Motor vehicles transporting passengers and certain types of hazardous materials, as cited in 49 CFR 392.10(a), are forbidden from crossing railroad tracks without first stopping within 50 feet but no closer than 15 feet, listening, and looking both ways for an approaching train. Drivers may cross the railroad tracks once it is safe to do so, though they are not permitted to shift gears while crossing the tracks. See 49 CFR 392.10(b) for a list of exceptions where a stop need not be made.