(A)   City personnel or contractors, while repairing or improving the streets of the city, and city personnel and utility companies, when installing, improving or repairing lines or other utility facilities in the streets, are hereby authorized as necessary, subject to control by the City Manager, to close any street or section thereof to traffic during the repair, maintenance or construction and in exercising the authority, shall erect or cause to be erected proper control devices and barricades to warn and notify the public that the street has been closed to traffic.
   (B)   (1)   When any street has been closed to traffic under the provisions of division (A) above and traffic-control devices or barricades have been erected, it is unlawful for any person to drive any vehicle through, under, over or around the traffic-control devices or barricades, or otherwise to enter the closed area.
      (2)   The provisions of this division shall not apply to persons while engaged in the construction, maintenance and repair or to persons entering therein for the protection of lives or property.  Persons having their places of residence or places of business within the closed area may travel, when possible to do so, through the area at their own risk.
   (C)   (1)   Whenever construction, repair or maintenance of any street or utility line or facility is being performed under traffic, the city personnel, contractor or utility company concerned shall erect or cause to be erected traffic-control devices to warn and guide the public.
      (2)   Every person using the street shall obey all signs, signals, markings, flagmen or other traffic-control devices which are placed to regulate, control and guide traffic through the construction or maintenance area.
(`90 Code, § 20-10)