Hampshire’s 20mph limits having ‘neutral’ impact on road safety

11.57 | 12 June | | 21 comments

There is no evidence that signed-only 20mph speed limits, which have been trialled across Hampshire since 2012, have improved road safety.

That is the headline conclusion following monitoring of the effects of the 20mph limits on vehicle speeds and casualties at 14 pilot schemes in residential areas.

The report was presented to Hampshire County Council on 5 June by Martin Wiltshire, the county’s highway safety manager.

The report says that while four of the pilot schemes have ‘demonstrated compliance’ with the 20 mph speed limits, ‘these have merely served to formalise existing low speed environments with very marginal speed reductions having been achieved’.

Reductions elsewhere are described as ‘modest’ and in some cases average speeds ‘have even increased’.

The only pilot schemes where average speeds are ‘below the new speed limit’ are in areas where averages were already under 20mph.

In terms of collision and injury data, the impact of the pilot schemes upon road safety is ‘projected to be neutral’, and the report says there is ‘no evidence of enhanced road safety benefits compared with that observed for the entire road network maintained by the county council’.

Hampshire Constabulary are not ‘routinely enforcing’ the 20 mph speed limits, except in circumstances where there is ‘evidence to support that a road or a given location presents a heightened risk’, which, the report says, ‘would in any case be consistent with the county council’s traffic management policy since 2016, which requires the prioritising of safety and casualty reduction initiatives over all other interventions’.

The report says the pilot schemes received some positive feedback from residents, the majority of whom observed that their own driving behaviour has become ‘more compliant’ as a result of the pilots – and one third had noticed a decrease in speeds in their area.

However, the majority of residents felt that motorists continue to exceed the speed limit and the report concludes that the pilots do not appear to have ‘won round’ residents who were initially opposed to the introduction of the 20mph limits.

Residents who responded to the survey felt that better enforcement and a more targeted approach to applying 20 mph speed limits would improve their effectiveness.



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    I’ve resisted from posting on this topic for quite a while for reasons probably obvious to some of this site’s more active readership but I’d just like to point out the woeful lack of consistency in the application of said 20mph limits. I live on a residential street where it is rather foolish to exceed 15mph, let alone 24mph (due to poor planning choices and some uhm… interesting parking skills of the locals) – yet this road is restricted, not 20mph zone’d.

    The other, much older side of town is full of 20mph zones, the limits on the main thoroughfares with good visibility are generally disobeyed (30 is what people tend to stick to around there).

    It’s all about context.

    > You only need to read the anonymous nature of their names to form a view of their credibility.

    I never anonymise my details.

    David Weston, Corby
    Agree (3) | Disagree (0)

    We come from very different points of view Rod. I am happy with evidence based specific 20mph speed limits to reduce casualties with self enforcing engineering measures to assist with compliance.

    With regard to some signed only 20s, the ‘bath’ you refer to should never have been filled in the first place as wide spread non-compliance was to be expected. Not much point in drawing up new rules/speed limits if there is no expectation of success.

    I look forward to a few bad 20s being thrown out as a few pieces of rotten fruit can spoil the lot.

    Pat, Wales
    Agree (6) | Disagree (0)


    Yes we agree about your first quote but would point out that the pertinent word is “excessive” rather than “any”.

    General self enforcing we accept, but that can include engagement, education and such as engineering and signs, staggered parking bays, white lining, etc.

    Yes, where a speed limit is not being complied with it is important to look at the reasons for non-compliance and look for ways to increase compliance. Abandoning what you think is the correct limit because you cannot either bother to do any enforcement or engagement is not valid. The correct speed limit exists regardless of the conditions that may affect compliance. Then setting speed limit then the needs of vulnerable road users must be fully taken into account.

    Your para three is of course only one half of para 26 in the DfT guidance which goes on to include :-

    “If the existing limit is in place for a good reason, solutions may include engineering measures or changes to the road environment to ensure it better matches the speed limit, or local education and publicity. Enforcement may also be appropriate, but should be considered only after the other measures and jointly with the police force.”

    There are plenty of options available to increase compliance before the baby is thrown out with the bath water.


    It strikes me strange that road safety professionals responsible for educating the public would find it better to communicate via “buttocks and spines” rather than “hearts and minds”. Have they given up on engagement and education? Other forces can provide a reasonable level of enforcement on 20 and 30mph roads which is not disproportionate. What is disproportionate is to decide that the speed limit most designed to protect the young, the elderly, the vulnerable is the one that can be ignored.


