Sidewalks between parking areas and principal structures, along aisles and driveways; along public roads where required by the approving authority, and wherever else pedestrian traffic shall occur shall be provided with a width of four feet of passable area and shall be raised six inches or more above any parking area except when crossing streets or driveways. Guardrails permanently anchored to the ground shall be provided in appropriate locations. Parked vehicles shall not overhang or extend over sidewalk areas.