ASTM E2302-03a(2022)
(Test Method)Standard Test Method for Measurement of the Luminance Coefficient Under Diffuse Illumination of Pavement Marking Materials Using a Portable Reflectometer
Standard Test Method for Measurement of the Luminance Coefficient Under Diffuse Illumination of Pavement Marking Materials Using a Portable Reflectometer
SIGNIFICANCE AND USE
5.1 The quality of the stripe for visibility in daylight or under road lighting is determined by the luminance coefficient under diffuse illumination, Qd, and depends on the materials used, age, and wear pattern. These conditions shall be observed and noted by the user.
5.2 Under the same conditions of illumination and viewing, higher levels of Qd correspond to higher levels of lightness.
5.3 Reflectivity of pavement (road) markings degrade with traffic wear and require periodic measurement to ensure that sufficient line visibility is provided to drivers.
5.4 For a given viewing distance, measurements of Qd made with a reflectometer having a geometry corresponding to that distance are a good indicator of the visual ranking of material measured.
5.5 specified by CEN, the measurement geometry of the instrument is based on a viewing distance of 30 m and an eye height of 1.2 m.
5.6 It shall be the responsibility of the user to employ an instrument having the specified co-viewing angle.
SCOPE
1.1 This test method covers measurement of the luminance coefficient under diffuse illumination of horizontal pavement markings, such as traffic stripes and surface symbols, and pavement surfaces, in a particular viewing direction using a portable reflectometer.
Note 1: The luminance coefficient under diffuse illumination is a measure of the reflection of horizontal pavement markings and pavement surfaces in a particular viewing direction in daylight or under road lighting. Diffuse illumination approximates daylight illumination from the overcast sky, and road lighting as an average of locations on the pavement surface.
1.2 The co-viewing angle of the reflectometer affects the readings. As specified by the European Committee for Standardization (CEN), the co-viewing angle shall be 2.29°.
1.3 This test method is intended to be used for field measurement of pavement markings and pavement surfaces but may be used to measure the performance of materials on sample panels before placing the marking material in the field.
1.4 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.
1.5 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.
General Information
Relations
Standards Content (Sample)
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.
Designation:E2302 −03a (Reapproved 2022)
Standard Test Method for
Measurement of the Luminance Coefficient Under Diffuse
Illumination of Pavement Marking Materials Using a Portable
Reflectometer
This standard is issued under the fixed designation E2302; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 measurement of the luminance 2.1 ASTM Standards:
coefficient under diffuse illumination of horizontal pavement E284Terminology of Appearance
markings, such as traffic stripes and surface symbols, and E809Practice for Measuring Photometric Characteristics of
pavement surfaces, in a particular viewing direction using a Retroreflectors
portable reflectometer.
2.2 Other Standard:
NOTE 1—The luminance coefficient under diffuse illumination is a
CEN EN 1436Road Marking Materials—Road Marking
measure of the reflection of horizontal pavement markings and pavement
Performance for Road Users
surfaces in a particular viewing direction in daylight or under road
lighting.Diffuseilluminationapproximatesdaylightilluminationfromthe
3. Terminology
overcastsky,androadlightingasanaverageoflocationsonthepavement
surface.
3.1 The terminology used in this test method generally
1.2 The co-viewing angle of the reflectometer affects the
agrees with that used in Terminology E284.
readings. As specified by the European Committee for Stan-
3.2 Definitions:
dardization (CEN), the co-viewing angle shall be 2.29°.
3.2.1 luminance coeffıcient under diffuse illumination; Qd,
1.3 This test method is intended to be used for field
n—the ratio of luminance, L, in a particular viewing direction,
measurementofpavementmarkingsandpavementsurfacesbut
of a projected surface to the illuminance of diffuse
may be used to measure the performance of materials on
illumination, E, at the surface on the plane of the surface,
-2 -1
sample panels before placing the marking material in the field.
expressed in candelas per square metre per lux (cd·m ·lx ).
3.2.1.1 Discussion—Qd has a range from zero up to a
1.4 This standard does not purport to address all of the
-2 -1
maximum of 1/π = approximately 0.318 cd·m ·lx . For
safety concerns, if any, associated with its use. It is the
convenience, the units used commonly are millicandelas per
responsibility of the user of this standard to establish appro-
-2 -1
square metre per lux (mcd·m ·lx ) providing a range from
priate safety, health, and environmental practices and deter-
-2 -1
zero up to 1000/π = approximately 318 mcd·m ·lx .
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
3.2.2 co-viewing angle, a, n—theanglebetweentheplaneof
dance with internationally recognized principles on standard-
the pavement marking surface and the observation axis.
ization established in the Decision on Principles for the
3.2.3 portable reflectometer, n—a hand-held instrument that
Development of International Standards, Guides and Recom-
can be used in the field or laboratory for measurement of
mendations issued by the World Trade Organization Technical
luminance coefficient under diffuse illumination.
