Summarised by Centrist
Lower speed limits introduced on hundreds of Auckland roads were associated with fewer crashes and may have prevented four deaths, according to an analysis by University of Auckland transport lecturer Dr Timothy Welch.
Auckland Council reduced speed limits on 662 roads during 2022 and 2023 and kept them in place for about 30 months.
Welch compared crash rates during that period with the previous five years, adjusting for factors including traffic volumes, weather, Covid disruptions and driver impairment.
He estimated the lower limits prevented 138 crashes, including 29 serious injuries and four deaths.
Crashes fell by 17% on local streets where limits were reduced and by 7% on higher-volume roads, according to the analysis.
Welch also examined Te Irirangi Drive, where the speed limit was lowered from 80km/h to 60km/h in 2023 before being restored to 80km/h in 2025.
A nine-year-old girl was killed in a crash on the road in March 2026 after a witness reported seeing a car travelling at high speed.
The cause of that crash remains under investigation, and the analysis does not establish whether the higher posted limit contributed to it.
Welch found the adjusted crash rate on Te Irirangi Drive was 32% lower during the period with the reduced limit.
However, he said the period since speed limits were raised again was still too short to support firm conclusions about the effect of the reversals.
The government has argued the previous speed-limit programme was too broad and imposed unnecessary travel delays rather than concentrating reductions on high-risk roads.
Former Transport Minister Simeon Brown described the policy as “anti-car ideology”, while Transport Minister Chris Bishop said the government was targeting major causes of fatal crashes, including alcohol and drug impairment.
Welch said the safety benefits outweighed any productivity gains from faster travel, estimating the reductions saved $66 million in social costs.
Editor’s note: The Spinoff presents Welch’s analysis as strong evidence against the government’s speed-limit reversals, but the article also acknowledges that the post-reversal data is too limited to support firm conclusions.
The Te Irirangi Drive death is relevant, but does not establish that the restored limit caused the crash. The vehicle was reportedly travelling at high speed, and the police investigation had not determined whether the driver was obeying the posted limit.
Welch’s findings do not, on their own, settle the broader argument over whether widespread reductions were justified or whether a more targeted road-by-road approach could deliver similar safety gains with fewer costs to motorists.
But it is also not just about safety and not everything can be measured. Is it unreasonable to enjoy driving at a decent speed, the same way you might enjoy a sport like skiing, even if there is a modestly higher risk?
