All traffic-control devices, signals, signs and markings heretofore installed by authority of the Board of Commissioners and which are in place on the effective date of this code shall be deemed to be official traffic-control devices until such time as they may be removed by authority of the Board of Commissioners, and until they are so removed it shall be unlawful for any person to fail to comply with any instruction or directive indicated by any such official traffic-control device.
(1991 Code, § 70.23) Penalty, see § 70.99