A new study by Queen’s University Belfast has cast doubt on the efficacy of 20mph zones in Northern Ireland’s capital. The report found that road collisions were only reduced by 2% and casualties by 5% since the city centre enforced the lower speed limit in certain areas.

Across the UK, city councils are increasingly adopting 20mph zones. Transport for London plans to extend the speed limit across an additional five boroughs for 2023, and local authorities are implementing 20mph as a norm for most urban and village streets.

This change has led to reductions in casualties of between 20% and 40% in cities like Edinburgh, Calderdale, Bristol, Cheshire West and Chester, Bath, Warrington, and many more.

Rod King MBE, founder and campaign director at 20’s Plenty for Us, has questioned the validity of the university’s study, suggesting that the report’s results are completely atypical when compared to the rest of the UK.

In Edinburgh, he notes that casualties have fallen by an impressive 39%, and collisions by 40% since slower speed limits were introduced.

King suggests that there were some key flaws in the methodology, stating: “The implementation in Belfast was on just 76 streets in the city centre, on which the average vehicle speed was well below 20mph. Of these 76 streets, 27 were already fully or partially pedestrianised.

“There was also little community engagement or marketing of the 20mph scheme. The total cost of the scheme was just £10,000.”

King also proposes a number of key success factors in the effective introduction of 20mph rules, which include:

• Making 20mph the norm city-wide, as these zones are more effective than if they are  limited to a handful of roads
• Delivering 20mph on driver’s home streets
• Engaging with the public on why the scheme is being implemented
• Deploying on faster roads for maximum impact

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