The speed limit's increasing on two major roads but it isn't likely to happen elsewhere anytime soon.

From today motorists can drive 110 kilometres on parts of  the Waikato Expressway and the Tauranga Eastern Link toll road - between Paengaroa and the Domain Road interchange.

NZTA said the roads are only ones in the country currently suitable for the raised limit. 

Safety and environment direction Harry Wilson told Rachel Smalley other roads would need work to be able handle these kinds of speeds.

"There's not many of them, there's about 100 kilometres in total across the network. We have to weigh it up against the safety case."

The two sections of road were selected first in the country because they have some of the best safety features in New Zealand, the New Zealand Transport Agency (NZTA) said last month.

Both roads have median-barriers and two lanes of direction which significantly reduces head-on collisions.

NZTA received almost 11,500 submissions from the public and stakeholders with 73 per cent in favour of increasing the speed limit.

Bay of Plenty inspector Brent Crowe is encouraging drivers to respect the conditions.

"We are focused on encouraging people to drive responsibly and to the conditions," he said.

"Our officers will still have discretion in how they deal with incidents and how they are enforced. Their focus will be on preventing harm on our roads.

"Over the holiday period - from 6am, December 18 to 6am, January 8 - if you're detected by a safe speed camera exceeding the area's posted speed limit by more than 4km, it is likely you will receive a fine," Crowe said.

In November last year, Labour's then police spokesman Stuart Nash - the current Police Minister - voiced his concerns about raising the speed limit.

"I think if you make it 110km/h, then 110km/h becomes the absolute new norm," he said at the time.

"But what happens in people's minds is they think, 110km/h is the limit, I can drive at 115km/h and get away with it.

"They go on to a road where the speed limit is 100km/h and they are still travelling at 110km/h, because they are doing that for the past hour.

"I just think we are playing with fire, and we are playing with the lives of Kiwis."

Asked today if he had changed his position on the speed limit increase now he was minister, Nash said in a statement: "I support the increase in the speed limit in these two cases, where the roads have been assessed to be safe enough and significant consultation has occurred.

"However ... drivers must continue to use their judgment and make safe decisions when behind the wheel."

LISTEN TO HARRY WILSON TALK WITH RACHEL SMALLEY ABOVE

- with content from NZ Herald