Drivers of vehicles carrying quantities of hazardous goods above certain levels are required to hold an ADR licence that covers the class of hazardous good being carried (there are 9) and the method of transportation (either in tanks or packages). For example a petrol tanker driver would require a licence for class 3 (flammable liquids) in tanks.

The 9 classes of hazardous goods are:

The 'standard' ADR course covers the 7 most common classes. Explosives and radioactives are special 1 day courses.

A full course covering the core module, which every candidate must sit, together with tanks, packages and 7 classes is of 5 days duration. If the tanks module is not required this is reduced to 4 days.

The multiple choice examinations are held on the last day of the course and are administered by SQA (Scottish Qualification Authority). Upon passing the examination, SQA inform DVLA Swansea who will issue a certificate that is valid for 5 years.

Candidates wishing to renew their ADR licence are required to sit a refresher course within the final 12 months for which their licence is valid. No refresher training may be commenced within the final 4 weeks for which the licence is valid.