(A) Packages secured in a motor vehicle.
Any package containing any hazardous material, not permanently attached to a motor vehicle, must be
secure against shifting, including relative motion between packages, within the vehicle on which it is being
transported, under conditions normally incident to transportation. Packages having valves or other fittings
must be loaded in a manner to minimize the likelihood of damage during transportation
(B) Each package containing a hazardous material bearing package orientation markings prescribed in 172.312
of this subchapter must be loaded on a transport vehicle or within a freight container in accordance with
such markings and must remain in the correct position indicated by the markings during transportation
(C) No smoking while loading or unloading. Smoking on or about any motor vehicle while loading or unloading
any Class 1 (explosive), Class 3 (flammable liquid), Class 4 (flammable solid), Class 5 (oxidizing), or Division
2.1 (flammable gas) materials is forbidden.
(D) Keep fire away, loading and unloading. Extreme care shall be taken in the loading or unloading of any
Class 1 (explosive), Class 3 (flammable liquid), Class 4 (flammable solid), Class 5 (oxidizing), or Division 2
(flammable gas) materials into or from any motor vehicle to keep fire away and to prevent persons in the
vicinity from smoking, lighting matches, or carrying any flame or lighted cigar, pipe, or cigarette.
(E) Hand brake set while loading and unloading. No hazardous material shall be loaded into or on, or unloaded
from, any motor vehicle unless the hand brake is securely set and all other reasonable precautions be
taken to prevent motion of the motor vehicle during such loading or unloading process.
(F) Use of tools, loading and unloading. No tools which are likely to damage the effectiveness of the closure of
any package or other container, or likely adversely to affect such package or container, shall be used for
the loading or unloading of any Class 1 (explosive) material or other dangerous article.
(H) Precautions concerning containers in transit; fueling road units. Reasonable care should be taken to
prevent undue rise in temperature of the containers and their contents during transit. There must be no
tampering with such container or the contents thereof nor any discharge of the contents of any container
between point of origin and point of billed destination. Discharge of contents of any container, other than
a cargo tank or IM portable tank, must not be made prior to removal from the motor vehicle. Nothing
contained in this paragraph shall be so construed as to prohibit the fueling of machinery or vehicles used
in road construction or maintenance.
(I) Attendance requirements
(1) Loading. A cargo tank must be attended by a qualified person at all times when it is being loaded. The
person who is responsible for loading the cargo tank is also responsible for ensuring that it is so
(2) Unloading. A motor carrier who transports hazardous materials by a cargo tank must ensure that the
cargo tank is attended by a qualified person at all times during unloading. However, the carrier’s
obligation to ensure attendance during unloading ceases when:
(i) The carrier’s obligation for transporting the materials is fulfilled;
(ii) The cargo tank has been placed upon the consignee’s premises; and
(iii) The motive power has been removed from the cargo tank and removed from the premises.
(3) Except for unloading operations subject to §§ 177.837(d), 177.840(p), and 177.840(q), a qualified
person ‘‘attends’’ the loading or unloading of a cargo tank if, throughout the process, he is alert and is
within 7.62m (25 feet) of the cargo tank. The qualified person attending the unloading of a cargo tank
must have an unobstructed view of the cargo tank and delivery hose to the maximum extent practicable
during the unloading operation.
(4) A person is ‘‘qualified’’ if he has been made aware of the nature of the hazardous material which is to be
loaded or unloaded, he has been instructed on the procedures to be followed in emergencies, he is
authorized to move the cargo tank, and he has the means to do so.
(J) Except for a cargo tank conforming to 173.29(b)(2) of this subchapter, a person may not drive a cargo tank
motor vehicle containing a hazardous material regardless of quantity unless:
(1) All manhole closures are closed and secured; and
(2) All valves and other closures in liquid discharge systems are closed and free of leaks.
(L) Use of cargo heaters when transporting certain hazardous material.
Transportation includes loading, carrying, and unloading.
(1) When transporting Class 1 (explosive) materials. A motor vehicle equipped with a cargo heater of any
type may transport Class 1 (explosive) materials only if the cargo heater is rendered inoperable by:
(i) Draining or removing the cargo heater fuel tank;
(ii) disconnecting the heater’s power source.
(2) When transporting certain flammable material
(i) Use of combustion cargo heaters. A motor vehicle equipped with a combustion cargo heater may be
used to transport Class 3 (flammable liquid) or Division 2.1 (flammable gas) materials only if each of
the following requirements are met:
(A) It is a catalytic heater.
(B) The heater’s surface temperature cannot exceed 54 °C (130 °F)—either on a thermostatically
controlled heater or on a heater without thermostatic control when the outside or ambient
temperature is 16 °C (61 °F) or less.
(C) The heater is not ignited in a loaded vehicle.
(D) There is no flame, either on the catalyst or anywhere in the heater.
