(a) The commissioner, with reference to state trunk highways, and local authorities, with reference to other highways under their jurisdiction, may designate through highways by erecting stop signs or yield signs at entrances thereto or may designate any intersection as a stop or yield intersection by erecting like signs at one or more entrances to such intersection; provided, that local authorities, with the consent of the commissioner, may designate through highway or stop or yield intersections on state trunk highways.
(b) Every driver of a vehicle shall stop at a stop sign or at a clearly marked stop line before entering the intersection, except when directed to proceed by a police officer or traffic-control signal.