CDL Hazmat highway carriage, loading and segregation study guide
49 CFR Part 177 sets the extra rules for carrying hazardous materials by public highway. This guide sets out what the rule text states on who is responsible and how drivers are trained, where the shipping paper goes in the vehicle, general loading and unloading rules, attendance of cargo tanks, loading rules for specific hazard classes, the segregation table and its notes, and what to do with stopped vehicles, leaking tanks and repairs. Many duties fall on a named person (the carrier, the person loading, the driver), and many rules carry an exception in the same section, so the exact words matter. The hazardous materials (H) endorsement also requires a TSA security threat assessment and a State knowledge test; this guide covers neither, and goraedu does not issue endorsements. Your State may have its own requirements, so check them too. Every point links to the regulation and quotes its exact words.
Scope, responsibility and training
Unless the Hazardous Materials Regulations specifically give a duty to another person, each carrier, including a connecting carrier, must perform the duties in Part 177, comply with its requirements and ensure its hazmat employees are trained in them.
“Unless this subchapter specifically provides that another person shall perform a particular duty, each carrier, including a connecting carrier, shall perform the duties specified and comply with all applicable requirements in this part and shall ensure its hazmat employees receive training in relation thereto.”
49 CFR 177.800, Purpose and scope of this part and responsibility for compliance and training
A carrier may not transport a hazardous material by motor vehicle unless each of its hazmat employees involved in that transportation is trained as required by Part 177 and subpart H of Part 172.
“A carrier may not transport a hazardous material by motor vehicle unless each of its hazmat employees involved in that transportation is trained as required by this part and subpart H of part 172 of this subchapter.”
49 CFR 177.800, Purpose and scope of this part and responsibility for compliance and training
A person transporting a quantity of hazardous materials that requires placarding, or any quantity of a material listed as a select agent or toxin in 42 CFR part 73, must comply with the safe clearance rules for highway-rail grade crossings in 392.12, and may not engage in, allow or require texting or the use of a hand-held mobile telephone while driving.
“A person transporting a quantity of hazardous materials requiring placarding under 49 CFR part 172 or any quantity of a material listed as a select agent or toxin in 42 CFR part 73: (1) Must comply with the safe clearance requirements for highway-rail grade crossings in § 392.12 of this title; (2) May not engage in, allow, or require texting while driving, in accordance with § 392.80 of this title; and (3) May not engage in, allow, or require the use of a hand-held mobile telephone while driving, in accordance with § 392.82 of this title.”
49 CFR 177.804, Compliance with Federal Motor Carrier Safety Regulations
In addition to the training required by 177.800, no carrier may transport, or cause to be transported, a hazardous material unless each hazmat employee who will operate a motor vehicle has been trained in the applicable requirements of 49 CFR parts 390 through 397 and the procedures needed to operate that vehicle safely.
“In addition to the training requirements of § 177.800, no carrier may transport, or cause to be transported, a hazardous material unless each hazmat employee who will operate a motor vehicle has been trained in the applicable requirements of 49 CFR parts 390 through 397 and the procedures necessary for the safe operation of that motor vehicle.”
Driver training subjects include procedures for tunnels, bridges and railroad crossings; attendance of vehicles, parking, smoking, routing and incident reporting; and loading and unloading, including compatibility and segregation of cargo in a mixed load, package handling methods and load securement.
“(4) Procedures for maneuvering tunnels, bridges, and railroad crossings; (5) Requirements pertaining to attendance of vehicles, parking, smoking, routing, and incident reporting; and (6) Loading and unloading of materials, including— (i) Compatibility and segregation of cargo in a mixed load; (ii) Package handling methods; and (iii) Load securement.”
Each person who operates a cargo tank, or a vehicle with a portable tank with a capacity of 1,000 gallons or more, must also receive training in the applicable regulations and hold the appropriate State-issued CDL required by Part 383.
“each person who operates a cargo tank or a vehicle with a portable tank with a capacity of 1,000 gallons or more must receive training applicable to the requirements of this subchapter and have the appropriate State-issued commercial driver's license required by 49 CFR part 383.”
The driver training in 177.816(a) and (b) may be satisfied by meeting the current requirements for a CDL with a tank vehicle or hazardous materials endorsement.
“The training required by paragraphs (a) and (b) of this section may be satisfied by compliance with the current requirements for a Commercial Driver's License (CDL) with a tank vehicle or hazardous materials endorsement.”
