Metal barriers could have saved the life of a man whose vehicle plunged off a narrow bridge in the Grey Valley, the Coroner's Court heard.
Coroner David Robinson found that Tamati Rae (32), of Kaikoura, died on September 10, 2017, when his four-wheel-drive vehicle crashed off the side of the Otututu River bridge, on Atarau Rd, and landed upside down in the river.
Mr Rae was trapped inside and drowned. His children were strapped in the back of the vehicle and were rescued by a passer-by, a Greymouth teenager who earned praise from the coroner for his bravery and forethought.
The coroner said a toxicology test from Mr Rae returned a positive result for recent cannabis use and that might have impaired his judgement.
He had failed to recognise the narrowing of the road leading on to the bridge and had crashed into the abutment, Mr Robinson said.
He said the crash investigation report suggested metal barriers across the bridge might have made the crash survivable.
''The report also states that replacement or installation of reflectorised road marker posts at regular intervals around the approaching curves could further draw the driver's attention to the changing curve and approach on to the bridge,'' Mr Robinson said.
The Grey District Council had responded to the coroner's recommendations and agreed about the barriers but noted the narrow width of the bridge was a complicating factor.
Notwithstanding that, the NZ Transport Agency was seeking funding for the replacement of timber bridge rails with metal barriers throughout New Zealand.
In the days before the accident, Mr Rae had left his children in the care of family members in Hokitika for the weekend while he flew from Westport to Wellington. He returned to Westport on the Sunday and then drove to Hokitika to pick them up.
Mr Rae's parents had contacted the family member in Hokitika asking them to encourage their son to stay the night before returning to Kaikoura, but he indicated he needed to get back for work.
He and the children left Hokitika about 8.15pm, and headed up the Grey Valley via Atarau Rd, rather than State Highway 7, crashing at the Otututu River.
Farm worker Andrew Field, of Greymouth, drove on to the bridge a short time later and noticed debris from the crash and parts of the guardrail missing. He looked over the side of the bridge and saw Mr Rae's vehicle upside down in the river below. He then drove on to the riverbed and through the water to the partially submerged vehicle.
''Mr Field saw Mr Rae in the driver's seat of the vehicle; he was upside down, with his upper torso in the water. Mr Field realised there were children in the back seat of the vehicle. He smashed the driver's side rear passenger window with a rock, and removed the children to his vehicle. He returned to Mr Rae's vehicle, but was unable to open the door to remove Mr Rae from the driver's seat.''
The coroner commended Mr Field for his bravery and decisiveness.
Mr Field received a police bravery award for his efforts.
