A new research briefing from the Parliamentary Office of Science and Technology (POST) provides a comprehensive overview of how 20mph speed interventions are affecting road safety, public health, and health equity across the UK.
The review offers strong evidence that 20mph zones—particularly those supported by physical measures—consistently reduce traffic collisions and casualties. By contrast, 20mph limits based on signage alone are less reliable without enforcement or supporting design changes. This matches findings from PACTS Lower Urban Speed Limits in Europe (LUSTRE) research published in 2023.
Beyond injury reduction, the POST report highlights broader public health benefits. These include:
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increases in the number of people making journey by walking and cycling, especially when combined with wider public realm improvements;
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Lower vehicle speeds, particularly in 20mph zones;
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Improved public perception, especially where benefits are effectively communicated;
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Potential to reduce health inequalities, although more robust, equity-focused evaluations are needed.
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Importantly, it emphasises that successful interventions should be multi-component—combining infrastructure changes, communication, and enforcement. This aligns with the Safe System principle which recognises that safety is achieved with a collective effort.
This publication, which PACTS Vice Chair Teresa Ciano and Deputy Executive Director Margaret Winchcomb contributed to, is timely and critical evidence for local authorities, planners, and public health professionals seeking to implement effective 20mph strategies.
