(a) The driver of any motor vehicle carrying passengers for hire, any school bus carrying any school child, or any vehicle carrying explosive substances or flammable liquids as a cargo or part of a cargo before crossing at grade any tracks of a railroad shall stop the vehicle within fifty feet (50') but not less than fifteen feet (15') from the nearest rail of the railroad and, while so stopped, shall listen and look in both directions along the track for any approaching train and for signals indicating that approach of a train, except as provided, and shall not proceed until he or she can do so safely. After stopping as required in this section and upon proceeding when it is safe to do so, the driver of any such vehicle shall cross only in the gear of the vehicle in which there will be no necessity for changing gears while traversing the crossing and the driver shall not shift gears while crossing the tracks.
(b) No stop need be made at any such crossing where a police officer or a traffic control signal directs traffic to proceed.
(c) This section shall not apply at street railway grade crossings within a business or residential district.