Why 30 km/h municipal speed limits Are the Right Thing to Do

Author(s): King, Semlyen

Poster Presentation:

4C King



It is recognized that prevailing traffic speeds have a huge influence on not only prevention of casualties, but also societal choices on walking and cycling and the impact of motor vehicle use on public health.

Generic 50km/h (or 30mph) municipal limits have traditionally been applied as a default at regional or national level with lower speeds only where specific site issues exist. This is most often accompanied by engineering required to sensitize drivers to diverge from the national and societal norm of 50km/h. Such isolated engineering “teaches” drivers to only slow down in such places and endorses higher speeds elsewhere.

It is internationally recognized that traffic speeds of 50km/h are sub-optimal in terms of risk to pedestrians and cyclists both through the inability to avoid crashes and the subsequent severity.

A population-wide setting of 30km/h as a default municipal speed limit resets the social consensus of appropriate vehicle speed in the presence of people. It recognises Rose’s “Prevention Paradox” whereby small changes in public health across a whole population can be far more beneficial than larger improvements for particular individuals.

This is now being advocated for casualty reduction, active travel encouragement, transport equality and reducing noise/pollution. Typically, casualties reduce by 10-20%. It lays down a foundation for active travel and transport equality. It reduces emissions and noise.

Formed in 2007, the 20’s Plenty for Us campaign in the UK has singularly focused on default 20mph(32km/h) urban/village limits by empowering communities campaigning for 20mph speed limits on their streets. 20’s Plenty (or Love 30 in km/h countries) now has 500 affiliated local community campaign groups across the world including UK, Ireland, Canada, USA and Australia. The focus has enabled it to understand the population-wide intervention with campaigning advice, evidence presentation, and showing the wide societal benefits. 20’s Plenty helps decision-makers to “do the right thing” and set a 30km/h limit as a default.

It provides support, resources, advice, briefing sheets, Zoom sessions, banners and stickers to local campaigns.

As a result of community campaigning empowered by 20’s Plenty, already 21m people (1/3rd of UK population) now live in city, town and county authorities where they have already set, or are committed to set, 20mph as such a maximum. This includes most large urban authorities, many counties and all of Inner London. Wales is in the process of setting a national default municipal/village speed limit of 20mph. Most of these have been implemented without physical or engineered traffic calming. Spain and Netherlands are also setting national 30km/h urban limits. It has done this by ”tapping in” to the majority community support for lower speed limits where people live, learn, shop, work and play.

Recently, the calls for a 30km/h default municipal speed limit have been endorsed at global level in the 3rd Ministerial Road Safety Conference (the Stockholm Declaration) in Feb 2020. This in turn has been incorporated into the UN General Assembly’s resolution for the 2nd Decade of Action on Road Safety 2021-2030, and will be the primary focus of UN Global Road Safety Week in May 2021.

This paper will present the case for default 30km/h with evidence from implementations and how it can be cost-effectively deployed with wide societal benefits.

Rod King MBE is the Founder and Campaign Director for 20’s Plenty – Love 30. In 2013 he was awarded and MBE for Services to Road Safety and in 2017 the International Light of Hope Award by the Irish Road Victims Association. His work is pro bono. 20’s Plenty has a small team of advocacy professionals providing support to local campaigners. See www.20splenty.org


• To empower communities to have a greater say in how their community streets are shared between different users.
• To move away from the old policy of 50km/h everywhere and only slowing down in selected places into a regime where 30km/h motor speeds are the norm that provides safety for pedestrians and cyclists and are only increased in selected places where they can be justified.
• To reduce vehicle speed in urban settings with subsequent wide benefits for casualty reduction, active travel and safer and more equitable communities.
• To take advantage of new developments such as the Intelligent Speed Assistance in new car models

Target Group:

The campaign has always targeted key groups in its influencing :
• Empowers communities to understand the guidance and setting fo local speed limits
• Liaise with public health professionals to understand the population-wide benefits.
• Influence politicians to see the benefit of population-wide 30km/h defaults
• Enable highway engineers to provide the right signage and roll-out procedures
• Educate police to see the benefits from using a social consensus around 30km/h and provide enforcement support where required.
• Lobby national governments to enable more cost-effective implementation at national rather than local level.


One of the most important aspects is to understand that population-wide interventions of lower default speed limits are radically different from either site specific engineering interventions or targeted road safety education. It is about engaging with communities to reset the public consensus of what is the correct maximum speed in community streets.

Once implemented, successful schemes being implemented by municipal authorities are encouraged to use high quality community engagement and messaging about the value of driving at appropriate lower speeds. This confers ownership of the benefits to drivers in their home street. These have included lamp post banners, advertisements on public transport, social media campaigns all around the theme of 20’s Plenty or Loving 30 on Our Streets. Public health organisations often play a role in such engagement bringing their experience of health campaigning such as reduced smoking, etc.

Population-wide limits are often rolled out in phases covering the whole city or authority. This may be over 1-2 years with appropriate signage and legislation to change speed limit.


This presentation will cover :

• The case for population-wide 30km/h default speed limits
• Evidence of success from UK and Europe
• Key factors in successful implementation at local and national level. Including social media messaging used, signage, legislation and methodology for identifying exceptions to 30km/h.