Road Safety News

ACPO clarifies position on 20mph enforcement

Thursday 7th March 2013

ACPO has moved to clarify its position on 20mph speed limit enforcement after a senior police officer told the All Party Parliamentary Cycling Group (APPCG) that forces around the country are not enforcing 20mph limits.

MPs were reportedly left astonished when Mark Milsom, assistant chief constable with West Yorkshire Police, disclosed that police had decided against enforcing the lower speed limit in residential areas.

In the letter to the APPCG, Suzette Davenport ACPO’s lead on roads policing, said: “We can clearly state that it is incorrect to say that police officers are not enforcing 20mph speed limits.

“20mph zones are predominantly introduced in residential areas where road safety has been raised as an issue by those who live locally. The approach of neighbourhood policing teams in every community is built around ensuring that local crime and disorder issues and concerns are identified, so that a police force delivers an appropriate policing response. This applies to enforcement of 20mph zones as to any other area of policing.

“Police and Crime Commissioners are now responsible for setting strategic policing priorities for each police force and in areas where 20mph zones are a local concern, may include enforcement within local policing plans.

“In most cases, 20 mph limits will follow DfT guidance* and include ‘road calming’ features such as speed bumps or traffic islands designed to slow traffic. Wherever possible, we agree with the DfT that 20mph zones should be ‘self‐enforcing’ through the use of such features.

“ACPO speed enforcement guidelines include thresholds for enforcement across all speed limits, intended to underpin a consistent policing approach. Within that framework local police forces will take a responsible and proportionate approach to enforcement of 20mph limits based on their assessment of risk to individuals, property and the seriousness of any breach. Where drivers are regularly and wilfully breaking the law we would expect that officers will enforce the limit and prosecute offenders.”

Click here to read the full ACPO letter to the APPCG.

*“The (DfT) guidance states: “Successful 20 mph zones and 20 mph speed limits are generally self‐enforcing, i.e. the existing conditions of the road together with measures such as traffic calming or signing, publicity and information as part of the scheme, lead to a mean traffic speed compliant with the speed limit. To achieve compliance there should be no expectation on the police to provide additional enforcement beyond their routine activity, unless this has been explicitly agreed.


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It has been my understanding that one significant difference between limit and zone in 20mph areas is the limit is enforceable and zone is discretionary and hence not enforceable.... and by enforceable I mean through penalty for an offence. I am finding it difficult to obtain ratification. Looking for unambiguous clarification please.
Phil Marriott

Agree (57) | Disagree (9)

Idris and Rod
Thanks for your contributions - I think we all know your respective positions on 20mph limits/zones, so let's see what others have to say on this matter from here onwards.
Nick Rawlings, editor, Road Safety GB newsfeed

Agree (16) | Disagree (5)

The introduction of 20mph speed limits addresses the symptoms and not the root causes. The decline of public open space, the sale of playing fields and the fencing off of school grassed areas is why we have more children in trafficked areas. Don't blame the motorist for the failings of the planners and the politicians.
Doug Harris Stockton-on-Tees

Agree (58) | Disagree (31)

Dear Idris

Your FBWF comments are not evidence, merely opinions. Your figures do not include any confidence levels which are critical at sample levels of less than 20. You make various assumptions about traffic levels but do not appear to have any figures for Portsmouth. You fail to offer any academic review of your figures which are largely aimed to back up your total opposition to anything which restricts speed.

Regarding the 1998 Mackie work. Wide-area 20mph limits are going in with much debate, community engagement and education. And you know that in Portsmouth faster streets reduced their speed by some 6mph on average. Very far from the Mackay experiments of simply putting up signs over very small lengths of road. And every wide-area 20mph pilot has gained wide community support that increased after implementation.
Rod King, Cheshire

Agree (18) | Disagree (21)

Rod King requests evidence that Portsmouth's 20mph scheme was a "disaster": (items 23-27.

Mr. King knows too that DfT Circular 1/06 (item 9 and others) states: "Research into 20 mph speed limits carried out by TRL (Mackie, 1998) showed that, where speed limits alone were introduced, reductions of only about 1 mph in before speeds were achieved..." as indeed happened at Portsmouth.
Idris Francis Fight Back With Facts Petersfield

Agree (18) | Disagree (15)

On the ACPO response, what did anyone expect them to say?

And what did it say, in any case? Nothing very much at all - no quantitative assurances, only warm words "signifying nothing" to quote the old Tom Lehrer song.

Of course they say they will police 20mph areas - they could hardly make an official statement saying they won't! But in practice, in the current economic climate? Too often road safety policy is based on wishful thinking, this is another example.
Idris Francis Fight Back With Facts Petersfield

Agree (22) | Disagree (13)

M Ashton

Thanks for your interest in this topic. It would be useful if you could say which TRL studies over many years and DfT statistics have "conclusively" shown that "standalone" schemes provide no benefit in casualty reduction and have led to a casualty increase. Also the exact basis for your conclusion that Portsmouth is a "disaster". Is that an opinion or based on fact?
Rod King, Cheshire

Agree (4) | Disagree (11)

I think that the comment “In most cases, 20 mph limits will follow ..." is slightly misleading. DfT guidance 01/2006 does allow 20mph limits without "road calming, speed bumps or islands". Circular 01/2013 is even more supportive of such limits.

Furthermore most wide-area implementations, and certainly in Liverpool, Oxford, Cambridge, Lancashire, Warrington, York, Bristol, Wigan, Bury, Newcastle, Edinburgh, Islington, Camden, Brighton & Hove, Portsmouth and Bath, have all been using appropriate guidance and without traffic calming.

With all 20mph limits requiring extensive repeater signs then it seems implausible that anyone exceeding the speed limit is doing so other than wilfully.

Our views on this matter can be seen at and
Rod King, Cheshire

Agree (15) | Disagree (17)

This is probably what the official line should have been in the first place. No-one would reasonably expect the Police to deploy resources enforcing 20s just because they’re there, or just for the sake of it, to any greater extent than they would do now in 30s. However, I am sure they will be responding to individual complaints of speeding by persistent offenders, particularly where these are high-end speeds - again just as they do now in 30s. In other words, enforcement as and when required - which seems a fair policy for the Police to adopt in this case. Also, if occasional random enforcement does take place, word soon spreads through the community. It doesn’t have to be the Traffic Police either - the local Policing teams and Community Speed Watch can show enough of a presence to keep the communities happy and still send an effective message to the motorists.
Hugh Jones, Cheshire

Agree (24) | Disagree (3)

tO QUOTE: In most cases, 20 mph limits will follow DfT guidance* and include ‘road calming’ features such as speed bumps or traffic islands designed to slow traffic. Wherever possible, we agree with the DfT that 20mph zones should be ‘self-enforcing’ through the use of such features.

What is actually happening with the introduction of 20 mph speed limits, especially in Liverpool, is that they are not including any road calming measures, just a blanket 20mph limit in residential areas.

Studies over many years by The Transport Research Laboratory plus DfT statistic for road casualties conclusively show that these standalone schemes provided no benefit in casualty reduction and in fact have led to a significant increase. The 20mph scheme in Portsmouth, which has been running for 4 years is a complete disaster. Given the significant budget cuts that local authorities are facing, these schemes are a waste of public money and resources.

If a particular area or street does have a road safety issue then put in the physical measures that will see a reduction in speed, otherwise leave well alone and spend public finance on more worthwhile causes such as driver and pedestrian education.
M Ashton

Agree (56) | Disagree (12)