20MPH Limit Areas


Cardiff Council supports slower speeds in residential areas and aims to become a 20 mph city.

20 mph speed limits reduce risk to vulnerable road users and can make it easier for people to use healthier and more sustainable modes of transport.

Evidence shows that for every 1mph speed reduction there is a 6% reduced risk of crashes, and pedestrians struck at 20mph have a 97% chance of survival. This is reduced to 80% at 30mph and 50% at 35mph.

Collisions are less serious and occur less frequently when traffic is travelling at 20mph. You are seven times more likely to be fatally injured in a collision with a vehicle travelling at 30mph than at 20mph.

Neighbourhoods with lower traffic speeds can also benefit from an improved social environment, with easier road crossing and safer conditions for everyone.

The idea is that 20 mph becomes the natural speed in Cardiff’s streets.

The City of Cardiff Council introduced a 'signs only' 20 miles per hour (mph) limit in the Cathays/Plasnewydd area in March 2014, as part of a two-year pilot project.

You can find read the report into the outcome by downloading the document on this page.


Since 2013 the Ask Cardiff annual survey has asked ‘Do you support the introduction of 20mph speed limits in residential areas and other suitable streets in Cardiff?’

The results show clear support for the introduction of limits with a rise from 68% in 2013 to 71% supporting them in 2015.

Where are you going to install the new limits?

The installation of 20 mph limits is a long term programme.

 Our programme will focus on installing 20 mph limits on streets:

 ·         that are mainly residential in nature

·         near to schools, shops, playgrounds and

·         in areas where pedestrian and cyclist movements are high or are potentially high. 

They won’t initially be installed on roads which are not suitable for 20mph limits, for example through routes, but eventually it is anticipated that some of these roads might become suitable for 20mph status.

We know that 20 limits may need to be supported by traffic calming in places where the local environment may encourage speeds to creep up. The aim is to support these places where needed and so this will mean that we will check what speeds are at key points before the limits are installed, and from time to time after that.

The overall plan is firstly to create a logical buffer covering the densely populated areas around the city centre, and then in the longer term, to gradually complete all areas that fall below the natural boundary created by the A48. Other areas will then be considered.

20 mph limit areas will not replace the 20 mph zones that are delivered through the Safe Routes to School programmes.


Cardiff Council will work closely with the police to ensure that limits are enforced appropriately but would remind motorists that, where a 20 mph limit is in place, this is the legal speed limit and that this should be observed.

Remember that keeping your speed down will help your neighbourhoods become more livable and offer a better quality of life for all people, especially for children and older residents who can find higher speeds hard to deal with.

How will I know where the limit is 20mph?

The Council aims to make sure that it is clear to drivers that they are in a 20 mph limit area, and to avoid, wherever possible, a situation where motorists find themselves leaving and re-entering the 20 mph limit areas.

20mph signs will be installed at all entrances to the area, with reminders such as signs and painted ‘roundels’ at regular intervals. 

Will it increase my journey time?

Research shows minimal impact on journey times by car and bus where 20mph limits have been put in place – a matter of seconds, not minutes.

How will I know where the new areas will be installed?

There will be information provided to the public via websites and through the Traffic Regulation Order processes. Cardiff Council has a commitment to consult the public about proposals that affect them.

 You can find out more about 20mph limits here.