Shipping papers in the vehicle
A person may not accept or transport a hazardous material by highway without a shipping paper prepared under Part 172, unless the material is excepted from shipping paper requirements. A subsequent carrier may not transport a hazardous material unless a shipping paper prepared under Part 172 accompanies it, except that § 172.204 is not required.
“A person may not accept a hazardous material for transportation or transport a hazardous material by highway unless that person has received a shipping paper prepared in accordance with part 172 of this subchapter or the material is excepted from shipping paper requirements under this subchapter. A subsequent carrier may not transport a hazardous material unless it is accompanied by a shipping paper prepared in accordance with part 172 of this subchapter, except for § 172.204, which is not required.”
An initial carrier may not accept a hazardous material unless the shipping paper includes a shipper's certification meeting 172.204. Except for a hazardous waste, the certification is not required for shipments transported entirely by private carriage or for bulk shipments in a cargo tank supplied by the carrier.
“An initial carrier may not accept a hazardous material offered for transportation unless the shipping paper describing the material includes a shipper's certification which meets the requirements in § 172.204 of this subchapter. Except for a hazardous waste, the certification is not required for shipments to be transported entirely by private carriage and for bulk shipments to be transported in a cargo tank supplied by the carrier.”
The driver of a motor vehicle containing hazardous material, and each carrier using it, must ensure the shipping paper is readily available to, and recognizable by, authorities in the event of an accident or inspection.
“A driver of a motor vehicle containing hazardous material, and each carrier using such a vehicle, shall ensure that the shipping paper required by this section is readily available to, and recognizable by, authorities in the event of accident or inspection.”
If the shipping paper is carried with other papers, it must be clearly distinguished by one of two options: distinctive tabbing, or having it appear first.
“Clearly distinguish the shipping paper, if it is carried with other shipping papers or other papers of any kind, by either distinctively tabbing it or by having it appear first; and”
When the driver is at the controls, the shipping paper must be within the driver's immediate reach while restrained by the lap belt, and also either readily visible to a person entering the driver's compartment or in a holder mounted inside the driver's side door (one of the two options).
“(A) Within his immediate reach while he is restrained by the lap belt; and (B) either readily visible to a person entering the driver's compartment or in a holder which is mounted to the inside of the door on the driver's side of the vehicle.”
When the driver is not at the controls, the shipping paper must be in a holder mounted inside the driver's side door, or on the driver's seat.
“When the driver is not at the vehicle's controls, the shipping paper shall be: (A) In a holder which is mounted to the inside of the door on the driver's side of the vehicle; or (B) on the driver's seat in the vehicle.”
Each person receiving a shipping paper must keep a copy or an electronic image of it, accessible at or through its principal place of business, and make it available on request to an authorized Federal, State or local official. The copy is kept three years after acceptance by the initial carrier for a hazardous waste, and one year after acceptance by the carrier for all other hazardous materials. Each copy must include the date of acceptance by the carrier.
“Each person receiving a shipping paper required by this section must retain a copy or an electronic image thereof, that is accessible at or through its principal place of business and must make the shipping paper available, upon request, to an authorized official of a Federal, State, or local government agency at reasonable times and locations. For a hazardous waste, the shipping paper copy must be retained for three years after the material is accepted by the initial carrier. For all other hazardous materials, the shipping paper copy must be retained for one year after the material is accepted by the carrier. Each shipping paper copy must include the date of acceptance by the carrier.”
General loading and unloading
Any package of hazardous material not permanently attached to the vehicle must be secured against shifting, including relative motion between packages, under conditions normally incident to transportation.
“Any package containing any hazardous material, not permanently attached to a motor vehicle, must be secured against shifting, including relative motion between packages, within the vehicle on which it is being transported, under conditions normally incident to transportation.”
Smoking on or about any motor vehicle is forbidden while loading or unloading Class 1, Class 3, Class 4, Class 5 or Division 2.1 materials.
“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.”
When loading or unloading those same classes, extreme care must be taken to keep fire away and to prevent persons nearby from smoking, lighting matches or carrying any flame or lighted cigar, pipe or cigarette.
“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 2.1 (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.”
No hazardous material may be loaded or unloaded unless the handbrake is securely set and all other reasonable precautions are taken to prevent motion of the vehicle.
“No hazardous material shall be loaded into or on, or unloaded from, any motor vehicle unless the handbrake be securely set and all other reasonable precautions be taken to prevent motion of the motor vehicle during such loading or unloading process.”
