The U.S. Department of Transportation (DOT), through its hazardous material regulations (HMRs), specifies requirements for the safe transportation of hazardous materials in commerce by rail, aircraft, vessel, and motor vehicle. DOT has general requirements for the loading, unloading, handling, and storage of explosives and hazardous materials as well as specific modal requirements. This section outlines DOT’s requirements for hazardous materials transporters over roads and highways.