20 Mile Per Hour (mph) Policy

This document sets out the background to such limits and the criteria that the council will use to consider whether to introduce such limits and how potential schemes would be prioritised across the county.

The document outlines the context and process by which requests for 20mph limits or zones are assessed and, where applicable, prioritised.

Dorset Council will consider the introduction of more 20mph limits and zones, over time, in urban areas and village streets that are primarily residential, to ensure greater safety for pedestrians and cyclists.

Dorset Council’s highways service will proactively identify and install 20mph schemes as part of highway improvement schemes such as town/village realm enhancements.

Dorset Council will also actively promote the installation of 20mph schemes, where appropriate, on new residential developments. Such developments have long been designed in such a way to encourage speeds at or below 20mph. Where practical, the extent of a 20mph scheme associated with a new development should look to include any adjoining residential areas to ensure consistency in a residential area.

The Department for Transport (DfT) has encouraged highway authorities to introduce 20mph limits in urban areas and village streets that are primarily residential. 

For speed limit changes to be considered by Dorset Council a formal request should be received from either the local Dorset Ward Member and/or the town/parish council.

DfT criteria underpins all speed limit reduction requests. The main reference document is DfT circular 01/2013 ‘Setting Local Speed Limits’.

Traffic authorities can, over time, introduce 20mph speed limits or zones on major streets where there are, or could be a significant number of journeys on foot or by bike. Associated benefits of such limits/zones should outweigh any associated disadvantage of longer journey times for motorised traffic.

This is in addition to residential streets in cities, towns and villages, particularly where the streets are being used by people on foot and on bicycles, there is community support, and the characteristics of the street are suitable.

Were they do so, general compliance needs to be achievable without an excessive reliance on enforcement.

The DfT state that the standard speed limit in urban areas is 30mph, which represents a balance between mobility and safety factors. However, for residential streets and other town and city streets with high pedestrian and cyclist movement, local traffic authorities should consider the use of 20mph schemes.

It may also be appropriate to consider 20mph limits or zones in built-up village streets which are primarily residential in nature, or where pedestrian and cyclist movements are high. Such limits should not, however, be considered on roads with a strategic function or where the movement of motor vehicles is the primary function.

DfT’s criteria for setting speed limits is a key consideration when reviewing all speed limit reduction requests.

The underlying aim should be to achieve a ‘safe’ distribution of speeds. The key factors that should be taken into account in any decisions on local speed limits are:

• history of collisions
• road geometry and engineering
• road function
• composition of road users (including existing and potential levels of vulnerable road users)
• existing traffic speeds
• road environment

The council will evaluate 20mph schemes on a location by location basis. As a guide locations can be considered for 20mph schemes when all three of the following criteria apply:

A. they are in towns or villages where there is a depth of residential development and high levels of pedestrian and cycle movement or there is a potential for high levels of pedestrian and cycle movement if a 20mph scheme was introduced; they should not be on roads where the movement of motor vehicles is the primary function.

B. where existing mean speeds provide a realistic opportunity for compliance: DfT guidance states that 20mph schemes should be self-enforcing. If the mean speed is already at or below 24mph, introducing a 20mph speed limit through signing alone is likely to lead to general compliance with the new speed limit. Means speeds above 24mph are likely to require additional traffic management or enforcement measures.

Town/parish councils should pay for traffic surveys to take place with the number of surveys required dependent upon the extent of the proposed 20mph scheme. Location of surveys to be discussed with Road Safety Team before taking place to best ensure suitable evidence.  To request a traffic survey please email trafficsurveys@dorsetcouncil.gov.uk.

C. there is significant community support; in assessing community support, the local Ward Member and town/parish councils should consider residents views to best ensure that there is broad consensus.

The full DfT guidance will be considered throughout the assessment.

Locations within conservation areas and other areas of high visual amenity can be considered suitable if the visual impact is minimal. In these areas any 20mph restrictions will normally be through 20mph zones.

