Placarding Rules
When you must placard, what the placards mean, and where they go.
Endorsement: Hazardous Materials (H) · Source: FMCSA CDL Manual (public domain)
Placarding is the visible signal that a vehicle is carrying hazardous materials, and the FMCSA Hazmat exam tests the placarding rules in detail. The general rule under 49 CFR 172.504 is that any quantity of a Table 1 material — explosives 1.1, 1.2, and 1.3; certain poisons 6.1 packing group I inhalation hazard; dangerous-when-wet 4.3 packing group I; radioactive yellow-III; and a few others — requires placarding regardless of weight. Materials in Table 2 (most other hazard classes) require placarding only when 1,001 pounds or more of total hazmat weight (combined for materials of any class) is on the vehicle.
Placards must be displayed on all four sides of the vehicle: front, both sides, and rear. They must be visible from the direction they face, mounted in the prescribed area, and not obscured by attachments or dirt. Mixed loads sometimes require multiple placards — for example, a load with 2,000 pounds of Class 3 and 500 pounds of Class 8 requires Class 3 placards (Class 3 alone exceeds 1,001 pounds) and the driver may also need Class 8 placards depending on the specific materials.
The Dangerous placard is a special-purpose placard that may be used in place of multiple class-specific placards when a vehicle carries non-bulk packages of two or more categories of hazardous materials, with no single class exceeding 5,000 pounds at any one loading facility. The exam tests this exception specifically. Subsidiary placards are required when a material has a subsidiary risk; for example, anhydrous ammonia (Class 2.2) with subsidiary corrosivity (Class 8) requires both placards. Drivers must verify placarding before driving — a missing or wrong placard is the carrier\'s and driver\'s responsibility, not the shipper\'s.
Key terms to memorize
- placard
- shipping paper
- Emergency Response Guidebook
- hazard class
- segregation table
- Safety Data Sheet
- TSA threat assessment
Other Hazardous Materials (H) topics
- Hazard Classes — The nine federal hazard classes and what each one looks like in the field.
- Shipping Papers — What every hazmat shipping paper must contain and where it must live in the cab.
- Segregation and Loading — Which hazardous materials cannot be loaded together, and how to comply.
- Emergency Response — What to do in the first minutes after a hazmat incident.
Test what you learned
Now that you have the Placarding Rules material in your head, drill the Hazardous Materials (H) practice test. The questions are drawn from the same FMCSA source material this article paraphrases. For state-specific framing, jump to your state page and pick the Hazardous Materials (H) test for your jurisdiction.