49 CFR § 392.10 - Railroad grade crossings; stopping required.
(a) Except as provided in paragraph (b) of this section, the driver of a commercial motor vehicle specified in paragraphs (a) (1) through (6) of this section shall not cross a railroad track or tracks at grade unless he/she first: Stops the commercial motor vehicle within 50 feet of, and not closer than 15 feet to, the tracks; thereafter listens and looks in each direction along the tracks for an approaching train; and ascertains that no train is approaching. When it is safe to do so, the driver may drive the commercial motor vehicle across the tracks in a gear that permits the commercial motor vehicle to complete the crossing without a change of gears. The driver must not shift gears while crossing the tracks.
(1) Every bus transporting passengers,
(2) Every commercial motor vehicle transporting any quantity of a Division 2.3 chlorine.
(3) Every commercial motor vehicle which, in accordance with the regulations of the Department of Transportation, is required to be marked or placarded with one of the following classifications:
(i) Division 1.1
(ii) Division 1.2, or Division 1.3
(iii) Division 2.3 Poison gas
(iv) Division 4.3
(v) Class 7
(vi) Class 3 Flammable
(vii) Division 5.1
(viii) Division 2.2
(ix) Division 2.3 Chlorine
(x) Division 6.1 Poison
(xi) Division 2.2 Oxygen
(xii) Division 2.1
(xiii) Class 3 Combustible liquid
(xiv) Division 4.1
(xv) Division 5.1
(xvi) Division 5.2
(xvii) Class 8
(xviii) Division 1.4
(4) Every cargo tank motor vehicle, whether loaded or empty, used for the transportation of any hazardous material as defined in the Hazardous Materials Regulations of the Department of Transportation, parts 107 through 180 of this title.
(b) A stop need not be made at:
(2) A railroad grade crossing when a police officer or crossing flagman directs traffic to proceed,
(3) A railroad grade crossing controlled by a functioning highway traffic signal transmitting a green indication which, under local law, permits the commercial motor vehicle to proceed across the railroad tracks without slowing or stopping.
(4) An abandoned railroad grade crossing which is marked with a sign indicating that the rail line is abandoned,
(5) An industrial or spur line railroad grade crossing marked with a sign reading “Exempt.” Such “Exempt” signs shall be erected only by or with the consent of the appropriate State or local authority.