No vehicle shall be driven or moved on any public street unless such vehicle is so constructed or loaded as to prevent any of its load from dropping, shifting, leaking, or otherwise escaping therefrom, except that sand or gravel may be dropped for the purpose of securing traction, or water or other substance may be sprinkled on a roadway surface in the cleaning or maintaining of such roadway by public authority having jurisdiction for the same or by persons under contract or other authorization by such public authority. (Ord. 697 § 18.1, 1973).