1、Designation:E254008Standard Test Method forMeasurement of Retroreflective Signs Using a PortableRetroreflectometer at a 0.5 Degree Observation Angle1This standard is issued under the fixed designation E2540;the number immediately following the designation indicates the year oforiginal adoption or,in
2、 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 retroreflec-tive properties of sign materials
3、such as traffic signs andsymbols(vertical surfaces)using a portable retroreflectometerthat can be used in the field.The portable retroreflectometer isa hand-held instrument with a defined standard geometry thatcan be placed in contact with sign material to measure theretroreflection in a standard ge
4、ometry.The measurements canbe compared to minimum requirements to determine the needfor replacement.Entrance and observation angles specified inthis test method are those used currently in the United Statesand may differ from the angles used elsewhere in the world.1.2 This test method is intended to
5、 be used for the fieldmeasurement of traffic signs but may be used to measure theperformance of materials before placing the sign in the field orbefore placing the sign material on the sign face.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are include
6、d in thisstandard.1.4 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.
7、2.Referenced Documents2.1 ASTM Standards:2E284 Terminology of AppearanceE808 Practice for Describing RetroreflectionE809 Practice for Measuring Photometric Characteristics ofRetroreflectorsE810 Test Method for Coefficient of Retroreflection ofRetroreflective Sheeting Utilizing the Coplanar Geometry3
8、.Terminology3.1 The terminology used in this test method generallyagrees with that used in Terminology E284.3.2 DefinitionsThe delimiting phrase“in retroreflection”applies to each of the following definitions when used outsidethe context of this or other retroreflection standards.3.2.1 annular geome
9、try,nthe portable instrument retrore-flection collection method where the retroreflected lux iscollected in an annulus 0.1 degrees wide centered on theillumination axis.3.2.1.1 DiscussionThe angle measured from the illumina-tion axis to the circle which divides the annulus into equalareas correspond
10、s to a specific observation angle.3.2.2 coeffcient of retroreflection,RA,nof a plane retrore-flecting surface,the ratio of the coefficient of luminousintensity(RI)of a plane retroreflecting surface to its area(A),expressed in candelas per lux per square metre(cd lx1 m2).3.2.3 datum axis,na designate
11、d half-line from the retrore-flector center perpendicular to the retroreflector axis.3.2.4 entrance angle,nthe angle between the illumina-tion axis and the retroreflector axis.3.2.5 entrance half-plane,nthe half plane that originateson the line of the illumination axis and contains the retrore-flect
12、or axis.3.2.6 instrument standard,nworking standard used tostandardize the portable retroreflectometer.3.2.7 observation angle,nthe angle between the illu-mination axis and the observation axis.3.2.8 observation half-plane,nthe half plane that origi-nates on the line of the illumination axis and con
13、tains theobservation axis.3.2.9 orientation angle,s,nthe angle in a plane perpen-dicular to the retroreflector axis from the entrance half-plane tothe datum axis,measured counter-clockwise from the view-point of the source.3.2.10 portable retroreflectometer,na hand-held instru-ment that can be used
14、in the field or in the laboratory formeasurement of retroreflectance.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 April 15,2008.Published May 2008.DOI:10.152
15、0/E2540-08.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.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 B
16、ox C700,West Conshohocken,PA 19428-2959.United States1 3.2.10.1 DiscussionIn this test method,“portable retrore-flectometer”refers to a hand-held instrument that can be placedin contact with sign material to measure the retroreflection in astandard geometry.3.2.11 presentation angle,nthe dihedral angle from theentrance half-plane to the observation half-plane,measuredcounter-clockwise from the viewpoint of the source.3.2.12 retroreflection,na reflection in which the reflectedrays are returned pr