The letter is addressed to Prime Minister Christopher Luxon and Minister of Transport Simeon Brown, and warned research evidence on road speeds was unequivocal — as mean vehicle speeds rise, so do the number of deaths and serious injuries.
University of Otago Transport Research Network director Dr Vanessa Beanland said she signed the letter because all the evidence she and her colleagues had gathered about the effect of increasing speed limits, both here and overseas, was "contrary" to the government’s beliefs.
"I and many others in the transport community have a lot of concern about the direction that the government has been pursuing in relation to speed limits.
"There’s a well-established relationship between speed limits and road deaths and road injuries.
"To the end of August this year, fatalities on New Zealand roads were down about 20% on last year — most likely attributable to the speed limit reductions that have occurred."
The letter said New Zealand had made considerable progress in recent years in adopting speed limits that align with safe system principles, saving countless lives in the process.
"We strongly urge you to reconsider the proposed blanket speed limit increases.
"Should this rule be adopted, the tragic consequence will be more New Zealanders losing their lives or suffering severe injury, along with a substantial burden on the nation's healthcare and rehabilitation services."
The letter also urged them to "carefully reflect" on New Zealand’s international commitments; the contradictions the proposal creates with global agreements; and economic and environmental considerations.
As a signatory to the United Nations Decade of Action for Road Safety, New Zealand has pledged to halve global road crash deaths and injuries by 2030.
The country is also bound by the Stockholm Declaration and various United Nations resolutions and political declarations aimed at reducing road trauma.
The proposed rule changes were at odds with these commitments, the letter said.
"A recent report from the World Bank (2024) details the economic advantages of effective speed management and refutes the misconception that higher speeds correlate with economic benefits.
"Additionally, increased vehicle speeds lead to higher fuel consumption and emissions of CO2 and NO2 (which kills over 2000 people per year in New Zealand), counteracting our efforts to reduce transport-related emissions."
