1、Designation:E254016Standard 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、1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to
8、Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE284 Terminology of AppearanceE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE808 Practice for Describing Retrorefle
9、ctionE809 Practice for Measuring Photometric Characteristics ofRetroreflectorsE810 Test Method for Coefficient of Retroreflection ofRetroreflective Sheeting Utilizing the Coplanar Geometry3.Terminology3.1 The terminology used in this test method generallyagrees with that used in Terminology E284.3.2
10、 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 geometry,nthe portable instrument retrore-flection collection method where the retroreflected lux iscollected in an
11、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 corresponds to a specific observation angle.3.2.2 coeffcient of retroreflection,RA,nof a plane retrore-flecting surface,t
12、he 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 designated half-line from the retrore-flector center perpendicular to the retroreflector axis.1This test method is under
13、 the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.10 onRetroreflection.Current edition approved Nov.1,2016.Published April 2017.Originallyapproved in 2008.Last previous edition approved in 2008 as E2540 08.DOI:10.1520/E2540-16.2For re
14、ferenced 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 Box C700,West Consh
15、ohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organi
16、zation Technical Barriers to Trade(TBT)Committee.1 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-flector 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 p
