Auckland Transport plans to increase road safety by reducing speed limits on some roads.

A new bylaw is proposed to slash speed limits on some Auckland roads with the aim of protecting the city's cyclists and pedestrians.

The majority of Auckland road deaths and serious injuries occur on 50kmh urban roads, and involve pedestrians and cyclists, according to Auckland Transport (AT).

AT is currently identifying roads subject to the Speed Limit Bylaw, which will reduce the speed limits on local roads deemed to be high-risk.

Reducing speed limits is one of the fastest and most cost effective ways to reduce road trauma, according to an Auckland Transport report.

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"For individuals, the risks of a severe crash might seem small, but from a societal point of view there are substantial safety gains from reducing average speeds on streets," the report stated.

DAVE MOORE/STUFF Reducing the speed limit on some roads is one way Auckland Transport plans to move towards zero deaths or serious injuries on Auckland's roads.

"Regardless of what causes a crash, whether someone walks away or is carried away will depend on the speed the vehicles are travelling."

Across Auckland, road deaths and serious injuries (DSi) increased by 67 per cent from a total of 486 in 2013 to 813 in 2017.

By comparison, in the Kaipātiki Local Board area on the North Shore, the increase was 93 per cent over the same time period.

RICKY WILSON/STUFF The majority of Auckland road deaths and serious injuries occur on 50kmh urban roads.

Serious injuries from crashes in Kaipātiki peaked at 33 in 2016.

Willem Petrus Myburgh ,who died in a crash between a bus and a van on Waipa Rd in Birkenhead in December 2016, was the only death on a Kaipātiki road that year.

In 2017, there were 26 serious injuries and one death on the roads in the area.

Ponsonby Rd's 40kmh speed limit is supported by residents on Auckland's North Shore who would like to see something similar in their neighbourhood.

AT identified four-high-risk intersections and three high-risk routes in the Kaipātiki area. All these high-risk roads had 50kmh speed limits.

Kaipātiki residents showed support for lowering speed limits on Neighbourly.

Jude Larkin from Glenfield wanted all roads passing through shopping centres to be reduced to 40kmh.

"Ponsonby Road is a good example, and just as we have 40kmh when passing schools, areas frequented by pedestrians going about their daily business should also be considered for a reduction in speed. This would include intersections where running the red is a norm for those passing through our suburban shopping hubs."

Fab Bovis from Beach Haven wanted greater enforcement of posted speed limits.

"The current speed limit of 50kmh should mean 50kmh - not 'under 60'. In addition, all shopping centres should be 40 kmh maximum (not 'under 50'). If it means formalising the limits at 30kmh and 40kmh in order to have a margin, then let's do it. But ultimately, we need enforcement - NZ Police need to be on the road."

Bayview's Christopher Coulter did not lend outright support to lower speed limits.

"There is an old adage that no law without popular support is enforceable.

"I never speed intentionally but I for one will not drive at 40kmh unless it is for a specific purpose like school zones."

AT acknowledged reducing speed limits is a "sensitive topic", but disputed lower speed limits in urban areas would significantly increase journey times.

AT's report pointed to an NZTA study of six different routes in New Zealand, finding when driving at the maximum posted speed limit wherever possible, drivers arrived at their destination 1.08 minutes faster than when they drove 10kmh slower.

The Speed Limit Bylaw will be consulted on Auckland-wide and once the bylaw has been approved by AT's board, the speed limits become legally enforceable.