(1) The driver of any vehicle shall obey the instructions of any official traffic control device applicable thereto, placed in accordance with the provisions of this chapter, unless otherwise directed by a police officer, subject to the exceptions granted the driver of an authorized emergency vehicle in this chapter. (2) No person shall drive any vehicle from a roadway to another roadway to avoid obeying the indicated traffic control indicated by such traffic control device. (3) 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. (4) 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. (5) 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. (6) A violation of this section is a noncriminal traffic infraction, punishable as a moving violation as provided in chapter 318.