(a) Preferential right-of-way may be indicated by stop signs or yield signs as authorized by the Department of Transportation or local authorities.

(b) Except when directed to proceed by a police officer, every driver of a vehicle approaching a stop sign shall stop at a clearly marked stop line but, if none, before entering the crosswalk on the near side of the intersection or, if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway before entering it. After having stopped, the driver shall yield the right-of-way to any vehicle in the intersection or approaching on another roadway so closely as to constitute an immediate hazard during the time when such driver is moving across or within the intersection or junction of roadways.

(c) The driver of a vehicle approaching a yield sign shall in obedience to such sign slow down to a speed reasonable for the existing conditions and, if required for safety to stop, shall stop at a clearly marked stop line but, if none, before entering the cross-walk on the near side of the intersection or, if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting road before entering it. After slowing or stopping, the driver shall yield the right-of-way to any vehicle in the intersection or approaching on another roadway so closely as to constitute an immediate hazard during the time the driver is moving across or within the intersection or junction of roadways. If such driver is involved in a collision with a vehicle in the intersection or junction of roadways, after driving past a yield sign without stopping, the collision shall be deemed prima facie evidence of his failure to yield right-of-way.