It shall be unlawful for any person to disobey the instructions of any official sign or signal upon the streets placed in accordance with the provisions of title, unless otherwise directed by a police officer; and no provision of title for which signs are required shall be enforceable against an alleged violator if, at the time and place of alleged violation, the sign herein required is not in proper position and sufficiently legible to be seen by an ordinarily observant person.
(Ord. passed - -) Penalty, see § 70.99