A 21-year-old NSW man has died and two people were injured after their vehicle, a late-model four-wheel drive, rolled two kilometres south of Royalla just after 6am.

ACT Policing said the dead man had been the driver. "The name of the deceased will not be released publicly. The investigation of this collision is ongoing."

Leonie Keogh, who said the crash scene was near the entrance to the family farm, said the smash was the latest in a long succession of incidents.

"It is the third fatality in as many years; the ACT government seriously need to do something about this stretch of road," she said.

Ms Keogh, who has lived at Royalla for the past 18 years, described turning into the family's driveway during the snow season as "Russian roulette".

"The car behind you knows you are turning but cars three or four back think you are just slowing down and pull out to overtake."

Her husband, Scott Keogh, said near misses were frighteningly common at this time of the year.

"The highway was realigned about 15 years ago and it is one of the first straight stretches after you get out of Canberra," he said. "Drivers just go for it. They pull out [to overtake] on what is a dangerous stretch of road where you can't always see what is coming the other way. We've had the mailbox taken out [by drivers doing this]."

Mr Keogh, who was called to Saturday's crash by his family who had been heading to the snow, said the experience was still "very raw".

"They were pulling out of the driveway and saw the car on its roof [a short distance down the road]," he said. "Of course it affects you. Our children are about the same age as the young people in the car."

The Keoghs and other travellers helped out with blankets and torches and stayed with the victims until emergency services arrived.

Ms Keogh said while, at first glance, many people thought the long straight stretch of road was quite safe this did not take into account the volume of snow traffic and the dips and hollows that made it hard to see what was coming the other way.

Mr Keogh said the family tried to avoid driving when the Monaro was at its busiest.

"The traffic can be bumper-to-bumper with everyone trying to move at 100km/h," he said. "I've seen cars banked up as far as Calwell. The Sydney traffic hits at about 8pm on Fridays and it starts again from about 4am on Saturday."

Royalla is 800 metres above sea level and frosty and cold conditions are common during the snow season.

"The ACT government seriously needs to do something about this stretch of road," Ms Keogh said. "They need to put in an overtaking lane."

Across the border in NSW six people died in five accidents between Friday and Sunday.

"In four [of the] crashes in which five people died vehicles left the road due to fatigue, speed, distraction and other factors," NSW Police Commissioner Andrew Scipione said.