A notorious, 'unforgiving' Hawke's Bay corner claimed the lives of a father and son after a heavy vehicle travelling at 60km/h to 75km/h rolled in wet conditions, a coroner's report says.
Aaron McDonald, of Gisborne, died when his truck and trailer unit left the road, rolled and crashed down a bank shortly after midnight on January 23, 2017, on State Highway 2 just north of Norsewood.
McDonald was not exceeding the speed limit, but was estimated to be travelling at between 60 and 75km an hour.
Signs in the area recommend that corners be taken at 55km/h.
The Road Code states heavy vehicles should travel at least 10 km/h slower than advisory speed signs.
McDonald and his son Cruz both died in the crash, which occurred shortly after a right-hand downhill bend about 500 metres south of the intersection of State Highway 2 and Whenuahou Rd.
Coroner Tracey Fitzgibbon concluded in her findings that McDonald would have been familiar with the corner as he had been working as a truck driver for about 10 years.
He had been travelling that particular run, heading south, for the preceding three weeks.
"Based on the evidence I am satisfied that he attempted to negotiate the corner, in wet conditions, at such speed that it resulted in loss of control and truck rollover," Fitzgibbon's report said.
"Whether that failure to reduce the speed of the vehicle to an appropriate speed in the conditions occurred as a result of a microsleep, fatigue, inattention or misjudgement is not able to be determined."
Senior Constable Christopher Pelosi, a crash analyst from the Central District Serious Crash Unit completed the investigation of the incident.
He reported that at the time of the crash, just after midnight, it was dark, raining and the road was wet.
"The road follows a flat left-hand bend then tight downhill right-hand bend. This is markedly different from preceding several kilometres, being straight and flat travel. Though not the prime contributing factor, the road is unforgiving," Pelosi observed.
He also stated the trailer's GPS gave a speed reading of 82km/h approximately 245 metres prior to the crash site, at the beginning of the left hand bend, south of the Whenuahou Rd intersection, preceding the downhill right hand bend at the crash scene.
Pelosi concluded that the speed range for the truck to roll would fall above 60km/h and likely below 75km/h.
Pelosi added, in his opinion, Cruz McDonald may not have been wearing a seatbelt.
Fitzgibbon stated she was satisfied the actions or inactions of McDonald were the main contributing factors in relation to the crash:
"As such, no formal recommendations in relation to the road configuration or the addition of any signage would prevent similar deaths in the future such as they occurred in this instance."