Reasonable care should be taken to prevent an undue rise in temperature of containers in transit. There must be no tampering with a container or its contents, and no discharge of contents, between the point of origin and the point of billed destination.
“Reasonable care should be taken to prevent undue rise in temperature of 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.”
Except for a cargo tank conforming to 173.29(b)(2), a cargo tank motor vehicle containing a hazardous material, regardless of quantity, may not be driven unless all manhole closures are closed and secured and all valves and closures in liquid discharge systems are closed and free of leaks. External emergency self-closing valves on MC 338 cargo tanks containing the residue of cryogenic liquids may be open or closed in transit.
“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, except external emergency self-closing valves on MC 338 cargo tanks containing the residue of cryogenic liquids may remain either open or closed during transit.”
A vehicle with a cargo heater of any type may transport Class 1 materials only if the heater is made inoperable by draining or removing its fuel tank and disconnecting its power source.
“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; and (ii) disconnecting the heater's power source.”
Cargo tank attendance
A cargo tank must be attended by a qualified person at all times while it is being loaded. The person responsible for loading the cargo tank is also responsible for making sure it is attended.
“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 attended.”
A motor carrier transporting hazardous materials by cargo tank must ensure it is attended by a qualified person at all times during unloading. That duty ends only when the carrier's transportation obligation is fulfilled, the cargo tank has been placed on the consignee's premises, and the motive power has been removed from the cargo tank and from the premises.
“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.”
A qualified person attends only if one of the listed options holds throughout the process. The first: except for unloading under 177.837(d) and 177.840(p) and (q), the qualified person is within 25 feet of the cargo tank, and when attending unloading must be alert and have an unobstructed view of the cargo tank and delivery hose to the maximum extent practicable.
“(3) A qualified person “attends” the loading or unloading of a cargo tank only if, throughout the process: (i) Except for unloading operations subject to §§ 177.837(d) and 177.840(p) and (q), the qualified person is within 7.62 m (25 feet) of the cargo tank. The qualified person attending the unloading of a cargo tank must be alert and have an unobstructed view of the cargo tank and delivery hose to the maximum extent practicable during the unloading operation; or”
Where a video monitoring system is used to meet the attendance requirement, the camera must be mounted to give an unobstructed view of all equipment involved in loading or unloading, including all valves, hoses, domes and pressure relief devices. Where an instrumentation and signaling system is used instead, it must give a surveillance capability at least equal to that of a human observer. Upon loss of video monitoring capability or of those systems, loading or unloading must be terminated immediately.
“(A) For a video monitoring system used to meet the attendance requirement, the camera must be mounted so as to provide an unobstructed view of all equipment involved in the loading or unloading operations, including all valves, hoses, domes, and pressure relief devices; (B) For an instrumentation and signaling system used to meet the attendance requirement, the system must provide a surveillance capability at least equal to that of a human observer; (C) Upon loss of video monitoring capability or instrumentation and signaling systems, loading or unloading operations must be immediately terminated;”
A person is qualified if made aware of the nature of the hazardous material and instructed on emergency procedures, and (except for remote observers and persons inspecting hoses under (i)(3)(iii)) is authorized to move the cargo tank and has the means to do so.
“A person is “qualified” if he has been made aware of the nature of the hazardous material which is to be loaded or unloaded, has been instructed on the procedures to be followed in emergencies, and except for persons observing loading or unloading operations by means of video cameras and monitors or instrumentation and signaling systems such as sensors, alarms, and electronic surveillance equipment located at a remote control station and persons inspecting hoses in accordance with paragraph (i)(3)(iii) of this section, is authorized to move the cargo tank, and has the means to do so.”
For a cargo tank unloading a combustible liquid as defined in 173.150(f), the qualified person must stay within 150 feet of the cargo tank and 25 feet of the delivery hose, and must observe both the cargo tank and the receiving container at least once every five minutes during unloading that takes more than five minutes.
“For a cargo tank unloading a material meeting the definition for combustible liquid in § 173.150(f) of this subchapter, the qualified person attending the unloading operation must remain within 45.72 meters (150 feet) of the cargo tank and 7.62 meters (25 feet) of the delivery hose and must observe both the cargo tank and the receiving container at least once every five minutes during unloading operations that take more than five minutes to complete.”
