Placard

Placards are the vehicle-sized version of the smaller diamond labels found on individual packages. Under the DOT hazmat rules in 49 CFR Parts 171-180, a vehicle usually carries one on each side and each end. The color and symbol follow the hazard class: a flame on red for flammables, for example, and a corrosive symbol on a black and white background.

Many placards display the class number at the bottom. Some also show a four-digit UN or NA identification number, either inside the placard or on a separate orange panel, which allows a responder to look up the material in the Emergency Response Guidebook (ERG) without seeing the paperwork. This is especially useful when the driver is injured or the shipping papers are out of reach.

Whether a placard is required depends on the class, the quantity and how the material is packaged. Some classes require placards for any amount, while others are placarded only above a threshold, and mixed loads may use a general DANGEROUS placard in some circumstances. These details are in the regulations and should be checked rather than assumed. A load that qualifies as a Limited quantity shipment may be exempt.

Placards are not the same as the NFPA 704 diamond or HMIS label used at fixed facilities. Those systems rate hazards on a numeric scale for people working at a site, while a transport placard identifies a class of hazard for people near a moving vehicle.