A woman has survived a terrifying road rage ordeal when her car was rammed twice by a 4WD, nearly tipping it onto its side.

The woman was driving a dark green Nissan on Johns Road, near the Sawyers Arms Road roundabout in Christchurch, when she slowed to 60kmh to pass through road works, police Senior Constable John Moore said.

"The driver had travelled around 500 metres past the roundabout, when a white four-wheel-drive vehicle, which had been following her, appeared to accelerate and rammed into the rear of her car," Moore said.

"The driver reports that she braked, and skidded as her wheels locked up. The four-wheel-drive appears to have backed off a little, but then accelerated again, hitting her car hard for a second time.

"The impact caused the Nissan to drift sideways and on to the side of the road. The car tipped over, but fortunately landed back on its wheels without rolling over."

The woman's car stopped about 300 metres north of McLeans Island Rd.

The four-wheel-drive vehicle left the scene without slowing or stopping. It may have turned right into McLeans Island Rd.

"The driver was not hurt, but was very shaken by the incident, which appeared to be totally unprovoked," Moore said.

"The only thing the driver has done was to slow down - correctly - for road works.

"This incident could easily have resulted in serious injuries to the victim and to other road users.

"We are appealing for any help to identify the offending vehicle and its occupants."

Police believe

there were two people in the four-wheel-drive at the time, about 7.45pm on Tuesday.The

driver was described as a clean-shaven man, caucasian and in his 20s, while the passenger was described as a female caucasian, of similar age, with long blonde hair.

Investigators have spoken to the driver of the Nissan and to another witness, but were appealing for more information.

"We know there were other witnesses, and we would like to hear from them as soon as possible.

"We are also seeking help from anyone who can help identify the white four-wheel-drive vehicle, or its occupants."

Anyone with information was asked to contact Moore on (03) 363 7336 or Christchurch police on (03) 363 7400.

To provide information anonymously contact Crimestoppers on 0800 555 111.

- © Fairfax NZ News