No person shall stop or suddenly decrease the speed of, or turn a vehicle from a street course or move right or left upon a roadway unless and until such movement can be made with reasonable safety, and then only after giving an appropriate signal in the manner provided herein:

    (1)     Slow or stop. An operator or driver, while stopping, or when checking the speed of his vehicle, if the movement of other vehicles or cycles may reasonably be affected by checking such speed, shall extend his arm at an angle below horizontal so the same may be seen from the rear of his vehicle.

    (2)     Right turn. An operator or driver intending to turn his vehicle to the right shall extend his arm at an angle above horizontal so that the same may be seen in front of and in the rear of his vehicle, and shall slow down and approach the intersecting highway as nearly as practicable to the right side of the highway along which he is proceeding before turning.

    (3)     Left turn. An operator or driver intending to turn his vehicle to the left shall extend his arm in a horizontal position so that the same may be seen from the rear of his vehicle, and shall slow down and approach the intersecting highway so that the left side of his vehicle shall be near as practicable to the centerline of the highway along which he is proceeding before turning.

    (4)     Method. Signals herein required shall be given either by means of the hand and arm or by a signal light or signal device in good mechanical condition of the type approved by the state highway patrol; however, when a vehicle is so constructed or loaded that a hand or arm signal would not be visible both from the front and rear of such vehicle, then such signal shall be given by such light or device. A vehicle shall be considered as so constructed or loaded that a hand or arm signal would not be visible both to the front and rear when the distance from the center of the top of the steering post to the left outside rim of the body, cab or load exceeds twenty-four (24) inches, or when the distance from the center of the top of the steering post to the rear limit of the body or load thereon exceeds fourteen (14) feet, which limit of fourteen (14) feet shall apply to single vehicles or combinations of vehicles. The provisions of this subsection shall not apply to any trailer which does not interfere with the clear view of the hand signals of the operator or of the signaling device upon the vehicle pulling such trailer; provided further, that the provisions of this section as far as mechanical signals on vehicles so constructed that a hand and arm signal would not be visible from the front and rear of such vehicle, as above provided, shall be applicable to new vehicles registered within the state after the first of January, 1954.

(Code 1964, § 12.294(J))