(a) Every person shall obey the instruction of any official traffic control device applicable thereto placed in accordance with this Chapter, unless otherwise directed by a police officer.
(b) It is unlawful for any person to leave the roadway and travel across private property to avoid an official traffic control device.
(c) No provision of this Chapter for which official traffic control devices are required shall be enforced against an alleged violator if at the time and place of the alleged violation an official device is not in proper position and sufficiently legible to be seen by an ordinarily observant person. Whenever a particular Section does not state that official traffic control devices are required, such Section shall be effective even though no devices are erected or in place.
(M.C. 1963, § 20.104.)