A coroner has found a cracked road in Northland was partly responsible for the deaths of two Spanish tourists in December 2009.
Eva Fajula Rovira and Joan Roma Serra, both 34 years old, were hit and killed when a Linfox truck and trailer driven by Ioane Etuale crossed the centre line on State Highway 1 in Towai north of Whangārei.
An inquiry had been held into the deaths previously; another was scheduled so Etuale could give evidence.
Coroner Ryan found the uneven, cracked road caused the truck's front wheels to bounce, causing a loss of contact with the road surface momentarily. Without the front wheels touching the road, Etuale was unable to steer the truck.
At the time the truck was taking a slight bend in the road. Without his steering, Etuale braked heavily but crossed the centre line into the path of the oncoming campervan the two tourists were in, killing them.
Serious Crash Unit evidence was that from the moment of the truck's "bounce" until impact was possibly three seconds, with a standard reaction time for a driver to perceive a hazard of 1.5 seconds, leaving another 1.5 seconds for either driver to take action.
There was a bank on the left-hand side of the road which meant the campervan, driven by Roma Serra, could not drive off the road to avoid the collision.
The Transport Agency provided a report on the section of the road that said the uneven pavement "caused quite noticeable wheel bounce in vehicles with less sophisticated suspension setups, such as trucks and trailers".
Etuale had driven the road on several other occasions, including four days before this crash.
Coroner Ryan continued: "I consider that the most likely explanation for the cause of this crash is a combination of momentary unpreparedness by Mr Etuale at the critical moment when his truck entered the section of uneven surface ... Mr Etuale was unprepared for the bounce and its effect on the truck.
"The condition of the road was a contributing factor to the crash, as it adversely affected the handling of trucks. Notwithstanding this, all other truck drivers had been able to cope with the condition of the road as there had been no reported crashes at the scene prior to this crash."
Etuale was charged following the crash with operating a vehicle carelessly causing death. He was acquitted of charges in court, after the district court accepted evidence he and another driver gave that the truck had an "intermittent steering fault".
The inquest made no such findings, stating that the "loss of steering" Etuale experienced was not a sudden mechanical fault but rather his front wheels having no contact with the road, allowing the steering wheel to turn with no resistance.
Etuale had accused police of washing away evidence which proved a mechanical fault caused the crash. Post-crash assessments found no evidence of any mechanical fault.