Dorset Council aims to ensure that any 20mph schemes have the maximum benefit for the affected communities, such as:

• improving quality of life
• the promotion of healthier lifestyles
• sustainability and environmental benefits
• improvements to the social interaction and economic wellbeing of an area

The above points are important considerations alongside:

• reduction of collisions
• regulation of traffic speeds

A Priority Criteria Matrix assessment incorporating the above factors will be used to prioritise schemes for Dorset Council funding. The matrix will use a scoring and weighting mechanism and is shown in Appendix A.

This process is to best ensure that 20mph schemes with the greatest need and/or likely benefit will be prioritised.

Dorset Council will allocate a budget to deliver the highest priority schemes.

Should an assessment be met for a 20mph scheme but is scored as a low priority, town/parish councils may be eligible to apply to fund the installation.

Information and criteria for town/parish council funded 20mph schemes can be found at Appendix B.

For speed limit changes to be considered by Dorset Council a formal application should be received from either the local Ward Member and/or the town/parish council. The form at Appendix C should be completed to support the request and submitted to the Road Safety Team roadsafety@dorsetcouncil.gov.uk who will be responsible for overseeing the policy.

On receipt of an application the Road Safety Team will make a request to the local Community Highways Team to complete an initial assessment using Appendix D. The local Community Highways Team have knowledge of their community and work closely with parish/town councils.

The assessment document is then returned to the Road Safety Team for consideration and if required further enquiries will be conducted to establish the strength of the application. If a request does not meet the criteria guidance a reason will be given. If it meets the criteria guidance the application will undergo a priority scoring assessment as described in Appendix A.

Dorset Council will be promoting 20mph schemes within the capital programme where they reach sufficient priority. Town and parish councils could promote schemes in urban areas or village streets not included in Dorset Council’s programme. 

It is assumed that the requested area has met the assessment in Dorset Council’s principles and criteria for 20mph schemes.

Department for Transport (DfT) guidance on setting local speed limits states: “the full range of management measures should always be considered before a new speed limit is introduced”.

Communities considering a 20mph scheme are strongly encouraged to establish a Community Speed Watch (CSW) as a way of gaining evidence of existing speeds and encouraging improved compliance with the speed limit. 

Details of how to set up a CSW team can be found on Dorset Police’s website.

An active CSW team should be in place for at least 12 months. It is recognised that on rare occasions some communities may have demonstrable difficulties with establishing a team and these difficulties would not on their own prevent an application being considered. This is to demonstrate a clear commitment from within the community. If, after 12 months there is still a wish to request a 20mph scheme the town or parish council should be able to demonstrate wide community support for the proposed 20mph scheme. This can be achieved by carrying out a survey of residents or holding public meetings.  It is important that there is a high level of community support as the installation of any 20mph scheme will involve a statutorily required period of formal public consultation costing a maximum of £1,000 (cost of two public adverts). 

Community support is included as an important consideration throughout DfT guidance for setting local speed limits. 

Key points for consideration are:

• a CSW team to have been active in the community for a minimum of 12 months unless there is clear demonstrable reason why a CSW team cannot not be established
• clear demonstrable evidence that there is significant community support
• should physical traffic calming measures be needed, support from Dorset Police and DWFRS is required
• all signage and any engineering measures should be erected/constructed using materials compliant with relevant regulations
• the requirements of the Road Traffic Regulation Act 1984 must be met so that the 20mph scheme is legal
• full costs of investigation, design and implementation and future maintenance should be met by the town/parish council.  Future maintenance being paid for as a single payment commuted sum

There is a risk of abortive expenditure – the Speed Limit Order process includes unavoidable advertising costs associated with the statutorily required period of public consultation. Should objections to the proposed 20mph scheme be received and upheld by Dorset Council’s relevant area Planning Board the scheme may not proceed to installation.

If you would like to apply please use the application form.

This policy was last reviewed in 2022.

The next review date is 2024.