Shyanne Wilson, 20, remained in a critical condition in St George Hospital on Sunday afternoon after a crash early on Thursday morning.

The mother of two was thrown from the back seat of a car and into the path of oncoming traffic on the Princes Highway, and was nearly struck by a car coming down an on-ramp. 

Her father Kevin Wilson said had it not been for the actions of the truck driver, who frantically waved down traffic at the scene, she could have been killed instantly.

‘‘Shyanne is still critical and in a medically induced coma, but as bad as it is my wife and I and her four siblings are able to spend time with her in hospital,’’ Mr Wilson said.

‘‘If the worst happens, if she doesn’t survive, then we would not have had that extra time with her if it weren’t for the truck driver’s actions.

‘‘Truckies get a bad rap – I used to be one so I know – but he could have kept driving but instead he put himself in harm’s way to help her.

‘‘I could never thank him enough, but I want to try and find him so I can at least try.’’

Mr Wilson has already reached out via social media to thank the driver of the car coming down the ramp, Amanda Coleman, who also stopped.

‘‘If the truck driver didn’t wave me down I wouldn’t like to think what would have happened,’’ Ms Coleman told the Mercury after the accident.

Mr Wilson, who used to work for Wollongong trucking companies, is now using his contacts to track down the driver.

‘‘He saved my daughter’s life, that’s obvious,’’ he said.

‘‘[On Thursday] she underwent surgery and they had to remove part of her skull to remove the pressure on her brain. 

‘‘At this stage she is in a medically induced coma ... to give her body a chance to recover. They are worried about brain damage because of the extent of injuries.’’

Mr Wilson said Shyanne, his middle child, was a single mum with two young children, aged four and 11 months.

‘‘The kids are staying with her sister in Picton,’’ he said. ‘‘My wife Deanne and I moved from Wollongong to Barmedman and our son came with us but the girls stayed [in the Illawarra].

‘‘I was hit by a car when I was 18 and I lost my father a couple of years ago due to head injuries after he fell through a roof, so I’m just physically sick about this.’’

Ms Wilson was taken by NSW Ambulance Rescue helicopter to the Sydney hospital after the crash. 

Police say a 21-year-old woman from Kiama Downs was turning right onto the Princes Highway from Woollybutt Drive when her car and another vehicle collided about 5.50am on Thursday.

The driver of the second car, a 61-year-old man from Wyong, allegedly rammed the rear of the woman’s car further along the highway, after she failed to stop and exchange details.

Police said the impact pushed the woman’s car into the centre median fence, which resulted in her passenger, Ms Wilson, being ejected through the rear window. 

The incident is being investigated by Lake Illawarra police. Witnesses should call Lake Illawarra Police Station on 4232 5599 or Crime Stoppers: 1800 333 000.