§ 70.21 SIGNS OR MARKS.
   Whenever authorized signs are erected indicating that no right or left or U-turn is permitted, no driver of a vehicle shall disobey the directions of the sign, and when authorized marks, buttons or other indications are placed within an intersection indicating the course to be traveled by vehicles turning there, no driver of a vehicle shall disobey the direction of these indications.
(`95 Code, § 50.16)