Auckland Transport says fewer people will die on our roads after a decision today to lower speed limits on scores of Auckland city streets from next year.

But the council-controlled organisation is under fire by the Automobile Association for failing to listen to public concerns over "large-scale" speed limits cuts, which could lead to poor compliance.

"AA Members and all Aucklanders support the idea of reduced speeds on high-risk roads, but the big-bang, blanket reductions that AT is proposing are too much, too fast," AA spokesman Barney Irvine said.

AT's board today gave the green light to a modified version of its original proposal that will now see Auckland's major four-lane CBD streets - Hobson St, Nelson St and Fanshawe St - reduced to 40km/h.

Speeds limits on other CBD streets will be reduced to 30km/h.

Auckland Transport says it will also spend $5 million to $10 million more (on a budget of $65m next year) to "engineer up" road safety factors.

AT made the unanimous decision at a board meeting this afternoon having considered nearly 12,000 public submissions and reviewed technical reports.

In a statement, AT chairman Dr Lester Levy said the move would see fewer motorists killed or maimed on the city's roads and followed an alarming trend of fatalities and serious injuries.

On average two people were killed or seriously injured every day on the city's roads.

"The evidence from our own trials and overseas experience shows that drivers who make mistakes at lower speeds have better outcomes," Levy said.

"AT and supporters of lower speeds have a message for Auckland drivers: if you value life, reduce your speed."

However AA said the changes were too big and rushed through too quickly.

The changes, when implemented mid next year, would create a "blanket" 30km/h zone for Auckland's CBD (excluding Hobson, Nelson and Fanshawe streets, which will be reduced to 40km/h) and see widespread reductions in town centres and rural areas.

Irvine said public feedback had consistently shown that a large proportion of people had not bought into AT's vision.

"The theme that comes through really clearly is that people don't think the changes make sense. If people don't see a speed limit as credible, they are unlikely to stick to it; and where compliance is low, you don't get the safety benefits – all you get is higher numbers of infringements. That all adds up to a really poor road safety outcome."

The Road Transport Forum said the move was confusing and costly.

Chief executive Nick Leggett said while everyone wanted to see safer roads, the package was a "vast array of speed limits that will have motorists traversing the affected 700km of Auckland roads in confusion, and will add costs to all New Zealanders for goods that travel on those roads".

Yesterday, Auckland Mayor Phil Goff said he expected AT to carry the community with it in the board's decision and for it to be evidence-based.

It's a testing time for AT to be making such a big decision with an independent review and reform of the five CCOs about to get under way.

Goff has made it a top priority of his second term to stop CCOs being unresponsive to communities, saying he shares public concerns about whether they can be held accountable.

Bike Auckland had supported the proposed restrictions, saying the city centre was now a major residential centre with a dense population and children needed to be kept safe walking to school.

"This is the sort of thing that happens in cities overseas everywhere and it's not a peculiar concept. It's just that we have been behind the eight ball," said Cuthbert, whose organisation supports a blanket 30km/h speed limit in the central city.

But National Party leader Simon Bridges said AT had ignored the views of Aucklanders and slowed the city down.

"It already takes too long to get around Auckland, particularly in the CBD. A central city reduced to 30 or 40km/h will be a nightmare for commuters.

"The majority of people who submitted to Auckland Transport (AT) didn't want this – but AT's ignored the very people this will affect."