DfT 20mph report – in-depth

11.58 | 22 November 2018 | | 36 comments

Following the publication of the DfT report into the effectiveness of 20mph speed limits, Road Safety News presents the findings in more detail.

In fact there are two reports – a 68-page headline report and a 221 page technical report.

In this instance, rather than editing the report, we have picked out some of the key points from the executive summary within the headline report, so readers can see exactly what the report says, rather than our interpretation of it.

What you see below is, effectively, an executive summary of the executive summary, beginning with the overall conclusions.

Conclusions and considerations for decision-makers
This study substantially strengthens the evidence base on perceptions, speed and early outcomes associated with 20mph (signed only) limits. It is the only major UK study to date to consider multiple case study areas and provide a national view.

Local authorities have responded positively to revised guidelines on the setting of local speed limits (DfT Circular 01/2013), resulting in a substantial growth in signed only 20mph area-wide limits in recent years, covering larger areas and often entire urban areas.

The majority of 20mph limits have been implemented on roads where the average speed prior to implementation was typically less than 24mph; and the case studies have generally been implemented on the basis that they should be self-enforcing, with no expectation of additional police enforcement.

Based on the findings of this study, the guidance set out in DfT Circular 01/2013 remains broadly valid.

However, consideration should be given to encouraging traffic authorities to work with relevant partners from the police, health, environment, urban planning, education, and the local community to deliver 20mph limits as part of an integrated approach to addressing transport, community, environment and health objectives.

The guidance also needs to recognise the concern amongst the public regarding the apparent lack of enforcement, and the general view that the likelihood of being caught exceeding the limit is very small.

Where a more proactive enforcement approach by the police is not practical, authorities should be encouraged to consider alternative approaches (e.g. community-based initiatives, use of vehicle activated signs, etc.), which may still require low level involvement of the police.

It is acknowledged that the current guidance is likely to lead to a mix of approaches across the country in terms of speed limits in built up areas, which creates a challenge in terms of embedding a culture of slower speeds in residential and pedestrian environments, and achieving driver compliance where 20mph limits are in place.

There may therefore be broader reasons for strengthening the guidance whilst recognising that authorities retain the responsibility for setting speed limits on their roads.

In July 2014, Atkins, AECOM and Professor Mike Maher of University College London, were commissioned by the DfT to evaluate the effectiveness of 20mph (signed only) speed limits, based on 12 case study schemes in England and various comparator areas with a 30mph limit in place.

The purpose of the research is to:

  • Examine the perceptions and attitudes of different user groups towards 20mph speed limits
  • Strengthen the evidence base regarding the effectiveness of 20mph limits
  • Inform future policy development on 20mph speeds and limits at a national and local level
  • Identify lessons learned regarding the implementation and monitoring of 20mph signed only speed limits, to guide local authorities considering introducing 20mph limits

The study comprises a process evaluation which looks at why and how case study schemes were delivered, and an impact evaluation which examines the effectiveness of schemes in delivering intended outcomes.

Support for 20mph limits
The study examines the level of support for 20mph (signed only) limits amongst different user groups through the questionnaire surveys. This shows high levels of post implementation support amongst cyclists (81%), residents (75%), and non-resident drivers (66%); but less support amongst residents in neighbouring 30mph areas (44%) and from motorcyclists (29% supportive, 47% unsupportive).There was also little call for the limit to be changed back to 30mph (12% support amongst residents and 21% amongst nonresident drivers).

The most common area of concern across all user groups considered was around compliance, with most focus group and survey participants of the opinion that stronger enforcement measures are needed if 20mph limits are to be effective.

Speeds and driver behaviour
Evidence from the journey speed analysis shows that following implementation, 47% of drivers in residential areas and 65% of drivers in city centre areas (equating to 51% across both categories) complied with the new 20mph limit, travelling at speeds of less than 20mph.

Whilst a substantial proportion are exceeding the limit, the majority are travelling at less than 24mph (i.e. at speeds close to 20mph): 70% in residential areas and 85% in city centre areas.

The nature of the roads where the limits have been introduced means that lower speeds were already ‘self enforced’. Reducing the speed limit to 20mph has helped reinforce this process. There are now slightly more drivers travelling at speeds of less than 24mph (+5% in residential areas, and +7% in city centre areas), suggesting faster drivers have slowed down.

20mph limit impact
Statistical analysis shows a significant reduction in speeds, relative to similar 30mph comparator areas, for ‘important local roads’ in residential areas and for an aggregation of all road types in city centre areas:

  • The relative change on important local roads in residential areas is estimated at -0.8mph for the median speed and -1.1mph for the 85th percentile speed.
    • The relative change across all roads in city centre area, is estimated at -0.6mph for the median speed, and -1.0mph for the 85th percentile speed.

