In order to operate a Hazmat vehicle, the driver has to carry a Class "B" commercial driver's license.
To carry a license of this class, a driver has to successfully complete a series written and practical general knowledge tests. Additionally, the specifics of the type of vehicle is also scrutinized in a secondary testing process.
After the driver completes these tests, further testing is required to acquire and carry specific operating endorsements based on particular categories. One of these is Hazmat operation and transportation.
Regardless of the state, rules associated with safe transportation and handling of Hazmat materials are mandated by the federal government, while each state executes those overarching rules as a practical matter.
The federal government requires following local oversight from each state, including compliance with federal motor carrier safety regulations, and state and local laws, ordinances and regulations.