(a) Except as provided in paragraphs (b) and (c) of this section, the position in a train of each loaded placarded car, transport vehicle, freight container, and bulk packaging must conform to the provisions of this section.

(b) A car placarded "RADIOACTIVE" must comply with train positioning requirements of paragraph (d) of this section and must be separated from a locomotive, occupied caboose, or carload of undeveloped film by at least one non-placarded car.

(c) A tank car containing the residue of a hazardous material must be separated from a locomotive or occupied caboose by at least one rail car other than a placarded tank car.

(d) Position of rail cars in a train. In the following table: Position in Train of Placarded Cars Transporting Hazardous Materials RESTRICTIONS Placard Group 1 Placard Group 2 Placard Group 3 Placard Group 4 Rail Car Tank Car Rail Car Tank Car Rail Car Rail Car 1. When train length permits, placarded car may not be nearer than the sixth car from the engine or occupied caboose X X X 2. When train length does not permit, placarded car must be placed near the middle of the train, but not nearer than the second car from an engine or occupied caboose X X X 3. A placarded car may not be placed next to an open-top car when any of the lading in the open top car protrudes beyond the car ends, or if the lading shifted, would protrude beyond the car ends. X X X 4. A placarded car may not be placed next to a loaded flat car, except closed TOFC/COFC equipment, auto carriers, and other specially equipped cars with tie-down devices for securing vehicles. Permanent bulk head flat cars are considered the same as open-top cars X X X 5. A placarded car may not be placed next to any transport vehicle or freight container having an internal combustion engine or an open-flame device in operation. X X X 6. Placarded cars may not be placed next to each other based on the following: Placard Group 1 X X X X X Placard Group 2 X X X X Placard Group 3 X X X X Placard Group 4 X X X X X PLACARD GROUP: Group 1 — Divisions 1.1 and 1.2 (explosive) materials. Group 2 — Divisions 1.3, 1.4, 1.5 (explosive), Class 2 (compressed gas; other than Div 2.3, PG I, Zone A), Class 3 (flammable liquid), Class 4 (flammable solid), Class 5 (oxidizing), Class 6 (poisonous liquid; other than Div 6.1, PG I, Zone A), and Class 8 (corrosive) materials. Group 3 — Divisions 2.3 (Zone A; poisonous gas) and 6.1 (PG I, Zone A; poisonous liquid) materials. Group 4 — Class 7 (radioactive) materials.   (1) Where an "X" appears at the intersection of a Placard Group column and a Restriction row, the corresponding restriction applies.   (2) "Rail Car" means a car other than a tank car.   (3) For purposes of this subpart, each unit of an articulated intermodal rail car shall be considered as one car.

[Amdt. 174-68, 55 FR 52680, Dec. 21, 1990, as amended at 57 FR 45464, Oct. 1, 1992; Amdt. 174-83, 61 FR 28678, June 5, 1996; Amdt.174-83, 61 FR 50255, Sept. 25, 1996; Amdt. 174-83, 61 FR 51339, Oct. 1, 1996; 64 FR 51919, Sept. 27, 1999; 66 FR 45383, Aug. 28, 2001]