Cutting speed limits to 20mph in built-up areas does not significantly improve safety, a new report suggests.
The findings, published online in the Journal of Epidemiology and Community Health, analysed data from before and after the 20mph limit was introduced on 76 roads in the centre of Belfast in 2016.
Comparisons with streets in the surrounding area and elsewhere in Northern Ireland that retained their 30pmh or 40pmh limit showed there were "no statistically significant differences" in terms of the number of crashes, casualty rates or average traffic speed.
However researchers found roads with a 20mph limit did experience a reduction in traffic.
Authors of the report, including Professor Ruth Hunter of Queen's University Belfast and Dr Ruth Jepson of the University of Edinburgh noted that their research was smaller in scale in comparison to some other studies on the same topic.
The report recommended that 20mph limits could be combined with other measures such as driver training, CCTV and police communications in order to "facilitate an ambitious culture change, that shifts populations away from the car-dominant paradigm".
The report added that speed limits are not simply for "road-safety intervention" but can be a "part of the fundamental reset of the way we choose our life priorities - people before cars."
The report comes as schemes to cut speed limits to 20mph have become increasingly popular in the UK and other parts of Europe.
Their aim is to reduce the number of vehicle crashes and injuries and bring areas closer to their climate change targets.
Back in July, Senedd members voted in favour of Welsh legislation to change the National Default Speed Limit in Wales from 30mph to 20mph. The law affects most residential roads and other busy streets and is said to come into force from 17 September, 2023.
The incoming law has already faced criticism. Paul Dyer, managing director at Cardiff Bus, is "concerned" that the 20mph will add to the challenges already faced by the industry, which struggles to recruit drivers.
In England, Witney in Oxfordshire chose to become the first town in the county to have 20mph residential zones in July.
Reported by the Oxford Mail, the county council said the emphasis is on drivers adhering to the new limits through a change of mindset, rather than enforcement and that "breaking the limit will become socially unacceptable for drivers".