Revealing the impact of 20mph speed limits in Wales and the implications for enforcement

Organisation: Agilysis

Date of Publication: January 2024

Uploaded to Knowledge Centre: 6 February 2024

This follow-up report examines the aftermath of the reduction of speed limits from 30mph to 20mph on roads throughout Wales.

The transition to lower speed limits in September 2023 sparked a surge in debate and deliberations among policymakers, road safety advocates, and the general public. Not only has it reshaped the landscape of Welsh roads but has also spurred a fundamental re-examination of attitudes towards speed, safety and overall road conduct.

An initial report, published on 25 September 2023, analysed speeds on nearly 500km of roads in ten Welsh towns and cities, revealing a 2.9mph drop in average speeds post-implementation. The study utilised data from TomTom, collected from hundreds of thousands of journeys immediately after the speed limit change.

This latest report focuses on the three-month period post-change, covering the same roads as the initial study, employing a new methodology to estimate speed compliance and discuss potential enforcement scenarios. Agilysis examined over 7,900 road sections, to reveal these insightful findings.

The most recent analysis shows a slight bounce back in speeds compared to the one-week post-change period, however overall average speeds are down by 2.4mph compared to pre-change levels.

Access the current report via the Agilysis website: