The Police Department is hereby authorized, empowered, and ordered to exercise all powers and duties, with relation to the management of street traffic and to direct, control, stop, restrict, regulate, and, when necessary, temporarily divert or exclude in the interest of public safety, health, and convenience the movement of pedestrian and animal and vehicular traffic of every kind in streets, in parks, and on bridges. The driver of any vehicle shall stop upon the signal of any police officer.
(`77 Code, § 5-309)