ASTM E2302-03
(Test Method)Standard Test Method for Measurement of the Luminance Coefficient Under Diffuse Illumination of Pavement Marking Materials with CEN-Prescribed Geometry Using a Portable Reflectometer
Standard Test Method for Measurement of the Luminance Coefficient Under Diffuse Illumination of Pavement Marking Materials with CEN-Prescribed Geometry Using a Portable Reflectometer
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E 2302 – 03
Standard Test Method for
Measurement of the Luminance Coefficient Under Diffuse
Illumination of Pavement Marking Materials with CEN-
Prescribed Geometry Using a Portable Reflectometer
This standard is issued under the fixed designation E 2302; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope CEN EN 1436 Road Marking Materials—Road Marking
Performance for Road Users
1.1 This test method covers measurement of the luminance
coefficient under diffuse illumination of horizontal pavement
3. Terminology
markings, such as traffic stripes and surface symbols, and
3.1 The terminology used in this test method generally
pavement surfaces, in a particular viewing direction using a
agrees with that used in Terminology E 284.
portable reflectometer.
3.2 Definitions:
NOTE 1—The luminance coefficient under diffuse illumination is a
3.2.1 luminance coeffıcient under diffuse illumination; Qd,
measure of the reflection of horizontal pavement markings and pavement
n—the ratio of luminance, L, in a particular viewing direction,
surfaces in a particular viewing direction in daylight or under road
of a projected surface to the illuminance of diffuse illumina-
lighting. Diffuse illumination approximates daylight illumination from the
tion, E, at the surface on the plane of the surface, expressed in
overcast sky, and road lighting as an average of locations on the pavement
-2 -1
candelas per square metre per lux (cd·m ·lx ).
surface.
3.2.1.1 Discussion—Qd has a range from zero up to a
1.2 The co-viewing angle of the reflectometer affects the
-2 -1
maximum of 1/p = approximately 0.318 cd·m ·lx . For
readings. As specified by the European Committee for Stan-
convenience, the units used commonly are millicandelas per
dardization (CEN), the co-viewing angle shall be 2.29°.
-2 -1
square metre per lux (mcd·m ·lx ) providing a range from
1.3 This test method is intended to be used for field
-2 -1
zero up to 1000/p = approximately 318 mcd·m ·lx .
measurement of pavement markings and pavement surfaces but
3.2.2 co-viewing angle, a, n—the angle between the plane
may be used to measure the performance of materials on
of the pavement marking surface and the observation axis.
sample panels before placing the marking material in the field.
3.2.3 portable reflectometer, n—a hand-held instrument that
1.4 This standard does not purport to address all of the
can be used in the field or laboratory for measurement of
safety concerns, if any, associated with its use. It is the
luminance coefficient under diffuse illumination.
responsibility of the user of this standard to establish appro-
3.2.4 instrument standard, n—working standard used to
priate safety and health practices and determine the applica-
standardize the portable reflectometer.
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 This test method involves the use of commercial por-
2.1 ASTM Standards:
table reflectometers for determining the luminance coefficient
E 284 Terminology of Appearance
under diffuse illumination in a particular viewing direction of
E 809 Practice for Measuring Photometric Characteristics
2 horizontal coatings materials used in pavement markings.
of Retroreflectors
4.2 The co-viewing angle is fixed at 2.29°.
2.2 Other Standard:
4.3 The reflectometers use an external panel or other instru-
ment standard of known luminance coefficient under diffuse
illumination, Qd.
