Cutting speed limits on urban roads to 20 miles per hour (32 kilometres per hour) does not significantly improve safety, a report has suggested.
Researchers analysed data from before and after the limit was introduced on 76 roads in central Belfast in 2016.
The study found “little impact on long-term outcomes” in the city.
Comparisons with streets in the surrounding area and elsewhere in Northern Ireland that retained their 30mph (42kph) or 40mph (64kph) limit showed there were “no statistically significant differences” in terms of the number of crashes, casualty rates or average traffic speed.
Roads with a 20mph limit did experience a reduction in traffic, the report, published online in the Journal of Epidemiology and Community Health, showed.
The report's authors, who include Ruth Hunter of Queen’s University Belfast and Ruth Jepson of the University of Edinburgh, noted that their research was smaller in scale than some other studies on the topic.
The report said that the limits could be combined with other measures such as driver training, CCTV and police communications to “facilitate an ambitious culture change that shifts populations away from the car-dominant paradigm”.
It added that reducing speed limits is “not simply a road-safety intervention” but can be “part of the fundamental reset of the way we choose our life priorities — people before cars”.
Plans to cut speed limits to 20mph have become increasingly popular in the UK and other parts of Europe in recent years as part of efforts to reduce crashes and injuries.
RAC road safety spokesman Simon Williams said the findings of the survey were “surprising” as they appear to suggest that drivers on 20mph roads in Belfast hardly slowed down at all, despite the lower speed limit.
“It seems there is a serious problem with compliance as we would expect that even without enforcement, average speeds would drop,” he said.
Mary Williams, chief executive of road safety charity Brake, described 20mph limits as “life saving”, particularly for pedestrians and people riding bicycles and motorbikes.
“It is a matter of physics. At speeds of 20mph or less, drivers have significantly more chance to spot hazards and stop in time, “she said.
“The difference between a 20mph limit and a 30mph limit is a doubled stopping distance.”
