(a) The driver of any vehicle shall obey the instructions of any traffic-control device applicable thereto placed in accordance with this title, unless otherwise directed as authorized in § 4103 of this title, subject to the exceptions granted the driver of an authorized emergency vehicle in this title.
(b) No provision of this chapter 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 traffic-control device is not in proper position and sufficiently legible to be seen by an ordinarily observant person. This subsection shall not operate to relieve a driver of the duty to operate a vehicle with due regard to the safety of all persons using the highway.
(c) Whenever a particular section does not state that traffic-control devices are required, such section shall be effective even though no traffic-control devices are erected or in place.
(d) In the event a traffic-control signal is erected and maintained at a place other than an intersection, this title shall be applicable except as to those provisions which by their nature can have no application.
(e) Whenever traffic-control devices are placed in position approximately conforming to the requirements of this title, 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.
(f) Any traffic-control device placed pursuant to this title and purporting to conform to the lawful requirements pertaining to such devices shall be presumed to comply with the requirements of this title, unless the contrary shall be established by competent evidence.