2.3 Markings, Labels & Placards

Three Ways the Hazard Is Communicated

The HMR use a layered hazard communication system so that anyone — a dock worker, a driver, a police officer, a firefighter — can recognize a danger without opening a package. Three terms are easy to mix up, and the test checks that you can tell them apart.

Think of it as a chain: markings tell you what it is, labels tell you the hazard on the box, and placards broadcast the hazard to everyone on the road. Other common markings include orientation arrows (two arrows showing which end of the package goes up, used on packages with liquids so they stay upright) and the CARGO AIRCRAFT ONLY label for materials forbidden on passenger aircraft.

When Placards Are Required

Placarding is driven by the type and quantity of material, set out in two tables in 49 CFR 172.504.

The 1,001-Pound Threshold

As a general rule, a vehicle must be placarded once it is carrying 1,001 pounds (455 kg) or more aggregate gross weight of hazardous materials covered by Table 2. "Aggregate gross weight" means the combined weight of the material and its packaging for all hazardous materials on the vehicle. Below 1,001 pounds, Table 2 materials generally do not require placards — but Table 1 materials are the major exception.

Table 1 vs. Table 2

The HMR split hazard categories into two placarding tables. The difference is the quantity that triggers placards.

Memory hook: Table 1 materials placard for 1 pound or more (any amount). Table 2 materials wait for the 1,001-pound threshold.

The Four-Side Rule

When placards are required, they must be displayed on all four sides of the vehicle — the front, the rear, and both sides (driver and passenger). This way the hazard is visible no matter which direction someone approaches from. Each placard must be readable, securely attached, away from ladders and other obstructions, and kept at least 3 inches from other markings.

The DANGEROUS Placard

A truck can carry several different Table 2 materials at once. Instead of hanging a separate placard for each class, the driver may use a single DANGEROUS placard when:

• The vehicle carries two or more categories of Table 2 hazardous materials, and
• The combined load reaches 1,001 pounds or more aggregate gross weight.

Exception: if 2,205 pounds (1,000 kg) or more of one Table 2 category is loaded at one place, that category's specific placard must be used in addition to or instead of DANGEROUS. The DANGEROUS placard is a convenience for mixed Table 2 loads only — it can never replace a Table 1 placard.

Subsidiary Placards and Orientation Arrows

Some materials have more than one hazard. The most severe hazard sets the primary placard; a subsidiary placard (or subsidiary label on the package) announces the secondary hazard. A flammable liquid that is also corrosive, for example, may carry a corrosive subsidiary placard. Orientation arrows are package markings, not placards, but they belong to the same communication system — the two upward arrows show that the package must stay upright so liquid contents do not leak.

Who Is Responsible?

Responsibility is shared, and the test expects you to know the split.

• The shipper classifies and describes the material, applies the markings and labels to packages, prepares the shipping paper, and provides the placards to the carrier.
• The carrier and driver are responsible for applying the placards to the vehicle and displaying them correctly on all four sides. The driver must refuse a shipment that is not properly marked, labeled, or accompanied by correct papers, and must make sure the right placards are up before driving.

In short: the shipper supplies and prepares; the driver checks and displays. If a placard is missing, wrong, or damaged, it is the driver's job to fix it before moving the vehicle.