Towed vehicles may be towed by either slings and/or cables, but in addition must be secured to the tow truck by means of a draw-bar or other connection of sufficient strength to hold the towed vehicle on any grade where operated or under conditions of severe braking and shall effectively eliminate whipping or weaving of the towed vehicle. Effective boom locking devices shall be used, and in addition, in the event of a failure of a boom lock, safety chains shall be attached to the towed vehicle. On tow trucks equipped with double booms, both booms shall be secured to prevent side swing. When one boom is used for lifting the towed vehicle, the unused boom shall be secured to prevent movement while tow truck is in motion. (Ord. 2546 § 2 (part), 2010: Ord. 577 § 23, 1972).