What general rule applies to attending a vehicle carrying certain hazardous materials (like explosives)?

Vehicles carrying certain hazardous materials (especially EXPLOSIVES — Division 1.1, 1.2, 1.3) must be ATTENDED at all times by a qualified person, except in specific permitted situations. CDL hazmat. An ATTENDED vehicle means a qualified driver/person is in the vehicle (and awake, not in the sleeper) or within a set distance with the vehicle in clear view, able to respond and move the vehicle if needed. PARKING is also restricted: such vehicles can't be parked within certain distances of bridges, tunnels, buildings, crowds, or open fires; must use safe, secure parking. These rules limit the risk of theft, tampering, or an unattended incident. Some materials have less strict attendance rules. Knowing the attendance requirement for high-hazard materials (especially explosives) is commonly tested.