P-plater charged over NSW crash that sent female driver off bridge

A P-plate driver has been charged over a crash that sent a woman's car plunging over a bridge on the NSW Central Coast.

The woman, 39, suffered serious injuries and was trapped for about 30 minutes near Stockton Creek Bridge at Morisset.

Emergency crews worked to free the woman, who was taken to John Hunter Hospital for a head injury and fractures, where she remains in a serious but stable condition.

All northbound lanes were closed for the delicate rescue operation, the traffic banking back for 9km.

Passing motorists who had stopped to help staged a citizens' arrest, as the other driver allegedly tried to flee.

The 20-year-old P-plater was detained in his vehicle until police arrived.

"We do consider that excessive speed was a contributing factor to this crash," Inspector David Matthews said. 

The male driver, in a Holden Commodore, had been travelling north on the M1

As he passed the Caltex twin service stations at Wyong, other motorists began calling Triple Zero, with concern about the erratic driving.

For the next 40km, the car was seen speeding and veering dangerously across the road.

The driver lost control just past Mandalong Rd at Morisset.

Witnesses estimate the Commodore was travelling around 200km/h in the emergency breakdown lane before it pulled out suddenly and crashed into the Toyota Hilux, sending it over the bridge.

The driver of the Commodore has been charged with dangerous driving occasioning grievous bodily harm as well as negligent driving occasioning grievous bodily harm.

His licence was suspended and he was given conditional bail to appear in Wyong Local Court on December 1.