§ 1110. Obedience to and required traffic-control devices. (a) Every
person shall obey the instructions of any official traffic-control
device applicable to him placed in accordance with the provisions of
this chapter, unless otherwise directed by a traffic or police officer,
subject to the exceptions granted the driver of an authorized emergency
vehicle in this title.

(b) No provision 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 be seen by an ordinarily observant person.
Whenever a particular section does not state that signs are required,
such section shall be effective even though no signs are erected or in
place.

(c) Whenever official traffic-control devices are placed in position
approximately conforming to the requirements of this chapter, such
devices shall be presumed to have been so placed by the official act or
direction of lawful authority, unless the contrary shall be established
by competent evidence.

(d) Any official traffic-control device placed pursuant to the
provisions of this chapter and purporting to conform to the lawful
requirements pertaining to such devices shall be presumed to comply with
the requirements of this chapter, unless the contrary shall be
established by competent evidence.

(e) For purposes of this article, "intersection" shall include the
area embracing the juncture of a highway with a private road or driveway
and "intersecting roadway" shall include an intersecting private road or
driveway.