"That was one hell of a ride," the man told the Mercury once freed from the wreckage.

Police, firefighters and paramedics were called to the Wollongong off-ramp, southbound on the M1, around 2:43pm on Sunday.

It's understood the semi-trailer went up the safety ramp and flipped over, trapping single occupant inside - believed to be aged 29

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A Farmborough Heights Rural Fire Service crew who were assisting with floods in Port Macquarie, were returning home when they saw the incident unfold and stopped to help.

"We saw smoke from the safety lane and as soon as the smoke cleared we saw a truck rolled over and we attended and called for assistance," Darren Morris told the Mercury.

Four crews from NSW Ambulance also headed to the scene, with paramedics assessing the driver who was trapped inside the vehicle.

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Crews from NSW Police and Fire and Rescue NSW were also on scene.

The Toll rescue helicopter was hovering overhead on standby, at 3:15pm, but eventually called off.

By 3:35pm Sunday the driver was able to be freed with minor leg injuries, and was seen walking around.

However, the man was transported to Wollongong hospital in a stable condition.