Scottish 20mph Default Limit Could Save £56M pa

£56M pa is the estimated value of preventing casualties on Scottish 30mph urban roads by lowering the limit to 20mph. 20’s Plenty for Us calculate that a 20mph default limit on Scottish roads would prevent 7 deaths, 123 serious and 812 slight casualties pa. 

20’s Plenty for Us have calculated the injury reduction benefits in Scotland if all urban 30mph roads changed to a 20mph speed limit. Road safety researchers reviewed the evidence and modelled that with even a conservative 15% fewer casualties. 942 fewer people would be hurt.


Scottish Urban 30mph roads are changed to a 20mph limit with locally decided exceptions with a 15% reduction in injuries








A: Road crash casualties on urban roads with a 30 mph limit in Scotland using 2011 to 2015 average[1]

49 people

823 people

5,410 people

6,282 people

B: Estimated value of prevention, per casualty





C: Estimated value of prevention of all 30 mph crash casualties (C=A*B)





D: Casualties avoided by default 20 mph limits with 15% fewer casualties (D=A*0.15)

7 people


123 people


812 people


942 people

E: Estimated casualty prevention value of default 20 mph urban limits in Scotland 2015 (E=D*B)










With lower limits there are other benefits also as air pollution related diseases fall sharply with many deaths and hundreds of life years saved.  A default 20mph wins out over a 30mph default for road traffic casualties, air quality, active travel (heart disease and obesity), noise pollution, greater social inclusion, greater community cohesion and local business viability. 


Anna Semlyen, 20’s Plenty for Us Campaign Manager, MSc Health Economics said

“20mph limits bring massive public health economic savings. Retaining 30mph is unethical when we know that so much risk and harm can be easily prevented. Politicians must vote for default 20mph limits.”


20’s Plenty for Us estimates a 20mph signed Scottish default would cost £5 Million[2] outside Edinburgh (which has already funded 20mph limits).  £5M is a tiny amount relative to the huge £56M pa in injuries saved. A default 20mph limit for Scotland has a First Year Rate of Return of 1,100% on casualties alone before other benefits. Setting a default 20mph limit across the country is far more efficient and costs substantially less than the English approach of each authority separately setting 20mph as funding and political will permits.


20’s Plenty for Us calls on the Scottish Government and Health Protection Scotland to work together to make 20mph default on urban roads a reality.   Mark Ruskell, Green MSP is launching a pre-legislative consultation on default 20mph limits for Scotland this April with the hashtag #20Scotland.

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  • Mary Cartwright
    commented 2017-04-22 10:59:45 +0100
    20’plenty for me
    1 life saved is fantastic
    But to have prevented those 7 deaths
    would mean everything to me.

    yes please
    Cllr. Mary Cartwright
    Mayor of Peterlee