23 CFR Appendix to Subpart F of Part 655: Appendix to Subpart F of Part 655—Alternate Method of Determining the Color of Retroreflective Sign Materials and Pavement Marking Materials

1. Although the FHWA Color Tolerance Charts depreciate the use of spectrophotometers or accurate tristimulus colorimeters for measuring the daytime color of retroreflective materials, recent testing has determined that 0/45 or 45/0 spectroradiometers and tristimulus colorimeters have proved that the measurements can be considered reliable and may be used.

2. The daytime color of non-fluorescent retroreflective materials may be measured in accordance with ASTM Test Method E1349, “Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Bidirectional Geometry” or ASTM Test Method E 1347 (Replaces E97), “Standard Test Method for Color and Color-Difference Measurement by Tristimulus (Filter) Colorimetry.” The latter test method specified bidirectional geometry for the measurement of retroreflective materials. The geometric conditions to be used in both test methods are 0/45 or 45/0 circumferential illumination or viewing. Uniplanar geometry is not recommended for material types IV or higher (designated microprismatic). The CIE standard illuminant used in computing the colorimetric coordinates shall be D65 and the 2 Degree Standard CIE observer shall be used.

3. For fluorescent retroreflective materials ASTM E991 may be used to determine the chromaticity provided that the D65 illumination meets the requirements of E 991. This practice, however, allows only the total luminous factor to be measured. The fluorescent luminous factor must be determined using bispectral fluorescent colorimetry. Commercial instruments are available which allow such determination. Some testing laboratories are also equipped to perform these measurements.

4. For nighttime measurements CIE Standard Illuminant A shall be used in computing the colorimetric coordinates and the 2 Degree Standard CIE Observer shall be used.

5. Average performance sheeting is identified as Types I and II sheeting and high performance sheeting is identified as Type III. Super-high intensity sheeting is identified as Types V, VI, and VII in ASTM D 4956.

6. The following ten tables depict the 1931 CIE Chromaticity Diagram x and y coordinates for the corner points defining the recommended color boxes in the diagram and the daytime luminance factors for those colors. Lines drawn between these corner points specify the limits of the chromaticity allowed in the 1931 Chromaticity Diagram. Color coordinates of samples that lie within these lines are acceptable. For blue and green colors the spectrum locus is the defining limit between the corner points located on the spectrum locus:

Table 1 to Appendix to Part 655, Subpart F—Daytime Color Specification Limits for Retroreflective Material With CIE 2° Standard Observer and 45/0 (0/45) Geometry and CIE Standard Illuminant D65.

Color Chromaticity Coordinates

1 2 3 4

x y x y y x x y

White 0.303 0.300 0.368 0.366 0.340 0.393 0.274 0.329

Red 0.648 0.351 0.735 0.265 0.629 0.281 0.565 0.346

Orange 0.558 0.352 0.636 0.364 0.570 0.429 0.506 0.404

Brown 0.430 0.340 0.430 0.390 0.518 0.434 0.570 0.382

Yellow 0.498 0.412 0.557 0.442 0.479 0.520 0.438 0.472

Green 0.026 0.399 0.166 0.364 0.286 0.446 0.207 0.771

Blue 0.078 0.171 0.150 0.220 0.210 0.160 0.137 0.038

Light Blue 0.180 0.260 0.240 0.300 0.270 0.260 0.230 0.200

Purple 0.302 0.064 0.310 0.210 0.380 0.255 0.468 0.140

Table 1a to Appendix to Part 655, Subpart F—Daytime Luminance Factors (%) for Retroreflective Material With CIE 2° Standard Observer and 45/0 (0/45) Geometry and CIE Standard Illuminant D65.

Color Daytime Luminance Factor (Y %) by ASTM Type

Types I, II, III and VI Types IV, VII, and VIII Type V

Minimum Maximum Minimum Maximum Minimum Maximum

White 27 40 15

Red 2.5 12 3.0 15 2.5 11

Orange 14 30 12 30 7.0 25

Brown 4.0 9.0 1.0 6.0 1.0 9.0

Yellow 15 45 24 45 12 30

Green 3.0 9.0 3.0 12 2.5 11

Blue 1.0 10 1.0 10 1.0 10

Light Blue 12 40 18 40 8.0 25

Purple 2.0 10 2.0 10 2.0 10

Table 2 to Appendix to Part 655, Subpart F—Nighttime Color Specification Limits for Retroreflective Material With CIE 2° Standard Observer and Observation Angle of 0.33°, Entrance Angle of + 5° and CIE Standard Illuminant A.

Color Chromaticity Coordinates

1 2 3 4

x y x y x y x y

White 0.475 0.452 0.360 0.415 0.392 0.370 0.515 0.409

Red 0.650 0.348 0.620 0.348 0.712 0.2550 0.735 0.265

Orange 0.595 0.405 0.565 0.405 0.613 0.355 0.643 0.355

Brown 0.595 0.405 0.540 0.405 0.570 0.365 0.643 0.355

Yellow 0.513 0.487 0.500 0.4700 0.545 0.425 0.572 0.425

Green 0.007 0.570 0.200 0.500 0.322 0.590 0.193 0.782

Blue 0.033 0.370 0.180 0.370 0.230 0.240 0.091 0.133

Purple 0.355 0.088 0.385 0.288 0.500 0.350 0.635 0.221

Light Blue Chromaticity coordinates are yet to be determined.

