No provision of the traffic code or other ordinances for which signs or markings are required shall be enforced against an alleged violator if at the time and place of the alleged violation an official sign is not in proper position and sufficiently legible to be seen by an ordinarily observant person. Whenever a particular section does not state that signs are required, the section shall be effective even though no signs are erected or in place.
(Prior Code, § 70.10)