(a) When one vehicle is towing another the drawbar or other connection shall be of sufficient strength to pull all weight towed thereby and said drawbar or other connection shall not exceed fifteen feet from one vehicle to the other except the connection between any two vehicles transporting poles, pipe, machinery, or other objects of structural nature which cannot readily be dismembered.
(b) When one vehicle is towing another and the connection consists of a chain, rope, or cable, there shall be displayed upon such connection a white flag or cloth not less than twelve inches square.