For liquefied petroleum gas or anhydrous ammonia unloaded in other than metered delivery service, the qualified person must stay within 25 feet of the cargo tank while the internal self-closing stop valve is open.
“An operator must use the following procedures for unloading liquefied petroleum gas or anhydrous ammonia from a cargo tank motor vehicle in other than metered delivery service: (1) The qualified person attending the unloading operation must remain within 7.62 m (25 feet) of the cargo tank when the internal self-closing stop valve is open.”
Loading rules by hazard class
Class 1 materials may not be loaded or unloaded with the engine running. The exceptions: the engine of a multipurpose bulk truck, and of a cargo tank motor vehicle carrying a single bulk hazardous material for blasting, may be used to run the vehicle's pumping equipment during loading or unloading.
“No Class 1 (explosive) materials may be loaded into or on or be unloaded from any motor vehicle with the engine running, except that the engine of a multipurpose bulk truck (see paragraph (d) of this section) and the engine of a cargo tank motor vehicle transporting a single bulk hazardous material for blasting may be used for the operation of the pumping equipment of the vehicle during loading or unloading.”
No bale hooks or other metal tools may be used to handle Class 1 materials, and no package of Class 1 materials may be rolled, except barrels or kegs. No package may be thrown or dropped.
“No bale hooks or other metal tools shall be used for the loading, unloading, or other handling of Class 1 (explosive) materials, nor shall any package or other container of Class 1 (explosive) materials, except barrels or kegs, be rolled. No packages of Class 1 (explosive) materials shall be thrown or dropped during process of loading or unloading or handling of Class 1 (explosive) materials.”
Division 1.1 or 1.2 materials may not be loaded into or carried on a vehicle or combination of vehicles if any listed condition applies. The conditions include more than two cargo carrying vehicles in the combination, any full trailer with a wheel base of less than 184 inches, or any vehicle in the combination being a cargo tank required to be marked or placarded under 177.823.
“Division 1.1 or 1.2 (explosive) materials may not be loaded into or carried on any vehicle or a combination of vehicles if: (1) More than two cargo carrying vehicles are in the combination; (2) Any full trailer in the combination has a wheel base of less than 184 inches; (3) Any vehicle in the combination is a cargo tank which is required to be marked or placarded under § 177.823; or”
Unless a cargo tank motor vehicle's engine runs a pump, Class 3 material may not be loaded into or unloaded from it with the engine running. A diesel engine may be left running if the outside temperature is at or below 10 °F (−12 °C).
“Unless the engine of a cargo tank motor vehicle is to be used for the operation of a pump, Class 3 material may not be loaded into, or on, or unloaded from any cargo tank motor vehicle while the engine is running. The diesel engine of a cargo tank motor vehicle may be left running during the loading and unloading of a Class 3 material if the ambient atmospheric temperature is at or below −12 °C (10 °F).”
For containers not in metallic contact with each other, one of two options (metallic bonds or ground conductors) must be provided to neutralize possible static charges before and during Class 3 transfers between them. The bonding is made by connecting the conductor first to the container to be filled and then to the container the liquid comes from, and not in any other order.
“For containers which are not in metallic contact with each other, either metallic bonds or ground conductors shall be provided for the neutralization of possible static charges prior to and during transfers of Class 3 (flammable liquid) materials between such containers. Such bonding shall be made by first connecting an electric conductor to the container to be filled and subsequently connecting the conductor to the container from which the liquid is to come, and not in any other order.”
Class 4 and Class 5 lading must be contained within the body and covered, with the tailgate closed and secured. This need not apply to pick-up and delivery vehicles used only in and about cities, towns or villages; water-tight bulk containers need not be covered by a tarpaulin.
“All of that portion of the lading of any motor vehicle transporting Class 4 (flammable solid) or Class 5 (oxidizing) materials shall be contained entirely within the body of the motor vehicle and shall be covered by such body, by tarpaulins, or other suitable means, and if such motor vehicle has a tailboard or tailgate, it shall be closed and secured in place during such transportation: Provided, however, That the provisions of this paragraph need not apply to “pick-up and delivery” motor vehicles when such motor vehicles are used in no other transportation than in and about cities, towns, or villages. Shipment in water-tight bulk containers need not be covered by a tarpaulin or other means.”
No packaging of nitric acid of 50 percent or greater concentration may be loaded above any packaging containing any other kind of material.
“No packaging of nitric acid of 50 percent or greater concentration may be loaded above any packaging containing any other kind of material.”
