CDL truck drivers are truckers that have a commercial driver's license (CDL). CDL trucks require special licenses for operation because of their bulk. Drivers must not only be able to maneuver these trucks for miles at a time, often in heavy traffic, but they must also be alert and follow all roadway safety regulations. They are responsible for such duties as loading and unloading heavy cargo, tracking their mileage, fuel, toll expenses, ensuring delivery, and maintaining their trucks.