Research and analysis

20 mph speed limits on roads

Report into the effectiveness of 20 miles per hour (mph) road speed limits.

• From: Department for Transport
• Published: 22 November 2018
• Last updated: 11 March 2019 — See all updates

Documents

20mph research study - process and impact evaluation: headline report

PDF, 1.15 MB, 68 pages

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20mph research study - process and impact evaluation: technical report

PDF, 3.63 MB, 221 pages

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Supporting technical appendix 1: case study description report

PDF, 13 MB, 74 pages

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Supporting technical appendix 2: analysis of GPS journey speeds in case study areas

PDF, 2.47 MB, 101 pages

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Supporting technical appendix 3: methodology description report

PDF, 1.55 MB, 39 pages

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Supporting technical appendix 4: rapid evidence review

PDF, 628 KB, 47 pages

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Supporting technical appendix 5: residents’ and drivers’ questionnaires – logistic regression analysis

PDF, 687 KB, 63 pages

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Supporting technical appendix 6: analysis of safety outcomes in case study areas

PDF, 6.87 MB, 111 pages

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Supporting technical appendix 7: analysis of spot speed data in case study areas

PDF, 16 MB, 167 pages

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Details

The research concludes that:

• 20mph limits are supported by the majority of residents and drivers
• there has been a small reduction in average (median) speed - less than 1mph
• vehicles travelling at higher speeds before the introduction of the 20mph limit have reduced their speed more than those already travelling at lower speeds

There is not enough evidence to conclude that that there has been a significant change in collisions and casualties following the introduction of 20mph limits in residential areas.

Atkins, Aecom and Professor Mike Maher (UCL) were commissioned by the Department for Transport in 2014 to address a gap in the evidence available on the effectiveness of 20mph speed limit (signed only) schemes. Twelve case study schemes were studied, from a variety of area types, road types and scale.

Published 22 November 2018
Last updated 11 March 2019 + show all updates

1. 11 March 2019

   Supporting technical appendices added.

2. 22 November 2018

   First published.