Barriers to Trade (TBT) Committee.
1 2
This test method is under the jurisdiction of ASTM Committee E12 on Color For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Appearance and is the direct responsibility of Subcommittee E12.10 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Retroreflection. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Feb. 1, 2022. Published February 2022. Originally the ASTM website.
approved in 2003. Last previous edition approved in 2016 as E2302–03a (2016). Available from European Committee for Standardization (CEN), Avenue
DOI: 10.1520/E2302-03AR22. Marnix 17, B-1000, Brussels, Belgium, http://www.cen.eu.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2302−03a (2022)
3.2.4 instrument standard, n—working standard used to directionoftraffic,ortheinstrumentdesignshallitselfindicate
standardize the portable reflectometer. the measuring direction in an obvious manner.
6.2 Illumination System Requirements:
4. Summary of Test Method
6.2.1 The illumination system shall provide diffuse
4.1 This test method involves the use of commercial por-
illumination, which can be obtained by indirect illumination
table reflectometers for determining the luminance coefficient
through a sample gate from a photometric sphere of interior
under diffuse illumination in a particular viewing direction of
white, matte finish.
horizontal coatings materials used in pavement markings.
6.2.2 The illumination system shall have compensation for
4.2 The co-viewing angle is fixed at 2.29°.
the increase of illumination caused by interreflection between
a sample surface and the interior surfaces of the illumination
4.3 The reflectometers use an external panel or other instru-
system, for instance by means of a reading of the illuminance
ment standard of known luminance coefficient under diffuse
at a location close to the sample gate.
illumination, Qd.
6.2.3 The diffuse illumination may be approximated by
4.4 The portable reflectometer is placed directly over the
reflection from the interior surface of sphere or other shape or
pavement marking to be measured, ensuring that the measure-
by other means. Enough testing shall be carried out to verify
ment area of the reflectometer fits within the width of the
that flux received on the sample is approximately homoge-
stripe, and the reading displayed by the reflectometer is
neous. For measurements from all positions in the sample gate
recorded.
and in all directions, using a collection cone of an included
4.5 Readings shall be taken for the direction of traffic.
angle of 8 degrees the ratio of the smallest to the largest
Readings shall be taken for each direction of traffic separately
measurement shall be minimum 0.8. The test shall be carried
for centerlines.
out with the sample gate open, and shall be repeated with the
samplegateclosedbyareflectingsurfaceofwhite,mattefinish
5. Significance and Use
with suitable openings to allow for the measurements.
5.1 The quality of the stripe for visibility in daylight or
6.2.3.1 The case of illumination by a sphere with a bottom
under road lighting is determined by the luminance coefficient
aperture is shown in Fig. 1. For this arrangement sample gate
under diffuse illumination, Qd, and depends on the materials
should not be larger than necessary in view of the illuminated
used,age,andwearpattern.Theseconditionsshallbeobserved
area needed in accordance with 6.4 and should stop at a
and noted by the user.
distance before the sphere surface opposing the observation
direction.Inorderthatreflectioninthesamplesurfaceshallnot
5.2 Under the same conditions of illumination and viewing,
distort the uniformity of luminance of the interior sphere
higher levels of Qd correspond to higher levels of lightness.
surface, the remaining part of the sphere, after introducing the
5.3 Reflectivity of pavement (road) markings degrade with
bottom aperture, shall be minimum 0.8×D, where D is the
traffic wear and require periodic measurement to ensure that
diameterofthesphere.Inthiscase,thetestof6.2.3needsonly
sufficient line visibility is provided to drivers.
to be applied with the sample gate open.
5.4 Foragivenviewingdistance,measurementsofQdmade
6.2.4 The sphere may be approximated by other shapes, but
with a reflectometer having a geometry corresponding to that
enough testing shall be carried out to verify that interior
distance are a good indicator of the visual ranking of material
surfaces have approximately constant luminance. The ratio of
measured.
the smallest to the largest luminance of interior surfaces shall
be minimum 0.8, when measured in different directions
5.5 specified by CEN, the measurement geometry of the
through different locations at the sample gate.The test shall be
instrument is based on a viewing distance of 30 m and an eye
carried out with the sample gate open, and shall be repeated
height of 1.2 m.
with the sample gate closed by a reflecting surface of white,
5.6 It shall be the responsibility of the user to employ an
matte finish with suitable openings to allow for the measure-
instrument having the specified co-viewing angle.
ments.
6. Apparatus
6.3 Receiver Requirements:
6.3.1 Thereceivershallhavesufficientsensitivityandrange
6.1 Portable Reflectometer:
6.1.1 Thereflectometershallbeportable,withthecapability to accommodate luminance coefficient in diffuse illumination
to be placed on various horizontal pavement markings in expected in use, typically from 1 to close to the maximum of
-2 -1
different locations. approximately 318 mcd·m ·lx .