    I have long ago learn’t that votes on these pages are not indicative of very much other than the ire felt by those who wish to have a relaxed attitude to speed control. You only need to read the anonymous nature of their names to form a view of their credibility.

    Rod King, Lymm, Cheshire
    Agree (1) | Disagree (3)

    I think I need to throw off my 3 posts limit per article on this occasion. Rod, yes you are right in your reply to Guzzi that you can consider 20s on main roads but don’t forget the DfT Circular 01/2013 also says:-
    -Where 20mph speed limits are being considered, general compliance needs to be achievable without an excessive reliance on enforcement.

    -Successful 20 mph zones and 20 mph speed limits are generally self-enforcing,

    -Where there is POOR COMPLIANCE with an existing speed limit on a road or stretch of road the reasons for the non-compliance should be examined before a solution is sought. If the speed limit is set too low for no clear reason and the risk of collisions is low, then it may be appropriate to increase the limit.

    Quoting just part of the story is a favourite of some campaigners, possibly misleading people who don’t have the full picture , so the fuller context above helps to put things back in balance.

    Perhaps it is also time to review failing 20s under paragraph 3 above?

    Pat, Wales
    Agree (12) | Disagree (0)

    Road safety professionals support the use of effective – by which I mean engineered – 20 mph limits where there is evidence of a road casualty reduction benefit.

    We know that the police generally won’t use disproportionate levels of resources to enforce signed only 20s so we are not prone to supporting wishful thinking.

    Guzzi, Newport
    Agree (11) | Disagree (1)

    Looking at the comments and voting on this site by (mainly I presume) road safety professionals I’m left to wonder why they don’t seem to support the use of effective – by which I mean enforced – 20 mph limits.

    Philip Jones, Birmingham
    Agree (6) | Disagree (6)

    M. Drivers are not actually advised or taught to drive much closer together as you put it, any more than they are being advised or taught to speed. As I’ve said earlier, if we get the answers as to why drivers consciously do both, it would actually help shape road safety and collision prevention techniques. Psychological profiles of such drivers need to be be the order of the day I think.

    Hugh Jones
    Agree (1) | Disagree (1)

    Its not going to matter much if vehicles are slowed to 21 or 22 mph from maybe 23 or 24 mph or indeed continuing at 30 mph as there are still accidents caused by the mere fact that drivers drive far to close together when in any urban slight traffic situation. It seems that we British like queues, especially when advised to drive much closer together and sacrifice the full stopping distance when in one.

    If that is what drivers today are being taught then how can there be an offence of tailgating. All driver who commit whilst following other traffic have a defence.

    Agree (5) | Disagree (2)

    Guzzi, Please do not misinform people. That is not what the DfT guidelines say. In fact DfT guidelines say 20mph should be considered on even main roads. It does say that roads with an average speed less than 24mph will be most successful in achieving compliance, but that is rather obvious. In wide area 20mph limits many streets are included where speeds are already 20mph or less and hence are there for consistency rather than speed reduction. This dilutes the higher reductions gained on faster roads.

    We note that the report gives little information about traffic volumes or speeds. The casualties are just too small to have much statistical significance. The complete absence of even a commitment to enforcement send a huge signal to drivers that there is no deterrent to their speeding and non-compliance.

    We know the ingredients for a successful behaviour change are :-

    1. Do it across the whole community or authority to maximise driver benefits on their home street.

    2. Do engagement, especially social media and other events to create community ownership.

    3. Do some enforcement. Do not send out a “speed at will on 20” signal to drivers from the chief constable.

    4. Have conviction. Make it happen, identify the factors needed for success.

    I cannot see any evidence of these ingredients for success in Hampshire.

    Rod King, Lymm, Cheshire
    Agree (5) | Disagree (18)

    I wonder if the maximum speeds recorded have reduced. If the carefree speeders carry on unabated, collisions are still highly likely. Intelligence from residents on times of day or discreet date and time stamped devices measuring speed of regular offenders would help the police catch them rather than hang around waiting in hope.

