Are DfT Guidelines on 20mph being misrepresented by your shire county

In its latest guidance the DfT is very supportive of 20mph limits, yet some shire county 20mph policies do not reflect this.

We have come across several instances, particularly in shire counties, where the DfT guidance is being quoted out of context in a manner which promotes a “can’t do” approach to speed reduction in communities. Guidance is being used to justify a half-hearted approach to making our streets better places to be for pedestrians, cyclists, older people, children and those who live there.

For example, Wiltshire Council in its policy[1] says :-

“Almost all of the research into 20 mph limits indicates they generally lead to relatively small reductions in ‘mean’ speed (1-2mph); as such they are most appropriate for roads where the average traffic speeds are already low. In order to ensure general compliance, the current guidance from the DfT (01/13) suggests they should only be considered for use on roads where mean speeds are already 24mph or less and where the layout and character of the road gives a clear indication to drivers that a lower speed is appropriate.” Para 2.4


Whilst the 1-2mph is correct, it must be remembered that when implementing over a whole authority for consistency then it includes many roads where mean speeds are already low and do not reduce. Policies like the one from Wiltshire Council quoted above fail to bring out that much higher mean speed reductions (6-7mph) have been achieved on roads where previous mean speeds were above 24mph. The comment saying that current guidance “suggests they should only be considered for use on roads where mean speeds are already 24mph ….”  also misrepresents DfT guidance[2]. The only references to 24mph in the guidance are  :-

These new arrangements should significantly reduce the requirement for signing and traffic calming features. Traffic authorities can now incorporate wider areas within a 20 mph zone, by effectively signing 20mph speed limits on distributor roads where traffic calming features are not suitable, or for small individual roads or stretches of road, where mean speeds are already at or below 24 mph. Para 94

If the mean speed is already at or below 24 mph on a road, introducing a 20 mph speed limit through signing alone is likely to lead to general compliance with the new speed limit. Para 95

The implementation of 20 mph limits over a larger number of roads, which the previous Speed Limit Circular (01/2006) advised against, should be considered where mean speeds at or below 24 mph are already achieved over a number of roads. Para 97

Para 94 enables the mix of repeaters signs (or carriageway roundels) and physical calming and therefore provides the opportunity to enable physical calming to be used sparsely where compliance problems persist despite engagement and enforcement efforts.

Para 97 says that 20mph limits should be considered where speeds are already at 24mph or below, it does NOT say that it should ONLY be considered here. One must ask why Wiltshire Council so misrepresents the DfT guidance.

DfT guidance allows Wiltshire Council to implement a wide-area zone across an area using predominantly signage and only add physical calming where absolutely needed. This is being used by many authorities in a pragmatic and progressive manner.

One other consideration is that mean speeds apply to a whole road and NOT just the most free flowing point. Often speed monitoring has only been done at such points (where traffic is most free flowing) and therefore does not represent the mean speed of the road in question.

This must be coupled with consideration of other benefits of lower speeds in the guidance which impose the requirement to set the correct speed limit as a priority and after having decided such a speed to take the necessary actions to achieve general compliance. The crucial “must” within the guidance is in para 32 :-

32.Different road users perceive risks and appropriate speeds differently, and drivers and riders of motor vehicles often do not have the same perception of the hazards of speed as do people on foot, on bicycles or on horseback. Fear of traffic can affect peoples’ quality of life and the needs of vulnerable road users must be fully taken into account in order to further encourage these modes of travel and improve their safety. Speed management strategies should seek to protect local community life.


One must ask exactly how a speed limit policy that rejects a 20mph limit because one section of road users drives faster than 24mph, when the current limit is 30mph, can ever be one that takes such needs fully into account. Yet incredibly the Wiltshire policy goes on to say “The safety of Wiltshire residents continues to be the overriding concern of the Council.” These surely are hollow words when the needs of vulnerable road users are being rejected.

Other local authorities are using 20mph limits to bring about major changes in the priority given to people over cars on the public spaces between buildings that we call streets. They are doing so using the guidance as a positive instrument for “can do” policies that complement 20mph limits  with signs, community engagement, education, engineering (where needed) and enforcement. They are doing this through multi-agency collaboration to bring better streets to the places where people live. Many of the “obstacles” raised by Wiltshire Council are being overcome elsewhere in counties such as Lancashire, Bath & NE Somerset and most of our larger conurbations and iconic cities.

Rod King MBE, 20’s Plenty for Us Founder said :-

Traffic Authorities have a duty to set local speed limits appropriately and have been urged by the DfT to prioritise 20mph for residential streets. Commitment and engagement are key to people understanding why it is to be implemented and maximising success. Whilst many “can do” authorities are getting on with the task by implementing wide area 20mph limits on most roads, residents should demand that other “make do” authorities recognise their commitments and stop putting unnecessary and unfounded obstacles in the way of creating the better communities that come with lower speeds.”  

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