Note: Materials used as High-Conspicuity, Retroreflective Traffic Signage Materials shall meet the requirements for Daytime Color Specification Limits, Daytime Luminance Factors and Nighttime Color Specification Limits for Fluorescent Retroreflective Material, as described in Tables 3, 3a, and 4, throughout the service life of the sign.

Table 3 to Appendix to Part 655, Subpart F—Daytime Color Specification Limits for Fluorescent Retroreflective Material with CIE 2° Standard Observer and 45/0 (0/45) Geometry and CIE Standard Illuminant D65.

Color Chromaticity Coordinates

1 2 3 4

x y x y x y x y

Fluorescent Orange 0.583 0.416 0.535 0.400 0.595 0.351 0.645 0.355

Fluorescent Yellow 0.479 0.520 0.446 0.483 0.512 0.421 0.557 0.442

Fluorescent Yellow-Green 0.387 0.610 0.369 .546 .428 .496 0.460 0.540

Fluorescent Green 0.210 0.770 0.232 0.656 0.320 0.590 0.320 0.675

Fluorescent Pink 0.450 0.270 0.590 0.350 0.644 0.290 0.536 0.230

Fluorescent Red 0.666 0.334 0.613 0.333 0.671 0.275 9.735 0.265

Table 3a to Appendix to Part 655, Subpart F—Daytime Luminance Factors (%) for Fluorescent Retroreflective Material With CIE 2° Standard Observer and 45/0 (0/45) Geometry and CIE Standard Illuminant D65.

Color Luminance Factor Limits (Y)

Min Max YF*

Fluorescent Orange 25 None 15

Fluorescent Yellow 45 None 20

Fluorescent Yellow-Green 60 None 20

Fluorescent Green 20 30 12

Fluorescent Pink 25 None 15

Fluorescent Red 20 30 15

*Fluorescence luminance factors (YF) are typical values, and are provided for quality assurance purposes only. YF shall not be used as a measure of performance during service.

Table 4 to Appendix to Part 655, Subpart F—Nighttime Color Specification Limits for Fluorescent Retroreflective Material With CIE 2° Standard Observer and Observation Angle of 0.33°, Entrance Angle of + 5° and CIE Standard Illuminant A.

Color Chromaticity Coordinates

1 2 3 4

x y x y x y x y

Fluorescent Orange 0.625 0.375 0.589 0.376 0.636 0.330 0.669 0.331

Fluorescent Yellow 0.554 0.445 0.526 0.437 0.569 0.394 0.610 0.390

Fluorescent Yellow-Green 0.480 0.520 0.473 0.490 0.523 0.440 0.550 0.449

Fluorescent Green 0.007 0.570 0.200 0.500 0.322 0.590 0.193 0.782

Fluorescent Red 0.680 0.320 0.645 0.320 0.712 0.253 0.735 0.265

Table 5 to Appendix to Part 655, Subpart F—Daytime Color Specification Limits for Retroreflective Pavement Marking Material With CIE 2° Standard Observer and 45/0 (0/45) Geometry and CIE Standard Illuminant D65.

Color Chromaticity Coordinates

1 2 3 4

x y x y x y x y

White 0.355 0.355 0.305 0.305 0.285 0.325 0.335 0.375

Yellow 0.560 0.440 0.490 0.510 0.420 0.440 0.460 0.400

Red 0.480 0.300 0.690 0.315 0.620 0.380 0.480 0.360

Blue 0.105 0.100 0.220 0.180 0.200 0.260 0.060 0.220

Purple 0.300 0.064 0.309 0.260 0.362 0.295 0.475 0.144

Table 5a to Appendix to Part 655, Subpart F—Daytime Luminance Factors (%) for Retroreflective Pavement Marking Material With CIE 2° Standard Observer and 45/0 (0/45) Geometry and CIE Standard Illuminant D65.

Color Luminance Factor (Y%)

Minimum Maximum

White 35

Yellow 25

Red 6 15

Blue 5 14

Purple 5 15

Table 6 to Appendix to Part 655, Subpart F—Nightime Color Specification Limits for Retroreflective Pavement Marking Material With CIE 2° Standard Observer, Observation Angle of 1.05°, Entrance Angle of + 88.76° and CIE Standard Illuminant A.

Color Chromaticity Coordinates

1 2 3 4

x y x y x y x y

White 0.480 0.410 0.430 0.380 0.405 0.405 0.455 0.435

Yellow 0.575 0.425 0.508 0.415 0.473 0.453 0.510 0.490

Purple 0.338 0.080 0.425 0.365 0.470 0.385 0.635 0.221

Note: Luminance factors for retroreflective pavement marking materials are for materials as they are intended to be used. For paint products, that means inclusion of glass beads and/or other retroreflective components.

Table 7 to Appendix to Part 655, Subpart F—Daytime Color Specification Limits for Non-Retroreflective Materials Used for Colored Pavements

Color Chromaticity coordinates

1 2 3 4

x y x y x y x y

Green 0.230 0.714 0.266 0.460 0.367 0.480 0.367 0.584

Red 0.420 0.330 0.450 0.380 0.560 0.370 0.540 0.320