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 July 10, 2003. Published September 2003. Available from European Committee for Standardization, Central Secretariat
Annual Book of ASTM Standards, Vol 06.01. (CEN), rue de Stassart 36, B1050 Brussels, Belgium.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E2302–03
4.4 The portable reflectometer is placed directly over the ing to 6.4 and should stop at a distance before the sphere
pavement marking to be measured, ensuring that the measure- surface opposing the observation direction. In order that
ment area of the reflectometer fits within the width of the reflection in the sample surface shall not distort the uniformity
stripe, and the reading displayed by the reflectometer is of luminance of the interior sphere surface, the remaining part
recorded. of the sphere, after introducing the bottom aperture, shall be
4.5 Readings shall be taken and averaged for the direction minimum 0.8 3 D, where D is the diameter of the sphere. The
of traffic. Readings shall be taken for each direction of traffic direct illumination shall cover all of the remaining part of the
and averaged separately for centerlines. sphere with such a degree of uniformity that the ratio of the
smallest to the largest luminance of the interior sphere surface
5. Significance and Use
is minimum 0.8, when measured in directions through the
5.1 The quality of the stripe for visibility in daylight or
center of the sample gate with a circular measuring field of
under road lighting is determined by the luminance coefficient
diameter of 0.1 3 D.
under diffuse illumination, Qd, and depends on the materials
6.2.4 The sphere may be approximated by other shapes, but
used, age, and wear pattern. These conditions shall be observed
enough testing shall be carried out to verify that interior
and noted by the user.
surfaces have approximately constant luminance. The ratio of
5.2 Under the same conditions of illumination and viewing,
the smallest to the largest luminance of interior surfaces shall
higher levels of Qd correspond to higher levels of lightness.
be minimum 0.8, when measured in different directions
5.3 Reflectivity of pavement (road) markings degrade with
through different locations at the sample gate. The test shall be
traffic wear and require periodic measurement to ensure that
carried out with the sample gate open, and shall be repeated
sufficient line visibility is provided to drivers.
with the sample gate closed by a reflecting surface of white,
5.4 For a given viewing distance, measurements of Qd made
matt finish with suitable openings to allow for the measure-
with a reflectometer having a geometry corresponding to that
ments.
distance are a good indicator of the visual ranking of material
6.3 Receiver Requirements:
measured.
6.3.1 The receiver shall have sufficient sensitivity and range
5.5 specified by CEN, the measurement geometry of the
to accommodate luminance coefficient in diffuse illumination
instrument is based on a viewing distance of 30 m and an eye
expected in use, typically from 1 to close to the maximum of
-2 -1
height of 1.2 m.
approximately 318 mcd·m ·lx .
5.6 It shall be the responsibility of the user to employ an
6.3.2 The combined spectral distribution of the illumination
instrument having the specified co-viewing angle.
and the spectral responsivity of the receiver shall match the
combined spectral distribution of CIE Illuminant D65 and the
6. Apparatus
V(l) spectral luminosity function according to the following
6.1 Portable Reflectometer:
criterion: For any relevant choice of plano parallel colored
6.1.1 The reflectometer shall be portable, with the capability
absorptive filter mounted in the path of light to the detector,
to be placed on various horizontal pavement markings in
when measuring a white reflective sample or calibration
different locations.
standard, the ratio of the Qd measured with the filter to the Qd
6.1.2 The reflectometer shall be constructed so that place-
measured without the filter shall be within 10 % of the
ment on the highway pavement markings will preclude any
Illuminant D65 luminous transmittance of the filter. See Fig. 2
stray light entering the measurement area of the instrument and
for the position of the absorptive filter. Relevant absorptive
affecting the reading. This may be done by shielding against
filters shall include at least a yellow filter of color at about the
stray light, or by subtraction of the stray light reading, or both.
acceptable limit toward green and a yellow filter of color at
6.1.3 For the convenience of the user, a marking shall be
about the acceptable limit toward red.
placed on the instrument to permit it to be aligned with the
NOTE 2—Absorptive long pass filters with pass wavelengths at about
direction of traffic, or the instrument design shall itself indicate
515 nm and 550 nm are commercially available and correspond to
the measuring direction in an obvious manner.
greenish yellow and reddish yellow. Illuminant D65 luminous transmit-
6.2 Illumination System Requirements:
tance values must be derived by measurement of the individual filters, but
6.2.1 The illumination system shall provide diffuse illumi-
typical values are given below.
nation, which can be obtained by indirect illumination through
Filter Type and Thickness 1 mm 2 mm 3 mm
a sample gate from a photometric sphere of interior white, matt
515 nm 0.803 0.777 0.758
550 nm 0.571 0.516 0.489
finish.
