The driver of a vehicle emerging from an alley, driveway or building shall stop the vehicle immediately before driving onto a sidewalk or into the sidewalk area extending across any alleyway or driveway and shall yield the right-of-way to any pedestrian as may be necessary to avoid collision, and upon entering the roadway shall yield the right-of-way to all vehicles approaching on the roadway.
('73 Code, § 21-124)