Hazmat Driving Rules
Updated October 27, 2026
Placarded drivers follow extra rules on the road, most of them in 49 CFR Part 397 and 392.10. They are a steady source of hazmat test questions because they come with exact numbers. Here they are in one place.
Railroad crossings
You must stop before a railroad crossing if your vehicle:
- is placarded;
- carries any amount of chlorine; or
- is a cargo tank used for hazardous materials, loaded or empty.
Stop within 50 feet of the nearest rail but no closer than 15 feet. Look and listen in both directions, and cross only when no train is coming and you can clear the tracks without stopping. Choose a gear that will not need changing, and do not shift gears while crossing.
You do not have to stop where a police officer or flagman directs traffic across, at a green traffic signal, at a crossing marked as exempt or abandoned, or at streetcar or industrial tracks within a business district.
Routes and tunnels
- When placarded, avoid heavily populated areas, crowds, tunnels, narrow streets and alleys. Take another route, even if it is less convenient, unless there is no practical alternative.
- States and localities may require permits or restrict hazmat routes, including some tunnels and bridges. Carrier drivers should ask their dispatcher; independent truckers should check with each state they will travel through.
- Division 1.1, 1.2 or 1.3 explosives require a written route plan, which the driver carries.
- Highway route controlled quantities of radioactive material must use preferred routes and have a written route plan.
Tires
- Examine each tire at the start of each trip and each time you park. This is the current rule in 49 CFR 397.17.
- Check pressure with a tire pressure gauge; kicking or thumping a tire is not enough.
- Do not drive with a flat or leaking tire except to the nearest safe place to fix it.
- Remove an overheated tire, place it a safe distance from the vehicle, and do not drive on until you fix what caused the overheating.
Smoking
No one may smoke, or carry a lit cigarette, cigar or pipe, within 25 feet of a vehicle carrying Class 1 explosives, Division 2.1 flammable gas, Class 3 flammable liquids, Division 4.1 or 4.2, or Class 5 oxidizers. The same 25-foot rule applies to an empty cargo tank that carried Class 3 or Division 2.1 and is still marked or placarded.
Fueling
Turn the engine off before fueling a vehicle that carries hazardous materials. Someone must be at the nozzle, controlling the fuel flow, the whole time.
Fire extinguisher
The power unit of a placarded vehicle must carry a fire extinguisher with a UL rating of 10 B:C or more.
No burning flares
If you break down, use reflective triangles or red electric lights. Never use flares or fusees near a tank used for Class 3 or Division 2.1, loaded or empty, or a vehicle with Division 1.1, 1.2 or 1.3 explosives.
Shipping papers
Keep the hazmat shipping papers within reach with your seat belt on, or in the driver’s door pouch. When you leave the cab, put them on the driver’s seat or in the door pouch. More in hazmat shipping papers.
Test yourself
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You stop your placarded truck 10 feet from the nearest rail at a crossing. Is that correct?Answer: AThe stop must be within 50 feet of the nearest rail but no closer than 15 feet. Ten feet is too close.
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Which vehicle must stop at railroad crossings even if it has no placards?Answer: BBesides placarded vehicles, vehicles carrying any amount of chlorine and cargo tanks used for hazmat, loaded or empty, must stop at crossings.
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What is the acceptable way to check tire pressure on a placarded vehicle?Answer: CThe only acceptable way to check tire pressure is with a tire pressure gauge. Kicking or thumping can miss a low tire.
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You find a tire leaking air on your placarded truck. How far may you drive on it?Answer: DDo not drive with a flat or leaking tire except to the nearest safe place to repair it.
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While you fuel a placarded truck, what must be true at the pump?Answer: ATurn off the engine before fueling, and someone must always be at the nozzle controlling the flow of fuel.
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When placarded, how should you choose your route?Answer: BPlacarded vehicles must avoid heavily populated areas, crowds, tunnels, narrow streets and alleys, even if another route is less convenient, unless there is no practical alternative.
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How close to a vehicle carrying Class 5 oxidizers may someone smoke?Answer: CThe 25-foot no-smoking rule covers vehicles carrying Class 1, Division 2.1, Class 3, Divisions 4.1 and 4.2, and Class 5 materials.
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The fire extinguisher required for a placarded vehicle must be carried where?Answer: DThe power unit of a placarded vehicle must have a fire extinguisher with a UL rating of 10 B:C or more.
See also: parking and attending rules.
Pass your hazmat endorsement test on the first try
- All 181 questions on hazard classes, shipping papers, placards, loading, cargo tanks, driving and parking rules and emergencies
- An explanation for every answer, from the CDL manual and the federal hazmat rules
- Unlimited full 30-question practice tests, scored like the real one (80% to pass)