Intensive advertising of changes to traffic give-way rules will be "short and sharp" to ensure motorists don't start altering their behaviour too early at intersections.
"We don't want people practising early," Transport Minister Steven Joyce said yesterday of the rule changes, which are to come into force at 5am on March 25.
That will be a Sunday, which the Transport Agency prays will be a quiet day on the roads, as drivers get used to changes to the rule about who gives way to whom.
Those turning left at intersections will no longer have to give way to right-turning vehicles heading their way.
The Government has finally decided to align New Zealand with the rest of the world, which already gives priority to left-turning vehicles.
It hopes that will eventually see an end to motorists dithering over whether it is safe to make turns, citing a 7 per cent fall in intersection crashes after the Australian state of Victoria made a similar rule change in 1993.
Mr Joyce believes it will also be safer for cyclists and pedestrians.
Changes are also planned for vehicles turning right at uncontrolled T-intersections.
Right-turning vehicles on continuing roads now have to give way to those turning right from terminating roads, but that is also due to be reversed in March.
Although the existing requirement for left-turning vehicles to give way has been in place since 1977, it remains a source of confusion at intersections, with drivers waiting to turn right often making poor judgments about perceived gaps in straight-ahead traffic.
But the Transport Agency acknowledges a challenge in helping drivers to get used to the change, and is promising an intensive if brief ad campaign for just two or so weeks beforehand.
"If you begin advertising it too early, it can potentially cause confusion and they start driving to the new rule too early," spokesman Andy Knackstedt said.
"It will be short and sharp."
Mr Knackstedt said the agency had learned from a mistake in Victoria. Its rule change was preceded by months of ads, which caused crashes "and all sorts of problems on the roads".
But he said the agency was encouraged by the long-term improvement in road safety in that state.
Although drivers on New Zealand roads would be need to take extra care from March 25, the Transport Agency expected to achieve high awareness of the rule changes by then.
As always, a sensible precaution before turning would be to make eye contact with other drivers.
* Motorists turning left give way to those turning right.
* Rule has been in place since 1977.
* Motorists turning left will have right of way.
* Change happens 5am March 25 2012.
* Intensive advertising campaign before change.
* Official estimates say the new rule will each year prevent: 1 death, 13 serious injuries and 84 minor injuries.