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CDL General Knowledge Test: Hazardous Materials Basics for All Drivers Concepts
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Overview
This chapter covers what every commercial driver must know about hazardous materials, even without the hazardous materials endorsement. Hazardous materials are products that pose a risk to health, safety, and property during transport, such as explosives, gases, flammable liquids, poisons, and corrosives.
The rules exist to contain the product, communicate the risk, and ensure safe drivers and equipment. Shippers describe the materials on shipping papers and put diamond-shaped labels on packages. Drivers must keep hazardous materials shipping papers where responders can find them: in a pouch on the driver's door, in clear view within reach while driving, or on the driver's seat when out of the vehicle.
Placards are diamond-shaped signs on the outside of the vehicle. A placarded vehicle needs at least four identical placards, on the front, rear, and both sides. If a vehicle requires placards, you may drive it only with the hazardous materials endorsement. Four-digit identification numbers, shown after UN or NA, help first responders identify the material.
Key concepts
Purpose of hazmat rules
The rules have three goals: contain the product, communicate the risk, and ensure safe drivers and equipment.
Memory tipContain, communicate, ensure safety.
Hazmat endorsement
You may carry some hazardous materials without placards. But if the vehicle requires placards, you must have the hazardous materials endorsement on your CDL to drive it.
Memory tipPlacards on the truck means the endorsement on the license.
Placards
Diamond-shaped signs on the outside of the vehicle that show the hazard class of the cargo. A placarded vehicle needs at least four identical placards, front, rear, and both sides, each at least 10 3/4 inches square.
Memory tipFour sides, four placards.
Source: New York State DMV Commercial Driver's Manual (CDL-10), Section 2 · as of 2026
Shipping papers
Hazardous materials shipping papers must be marked or kept on top of other papers, and kept in a door pouch, in clear view within reach while driving, or on the driver's seat when you are out of the vehicle.
Memory tipOut of the cab, papers on the seat.
Identification number
A four-digit code, shown after the letters UN or NA, that first responders use to identify hazardous materials. The Emergency Response Guidebook lists them.
Memory tipFour digits after UN or NA.
Often tested
- A vehicle that requires placards needs a driver with the hazardous materials endorsement.
- A placarded vehicle needs at least four identical placards.
- Keep hazmat shipping papers in the door pouch, within reach, or on the seat when you are out.
- The rules aim to contain the product, communicate the risk, and ensure safe drivers and equipment.
3 sample questions
Verified practice questions from this unit.
Question 1. When do you need a hazardous materials endorsement on your CDL?
- ① Any time you carry any amount of a hazardous material
- ② Only when you carry explosives
- ③ When you drive a vehicle that requires placards
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Answer: ③ When you drive a vehicle that requires placards
Key point: Placards required = hazmat endorsement
Not every vehicle with hazardous materials needs placards. If the vehicle requires placards, you must have the hazardous materials endorsement to drive it. Driving it without the endorsement is a crime.
Wrong choices
- Any time you carry any amount of a hazardous material: You can carry some hazardous materials without placards and without the endorsement.
- Only when you carry explosives: The rule covers all placarded loads, not only explosives.
Question 2. How many placards must a placarded vehicle display?
- ① At least four identical placards: front, rear, and both sides
- ② Two placards, one on each side
- ③ One placard on the rear
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Answer: ① At least four identical placards: front, rear, and both sides
Key point: Four placards, readable from all directions
A placarded vehicle must have at least four identical placards, on the front, rear, and both sides, so they can be read from all four directions. They are diamond shaped and at least 10 3/4 inches square.
Wrong choices
- Two placards, one on each side: Placards must be readable from all four directions.
- One placard on the rear: One placard cannot be read from the front or sides.
Question 3. You are carrying hazardous materials and get out of the cab. Where must the shipping papers be?
- ① Locked in the glove box
- ② On the driver's seat
- ③ In the sleeper berth
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Answer: ② On the driver's seat
Key point: Out of the cab: papers on the driver's seat
Hazardous materials shipping papers must be easy for responders to find. Keep them:
- in a pouch on the driver's door, or
- in clear view within reach while driving, or
- on the driver's seat when you are out of the vehicle.
Wrong choices
- Locked in the glove box: Responders may not find or open it.
- In the sleeper berth: This is not one of the allowed places.