6.2.2 The illumination system shall have compensation for 6.3.2.1 If the instrument is intended to be used for materials
the increase of illumination caused by interreflection between
of other colors, relevant absorptive filters shall include filters of
a sample surface and the interior surfaces of the illumination such colors. It is recommended to test also the response to
system, for instance by means of a reading of the illuminance
infrared radiation by means of an infrared absorptive filter, and
at a location close to the sample gate. to request that the Qd measured with the filter is small.
6.2.3 A sphere with a bottom aperture such as shown in Fig.
NOTE 3—Some combinations of light sources and detectors tend to give
1 is suitable for the purpose. The bottom aperture is closed by
response to infrared radiation. An absorptive long pass filter with pass
a bottom surface with a sample gate, whose design is open for
wavelength at about 715 nm is suitable. The Qd measured with the filter
-2 -1
various considerations. The sample gate should not be larger
inserted should theoretically be zero, but a value from −3 to 3 mcd·m ·lx
than necessary in view of the illuminated area needed accord- is acceptable.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E2302–03
FIG. 1 Illumination 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
6.3.3 The receiver may be either at optical infinity or at a vertical directions. The frame shown in Fig. 4 can also be used
finite distance from the measurement area, and the co-viewing to test the aperture angle, when the targets indicate maximum
dimensions.
angle shall be 2.29 6 0.02° as determined from the center of
the measurement area. See Fig. 3 for a diagram of the optics
NOTE 5—The maximum receiver aperture dimensions are in agreement
geometry. The co-viewing angle can be tested with light
with CEN EN 1436.
through the aperture stop at the detector, using a frame with
6.3.5 The combined stability of the output of the light
pinholes and targets as shown in Fig. 4. For a non-collimated
source and the receiver shall be such that readings will not
instrument, the pinholes shall be at a location corresponding to
change more than 6 1 % after 10 s when the reflectometer is
the center of the measurement field.
in contact with the pavement marking and ready to measure.
NOTE 4—To send light through the aperture stop at the detector
6.3.6 The linearity of the reflectometer photometric scale
involves opening of the reflectometer, which should be done according to
over the range of readings expected shall be within 2 %.
instructions by the manufacturer of the reflectometer.
Correction factors may be used to ensure a linear response. A
method for determining linearity is found in Annex A2 of
6.3.4 As determined from the center of the measurement
Practice E 809.
area, the aperture of the receiver shall not be larger than a
square subtending 20 min of arc (0.33°) in both horizontal and 6.4 Measurement Geometry:
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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E2302–03
FIG. 2 Use of Absorptive Filter and White Reflective Sample or Calibration Standard to Test the Spectral Responsivity of the Receiver
FIG. 3 Optics Geometry Diagram for Portable Reflectometer: a) Angle and Aperture for Non-Collimating Portable Reflectometer; b)
Angle and Aperture for Collimating Portable Reflectometer
the reflectometer that are unavoidable in practical field measurements.
6.4.1 The measurement area and the illuminated area shall
be according to: arrangement A—the measurement area is fully
6.4.2 The smaller of the two areas, measurement area or
included within the illuminated area; or arrangement B—the
illuminated area, shall be minimum 50 cm . See Fig. 5 for a
illuminated area is fully included within the measurement area.
method of testing this area.
NOTE 6—Arrangement A is advantageous to arrangement B in the sense
that it leads to less variation of the measured Qd value with small tilts of
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E2302–03
FIG. 4 Frame with Pinholes and Targets for Alternative Testing of the Co-viewing Angle and the Aperture
FIG. 5 With Light through the Aperture Stop at the Detector, the Measurement and Illuminated Areas are Projected onto a Plate against
the Feet of the Instrument. The Smaller Area is Measured from “Middle of Blur” to “Middle of Blur”
NOTE 7—The plate mentioned in Fig. 5 needs in most cases to be a
dimensions, with the datum mark indicated on the standard.
glass plate with a diffuse upper surface, so that the area can be studied
The instrument standard shall have a standardization value of
from the underside.
the lu
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