As companies where taking up from a box on Dulles Ave. Engine 23 was dispatched to the reported vehicle fire in the 12000 block of US59 northbound. Upon additional that it was on the main lanes of the freeway Ladder 2, returning from the box, was added as a blocking apparatus and to assist. Upon arrival the rear of a Kenworth tractor pulling a dump trailer was involved in fire. Deploying a Class A crosslay the fire was quickly knocked down on tank water and then personnel assisted the investigators. Upon completion of assignments all units returned to service.