ASTM E2177-20

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Designation: E2177 − 19 E2177 − 20
Standard Test Method for
Measuring the Coefficient of Retroreflected Luminance (R )
L
of Pavement Markings using the Bucket Method in a
Standard Condition of WetnessWet Recovery
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
1.1 This test method covers the measurement of the wet retroreflective (R ) properties of horizontal pavement marking materials,
L
such as traffic stripes and road surface symbols, using a portable or mobile retroreflectometer that can be placed on or before the
road marking to measure the retroreflection at the prescribed geometry.
1.2 This method of measuring the wet retroreflective properties (R ) of pavement markings measures the wet retroreflectivity in
L
a standard condition of wetness wet recovery (see Fig. 1).
1.2.1 Discussion—This test condition typically exists (1) after a rainfall has ended and the pavement markings are still wet or (2)
as the markings are wet from dew or humidity.
1.3 Retroreflective performance obtained with this test in conditionscondition of wetness wet recovery does not necessarily relate
to how markings perform in conditions of rain, that is, as markings are being rained upon. Test Method E2832 defines a method
to measure the performance of pavement markings in conditions of simulated rain.
1.4 This test method specifies the use of portable or mobile reflectometers that can measure pavement markings in accordance with
Test Method E1710. The entrance and observation angles required of the retroreflectometer in this test method are commonly
referred to as “30 meter geometry.”
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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 Jan. 1, 2019Oct. 1, 2020. Published February 2019October 2020. Originally approved in 2001. Last previous edition approved in 20182019 as
E2177 – 18.E2177 – 19. DOI: 10.1520/E2177-19.10.1520/E2177-20.
Reference ASTM E1710 “Standard Test Method for Measurement of Retroreflective Pavement Markings with CEN-Prescribed Geometry Using a Portable
Retroreflectometer.” The standard measurement condition is intended to represent the angles corresponding to a distance of 30 m for the driver of a passenger car with an
eye height of 1.2 m and a headlight height of 0.65 m above the road. See Appendix X1.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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FIG. 1 Illustration of Measurement
2. Referenced Documents
2.1 ASTM Standards:
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E965 Test Method for Measuring Pavement Macrotexture Depth Using a Volumetric Technique
E1710 Test Method for Measurement of Retroreflective Pavement Marking Materials with CEN-Prescribed Geometry Using a
Portable Retroreflectometer
E2832 Test Method for Measuring the Coefficient of Retroreflected Luminance of Pavement Markings in a Standard Condition
of Continuous Wetting (R )
L-2
2.2 Other Standard:
CEN–EN 1436 Road Marking Materials—Road Marking Performance for Road Users and Test Methods
3. Terminology
3.1 coeffıcient of retroreflected luminance, R ,n—the ratio of the luminance, L, of a projected surface to the normal illuminance,
L
2 1
E, at the surface on a plane normal to the incident light, expressed in candelas per square meter per lux (cd/m /lx ). Because of
the low luminance of pavement markings, the units commonly used are millicandelas per square meter per lux (mcd/m /lx).
3.2 condition of wetness, wet recovery, n—the test condition is created by liberally wetting the pavement marking and waiting a
certainspecific time period after wetting for water to run off.off (recover) before taking a retroreflectivity reading.
3.2.1 Discussion—
Similar conditions exist when pavement markings are wet or damp such as typically found after a rain has ended or from dew and
high humidity.
3.3 mobile retroreflectometer, n—a retroreflectometer that has been mounted to a vehicle for purposes of taking measurements
while the vehicle is moving.
3.4 portable retroreflectometer, n—an a hand held instrument that can be used in the field or laboratory for measuring the
coefficient of retroreflected luminance, R .
L
3.5 “recovery method” or “bucket method”, n—alternative names commonly used to describe this test method for achieving
measurements in condition of wetness.wet recovery.
3.6 R ,n—the retroreflectance value, R , obtained 45 s after wetting. (See Fig. 2.)
L-wet L
4. Significance and Use
4.1 The nighttime performance of pavement markings is determined by the coefficient of retroreflected luminance, R , be it dry
L
or wet, and depends on the materials used, age, and wear pattern. These conditions shall be observed and noted by the user.
4.2 Under the same conditions of headlight illumination and driver’s viewing, larger values of R correspond to higher levels of
L
visual performance at corresponding geometry.
4.3 The pavement marking’s measured performance in the standard condition of wetness wet recovery is used to characterize the
performance of the marking on the road when wet.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from European Committee for Standardization (CEN), 36 rue de Stassart, B-1050, Brussels, Belgium, http://www.cenorm.be.
E2177 − 20
FIG. 2 Definition of R
L-Wet
4.4 Newly installed pavement markings may have a natural surface tension or release agents that prevent wetting of the product
by water. The water will tend to “bead up” on the marking. This “non wetting” condition is usually short lived. Pavement markings
that have been on the road for one month prior to testing usually do not exhibit this non-wetting phenomenon. (Warning—
WarningThis–This phenomenon produces an interference when assessing the wet characteristics of a pavement marking. Attempts
to measure markings with this surface “non-wetting” or “beading” of the water may give higher values.)
4.5 The retroreflectivity, R , of pavement (road) markings degrades with traffic wear and requires periodic measurement to ensure
L
that sufficient line visibility is provided to drivers.
4.6 For a given viewing distance, measurements of R made with a retroreflectometer having a geometry corresponding to that
L
viewing distance are a good indicator of the visual ranking of the material measured.
4.7 As specified by Test Method E1710, the measurement geometry of the instrument is based on a viewing distance of 30 m, an
eye height of 1.2 m and a headlight mounting height of 0.65 m (see Appendix X1).
4.8 It shall be the responsibility of the user to employ an instrument having the specified observation and entrance angles.
5. Apparatus
5.1 Portable or Mobile Retroreflectometer—The reflectometer 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 A bucket capable of holding 3 litersL shall be used to create the wet condition by pouring the water over the marking.
5.3.2 The water shall be clean tap water.
6. Sampling
6.1 The number of test results obtained at each test location and the spacing between test locations shall be specified by the user.
6.2 A test site shall consist of three measurement areas spaced as closely as possible, while maintaining a distance between
measurement areas sufficient to ensure no interference in preparation and testing.
6.3 Test results for each line type shall be averaged for a final result.
7. Calibration and Precautions
7.1 The portable or mobile retroreflectometer shall be calibrated (standardized) using the instructions from the instrument
manufacturer. A reference or working standard is used and is supplied with the instrument.
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7.2 Transporting the portable reflectometer from an air conditioned area to the test site may result in fogging of mirrors in the
instrument. If there is any doubt concerning the calibration or if the readings of a reference or working standard are not constant,
allow the instrument to reach ambient conditions and recalibrate with the reference or working standard.
7.3 Verification must be made that there is no moisture on the instrument’s lens when the instrument is being used for wet readings.
Sometimes the reflectometer’s lens will become “fogged over” in high temperatures due to water evaporation. When roads are hot
one can pre-cool the road with water before applying the test method to prevent the reflectometer from fogging.
7.4 Calibration Recheck—If the subsequent readings on the reference standard deviate by more than 5 % from the initial one
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