6.1.2 The reflectometer shall be constructed so that place- 6.3.2 The combined spectral distribution of the illumination
ment on the highway pavement markings will preclude any and the spectral responsivity of the receiver shall match the
straylightenteringthemeasurementareaoftheinstrumentand combined spectral distribution of CIE Illuminant D65 and the
affecting the reading. This may be done by shielding against V(λ) spectral luminosity function according to the following
stray light, or by subtraction of the stray light reading, or both. criterion: For any relevant choice of plano parallel colored
Alternatively, the reflectometer shall produce a warning signal absorptive filter mounted in the path of light to the detector,
when stray light could affect the reading. when measuring a white reflective sample or calibration
6.1.3 For the convenience of the user, a marking shall be standard, the ratio of the Qd measured with the filter to the Qd
placed on the instrument to permit it to be aligned with the measured without the filter shall be within 10% of the
E2302−03a (2022)
FIG. 1Illumination System for a Portable Reflectometer: a) Part of a Sphere; b) Bottom Aperture Closed by a Bottom Surface with a
Sample Gate; c) Bottom Surface with Sample Gate
NOTE3—Somecombinationsoflightsourcesanddetectorstendtogive
Illuminant D65 luminous transmittance of the filter. See Fig. 2
response to infrared radiation. An absorptive long pass filter with pass
for the position of the absorptive filter. Relevant absorptive
wavelength at about 715 nm is suitable. The Qd measured with the filter
filters shall include at least a yellow filter of color at about the
-2 -1
insertedshouldtheoreticallybezero,butavaluefrom−3to3mcd·m ·lx
acceptable limit toward green and a yellow filter of color at
is acceptable.
about the acceptable limit toward red.
6.3.3 The receiver may be either at optical infinity or at a
NOTE 2—Absorptive long pass filters with pass wavelengths at about
finite distance from the measurement area, and the co-viewing
515 nm and 550 nm are commercially available and correspond to
angle shall be 2.29 6 0.05° as determined from the center of
greenish yellow and reddish yellow. Illuminant D65 luminous transmit-
tance values must be derived by measurement of the individual filters, but
the measurement area. See Fig. 3 for a diagram of the optics
typical values are given below.
geometry. The co-viewing angle can be tested with light
Filter Type and Thickness 1 mm 2 mm 3 mm
through the aperture stop at the detector, using a frame with
515 nm 0.803 0.777 0.758
pinholes and targets as shown in Fig. 4. For a non-collimated
550 nm n/a n/a 0.489
instrument, the pinholes shall be at a location corresponding to
6.3.2.1 If the instrument is intended to be used for materials
the center of the measurement field.
ofothercolors,relevantabsorptivefiltersshallincludefiltersof
such colors. It is recommended to test also the response to
NOTE4—Tosendlightthroughtheaperturestopatthedetectorinvolves
infraredradiationbymeansofaninfraredabsorptivefilter,and
opening of the reflectometer, which should be done according to instruc-
to request that the Qd measured with the filter is small. tions by the manufacturer of the reflectometer.
E2302−03a (2022)
FIG. 2Use of Absorptive Filter and White Reflective Sample or Calibration Standard to Test the Spectral Responsivity of the Receiver
FIG. 3Optics Geometry Diagram for Portable Reflectometer: a) Angle and Aperture for Non-Collimating Portable Reflectometer; b)
Angle and Aperture for Collimating Portable Reflectometer
6.3.4 As determined from the center of the measurement change more than 61% after 10 s when the reflectometer is in
area, the aperture of the receiver shall not be larger than a contact with the pavement marking and ready to measure.
square subtending 20 min of arc (0.33°) in both horizontal and 6.3.6 The linearity of the reflectometer photometric scale
vertical directions. For a collimated instrument, the frame
over the range of readings expected shall be within 2%.
shown in Fig. 4 can also be used to test the aperture angle, Correction factors may be used to ensure a linear response. A
when the targets indicate maximum dimensions.
method for determining linearity is found in Annex A2 of
Practice E809.
NOTE 5—The maximum receiver aperture dimensions are in agreement
6.3.7 The reflectometer shall have a zero-adjust control, or
with CEN EN 1436.
an auto-zero function.
6.3.5 The combined stability of the output of the light
source and the receiver shall be such that readings will not 6.4 Measurement Geometry:
E2302−03a (2022)
FIG. 4Frame with Pinholes and Targets for Alternative Testing of the Co-viewing Angle and the Aperture
for Only the Collimated Instruments
6.4.1 The detected area shall either be fully included within 7. Standardization
the illuminated area (called arrangementA) or the illuminated
7.1 The reflectometer shall be standardized using an instru-
area shall be fully included within the detected area (called
ment standard consisting of a separate panel or other instru-
arrangement B).
ment standard with a known and reproducible luminance
NOTE6—ArrangementAisadvantageoustoarrangementBinthesense
coefficient under diffuse illumination measured at the same
that it leads to less variation of the measured Qd value with small tilts of
geometry as used in the port
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.