§ 17-6.  Authorized signs, signals, directions.
   All traffic signs, signals, parking signs or lines, tokens, crosswalk lines or other devices placed in or on the streets or public ways of the city regulating traffic shall be presumed to have been placed in or on the streets or public ways of the city by authority of the board of commissioners or by an officer of the city duly authorized so to do, unless the contrary be clearly shown.
(Code 1977, § 50.060(1)(a))