(a) Except as provided in subsection (b), the driver of any vehicle described in regulations issued pursuant to subsection (c), before crossing at grade any track or tracks of a railroad, shall stop such vehicle within 50 feet but not less than 15 feet from the nearest rail of such railroad and while so stopped shall listen and look in both directions along such track for any approaching train, and for signals indicating the approach of a train and shall not proceed until he can do so safely. After stopping as required herein and upon proceeding when it is safe to do so the driver of any said vehicle shall cross only in such gear of the vehicle that there will be no necessity for manually changing gears while traversing such crossing and the driver shall not manually shift gears while crossing the track or tracks. Nothing contained in this section is intended to abrogate or modify the present Alabama doctrine of "stop, look and listen" obtaining in the courts of Alabama.
(b) This section shall not apply at:
(1) Any railroad grade crossing at which traffic is controlled by a police officer or human flagman;
(2) Any railroad grade crossing at which traffic is regulated by a traffic-control signal;
(3) Any railroad grade crossing protected by crossing gates or any alternately flashing light signal intended to give warning of the approach of a railroad train;
(4) Any railroad grade crossing at which an official traffic control device gives notice that the stopping requirement imposed by this section does not apply.
(c) The Director of Transportation shall adopt such regulations as may be necessary describing the vehicles which must comply with the stopping requirements of this section. In formulating such regulations the Director of Transportation shall give consideration to the number of passengers carried by the vehicle and the hazardous nature of any substance carried by the vehicle in determining whether such vehicle shall be required to stop. Such regulations shall correlate with and so far as possible conform to the most recent regulation of the United States Department of Transportation.