The Transport Management Centre advised at 4pm that the road may be forced to close again during the salvage operation.

Northbound and southbound traffic are moving in a stop start motion through the single lane, and significant delays are still expected.

There are eight kilometre queues to the north and south of the crash. 

Thursday, 1pm: One lane of traffic reopened briefly for alternating traffic about 12.30pm, but has closed again after a crane was allowed through to continue to salvage operation, according to a spokeswoman for the Transport Management Centre.

She urged motorists to find an alternate route, and suggested trying the New England Highway. The traffic is currently banked up on the Pacific Highway more than 12 kilometres in both directions.

It is still not known when the road will re-open. 

The spokeswoman stated that the centre has "assessed photographs which appear to show the truck was travelling north bound" at the time of the crash.

Thursday, 11.45am: Paramedics have confirmed the driver is no longer trapped in the vehicle.

The information came as the Transport Management Centre confirmed clean-up crews are on site and part of the truck has been moved.

A spokesman said the trailer of the truck - which was carrying furniture - had been flipped onto its wheels and moved. However, he said, attempts are still underway to get the prime mover upright.

"If they fail in those attempts, they will drag it off the road to get one lane open in alternating stop and start conditions," the spokesman said.

The spokesman was unable to approximate when the Pacific Highway  will be open again. He did say say the clean-up crews are currently removing spilled diesel from the road.

Thursday, 10.10am: Central Coast resident Jon, who did not wish to give his surname, was driving ahead of the truck just prior to it overturning. 

He said the crash happened so quickly that he only caught the aftermath.

"I was listening to the radio, and I looked and I'm pretty sure there wasn't a truck following behind or cars," he said. "Then I looked up again and there was all this dust everywhere behind me. I saw a semi trailer right across the highway, and I just hoped no one was hurt."

The condition of the driver is still not known.

Thursday, 9.40am: Variable message signs north of Kempsey and south of Port Macquarie are advising motorists the Pacific Highway is closed five kilometres south of Kundabung. 

The New England Highway is suggested as an alternative route. 

Thursday, 9.30am: The Transport Management Centre reports that traffic is closed in both directions due to the accident. They were unable to confirm reports that the driver was trapped in the truck.

They were unable to say when traffic conditions might change. 

Thursday, 9.18am: Emergency services are attending the scene of a truck accident on the Pacific Highway at Kundabung, 35 kilometres north of Port Macquarie.

A spokesman for the Mid North Coast Local Area Command said it appears the truck was travelling in the southbound lane at the time of the accident. 

Police believe the driver to be out of the vehicle, Inspector Ron Mudford said.  

"At this stage it looks like southbound traffic is blocked," he said.

Northbound traffic is still moving, however police have asked for caution from all motorists in the area.

Paramedics and personnel from Fire and Rescue NSW are also attending.

More to come.