They were "extremely lucky" Mr Lack said, as the crash was very similar to the one last September that killed former All Black Ian Uttley and his wife of 50 years, Christine.
Mr Lack said the Uttley's, faced with a similar situation, swerved and collided with an oncoming truck.
The woman involved in yesterday's crash swerved and hit the bank.
On September 15, the grandparents were returning from their Taupo holiday home when they collided with a logging truck.
Police said it appeared the couple may have been taking evasive action on the brow of Titiokura Hill north of Te Pohue. Their car's tyres went on to the grass verge and the driver lost control, crossing the centre line and heavily hitting the truck, which pushed the gold-coloured sedan down a small bank.
The couple died at the scene.
Since then the road had been widened by about 1.5m and double yellow lines painted down the centre, Mr Lack said.
"The realignment of that road probably saved some lives."
There has been a serious accident on State Highway 5 every month since September.