S.D. Codified Laws § 32-29-5
The driver of any motor vehicle carrying passengers for hire, any school bus carrying passengers, any vehicle carrying passengers owned or operated by a nonprofit organization that requires inspection pursuant to § 32-21-3.1, or any vehicle carrying explosive substances or combustible or flammable liquid as a cargo or part of a cargo, before crossing at grade any track of a railroad, except where a police officer or traffic control signal directs traffic to proceed or the track is nonoperational and is marked with a supplemental sign as provided in § 31-28-7, shall stop such vehicle within fifty feet from the nearest rail of such railroad and may not proceed until he has ascertained that he can do so safely. After stopping and upon proceeding, the driver of the vehicle shall cross only in such gear of the vehicle that there will be no necessity of changing gears while traversing the crossing and may not shift gears while crossing the track or tracks. This section does not apply to a driver of a taxicab or limousine. Any person failing to comply with the provisions of this section is guilty of a Class 2 misdemeanor.
SDCL 32-29-5