Except as 177.841(e)(3) provides, a motor carrier may not transport a package bearing or required to bear a POISON or POISON INHALATION HAZARD label or placard in the same vehicle as material marked as or known to be foodstuffs, feed or edible material intended for consumption by humans or animals, unless the poisonous material is packaged as required and is either overpacked in a metal drum as specified in 173.25(c), or loaded into a closed unit load device with the food, feed or other edible material in another closed unit load device.
“A motor carrier may not transport a package: (1) Except as provided in paragraph (e)(3) of this section, bearing or required to bear a POISON or POISON INHALATION HAZARD label or placard in the same motor vehicle with material that is marked as or known to be foodstuffs, feed or edible material intended for consumption by humans or animals unless the poisonous material is packaged in accordance with this subchapter and is: (i) Overpacked in a metal drum as specified in § 173.25(c) of this subchapter; or (ii) Loaded into a closed unit load device and the foodstuffs, feed, or other edible material are loaded into another closed unit load device;”
49 CFR 177.841, Division 6.1 (poisonous) materials and Division 2.3 (poisonous gas) materials
The total transport index of Class 7 packages in any transport vehicle may not exceed 50. This does not apply to exclusive use shipments described in 173.441(b), 173.457 and 173.427.
“The number of packages of Class 7 (radioactive) materials in any transport vehicle or in any single group in any storage location must be limited so that the total transport index number does not exceed 50. The total transport index of a group of packages and overpacks is determined by adding together the transport index number on the labels on the individual packages and overpacks in the group. This provision does not apply to exclusive use shipments described in §§ 173.441(b), 173.457, and 173.427 of this subchapter.”
Not covered here
The detonator rules in 177.835(g), the Class 2 cryogenic, chlorine and metered delivery rules in 177.840, the Class 7 separation distance table in 177.842(b), and the rules for passenger-carrying vehicles in 177.870 are not covered here; read them in the regulation. We only write what an official source states, so study these parts with your certifying program's materials.
Segregation
177.848 applies to materials that meet one or more hazard classes and are in any one of these: packages that must be labeled or placarded under Part 172, a compartment within a multi-compartmented cargo tank subject to 173.33, or a portable tank loaded in a transport vehicle or freight container.
“This section applies to materials which meet one or more of the hazard classes defined in this subchapter and are: (1) In packages that must be labeled or placarded in accordance with part 172 of this subchapter; (2) In a compartment within a multi-compartmented cargo tank subject to the restrictions in § 173.33 of this subchapter; or (3) In a portable tank loaded in a transport vehicle or freight container.”
In addition to the table and except as provided in 173.12(e): cyanides may not be stored, loaded and transported with acids if a mixture would generate hydrogen cyanide; Division 4.2 materials may not be with Class 8 liquids; and Division 6.1 PG I, Hazard Zone A material may not be with Class 3 material, Class 8 liquids, or Division 4.1, 4.2, 4.3, 5.1 or 5.2 materials.
“In addition to the provisions of paragraph (d) of this section and except as provided in § 173.12(e) of this subchapter, cyanides, cyanide mixtures or solutions may not be stored, loaded and transported with acids if a mixture of the materials would generate hydrogen cyanide; Division 4.2 materials may not be stored, loaded and transported with Class 8 liquids; and Division 6.1 Packing Group I, Hazard Zone A material may not be stored, loaded and transported with Class 3 material, Class 8 liquids, and Division 4.1, 4.2, 4.3, 5.1 or 5.2 materials.”
Except as otherwise provided in the regulations, hazardous materials must be stored, loaded or transported according to the segregation table in 177.848(d) and the rest of the section.
“Except as otherwise provided in this subchapter, hazardous materials must be stored, loaded or transported in accordance with the following table and other provisions of this section:”
A hazard class or division missing from the table, or a blank space, means no restrictions apply.
“The absence of any hazard class or division or a blank space in the table indicates that no restrictions apply.”
An "X" means the materials may not be loaded, transported or stored together in the same transport vehicle or storage facility during transportation.
“The letter “X” in the table indicates that these materials may not be loaded, transported, or stored together in the same transport vehicle or storage facility during the course of transportation.”
An "O" means the materials may not be together unless separated so that, if packages leak under normal transportation conditions, the materials would not commingle. Whatever separation is used, Class 8 liquids may not be loaded above or adjacent to Class 4 or Class 5 materials, except that shippers may load truckload shipments together when it is known the mixture would not cause a fire or a dangerous evolution of heat or gas.
