The 40-year-old was driving his low-loader, which had a mobile cherry picker attached, north at 2pm when the rig drifted off the road about 500 metres north of Post Office Lane.
It squashed a 30-metre length of wire which was protecting a culvert and then slammed into the culvert, rupturing the fuel tank.
The rig then crossed to the wrong side of the road and careered through scrub for 50 metres before smashing into a large number of gum trees, causing major damage to the prime mover.
The load was then propelled another 20 metres to the east of the wreck.
Passing motorists were forced to think quickly and used fire extinguishers to douse a fire in the truck.
Ambulance officers treated the driver at the scene for minor head injuries and took him to Coffs Harbour Health Campus, where his condition was listed as stable late yesterday.
The accident did not block the highway, but firefighters were needed to clean up a diesel spill which covered the road.
The semi-trailer and its load are to be recovered at 9am today.
The incident comes hot on the heels of a B-double rollover on the Pacific Highway near the Big Banana early on Saturday.
That driver was not hurt.