20mph speed limits and zones

There is currently great interest across the country in introducing 20mph speed limits and it is a subject that is often raised by residents in this Borough.

Our approach to 20mph speed limits

20mph speed limits and zones are intended to improve safety. We believe that proposals for them should be evidence based and assessed against objective criteria.

While some local authorities have adopted a blanket approach to 20mph limits and introduced them across large areas of residential streets, others, including Richmond, have followed a more local implementation. We are not averse to introducing speed limits and have a process for evaluating proposals that we receive from residents.

Main roads may be unsuitable for traffic calming due to bus routes, emergency services requirements, etc.

We may choose to introduce 20mph limits and zones without requiring majority support from residents in some priority locations:

  • places where large numbers of vulnerable pedestrians congregate near busy roads (e.g. near schools and along high streets)
  • places with higher accident rates

Alternatives to speed limits

You may feel less intrusive approaches could be tried in the first instance, rather than a fully signed speed limit. If so, we would be interested to hear from you.

Speed detection devices are erected on lamp columns and show motorists their speed, often with a ‘smile’ or ‘frown’. Such devices are usually erected for 2 or 3 weeks before being moved to another site and then brought back at regular intervals. This is to avoid complacency and familiarity among drivers.

In some situations adjustment to parking bays can help to calm traffic but each situation would need to be considered on its merits.

Speeding traffic can also occur at certain times of the day indicating a possible ‘rat running’ problem and other restrictions can, on occasions, prove successful.

Criteria and process for assessing nominations

Each nomination is carefully considered on its merits against objective criteria.


Council officers will firstly evaluate the impact of a suggested 20mph location in the context of the wider area and traffic management requirements. For example:

  • The introduction of a reduced speed limit in one or more roads should not be expected to increase danger elsewhere, significantly increase congestion, or divert traffic to other residential or unsuitable roads.
  • The practicality and likelihood of enforcement will be appraised. Many 20 mph limits have been criticised for lack of enforcement leading to disillusionment and frustration among residents.
  • The effect on the environment and streetscene. Additional signage adds clutter and is contrary to our streetscape policy. The impact for conservation areas is a particular concern that should be minimised.

Data collection

Officers will determine a survey area and collect data including accident rates, vehicle speeds and traffic volumes as appropriate.

  • If average speeds in the survey period exceed 24 mph then a 20 mph limit will not be appropriate and traffic calming features should therefore be considered. On the other hand the Council will not generally see any merit pursuing a 20 mph limit if measured average speeds are already lower than 20 mph.
  • There should be a realistic expectation that speed related accidents can be prevented by reducing the speed limit and at least three years of historic accident data will be analysed. The absence of historic speed related accidents will not preclude 20 mph limits, but it will be a consideration when determining priority for action.


Funding for the scheme, including any traffic calming requirements and the ongoing maintenance of signage, must be identified and approved by the Cabinet Member for Highways and Streetscene.


The scheme will then be presented as a formal consultation to households across the area likely to be affected by the proposals. If a 20mph zone with traffic calming is proposed then residents will be consulted on any required alterations to parking arrangements at the same time.


If 51% of consulted households agree to the proposals then they will be taken forward.

Updated: 6 November 2017