“The letter “O” in the table indicates that these materials may not be loaded, transported, or stored together in the same transport vehicle or storage facility during the course of transportation unless separated in a manner that, in the event of leakage from packages under conditions normally incident to transportation, commingling of hazardous materials would not occur. Notwithstanding the methods of separation employed, Class 8 (corrosive) liquids may not be loaded above or adjacent to Class 4 (flammable) or Class 5 (oxidizing) materials; except that shippers may load truckload shipments of such materials together when it is known that the mixture of contents would not cause a fire or a dangerous evolution of heat or gas.”
A "*" means segregation among different Class 1 materials is governed by the compatibility table in 177.848(f).
“The “*” in the table indicates that segregation among different Class 1 (explosive) materials is governed by the compatibility table in paragraph (f) of this section.”
Note "A" means that, despite an "X", ammonium nitrate (UN1942) and ammonium nitrate fertilizer may be loaded or stored with Division 1.1 or Division 1.5 materials, unless 177.835(c) prohibits it.
“The note “A” in the second column of the table means that, notwithstanding the requirements of the letter “X”, ammonium nitrate (UN1942) and ammonium nitrate fertilizer may be loaded or stored with Division 1.1 (explosive) or Division 1.5 materials, unless otherwise prohibited by § 177.835(c).”
When the 172.101 table or 172.402 requires a subsidiary hazard label, the segregation for the subsidiary hazard applies when it is more restrictive than that for the primary hazard. However, materials of the same class may be stored together without regard to segregation for a secondary hazard if they cannot react dangerously with each other (combustion, dangerous evolution of heat, evolution of flammable, poisonous or asphyxiant gases, or formation of corrosive or unstable materials).
“When the § 172.101 table or § 172.402 of this subchapter requires a package to bear a subsidiary hazard label, segregation appropriate to the subsidiary hazard must be applied when that segregation is more restrictive than that required by the primary hazard. However, hazardous materials of the same class may be stored together without regard to segregation required for any secondary hazard if the materials are not capable of reacting dangerously with each other and causing combustion or dangerous evolution of heat, evolution of flammable, poisonous, or asphyxiant gases, or formation of corrosive or unstable materials.”
Notwithstanding 177.848(d), certain listed Division 4.2 (self-heating) materials may travel with Class 8 materials if palletized at least 4 inches (100 mm) off the floor and separated from the corrosive material by at least 4 feet (1.2 m) horizontally.
“Notwithstanding the segregation requirements of § 177.848(d), the following Division 4.2 (self-heating) materials may be transported on the same transport vehicle with Class 8 (corrosive) materials. The hazardous materials must be palletized with a minimum height of 100 mm (4 inches) off the floor of the vehicle, and the self-heating material must be separated from the corrosive material by a minimum horizontal distance of 1.2 m (4 feet).”
Not covered here
The full segregation table in 177.848(d) and the Class 1 compatibility table in 177.848(f) are not reproduced here; read them in the regulation. We only write what an official source states, so study these parts with your certifying program's materials.
Emergencies, disabled vehicles and repairs
A carrier may not move a transport vehicle containing a hazardous material unless it is marked and placarded (or as authorized in 171.12a), unless, in an emergency, one of these applies: it is escorted by a State or local government representative, the carrier has permission from the Department, or the movement is necessary to protect life or property.
“A carrier may not move a transport vehicle containing a hazardous material unless the vehicle is marked and placarded in accordance with part 172 or as authorized in § 171.12a of this subchapter, or unless, in an emergency: (1) The vehicle is escorted by a representative of a state or local government; (2) The carrier has permission from the Department; or (3) Movement of the transport vehicle is necessary to protect life or property.”
49 CFR 177.823, Movement of motor vehicles in emergency situations
Smoking, and any other source of ignition, is not permitted in the vicinity of a leaking cargo tank.
“Smoking, and any other source of ignition, in the vicinity of a leaking cargo tank is not permitted.”
49 CFR 177.823, Movement of motor vehicles in emergency situations
A leaking cargo tank may be transported only the minimum distance needed to reach a place where its contents can be disposed of safely.
“A leaking cargo tank may be transported only the minimum distance necessary to reach a place where the contents of the tank or compartment may be disposed of safely.”
