§ 70.20  OBEDIENCE REQUIRED; WHEN SIGNS REQUIRED FOR ENFORCEMENT.
   (A)   Any person failing or refusing to comply with the directions indicated on any sign, marker or device for the control or direction of traffic, erected or placed in accordance with the provisions of this chapter, when so placed or erected, shall be guilty of a violation.  This section shall not be construed to apply when the driver of a vehicle is otherwise directed by a police officer or when an exception is granted to the driver of an authorized emergency vehicle under § 70.04.
   (B)   No provisions of this title for which signs 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 an ordinarily observant person.