(A) Any person operating a specialty vehicle shall obey the instructions of official traffic control signals, signs and other control devices applicable to vehicles, unless otherwise directed by a police officer.
(B) Wherever authorized signs are erected indicating that no right, left or U-turn is permitted, no person operating a vehicle shall disobey the direction of any such sign, except where such person dismounts from the vehicle to make any such turn; in which event, such person shall then obey the regulations applicable to pedestrians.
(`85 Code, § 22-82)