    Hugh Jones
    Agree (3) | Disagree (1)

    The DfT guidelines indicate that if a signed only 20mph speed limit is being considered in lieu of 30mph, it should be on roads where the average speed is at or below 24mph. So it is quite likely that Hampshire Council have just followed the DfT guidance in choosing the roads that already have lower speeds for their residential pilot scheme.

    A pilot is test sample so if signed only 20mph schemes don’t show exceptionally good results here, where will they be successful other than busy city centres?

    Guzzi, Newport
    Agree (14) | Disagree (0)


    I wonder what the circulation comparison is between the Hampshire Chronicle and the Police Policy. Is the later available in shops and newsagents?

    Somehow I think a headline in the Hampshire Chronicle has far more effect on driver attitudes to compliance than some words in a police policy document.

    Rod King, Lymm, Cheshire
    Agree (2) | Disagree (20)

    If literally nobody complied with a particular 20 limit, it would imply that it is an unreasonable limit but where say 50% comply and 50% don’t, rather than argue about the appropriateness or otherwise of the limit itself, we should be asking ourselves why the non-compliers didn’t comply. Clearly 50% don’t have a problem with it, so what is it that makes the rest not comply? If we ever find the answer, we’ll also have the answer to a lot of other behavioural problems on the roads.

    Hugh Jones
    Agree (5) | Disagree (6)

    It further appears to me and this may be backed up by evidence that the roads chosen that were reduced down to 20 mph were ones that were in fact being driven at slower speeds anyway. Thus if they were in effect reducing the speeds down close to 20 then it would look better for the campaign but as said they were slower roads anyway. Drivers drove closer to the 20 mph limit than the 30 mph so the 20 mph limit has made little difference. Can we ask Hampshire just how much this intervention has cost the ratepayer or the tax payer as the monies may have come through some intermediate organisation but that monies came from the public purse in the first place.

    Agree (10) | Disagree (2)

    Old news Rod, the quote you referred to is from an article 25 September 2014 and anyway the lady ‘B K’ who you quoted “only” oversees the Community SpeedWatch initiative for Hampshire Constabulary from a volunteer perspective. She is/was not the Roads Policing Unit spokesperson.
    The Hampshire Police position statement I quoted from is the current policy as referred to in section 7 of the Hampshire CC report 5 June 2018.

    Pat, Wales
    Agree (21) | Disagree (1)

    The compliance – or not – with speed limits, particularly 20s, says more about those who drive, their vehicles, their social background, personality, level of social and civic responsibility than it ever could about the actual limits themselves.

    One encouraging point from the report “.. the majority of whom (the residents) observed that their own driving behaviour has become ‘more compliant’..” – if that’s an honest and accurate self-assessment and something that will be sustained, then that can’t be a bad thing.

    Hugh Jones
    Agree (9) | Disagree (2)

    “Belinda Kingsley, of Hampshire Constabulary, said that police could visit speeding “hot-spots” but would not enforce the limit.”


    Rod King, Warrington
    Agree (1) | Disagree (19)

    I consider the Hampshire Police position of treating 20mph speed limits like any other speed limit and utilizing their finite enforcement resources on the basis of a threat risk and harm approach to be very sensible. Where there is evidence to support that a road presents heightened risk the police will deploy resources. It takes a peculiar mind to mis-quote that as ‘refusing to enforce’.

    Pat, Wales
    Agree (24) | Disagree (2)

    Rod. I think that the Authority were either mistaken or misinformed to believe that nothing else was required and that it was simply enough to put up a few 20 mph signs without any of the other trappings that you now would put forward as being necessary in order to force drivers to accept your new limits.

    This is not Calderstone. There the Police admit that they were actively establishing and enforcing the new speed limits in residential areas but going further and enforcing the main roads with speed limits of 30 up to 50 mph. Enforcing the lot, not just the new 20 mph limits on residential roads. In fact without their active engagement on their main roads one would not have seen such a dramatic decrease in collisions over the last couple of years.

    Agree (6) | Disagree (8)

    Sour grapes Rod ‘cos there’s a 20s report not in your favour?

    Pat, Wales
    Agree (28) | Disagree (9)

    The concerning aspect of this report is that after having implemented a half-hearted trial with little conviction, a constabulary refusing to enforce, no social media engagement and no delivery to most households the council doesn’t even ask what it could have done better but immediately kicks any consideration of wide-area 20mph limits into touch.

    Rod King, Lymm, Cheshire
    Agree (9) | Disagree (32)