Who this is for: CDL drivers, fleet managers, owner-operators, compliance assistants
Hazmat Placarding Requirements for CMV Drivers
Most hazardous materials require placards on all four sides of a CMV when transported in quantities of 1,001 lbs or more. Certain high-hazard materials require placards in any quantity. Placards must match the hazard class, be properly placed, and remain visible and legible throughout transport.
Important Notice
Placard requirements are set in 49 CFR Part 172 Subparts E and F. Specific requirements vary by hazard class, quantity, and material type. Consult 49 CFR 172.500–172.560 and the current hazardous materials table (172.101) for applicable rules. This page is an educational overview.
When placards are required
Under 49 CFR Part 172 Subpart F, placards are required when transporting hazardous materials in quantities that meet or exceed thresholds. For most hazard classes (Table 2 materials), placards are required when the total gross weight of a hazard class is 1,001 lbs (454 kg) or more. For certain high-hazard materials listed in Table 1 — including explosives (Division 1.1, 1.2, 1.3), poison gas, and radioactive materials — placards are required regardless of quantity.
Placard types and hazard class matching
Placards are color-coded and labeled to correspond to the nine hazard classes: Class 1 (Explosives), Class 2 (Gases), Class 3 (Flammable Liquid), Class 4 (Flammable Solid), Class 5 (Oxidizer/Organic Peroxide), Class 6 (Toxic/Infectious), Class 7 (Radioactive), Class 8 (Corrosive), and Class 9 (Miscellaneous). Each placard must display the appropriate hazard class label and, for most materials, the four-digit UN identification number. The placard must correspond to the hazard class listed on the shipping papers.
Placard placement — four-sides rule
Placards must be affixed to all four sides of the vehicle: front, rear, and both sides. On a combination vehicle (tractor-trailer), the front placard goes on the front of the power unit, and the other three placards go on the trailer. Placards must be visible from the direction they face, be kept clean and legible, be securely attached, and not be obscured by other markings or equipment. Placards must remain in place throughout the entire trip.
DANGEROUS placard — mixed loads
When a vehicle carries two or more Table 2 materials with different hazard classes that each require a placard, the DANGEROUS placard may be used in place of the individual class placards — provided that no single hazard class reaches 2,205 lbs (1,000 kg) or more, in which case the specific placard for that class is required in addition to (or instead of) DANGEROUS. Carriers may always choose to use the specific placard rather than the DANGEROUS placard.
Placard visibility and condition requirements
Placards must be displayed squarely on point (diamond orientation), with each side measuring at least 10.8 inches (273.5 mm). They must be unobstructed and readable from at least 100 feet in daylight. Damaged, faded, or missing placards during transport are a violation. If a placard is damaged in transit (accident, weather), the driver must take corrective action as soon as practicable. Placards must be removed when the hazardous material is no longer on board.
Checking placard condition before departure
Before pulling out, walk the vehicle and verify all four placards are secure, correctly oriented (diamond-point up), and legible from a distance. A placard held on with aging tape or a loose clip will not stay put at highway speed. Carry spare placards for the hazard classes you regularly haul — replacing a damaged or missing placard before departure takes two minutes. A placard that falls off en route creates a compliance problem and, more importantly, leaves emergency responders without accurate hazard information if something goes wrong on the road.
Frequently Asked Questions
Do placards stay on the vehicle after the hazmat is delivered?
No. Placards must be removed or covered as soon as the hazardous materials are no longer in the vehicle. Operating a CMV with hazmat placards when no hazmat is present is a violation.
Who is responsible for ensuring the correct placards are applied?
Both the shipper and the carrier share responsibility for proper placarding. The shipper provides the hazmat description and placard information. The carrier (and driver) must verify that the correct placards are in place before departure. If the vehicle is improperly placarded, both parties may be subject to enforcement action.
What about empty tanks that previously carried hazmat?
An empty tank that transported a hazardous liquid may still require placards until the tank is purged or certified residue-free to the applicable standard for that material. The specific requirements depend on the material previously transported. Do not assume empty means placard-free — verify the applicable rule for your tank and material before removing placards.