Auckland Transport has announced a plan to decrease speed limits around the city.

Details of a proposed safety initiative to lower speeds limits in Auckland show nearly 800 roads spread across the region will be affected.

The 800 roads are split almost evenly between suburban streets and rural roads.

National's transport spokesman Paul Goldsmith said the plan was driven by "anti-car zealotry", while the AA said its members opposed a blanket 30kmh in the CBD.

CALLUM MCGILLIVRAY/STUFF Roads in both rural and town areas across Auckland face lower speed limits (file photo).

Auckland Transport will consult in the New Year on the lower limits, aimed at reducing speed-related death and injury.

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The schedule of proposed roads, obtained by Stuff, shows both the geographic spread and the intended new speed limits.

Most of the city centre would have 30kmh limits, while existing "shared spaces" where cars and pedestrians mix would have 10kmh limits.

But 30kmh limits are also planned across the region, from Griffiths Place in Te Atatu South, to Erceg Road in Papakura in the south, and Hastings Road in Mairangi Bay in the north.

Hundreds of 60kmh limits are proposed for roads outside the urban areas, from Leigh in the north, to Waiuku in the south, and Kawakawa Bay in the south-east.

SUPPLIED A 30kmh speed limit, shown in purple, is proposed for most streets in Auckland's CBD.

Auckland Transport said its proposed by-law would tackle inappropriate speed, which contributes to more than 20 per cent of the region's deaths and serious road injuries.

"Setting safe speeds is one of the quickest and most effective tools we have in reducing road trauma," said AT's chief executive Shane Ellison.

The agency believed dozens of lives and hundreds of injuries could be avoided due to lower speed limits.

Transport advocates and the pedestrian lobby group Living Streets Aotearoa have backed the move.

But the Automobile Association (AA) said the reductions were too large, and 62 per cent of members surveyed opposed the blanket CBD limit.

"There is strong justification for slower speeds on most CBD roads on safety grounds, but the AA will be pushing for reductions to 40kmh, not 30kmh," AA spokesman Barney Irvine said.

"Sydney and Melbourne have both moved to 40kmh CBDs to good effect and we've seen it work well on Ponsonby Rd here as well."

National's transport spokesman and Auckland-based list MP Paul Goldsmith said while 2017's Auckland toll of 28 deaths in speed-related crashes needed tackling, AT's plans went too far.

"A 30 kmh limit will make sense in some streets, but a blanket speed reduction across the entire CBD is an overreaction," he said.

Auckland Mayor Phil Goff has previously been cool on the idea of widespread speed reductions.

"AT would need to have evidence that it would lead to fewer deaths and injuries on that road," Goff told Stuff in September.

"They would need to focus on those areas where a likely reduction could be shown."