The National-led government has raised speed limits. New data reveals the potential human cost of that move.

Between 2022 and 2023 Auckland Transport lowered speed limits on hundreds of roads. In 2025 many were raised again following the National government's changes to the Land Transport Rule: Setting of Speed Limits (2024). Dr Timothy Welch, an Auckland University lecturer specialising in transport, has carried out an assessment on the entirety of Auckland. After accounting for traffic flows, weather and contributing factors such as driver impairment, he has concluded that the lower speed limits put in place by Auckland Council between 2022 and 2025 likely averted 138 crashes.

Though the numbers come with a statistical range, Welch’s best estimate is the changes were responsible for preventing 29 serious injuries and four deaths over the 30 months they were in place.  The difference is stark. Crashes on the local streets with reduced limits were down 17% compared to the period prior to the changes. On corridors with higher traffic volumes, they were down 7%. 

Former transport minister Simeon Brown cited lost productivity from slower travel times as a reason to reverse speed limit changes made during the term of the last Labour government. Welch argues his latest analysis undermines the productivity case for higher speeds. Using the NZTA’s value of a statistical life, Welch estimates lower speed limits saved $66 million in social cost. “One single serious injury, or one death on the road, is enough to cancel out all of the productivity savings you might gain from a slightly higher speed,” he says

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