R.I. Gen. Laws § 31-24-2: Means of measuring distance of visibility.

Whenever a requirement is declared in this chapter as to the distance from which certain lamps and devices shall render objects visible or within which the lamps or devices shall be visible, the provisions shall apply during the times stated in § 31-24-1 in respect to a vehicle without load when upon a straight, level, unlighted highway under normal atmospheric conditions unless a different time or condition is expressly stated.