You need this licence to use specific vehicles to transport dangerous goods by road in a receptacle with a capacity of more than 500 litres or 500 kilograms. A vehicle licence is not required when the dangerous goods are in an Intermediate Bulk Container, and the IBC is not packed or unpacked on the vehicle and the total capacity of the IBC is not more than 3000 litres.
To drive a vehicle transporting dangerous goods by road in a receptacle with a capacity of more than 500 litres or more than 500 kilograms, you must also hold a current 'Dangerous goods driver licence'.