ASTM E2177-01

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Designation: E2177 – 01
Standard Test Method for
Measuring the Coefficient of Retroreflected Luminance (R )
L
of Pavement Markings in a Standard Condition of Wetness
This standard is issued under the fixed designation E2177; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers the measurement of the wet
retroreflective (R ) properties of horizontal pavement marking
L
materials, such as traffic stripes and road surface symbols,
usingaportableormobileretroreflectometerthatcanbeplaced
on or before the road marking to measure the retroreflection at
the prescribed geometry.
FIG. 1 Illustration of Measurement
1.2 This method of measuring the wet retroreflective prop-
erties (R ) of pavement markings measures the wet retroreflec-
L
2.1 ASTM Standards:
tivity in a standard condition of wetness (see Fig. 1).
D6359 Specification for Minimum Retroreflectance of
1.2.1 Discussion—This test condition typically exists (1)
Newly Applied Pavement Marking Using Portable Hand-
after a rainfall has ended and the pavement markings are still
Operated Instruments
wet or (2) as the markings are wet from dew or humidity.
E691 Practice for Conducting an Interlaboratory Study to
1.3 Retroreflective performance obtained with this test in
Determine the Precision of a Test Method
conditions of wetness does not necessarily relate to how
E965 Test Method for Measuring Pavement Macrotexture
markings perform in conditions of rain, that is, as markings are
Depth Using a Volumetric Technique
being rained upon.
E1710 Test Method for Measurement of Retroreflective
NOTE 1—Test Method E2176 defines a method to use to measure the
Pavement Marking Materials with CEN-Prescribed Geom-
performance of pavement markings in conditions of simulated rain.
etry Using a Portable Retroreflectometer
1.4 This test method specifies the use of portable or mobile
E2176 Test Method for Measuring the Coefficient of Ret-
reflectometers that can measure pavement markings in accor-
roreflected Luminance of Pavement Markings in a Stan-
dance with Test Method E1710. The entrance and observation
dard Condition of Continuous Wetting (R )
L-Rain
angles required of the retroreflectometer in this test method are
2.2 Other Standard:
commonly referred to as “30 meter geometry.”
CEN–EN 1436 Road Marking Materials—Road Marking
1.5 This standard does not purport to address all of the
Performance for Road Users
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.1 coeffıcient of retroreflected luminance, R —the ratio of
L
bility of regulatory limitations prior to use.
the luminance, L, of a projected surface to the normal illumi-
nance, E, at the surface on a plane normal to the incident light,
-2
expressed in candelas per square metre per lux [(cd·m )/lx].
This test method is under the jurisdiction of ASTM Committee E12 on Color
and Appearance and is the direct responsibility of Subcommittee E12.10 on
Retroreflection.
Current edition approved Dec. 10, 2001. Published February 2002. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/E2177-01. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Reference ASTM E1710 “Standard Test Method for Measurement of Retrore- Standards volume information, refer to the standard’s Document Summary page on
flective Pavement Markings with CEN-Prescribed Geometry Using a Portable the ASTM website.
Retroreflectometer.” The standard measurement condition is intended to represent Withdrawn. The last approved version of this historical standard is referenced
the angles corresponding to a distance of 30 m for the driver of a passenger car with on www.astm.org.
an eye height of 1.2 m and a headlight height of 0.65 m above the road. See Available from European Committee for Standardization (CEN), 36 rue de
Appendix X1. Stassart, B-1050, Brussels, Belgium, http://www.cenorm.be.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2177 – 01
Because of the low luminance of pavement markings, the units 4.5 The retroreflectivity, R , of pavement (road) markings
L
commonly used are millicandelas per square metre per lux degrades with traffic wear and requires periodic measurement
-2
[(mcd·m )/lx]. to ensure that sufficient line visibility is provided to drivers.
3.2 condition of wetness—the test condition is created by For example see Specification D6359 for dry retroreflectivity
liberally wetting the road marking and waiting a certain time requirements.
period after wetting for water to run off. 4.6 For a given viewing distance, measurements of R made
L
3.2.1 Discussion—Similar conditions exist when road with a retroreflectometer having a geometry corresponding to
markings are wet or damp such as typically found after a rain that viewing distance are a good indicator of the visual ranking
has ended or from dew and high humidity. of the material measured.
3.3 mobile retroreflectometer—a retroreflectometer that has 4.7 As specified by Test Method E1710, the measurement
been mounted to a vehicle for purposes of taking measure- geometry of the instrument is based on a viewing distance of
ments while the vehicle is moving. 30 m, an eye height of 1.2 m and a headlight mounting height
3.4 portable retroreflectometer—an instrument that can be of 0.65 m (see Appendix X1).
used in the field or laboratory for measuring the coefficient of 4.8 It shall be the responsibility of the user to employ an
retroreflected luminance, R . instrument having the specified observation and entrance
L
3.5 “recovery method” or “bucket method”—alternative angles.
names commonly used to describe this test method for achiev-
5. Apparatus
ing measurements in condition of wetness.
5.1 Portable or Mobile Retroreflectometer—The reflecto-
3.6 R —the retroreflectance value, R , obtained 45 s
L-wet L
after wetting. (See Fig. 2.) meter must comply with Test Method E1710.
5.2 Stopwatch or Watch, with second hand.
5.3 Water, for wetting the pavement marking.
5.3.1 Aportable hand sprayer (garden sprayer) may be used
to wet the pavement marking to create the wet condition. The
portablehandsprayershallhaveanadjustablenozzle.Abattery
operated unit works well.
5.3.2 Alternatively a bucket may be used to create the wet
condition by pouring the water over the marking. Approxi-
mately 2 to 5 L of water are needed.
5.3.3 The water shall be clean tap water.
6. Sampling
6.1 The number of readings to be taken at each test location
and the spacing between test locations shall be specified by the
FIG. 2 Definition of R
L-Wet
user.
6.2 It is common to take less frequent measurements than
4. Significance and Use
one would do when assessing dry retroreflectance.
4.1 The nighttime performance of pavement markings is
6.3 Measurements for each line type shall be averaged for a
determined by the coefficient of retroreflected luminance, R , final result.
L
be it dry or wet, and depends on the materials used, age, and
7. Calibration and Precautions
wear pattern. These conditions shall be observed and noted by
the user. 7.1 The portable or mobile retroreflectometer shall be cali-
4.2 Under the same conditions of headlight illumination and brated (standardized) using the instructions from the instru-
driver’s viewing, larger values of R correspond to higher ment manufacturer. A reference or working standard is used
L
levels of visual performance at corresponding geometry.
and is supplied with the instrument.
4.3 The pavement marking’s measured performance in the 7.2 Transporting the portable reflectometer from an air
standard condition of wetness is used to characterize the conditionedareatothetestsitemayresultinfoggingofmirrors
performance of the marking on the road when wet. in the instrument. If there is any doubt concerning the
4.4 Newly installed pavement markings may have a natural calibrationorifthereadingsofareferenceorworkingstandard
surface tension or release agents that prevent wetting of the are not constant, allow the instrument to reach ambient
product by water. The water will tend to “bead up” on the conditions and recalibrate with the reference or working
marking. This “non wetting” condition is usually short lived. standard.
Pavement markings that have been on the road for one month 7.3 Verification must be made that there is no moisture on
prior to testing usually do not e
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