(A) Whenever any public street, alley, bridge, culvert or sidewalk in the city is being built or repaired, or any public street or alley oiled, the Commissioner of Streets and Public Improvements or other public officials having such work in charge shall, when they deem it necessary, erect or cause to be erected at such points as they may deem desirable, suitable barriers, with signs thereon, stating that such street or alley is closed, and by whose order such street or alley has been closed. The officials shall erect or cause to be erected at such places as they may deem necessary or best, detour signs directing travel around such construction or repair work.
(B) Whenever a street or alley has been closed as provided herein, it shall be unlawful for any person to remove such barrier or signs, or to deface or injure the same, or to walk, ride or drive upon any part of said street so closed, except such persons duly authorized to do so.
('72 Code, § 6.09) Penalty, see § 97.999