The findings suggest that the absolute changes in speed observed in the case study areas are partly due to the implementation of 20mph limits, but also reflect background trends in speed on urban roads.

Speeds on neighbouring roads
Journey speed analysis shows a small decline in speeds on surrounding 30mph and 40mph roads across the case study areas; suggesting that in general, drivers are not trying to make up for lost time when leaving a 20mph limit area.

Factors influencing speed compliance
Lack of enforcement and lack of concern about the consequences of speeding were identified as the primary reason for non-compliance in driver interviews and the various focus groups.

There is a widespread view amongst the public that 20mph limits are not enforced, and the likelihood of being caught exceeding the limit is very small; and this is one reason why bigger reductions in speed have not been observed in scheme areas.

Perceptions about walking and cycling in 20mph limits
Overall, 20mph limits are perceived to be beneficial for cyclists and pedestrians:

• 69% of residents agreed that the 20mph limits are beneficial for cyclists and pedestrians;
• 74% and 77% of non-resident drivers agreed that the 20mph limits are beneficial for cyclists and pedestrians respectively;<%2


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    I agree with residential back streets being 20 mph zones. But the main A Roads going through the boroughs are much better bring 30-40 zones eg: between Tower bridge / Waterloo towards Mitcham.

    The thing is with the 20 zones all the traffic lights are not helping the traffic flow and we end up with worse congestion than previously before these 20 restrictions and the bus lane cycle ways.

    That light goes green after waiting for 5 mins especially on the way south thru elephant castle.

    Enough time for two vehicles to get thru or none because a bus driver decided to jump the lights and block the road ahead.

    The worse is when the vehicle in front because it’s 20 mph will not accelerate much on the green light so by the time you get to accelerate the light goes red.

    This just causes more infuriation drivers end up with a all for one and one for all mentality and road rage is always on the cards.

    Andrew, London
    Agree (1) | Disagree (0)

    The 20 mph Limit is a limit that is not equally applied to all road users since the law stands that a cycle is not able to be prosecuted for exceeding the 20mph limit. This therefore makes the 20 limit selective in its application no wonder cyclists were supportive of the limit as they know they have no need to obey it.
    The 20 limit has also become a political statement by councils as locally to me there are roads that 20 restricted suddenly stopping where it crosses into another authority. The road conditions have not changed only the councils political leaning. These sort of differences do lot encourage compliance by the average mororist

    Derrick, London
    Agree (6) | Disagree (2)

    Our response to this report may be found at


    Back in 2014 the question for the government and DfT was whether 20mph limits were popular, are they the correct limit and should there be more of them. But the more we look at how the whole 20mph movement has developed we see that these questions have already been answered for us.

    Our full critique of the report may be found at


    20’s Plenty for Us welcomes the publication of the long-awaited DfT Evaluation of 20mph limits. It confirms the public support and acceptance of 20mph limits but has failed to meet the original DfT objectives or provide increased evidence on how to make our streets safer.

    Rod King, Warrington
    Agree (0) | Disagree (5)

    Much of this discussion was picked up in the recent parliamentary debate on road safety on 22nd November.


    Worth a look.

    Adrian Berendt, 20’s Plenty for Us, Tunbridge Wells, 20’s Plenty for Kent
    Agree (0) | Disagree (5)


    All that you say is interesting and makes sense in a hypothetical scenario but unfortunately, whether good or bad, we can’t just wipe the slate clean and start again. What you suggest is the total redesign and reconstruction of the majority of roads in Britain.

    Interesting as blue sky thinking but totally unfeasable in the real world.

    Iain, Edinburgh
    Agree (6) | Disagree (2)

    Considering how few collisions do take place and how many don’t, I would suggest the roads are fine as they are Charles. Targeting the deliberately wanton and neglectful anyway would certainly improve things even more. I would suggest the normal conscientious human beings are not the problem.

    Hugh Jones
    Agree (3) | Disagree (0)

    Hugh, that might be the solution for drivers who are deliberately and wantonly negligent, but it certainly isn’t the solution for (the vast majority of drivers) who are normal conscientious human beings and invariably subject to the laws of human nature and human behaviour.

    Public road design needs to tolerate the range of capabilities reasonably expected amongst the general public, and not be engineered so that only the elite can be allowed to use them.

    Charles, London
    Agree (6) | Disagree (2)

    If a gas fitter or electrician did not ‘obey the rules’, in the interests of public safety the first step would be to bar them from working on gas and electrical installations I would think, rather than revamp the whole gas and electric distribution system to make them ‘idiot proof’. Same for the road network – it’s inherently safe, but will never be ‘idiot proof’ so we bar the idiots from using them..the technology and the rules are there to do it!

