Hazmat Study Guide
This study guide condenses the AAMVA CDL Manual chapter on Hazmat into the concepts that show up most often on the knowledge exam. Read it through once, take the practice test, then come back to anything you missed.
The shipper, carrier, driver triangle
Three parties share responsibility for safe hazmat transport. The shipper packages and labels the materials, prepares the shipping paper, and certifies that the shipment complies with HMR. The carrier transports the load and trains the driver. The driver inspects the shipment, refuses leaking or improperly marked containers, placards the vehicle, follows route restrictions, and responds to incidents.
Shipping papers
The hazmat shipping paper must show: proper shipping name, hazard class, ID number (preceded by UN or NA), packing group (I, II, or III), total quantity and unit of measure, number and type of packages. The driver must keep the shipping paper within reach in the cab — clipped to a clip on the driver's side or on the seat — when the engine is running. When out of the vehicle, leave it in the driver's door pouch or on the driver's seat.
Placards
Placards are diamond-shaped warnings, at least 250 mm (about 10.75 inches) on each side, displayed on all four sides of the vehicle. A vehicle generally needs placards if it carries any amount of a Table 1 material (most explosives, poison-inhalation hazards, dangerous when wet) or 1,001 lbs or more total of Table 2 materials. Driving an unplacarded vehicle that should be placarded is a serious violation.
Loading rules
Turn off the engine before fueling and before loading or unloading any flammable. Set the parking brake. Never smoke within 25 feet of a vehicle being loaded with Class 1 explosives, Class 2.1 flammable gases, Class 3 flammable liquids, or oxidizers. Use chock blocks for cargo tanks during loading or unloading. Check segregation rules: certain materials cannot be loaded in the same vehicle or near each other.
Routes and parking
Hazmat vehicles must follow routes designated by state and local authorities. Avoid heavily populated areas, narrow streets, crowded streets, tunnels, and tunnels with a no-hazmat designation, when possible. A vehicle hauling Class 1.1, 1.2, or 1.3 explosives, or any quantity of Division 2.3 or 6.1 poison gas, must have an attended parking — a qualified person within 100 feet, awake, and with a clear view of the vehicle. Never park within 5 feet of the traveled portion of a road.
Emergency response
Carry the Emergency Response Guidebook (ERG) and use it to look up the four-digit ID number on the placard or shipping paper. The guidebook gives you a guide page with isolation distance, evacuation distance, fire and spill response, and first aid. In a hazmat incident: protect yourself first, secure the scene, notify emergency responders (911), provide them the shipping paper or its location, never drive a leaking vehicle further than absolutely necessary, never use a flame to check for leaks.
How to use this guide before your exam
Read each section carefully and try to put the rule in your own words before moving on. The CDL knowledge exam tests recognition more than recall — you'll see the right answer in front of you and have to pick it from distractors that all sound plausible. The way to defeat distractors is to know the underlying rule cold.
Once you can read this guide and answer "what's the rule?" without checking, return to the full practice test. If you score 85% or higher across two consecutive runs, you are ready to schedule the official knowledge test at your DMV.