(E) The manufacturer has certified that the heater meets the requirements under paragraph (l)(2)(i) of
this section by permanently marking the heater ‘‘MEETS DOT REQUIREMENTS FOR CATALYTIC
HEATERS USED WITH FLAMMABLE LIQUID AND GAS.’’
(F) The heater is also marked ‘‘DO NOT LOAD INTO OR USE IN CARGO COMPARTMENTS CONTAINING
FLAMMABLE LIQUID OR GAS IF FLAME IS VISIBLE ON CATALYST OR IN HEATER.’’
(G) Heater requirements under 393.77 of this title are complied with.
(ii) Effective date for combustion heater requirements. The requirements under paragraph (l)(2)(i) of
this section govern as follows:
(A) Use of a heater manufactured after November 14, 1975, is governed by every requirement
under (l)(2)(i) of this section;
(B) Use of a heater manufactured before November 15, 1975, is governed only by the
requirements under (l)(2)(i)(A), (C), (D), (F) and (G) of this section until October 1, 1976; and
(C) Use of any heater after September 30, 1976, is governed by every requirement under
paragraph (l)(2)(i) of this section.
(iii) Restrictions on automatic cargospace-heating temperature control devices. Restrictions on these
devices have two dimensions: Restrictions upon use and restrictions which apply when the device
must not be used.
(A) Use restrictions. An automatic cargo-space-heating temperature control device may be used when
transporting Class 3 (flammable liquid) or Division 2.1 (flammable gas) materials only if each of the
following requirements is met:
(1) Electrical apparatus in the cargo compartment is nonsparking or explosion proof.
(2) There is no combustion apparatus in the cargo compartment.
(3) There is no connection for return of air from the cargo compartment to the combustion
(4) The heating system will not heat any part of the cargo to more than 54°C (129 °F).
(5) Heater requirements under § 393.77 of this title are complied with.
(B) Protection against use. Class 3 (flammable liquid) or Division 2.1 (flammable gas) materials may be
transported by a vehicle, which is equipped with an automatic cargospace heating temperature
control device that does not meet each requirement of paragraph (l)(2)(iii)(A) of this section, only
if the device is first rendered inoperable, as follows:
(1) Each cargo heater fuel tank, if other than LPG, must be emptied or removed.
(2) Each LPG fuel tank for automatic temperature control equipment must have its discharge valve
closed and its uel feed line disconnected.
(M) Tanks constructed and maintained in compliance with Spec. 106A or 110A (§§ 179.300, 179.301 of this
subchapter) that are authorized for the shipment of hazardous materials by highway in part 173 of this
subchapter must be carried in accordance with the following requirements:
(1) Tanks must be securely chocked or clamped on vehicles to prevent any shifting.
(2) Equipment suitable for handling a tank must be provided at any point where a tank is to be loaded upon
or removed from a vehicle.
(3) No more than two cargo carrying vehicles may be in the same combination of vehicles.
(4) Compliance with §§ 174.200 and 174.204 of this subchapter for combination rail freight, highway
shipments and for trailer-on-flat-car service is required.
(N) Specification 56, 57, IM 101, and IM 102 portable tanks, when loaded, may not be stacked on each other
nor placed under other freight during transportation by motor vehicle.
(O) Unloading of IM and UN portable tanks. No person may unload an IM or UN portable tank while it remains
on a transport vehicle with the motive power unit attached except under the following conditions:
(1) The unloading operation must be attended by a qualified person in accordance with the requirements in
paragraph (i) of this section. The person performing unloading functions must be trained in handling
emergencies that may occur during the unloading operation.
(2) Prior to unloading, the operator of the vehicle on which the portable tank is transported must ascertain
that the conditions of this paragraph (o) are met.
(3) An IM or UN portable tank equipped with a bottom outlet as authorized in Column (7) of the § 172.101
Table of this subchapter by assignment of a T Code in the appropriate proper shipping name entry, and
that contains a liquid hazardous material of Class 3, PG I or II, or PG III with a flash point of less than
100 °F (38 °C); Division 5.1, PG I or II; or Division 6.1, PG I or II, must conform to the outlet
requirements in §178.275(d)(3) of this subchapter; or, until October 1, 2004, be unloaded only at a
facility conforming to the following;
(i) The applicable fire suppression requirements in 29 CFR 1910.106(e), (f), (g), (h), and (i);
(ii) The emergency shutdown requirements in 29 CFR 1910.119(f), 1910.120(q) and 1910.3 (a);
(iii) The emergency response planning requirements in 29 CFR part 1910 and 40 CFR part 68;
(iv) An emergency discharge control procedure applicable to unloading operations, including instructions
on handling emergencies that may occur during the unloading operation; and
(v) Public access to the unloading area must be controlled in a manner ensuring no public access during
(4) Alternatively, conformance to equivalent or more stringent non-federal requirements is authorized in
place of paragraphs (o)(3)(i) through (o)(3)(iv) of this section.