    Hugh Jones
    Agree (3) | Disagree (4)

    Hugh, we are getting closer to common ground I think. 😎

    Because we know that the personalities and personal characteristics of individual drivers varies considerably, we therefore know that their individual reactions to road characteristics are likely to vary too. Hence, we need to carefully consider what the characteristics of each road should be to maximise the chances of drivers choosing appropriate speeds (yes, we know there will always be the feral minority who cannot be tamed, but road regs aren’t the appropriate tool to tackle those).

    Otherwise we will continue to have a road system that can only be safely driven by an elite group of drivers, and for which we will perpetually be adding regulations to (and penalties for infringement of) in a vain attempt to force everyone into the same mould.

    I suggest we are more likely to succeed in adjusting the road system characteristics to match the characteristics of drivers than we are to change the drivers to match the characteristics of the road system. The former will be sustainable too, where the latter will continue as now, to be completely unsustainable.

    Charles, London
    Agree (3) | Disagree (3)

    It’s the personalities and personal characteristics of those behind the wheel that induce the inappropriate speeds and other undesirable driving behaviour Charles more than the road environment ever does, otherwise all the speeds would be ‘appropriate’.

    Hugh Jones
    Agree (1) | Disagree (4)

    Hugh, all those things you say the authorities have installed add to the problem and not to the solution.

    They send the (possibly subliminal) message to motorists that pedestrians shouldn’t be expected to cross anywhere else, and thus induce them to go faster than they would otherwise feel comfortable with, and they send the message to pedestrians that they should kowtow to motorists and not try to cross elsewhere.

    If we want sustainably safe roads we need to start eliminating the things that induce drivers to go at inappropriate speeds and start introducing the things that induce them to drive at more appropriate speeds. As it is not practical to effectively segregate the modes on most of our roads and streets, we need to accept that they should therefore be shared fairly and designed to facilitate, rather than to hinder, that sharing.

    Surely, in the same way that we no longer accept apartheid on the grounds of race, we should stop accepting, and definitely stop introducing, apartheid on our community roads and streets on the grounds of usage mode.

    Charles, London
    Agree (4) | Disagree (5)

    The vehicles on the road you want to cross have a right to be there too Charles and it is unreasonable to expect them to keep stopping if they think a pedestrian wants to cross. That in itself can be hazardous anyway.

    You may have noticed the authorities have, over the years, installed refuges, zebra crossings, controlled crossing points, tactile paving, dropped kerbs, underpasses, footbridges, footpaths etc.for the benefit of pedestrians. Where they are not present, I would suggest the traffic is not so heavy that you couldn’t cross reasonably quickly.

    Hugh Jones
    Agree (3) | Disagree (4)

    Hugh, but, as you must know, that is not what I meant (although actually, that often seems to happen with cyclists nowadays). The pedestrian would generally stand-in to allow faster traffic to pass. But the point is that pedestrians should have just as much right as anyone to be there, and shouldn’t be expected to wait for all cars to pass before being gaining access to roadspace. Equally, they (and cyclists) should be helpful, where possible, in letting others pass.

    Charles, London
    Agree (7) | Disagree (4)

    Rod, it appeared to me that you were conflating “appropriate speeds” (I didn’t say “20mph speed”) with 20mph speed limits. Clearly those two are not comparable, as I tried to elucidate.

    If “compliance” is a problem then, almost certainly, the underlying measure (20mph speed limits in your case) isn’t sustainable, and probably not worth even attempting. You talk about “public consensus”, public opinion is often fickle, and easily led. If the public are fed half-truths, cherry-picked statistics and misleading propaganda then clearly the opinions of the less savvy may be influenced by that. Think of the difference in the information we were fed before the Brexit referendum and the information we are finding out now.

    My opinion is that those in a position of trust and in a position to influence the public and the policy makers have an obligation to be open and honest in the information they publish, giving all non-fringe opinions, and pointing out controversies and serious opposition where it exists. Without them having been exposed to all sides of an argument, it is misleading, to say the least, to claim wide support for schemes promoted in such a one-sided fashion.

    Charles, London
    Agree (7) | Disagree (1)

    “..first come, first served, at any particular point, whether travelling longitudinally or laterally on the Queen’s highway..” Imagine Charles you’re driving along a narrow country lane and you come up behind a pedestrian and there’s no room to drive past. As the pedestrian was ‘there first’, would you be prepared to drive behind at 4 mph for say a mile or so until the pedestrian cleared the road? It doesn’t work does it?

    Hugh Jones
    Agree (5) | Disagree (4)

    Charles. I never conflate 20mph limits with 20mph speed.

