36 CFR 4.13 Title 36: Parks, Forests, and Public Property
PART 4—VEHICLES AND TRAFFIC SAFETY
§ 4.13 Obstructing traffic.
The following are prohibited:
(a) Stopping or parking a vehicle upon a park road, except as authorized by the superintendent, or in the event of an accident or other condition beyond the control of the operator.
(b) Operating a vehicle so slowly as to interfere with the normal flow of traffic.