The following supplemental paragraph is hereby added to section 7B-12, "School Speed Limit Signs (S4-1, S4-2, S4-3, S4-4)," of the MUTCD:

The supplemental or lower panel of a "School Speed Limit 20" sign which reads "When Children are Present" shall indicate to the motorist that the 20 mile per hour school speed limit is in force under the following conditions:

(1) School children are occupying or walking within the marked crosswalk.

(2) School children are waiting at the curb or on the shoulder of the roadway and are about to cross the roadway by way of the marked crosswalk.

(3) School children are present or walking along the roadway, either on the adjacent sidewalk or, in the absence of sidewalks, on the shoulder within the posted school speed limit zone which extends 300 feet in either direction from the marked crosswalk.