49 CFR § 174.112 - Loading Division 1.3 materials and Division 1.2 (explosive) materials (Also see § 174.101).
(a) Division 1.3 materials and Division 1.2 (explosive) materials may not be loaded, transported or stored in a rail car equipped with any type of lighted heater or open-flame device, or in a rail car equipped with any apparatus or mechanism utilizing an internal combustion engine in its operation.
(b) Except as provided in § 174.101(b), (n), or (o), Division 1.3 materials and Division 1.2 (explosive) materials must be transported in a closed car or container car which is in good condition, and into which sparks cannot enter. The car does not require the car certificates prescribed in § 174.104(c) through (f). If the doors are not tight, they must be stripped to prevent the entrance of sparks. Wood floored cars must be equipped with spark shields (see § 174.104). Packages of Division 1.3 materials and Division 1.2 (explosive) materials must be blocked and braced to prevent their shifting and possible damage due to shifting of other freight during transportation. For recommended methods of blocking and bracing see the Intermodal Loading Guide for Products in Closed Trailers and Containers (see Table 1 to § 171.7 of this subchapter).
(c) Division 1.3 materials and Division 1.2 (explosive) materials may not be transported in a truck body, trailer, or container on a flatcar unless:
(1) The truck body, trailer, or container is closed and tight;
(2) All automatic heating or refrigerating machinery with which the truck body, trailer, or container is equipped is inoperative; and
(3) Packages of Division 1.2 materials and Division 1.3 (explosive) materials are blocked and braced within the truck body, trailer, or container to prevent their shifting and possible damage due to shifting of other freight during transportation (ends, sidewalls, or doors of the truck body, trailer, or container may not be relied on to prevent the shifting of heavy loads). For recommended methods of blocking and bracing see the Intermodal Loading Guide for Products in Closed Trailers and Containers (IBR, see § 171.7 of this subchapter).