N.D. Admin. Code 37-02-01-04
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 Angle, degrees | Incidence Angle, degrees | Reflective 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.
R = (Lr) (d2)/(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.
General Authority: NDCC 39-21-50
Law Implemented: NDCC 39-21-50
N.D. Admin Code 37-02-01-04