(1) The driver of any vehicle shall obey the instructions of any traffic control device applicable thereto placed in accordance with the Nebraska Rules of the Road, unless otherwise directed by a peace officer, subject to the exceptions granted the driver of an authorized emergency vehicle in the rules.
(2) No provision of the rules for which 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 a reasonably observant person. Whenever any provision of the rules does not state that traffic control devices are required, such provision shall be effective even though no devices are erected or in place.
(3) Whenever traffic control devices are placed in position approximately conforming to the requirements of the rules, such devices shall be presumed to have been so placed by the official act or direction of lawful authority unless the contrary is established by competent evidence.
(4) Any traffic control device placed pursuant to the rules and purporting to conform with the lawful requirements pertaining to such devices shall be presumed to comply with the requirements of the rules unless the contrary is established by competent evidence.