Loading, Unloading, and Segregation
Loading and unloading rules protect against incompatible materials, shifting loads, and ignition sources. Candidates must understand segregation: certain hazardous materials cannot be loaded together because a leak or reaction could create fire, toxic gas, or explosion. Cyanides and acids, for example, must be kept apart because contact can release deadly hydrogen cyanide gas. Oxidizers must be separated from flammables.
Other key concepts include securing packages against movement, keeping the cargo area clean and free of incompatible residue, and ensuring packages are loaded so labels and markings are visible. Questions often test whether a driver may load a hazardous material near a heat source or in a compartment with an incompatible material. Traps include assuming that a placard on the vehicle makes any combination of materials legal, or that segregation rules apply only to bulk shipments.
Rule of thumb: if a leak from one package could react dangerously with another, they are incompatible and must be separated or not loaded together.
Worked example: A load includes both acid and cyanide packages. Even though both are properly labeled and placarded, they must not be loaded together because a leak could mix them and generate toxic gas.