The Supervisor's Placard Arithmetic at the LTL Dock

FLAMMABLE GAS - required. Division 2.1 is a Table 1 material, and Table 1 materials must be placarded for any quantity, including four 45-lb cylinders. The supervisor's per-cylinder weight reasoning is irrelevant.

FLAMMABLE (Class 3) - required. 2,400 lb gross alone exceeds the threshold.

CORROSIVE (Class 8) - required. The supervisor is wrong. The 1,001 lb rule is not applied per hazard class; it applies to the aggregate gross weight of all Table 2 materials in the load. Here: 2,400 + 900 + 1,500 + 400 = 5,200 lb, far above 1,001 lb. Once the aggregate threshold is crossed, every Table 2 hazard class present in the load gets its placard - including the 900 lb of acid.

FLAMMABLE SOLID (Division 4.1) - required. Table 2 material, and the aggregate threshold is met.

Class 9 - not required. The Class 9 placard is not required for domestic transportation. But note the 400 lb still counts toward the 5,200 lb aggregate. It is a mistake to drop Class 9 out of the arithmetic just because it does not need a placard.

Result: four placard types - FLAMMABLE GAS, FLAMMABLE, CORROSIVE, FLAMMABLE SOLID.

Each required placard type goes on all four sides: one on the left side, one on the right side, one on the front, one on the rear. On a straight truck the front placard belongs on the front of the vehicle body; on a tractor-trailer combination the front placard may be placed on the front of the tractor instead of the front of the trailer. Either way, every required class must be visible from each of the four directions before the vehicle enters a public road.

Check for the errors that actually get drivers cited:

• Placards hidden by equipment. A lift gate, a mud flap bracket, or a reefer unit can block the rear placard. Readability from the approach direction is the test, not whether the placard exists.
• Classic mix-up. FLAMMABLE SOLID (red-and-white vertically striped) hung where FLAMMABLE (red) belongs, or a FLAMMABLE GAS (red) used for the Class 3 pails.
• Legibility and attachment. Torn, faded, greasy or taped-on placards are defective and must be replaced, not patched.
• Partial placarding. Drivers sometimes run only the placards for the heaviest item because that is what the last load needed. Here, four distinct classes are present.
• Paperwork match. The placards on the truck must match the shipping paper descriptions; a mismatch between placards and manifest is what triggers a full inspection.

Recompute the Table 2 aggregate for what remains on board.

Remaining: acid 900 lb + Class 9 bags 400 lb = 1,300 lb aggregate, still above 1,001 lb.

Therefore:

• CORROSIVE stays. This is the key judgment point. The acid by itself is under 1,001 lb, and after the drop it is the only Table 2 hazard class requiring a placard - but the aggregate test still includes the 400 lb of Class 9, so the threshold is still met and CORROSIVE must remain displayed.
• FLAMMABLE and FLAMMABLE SOLID come off. Those materials are no longer on the vehicle. Placards must reflect the current load; leaving them up is itself a violation and misleads responders.
• FLAMMABLE GAS stays, because Division 2.1 is a Table 1 material and the cylinders are still aboard.

Now run the forward case: if the second stop also delivered the Class 9 bags, the remaining Table 2 aggregate would be 900 lb - under 1,001 lb - and you could legally remove the CORROSIVE placards. FLAMMABLE GAS would still stay until the last cylinder came off. Never remove placards while the material is still loaded; never leave them up after it is gone.