Warning: This story contains some details readers might find upsetting

It was late on a summer’s night in January last year when five mates in a recently modified Nissan Terrano headed away on a weekend four-wheel-drive trip.

The music was turned up on the car stereo, and a box of beers and some cider had been passed among the four passengers, but driver Joseph Kenny wasn’t drinking.

His mates’ safety was paramount, he told the Nelson District Court this week.

The 18-year-old, on a learner’s licence at the time, was keen to show them how his recently modified four-wheel-drive performed on the dirt tracks around St Arnaud in the south Tasman District.

None in the vehicle had a full driver’s licence when it rolled up to eight times before crashing down a bank and leaving Kenny with such serious injuries that he required staples to close a hole in his head.

More than 18 months later the Nissan remains down the bank. The injuries have healed, and three of Kenny’s four mates were in the court to help him defend two charges of careless use of a vehicle causing injury.

They, and Kenny himself, were adamant he had lost control of the vehicle after hitting a small patch of gravel at an intersection with a forestry service road and the highway to St Arnaud in the Nelson Lakes National Park.

The police argued that was not possible, judging by the modest speed Kenny said he had been travelling and the distance from the first gouge marks in the road to the point where the vehicle left the road – almost 200 metres on an uphill gradient.

The officer who attended the crash on the night, and revisited the site the next morning, saw no gravel on the road where Kenny claimed the vehicle began to slide and then “wiggle waggle” down the road before rolling.

The young Blenheim man thought he might die from a head injury suffered in the crash.

He gave a compelling argument in court: Perhaps the gravel he and others had seen had been swept up when the road was cleared after the investigation.

But Judge Tony Zohrab preferred the police and crash expert evidence.

Kenny was convicted and disqualified from driving for six months, which he said was unlikely to be a problem. These days the only wheels the single dad had were on the pram he used to take his young child out.

Drone footage played in court during the defended hearing showed the gently curved road winding through densely forested hills and the intersection with the forestry road and Kerr Hill Road.

It was January 12 last year, and the night was dark.

Aiden Higgins was in the rear passenger seat behind Kenny. He’d had “three or four drinks” including one while in the car.

He was knocked out in the crash and initially said he couldn’t remember it, except for the hour’s walk through the black night afterwards to get help.

A passer-by on the remote highway had stopped to help.

Higgins ended up in hospital with staples in his head to close the hole.

In court, he remembered a lot, including the music playing in the vehicle, mates yarning and then suddenly sliding on the small patch of loose gravel he’d glimpsed from the back seat, and Kenny trying to correct the motion.

“We were sliding, I looked down and saw a patch of gravel.”

It was gravel they claimed to have noticed on the walk to get help after the crash – a point Judge Zohrab found hard to grasp.

“I find it difficult to accept, given the terrible accident that any thought would be given to what the state of play was as far as gravel was concerned.”

Ashley Tunbridge was in the front seat beside Kenny; his best mate since they were aged 11 or 12.

“He used to wake me up and take me to school.”

Tunbridge, who had also been drinking, had been checking a text on his phone and had looked up when “everything happened”.

He remembered the wheels hitting gravel on the side of the road before it suddenly “kicked sideways”, grabbed, slid and then rolled seven or eight times before it stopped beside a gorse bush.

Police prosecutor Shania Nicholson asked if he thought Kenny had come around the corner too fast and had simply lost control.

Tunbridge said he recalled looking at the speedometer and seeing they’d been travelling at 80km/h at the time.

“We got out by ourselves but Joe … he had his hands still clenched on the wheel and he was making strange noises. He had a lot of blood coming from his head.”

Tunbridge told the court he was “done talking” when pressed further about where in fact the gravel was.

Connor Williams was keen to join the trip and see the $10,000 worth of modifications to the Nissan.

“It was a nice rig,” he said.

Williams was seated in the middle of the back seat and walked away with little more than a sore back, unlike Kenny who had a “chunk taken out of his head” and was left wearing a neck brace.

He claimed the gravel and dirt they hit was spread across the road, and that he, too, had been watching the speedo – they were doing 80km/h in a 100km/h zone.

Constable Matthew Berquist, who was the Wakefield police officer on the night shift, got the call and headed to the scene.

He found Kenny, who’d been picked up by a passing motorist, with his head wrapped and in the onset of shock. The others were on the side of the road where they had walked from the crash site.

Berquist did a preliminary examination and returned the next day with a colleague for a more detailed examination and discovered marks on the road that led them to the vehicle down the bank.

Judge Zohrab said it was regrettable he hadn’t taken photos of the road at the intersection, only further down, but acknowledged he hadn’t because nothing had leapt out as obvious – he hadn’t seen any gravel.

Berquist estimated the distance using Google Maps was 180 metres from the gouge marks left by the vehicle’s tyre rim to the point where the vehicle left the road.

The point at which Kenny claimed to have hit the gravel to where he went over the bank was about 210 metres.

Berquist believed speed had been a factor and sought input from a serious crash investigator, because what he was seeing “didn’t make sense”.

It was eight months later, in August 2022, that Senior Constable Simon Burberry of the Tasman District Crash Investigation Unit got involved and prepared a basic analysis from the evidence gathered by Berquist and his own visit to the site at Kerr Hill Road.

By his calculations, Kenny could have stopped the vehicle within 68 metres if he had been driving at 80 km/h.

He said 180 to 200 metres was a “hell of a distance” to travel uncontrolled before the vehicle left the road and went down the bank.

Burberry also said if it had hit gravel, it would have either under-steered or over-steered.

“Neither of these things would have resulted in the ‘wiggle waggle’ the witnesses describe happening,” Burberry said.

Judge Zohrab concluded that the prosecution had proven beyond reasonable doubt that there had been no gravel on the road at the time and that excessive speed was the most likely factor in the crash.

“You were young, on a learner licence and in a reasonably powerful vehicle.

“Stay out of trouble, and keep your foot off the pedal,” he told a relieved Kenny.