Truck fire causes M1 chaos

A B-double truck has burst into flames after crashing into a wall on the M1 motorway north of Sydney, with traffic backed up eight kilometres.

The accident happen at Mt White just after 5am on Monday, with the driver being airlifted to Sydney's Westmead Hospital with spinal, pelvic and leg injuries, according to an ambulance spokeswoman.

The fire has been extinguished and one of three southbound lanes has been re-opened, but commuters heading south to Sydney can expect delays, transport management said.