(a) The provisions of this chapter shall not be deemed to prevent local authorities with respect to streets and highways under their jurisdiction and within the reasonable exercise of the police power from-
1. Regulating the standing or parking of vehicles;
2. Regulating traffic by means of police officers or traffic control signals;
3. Regulating or prohibiting processions or assemblages on the highways;
4. Designating particular highways as one-way highways and requiring that all vehicles thereon be moved in one specific direction;
5. Regulating the speed of vehicles in public parks;
6. Designating any highway as a through highway and requiring that all vehicles stop before entering or crossing the same or designating any intersection as a stop intersection and requiring all vehicles to stop at one or more entrances to such intersections;
7. Restricting the use of highways as authorized in Chapter 5 of this title.
(b) No ordinance or regulation enacted under subdivision 4, 5, 6, or 7 of this section shall be effective until signs giving notice of such local traffic regulations are posted upon or at the entrances to the highway or part thereof affected as may be most appropriate.