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CDL · Communication Rules

Where must hazardous materials placards be displayed on a transport vehicle?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

On all four sides of the vehicle (front, back, and both sides) so they are visible from any direction

  1. A Only on the front
  2. B Only on the back
  3. C Inside the cab
  4. D On all four sides of the vehicle (front, back, and both sides) so they are visible from any direction

Why this is the answer

Hazmat PLACARDS must be displayed on ALL FOUR SIDES of the vehicle — front, rear, and both sides — so the hazard is visible from ANY direction. CDL hazmat. This ensures emergency responders, other drivers, and the public can identify the hazard regardless of which side of the vehicle they approach. Placards must be: readable (right-side up, not faded/obscured), securely attached, kept clean and visible, and removed when no longer carrying the hazmat (or when the vehicle is empty/cleaned, per rules). The correct placard corresponds to the material's hazard class. Placement on all four sides is a specific, commonly tested placarding requirement. Knowing placards go on all four sides is fundamental hazmat knowledge.
Source: FMCSA CDL Manual — Hazmat, Placard Placement

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About this topic: Communication Rules

Communication rules cover shipping papers, placards, labels and markings: what each must show, where papers must be kept in the cab, and when placards are required. This is the most heavily tested hazmat topic. This is one of 19 Hazardous Materials questions on communication rules, each with a full explanation on a single study page.

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