49 CFR 177.823, Movement of motor vehicles in emergency situations
When a hazmat vehicle is stopped on the traveled portion of a highway or its shoulder for any cause other than a necessary traffic stop, special care must be taken to guard the vehicle and load, and special effort made to move it to a place where the hazards can be provided against.
“Whenever for any cause other than necessary traffic stops any motor vehicle transporting any hazardous material is stopped upon the traveled portion of any highway or shoulder thereof, special care shall be taken to guard the vehicle and its load or to take such steps as may be necessary to provide against hazard. Special effort shall be made to remove the motor vehicle to a place where the hazards of the materials being transported may be provided against.”
49 CFR 177.854, Disabled vehicles and broken or leaking packages; repairs
When a vehicle carrying Class 2, 3, 4, 5 or 8 or Division 6.1 materials is stopped on the traveled portion of a highway or its shoulder for any cause other than a necessary traffic stop, cargo tanks used for Class 3 or Division 2.1 materials (loaded or empty) and vehicles carrying Division 1.1, 1.2 or 1.3 materials must set out warning devices as prescribed by 392.25. Other vehicles set them out as prescribed in 392.22.
“Whenever any motor vehicle transporting Class 3 (flammable liquid), Class 4 (flammable solid), Class 5 (oxidizing), Class 8 (corrosive), Class 2 (gases), or Division 6.1 (poisonous) materials, is stopped for any cause other than necessary traffic stops upon the traveled portion of any highway, or a shoulder next thereto, the following requirements shall be complied with during the period of such stop: (1) For motor vehicles other than cargo tank motor vehicles used for the transportation of Class 3 (flammable liquid) or Division 2.1 (flammable gas) materials and not transporting Division 1.1, 1.2, or 1.3 (explosive) materials, warning devices must be set out in the manner prescribed in § 392.22 of this title. (2) For cargo tanks used for the transportation of Class 3 (flammable liquid) or Division 2.1 (flammable gas) materials, whether loaded or empty, and vehicles transporting Division 1.1, 1.2, or 1.3 (explosive) materials, warning devices must be set out in the manner prescribed by § 392.25 of this title.”
49 CFR 177.854, Disabled vehicles and broken or leaking packages; repairs
No person may use heat, flame or spark producing devices to repair or maintain the cargo or fuel containment system of a vehicle required to be placarded, other than COMBUSTIBLE.
“No person may use heat, flame or spark producing devices to repair or maintain the cargo or fuel containment system of a motor vehicle required to be placarded, other than COMBUSTIBLE, in accordance with subpart F of part 172 of this subchapter.”
49 CFR 177.854, Disabled vehicles and broken or leaking packages; repairs
A cargo tank (or compartment) used for Class 3 or Division 6.1 liquid, or any fuel container, may not be repaired by flame, arc or other welding unless it has first been made gas-free.
“No repair of a cargo tank used for the transportation of any Class 3 (flammable liquid) or Division 6.1 (poisonous liquid) material, or any compartment thereof, or of any container for fuel of whatever nature, may be repaired by any method employing a flame, arc, or other means of welding, unless the tank or compartment shall first have been made gas-free.”
49 CFR 177.854, Disabled vehicles and broken or leaking packages; repairs
Sources
- eCFR: 49 CFR 177.800, Purpose and scope of this part and responsibility for compliance and training (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.804, Compliance with Federal Motor Carrier Safety Regulations (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.816, Driver training (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.817, Shipping papers (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.834, General requirements (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.837, Class 3 (flammable liquid) materials (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.840, Class 2 (gases) materials (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.835, Class 1 (explosive) materials (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.838, Class 4 (flammable solid) materials, Class 5 (oxidizing) materials, and Division 4.2 (self-heating and pyrophoric liquid) materials (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.839, Class 8 (corrosive) materials (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.841, Division 6.1 (poisonous) materials and Division 2.3 (poisonous gas) materials (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.842, Class 7 (radioactive) material (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.848, Segregation of hazardous materials (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.823, Movement of motor vehicles in emergency situations (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 49 CFR 177.854, Disabled vehicles and broken or leaking packages; repairs (as of Nov 4, 2026)Checked November 6, 2026
Other CDL study guides: License standards, Driver qualifications, Driving rules, Hours of service, Inspection and maintenance, Brakes, Cargo securement, Drug and alcohol testing, Hazmat classes and definitions, Hazmat shipping papers and emergency information, Hazmat marking, Hazmat placarding, Hazmat driving, parking and training