1、Designation:E 2176 08Standard Test Method forMeasuring the Coefficient of Retroreflected Luminance ofPavement Markings in a Standard Condition of ContinuousWetting(RL-Rain)1This standard is issued under the fixed designation E 2176;the number immediately following the designation indicates the year
2、oforiginal adoption 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 a measurement of the wetretroreflective(
3、RL-Rain)properties of horizontal pavementmarking materials,such as traffic stripes and road surfacesymbols.1.2 This method of measuring wet retroreflective properties(RL)of pavement markings utilizes a method of continuouslywetting the marking during measurement(see Fig.1).NOTE1Test Method E 2177 ma
4、y be used to describe the retroreflec-tive properties of pavement markings in conditions of wetness after aperiod of rain.1.3 This test method is most suitable for laboratory useunder controlled conditions,but may also be used for fieldmeasurements when the necessary controls and precautions arefoll
5、owed.1.4 This test method specifies the use of reflectometers thatcan measure pavement markings per Test Method E 1710.2Theentrance and observation angles required of the retroreflecto-meter in this test method are commonly referred to as“30meter geometry.”21.5 This test method has been shown to pro
6、duce reasonableresults for pavement marking systems with optics having anindex of refraction greater than 2.0 and structured markingshaving vertical structures greater than or equal to 3 mm.3Usersshould exercise caution when using this test method forpavement marking systems with optics having an in
7、dex ofrefraction less than 2.0 or markings having vertical structuresless than 3 mm.1.6 Results obtained using this test method should not be thesole basis for specifying and assessing the wet retroreflectiveeffectiveness of pavement marking systems.Users shouldcomplement the results of this test me
8、thod with other evalua-tion results,such as nighttime visual inspections.1.7 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
9、 applica-bility of regulatory limitations prior to use.NOTE2An alternative test method designed to better represent theretroreflective efficiency of pavement marking systems under typical rainevents is under development.2.Referenced Documents2.1 ASTM Standards:4E 691 Practice for Conducting an Inter
10、laboratory Study toDetermine the Precision of a Test MethodE 965 Test Method for Measuring Pavement MacrotextureDepth Using a Volumetric TechniqueE 1710 Test Method for Measurement of RetroreflectivePavement Marking Materials with CEN-Prescribed Geom-etry Using a Portable RetroreflectometerE 2177 Te
11、st Method for Measuring the Coefficient of Ret-roreflected Luminance(RL)of Pavement Markings in aStandard Condition of Wetness3.Terminology3.1 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
12、the incident light,expressed in candelas per square metre per lux(cdm-2)/lx.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.1,2008.Published December 2008.O
13、riginallyapproved in 2001.Last previous edition approved in 2001 as E 2176-01.2Reference ASTM E 1710.The standard measurement condition is intended torepresent the angles corresponding to a distance of 30 m for the driver of a passengercar with an eye height of 1.2 m and a headlight height of 0.65 m
14、 above the road.SeeAppendix X1.3The 3 mm minimum vertical structure height is based on a survey of materialsevaluated and reported on in:FHWA/VTRC 05-CR3 Wet Night Visibility ofPavement Markings,VTRC(October 2004),FHWA/TX-06/0-5008-1 Evaluation ofWet-Weather Pavement Markings,First Year Report,TTI(S
15、ept 2005),FHWA/TX-07/0-5008-2 Evaluation of Wet-Weather and Contrast Pavement Markings,FinalReport,TTI(Aug 2007).4For 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 stan
16、dards Document Summary page onthe ASTM website.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.Copyright ASTM International Provided by IHS under license with ASTM Licensee=Ohio State University/5967164005 Not for Resale,03/02/2012 21:31:20 MSTNo reproduction or networking permitted without license from IHS-,-,-Because of the low luminance of pavement markings,the unitscommonly used are millicandelas per square metre per lux(mcdm-2)/l
