Whenever special pedestrian-control signals exhibiting the words WALK or DON'T WALK or symbols so directing a pedestrian are in place, such signals shall indicate as follows:

(1) Word or symbol message WALK -- Pedestrians facing such signal may proceed across the roadway in the direction of the signal. Every driver of a vehicle shall stop and remain stopped for such pedestrians; and

(2) Flashing or steady DON'T WALK -- No pedestrian shall start to cross the roadway in the direction of such signal, but any pedestrian who has partially completed his crossing on the WALK signal shall proceed to sidewalk or safety island while the DON'T WALK signal is showing.