Minimum reflective values

The reflective material shall have minimum intensity values at each of the angles listed in this section. After the durability test under section 37-02-01-08, the minimum reflective intensity values for the reflective material shall not change more than twenty percent from the values specified in this section. MINIMUM REFLECTIVE INTENSITY VALUES, R * Divergence Incidence Reflective Angle, degrees Angle, degrees Intensity, R 0.2 0 10 0.2 15 7 0.2 30 5 0.5 0 5 0.5 15 4 0.5 30 2 * Measurements shall be conducted in accordance with photometric testing procedures for reflex-reflectors as specified in Society of Automotive Engineers Standard, SAE J594, Reflex Reflectors, and using fifty, plus or minus five square inches [322.6, square centimeters] of reflective material. The maximum dimension of the test surface shall not be greater than one and one-half times the minimum dimension. The reflective intensity (R) is computed from the equation. (Lr) (d2) R = (Ls) (A) Where: R = reflective intensity, candlepower per incident foot-candle per square foot. Lr = illumination incident upon receiver at observation point foot-candles Ls = illumination incident upon a plane perpendicular to the incident ray at the test specimen position, foot-candles. d = distance from test specimen to source of illumination one hundred feet (specified in SAE J594). A = area of test surface, square feet.