Media release: Increasing speed limits defies the science - more deaths and pollution predicted

The government’s proposal to increase speed limits will lead to more deaths and serious injuries on our roads, according to experts. 

In the latest Briefing from the Public Health Communication Centre the University of Canterbury’s Professor Simon Kingham says the proposed speed limit increases will also likely worsen air quality and increase greenhouse gases while failing to improve economic productivity as promised.

Professor Kingham, the former chief science advisor to the Ministry of Transport, and co-author, social scientist Dr Angela Curl of the University of Otago, have examined the health impacts of raising speed limits. They say the consequences are likely to be significant and wide-ranging with costs outweighing any benefits.

“Simply put deaths and serious injuries are much higher at increased speeds, primarily as a result of increased stopping distances,” says Professor Kingham. “The chances of a pedestrian surviving a crash are around 90% at 30km/h, compared to around 10% at 50km/h. Evidence shows that reduced speed limits lead to notable decreases in deaths and injuries.”

He also highlights that more than 2,000 people die each year in Aotearoa NZ from traffic-related air pollution. “Aggressive driving (speeding, rapid acceleration and braking) also increases emissions. Urban speed limits of 30km/h result in significantly lower emissions than 50km/h, while having only a small effect on total journey times.” 

The Briefing also explores the negative impact of increased speed limits on communities and equality. “People are less likely to walk and cycle in higher-speed areas. Additionally, research shows exposure to traffic-related air pollution is worse in lower-income areas,” says Professor Kingham. 

“The government’s argument for raising speed limits defies the evidence. They say it will save time and increase productivity, but research on this is unclear. In contrast, there is overwhelming evidence that higher speed limits have a significant negative impact on health and wellbeing and will cost the country financially.”