03 1650.2 4.00 0.00 180E1709 1646.4.5 The combined stability of
49、 the output of the light source and receiver shall not change more than 61 % afterafter10 s when the retroreflectometer is in contact with the sign face.6.4.6 The linearity of the retroreflectometer photometric scale over the range of readings expected shall be within 2 %.Correction factors may be used to ensure a linear response. A method for determining linearity can be
