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Do 20mph speed limits affect levels of physical activity?

By Guest Blogger,
man crossing 20mph road with pushchair

image credit: Jonathan Bewley

Have you seen a 20mph sign in your town, village or city? What did you think? Did it prompt you to drive more slowly? These are exactly the questions that a new research project is trying to assess. In this blog, G.F.Nightingale, P. Kelly, and the "Is twenty plenty?" research team discuss the major study they have embarked on to evaluate the effects of the 20mph speed limit implementations in Edinburgh and Belfast.

The “Is Twenty Plenty?” study, led Dr. Ruth Jepson of the Scottish Collaboration for Public Health Research and Policy (SCPHRP), will compare the number of people cycling and walking, the perceptions of local residents and drivers and trends in the monthly/annual numbers of road traffic collisions and casualties from before and after the speed limit restriction was put in place.

The final phase of the speed restriction has been implemented and 80% of city roads in Edinburgh now have a 20mph speed limit.

This project draws upon data collected from multiple sources such as the City of Edinburgh household survey, the Northern Ireland Continuous Household Survey, Sustrans (surveys, walking and cycling counters) and Police data (STATS19 and the Northern Ireland Police Recorded Injury Road Traffic Collision Data). 

Road users in each area will also be asked about their perceptions of the 20mph speed limit at various points across the course of the project.

Under consideration by the study and the authorities in Edinburgh and Belfast are the numbers of people choosing to walk and cycle in the new 20mph zones, with the number of people walking and cycling expected to rise post-implementation, resulting in increased public physical activity.

There has been a UK-wide effort to encourage and facilitate cycling and walking as a public health priority. Kahlmeier et.al. (2010)1notes that “these forms of physical activity are also more practicable for groups of the population for which sport is either not feasible because of physical limitations or is not an accessible leisure activity for economic, social or cultural reasons”. 

Overall, walking and cycling has received immense support also from the Global Advocacy for Physical Activity (GAPA) which state that “’Active transport’ is the most practical and sustainable way to increase physical activity on a daily basis”. 

Interim reports on the latest findings of the project, press releases, and publications can be found on the project website. Dr Ruth Jepson can also be seen discussing the study in detail in this video. If you have any queries or would like to know more information about the study, please contact Dr Jepson at:  [email protected]

The ‘Is Twenty Plenty?’ study is funded by the National Institute for Health Research (NIHR), and involves partnership with The Scottish Collaboration for Public Health Research & Policy (SCPHRP - University of Edinburgh), The Physical Activity for Health Research Centre (PAHRC – University of Edinburgh), University of Cambridge, University of Bristol, University of Exeter, University of East Anglia, Queen’s University Belfast, NHS Health Scotland, Sustrans and various charities.


1 Kahlmeier S, Racioppi F, Cavill N, Rutter H, Oja P. “Health in all policies” in practice: guidance and tools to quantifying the health effects of cycling and walking. Journal of Physical Activity and Health. 2010 Mar; 7(s1):S120-5.