Loading, Unloading, and Segregation of Hazardous Materials
Loading, Unloading, and Segregation of Hazardous Materials
This domain tests 49 CFR 177 loading rules: securing packages, setting brakes and chocking wheels, keeping the vehicle attended, and keeping incompatible materials apart. Indiana questions often present two commodities and ask whether they may share a truck.
Core loading rules
- Packages must be secured against shifting, and nothing may be stacked in a way that damages closures or labels (177.834). Before loading or unloading, set the parking brake and chock wheels when necessary.
- No smoking or open flame is allowed on or near a vehicle carrying flammable or oxidizing materials; 49 CFR 397.13 sets a 25-foot smoking prohibition for vehicles containing certain flammable, oxidizing, or corrosive materials.
- The segregation table in 177.848 uses X for materials that may not be loaded, transported, or stored together in the same vehicle, and O for materials that require separation. The table covers class-to-class combinations; Class 1 materials also have compatibility-group restrictions.
- Common incompatible pairs: cyanides and acids (hydrogen cyanide gas); hypochlorites and acids (chlorine gas); oxidizers and flammable liquids; organic peroxides and accelerators; acids and caustics. Division 6.1 PG I inhalation hazards must not be loaded with food, feed, or edible materials.
- The driver must attend the vehicle during loading and unloading unless the vehicle is secured and the situation meets an exception. Do not move a vehicle with the hose connected or the dome cover open.
Worked example
You are asked to load 500 lb of sodium cyanide, UN1689, 6.1 PG I, and 300 lb of hydrochloric acid, UN1789, 8 PG II, into one straight truck. The segregation table bars this combination: acid plus cyanide can release hydrogen cyanide gas. The correct answer is refuse the load or arrange separate vehicles-not separate them with a plywood sheet.
Traps
Segregation applies to the same transport vehicle, not just packages touching. A label does not cure an incompatible load. O does not mean no restriction. Do not overlook food and feed restrictions for poison inhalation hazards.