(a) The director, division of traffic engineering is authorized to place markers, buttons, or signs within or adjacent to intersections, indicating the course to be traveled by vehicles turning at such intersections; and such course to be traveled as so indicated may conform to or be other than as prescribed by law or ordinance.
(b) When authorized markers, buttons or other indications are placed within and adjacent to an intersection indicating the course to be traveled by vehicles turning thereat, no driver of a vehicle shall disobey the directions of such indications.