A woman who jumped out of a moving car on Route K was serving a home-detention sentence and was on her way to Tauranga District Court.
The 20-year-old woman jumped out of the front passenger seat of the car that was travelling on the 100km/h stretch of road about 1km past the toll booths on Route K about 4pm on Wednesday.
The woman was taken to hospital with abrasions on her limbs.
A Department of Corrections spokeswoman said the woman was in a car, not a prison van, and neither the police nor the department would be investigating the incident.
"Quite often our probation staff will assist our offenders with transport where it's needed," she said. "It was in a 100km/h zone but when the driver heard the door open they applied the brakes so they would have slowed down quite quickly."
The probation staff member assisted with first aid until St John arrived, she said.
It was not known why the woman jumped from the car.
Former city councillor Murray Guy and his wife Marion found the woman lying across the centre line.
"There was about half a dozen cars there and the woman was lying across the centre line and was being attended to by an anaesthetist from the hospital. She ascertained the woman wasn't critical ... she was fairly significantly grazed they made sure she was comfortable until the ambulance came.
"She mostly had grazing to her limbs. You would think she had come off a motorbike.
"She was conscious and talking, albeit a little incoherent."
A Tauranga Hospital spokesman confirmed the woman was in a stable condition yesterday.