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 D 65 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 D 65 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 D 65 . 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 D 65 . 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 D 65 . 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 D 65 . Color Luminance Factor Limits (Y) Min Max Y F * 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 D 65 . 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 D 65 . 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 [67 FR 49572, July 31, 2002, as amended at 67 FR 70163, Nov. 21, 2002; 68 FR 65582, 65583, Nov. 20, 2003; 74 FR 66862, 66863, Dec. 16, 2009; 88 FR 87695, Dec. 19, 2023]