    We already know what the key drivers of compliance are :-

    Public consensus
    Fear of being caught

    The former is conditioned by the latter in that if the establishment (police) consensus is that this isn’t important enough for them to bother about then that will condition the public consensus which in turn will condition the personal consensus regarding a person complying.

    The DfT guidance is also broken with conflicting musts and wants :-

    When setting speed limits local authorities must take full account of the needs of vulnerable road users

    When setting 20mph limits local authorities must expect no more than routine enforcement activity.

    That in an environment that the Home Office cuts tens of thousands of police resources and imposes heavy restrictions on speed camera location and visibility.

    We know that reducing speeds reduces casualties and has many wide benefits. What we need to do is to be far, far smarter in how we do it.

    That is why we are calling for a national consistent urban/village default limit of 20mph with exceptions decided by local authority. This to be implemented with public engagement, adequate enforcement and the humanisation of roads so that those public spaces between buildings look far more like streets for people rather than roads for cars.

    Rod King, Warrington
    Agree (2) | Disagree (8)

    I mean merely freedoms of choice conflict and you need to choose a hierarchy. In the case of roads I put freedom of choice for pedestrians at the top, particularly the very young and the very old. The question then is whether speed LIMITS have a part to play. I see 20mph as a way in. Here is a real local example:

    Resident (me): “We want a crossing on this road for children to get to the park”
    Local Authority: “You can’t; it’s not safe”
    Resident: “Eh? There are million pedestrians crossing each year”
    LA: “Yes, but if we put in a crossing and someone gets hurt, we’re liable”
    Resident: “OK, what if we have a 20mph?”
    LA: “You can’t without a physical traffic calming measure because the average speed is above 24mph”
    Resident: “What about having a crossing as a traffic calming measure AND a 20mph speed limit”
    LA: “That’ll be absolutely fine”

    Adrian Berendt, Tunbridge Wells, 20's Plenty for Kent
    Agree (2) | Disagree (6)

    Adrian, freedom of choice?

    What I do agree is that speeds should be appropriate for the environment and conditions at the time and place – which may mean they need to be slower in some places at some times. OTOH, I don’t care what speeds drivers choose at times and in places where the amenity for other road users isn’t impacted.

    My bugbear is that when standing at a kerb waiting to cross a busy road, I am not generally granted the courtesy of being allowed to cross without fear of injury, even by drivers who have arrived at that section of road long after I did. I am expected to wait until all motor traffic, that wants to, has passed, and the road is clear. My rule of thumb would be first come, first served, at any particular point, whether travelling longitudinally or laterally on the Queen’s highway, as would be normal in similar encounters between people away from the road. The appropriate speed for this to be able to occur will vary, depending on the number of non-motorised users there are in the frame. But it will certainly be less than 20mph for many situations.

    For me the major cause of the problem is the combination of the 1930s priority system that we have implemented on our roads and the way we pre-condition (brainwash if you like) people (starting from when they can barely walk) to take advantage of that flawed system when they become drivers.

    Charles, London
    Agree (4) | Disagree (2)

    In response to Mr Bell’s earlier comment, those with professional experience and expertise closely involved with collisions on the road, have differing opinions and views on the subject amongst themselves, never mind the laymen.

    We shouldn’t assume highways design engineers – as an example – are necessarily experts behind the wheel and their perception and understanding of driving standards (theirs and others) and the causes of collisions may therefore be flawed and not necessarily better than the laymen.

    Hugh Jones
    Agree (3) | Disagree (2)

    Rod, you are surely conflating appropriate speeds with 20mph speed limits. Of course appropriate speeds are essential, but equally so whether they be 4mph, 15mph, 20mph or whatever. However, they cannot be delivered by the use of dumb fixed speed limits, even if those limits are enforced 24/7.

    It is time to concentrate on figuring out what it is that actually delivers appropriate speeds in the locations where multi-modal traffic co-exists in harmony, and then to mimic that into areas where there is still conflict.

    “Sustainably safe” should be the objective and not draconian (and generally ill-founded) regulation and enforcement which can never deliver the streets that the communities deserve.

    Charles, London
    Agree (7) | Disagree (1)

    Thanks for that Charles. I can see that we need to debate freedom of choice over a beer or two! I think what you’re saying is that you agree with the need for slower speeds, but are questioning how to achieve. I agree that speed limits by themselves aren’t the silver bullet, but they can help to change behaviour – see my response to Pat. ‘Nudge theory’, ‘virtue signalling’ etc…

    Adrian Berendt, Tunbridge Wells, 20's Plenty for Kent
    Agree (1) | Disagree (2)

    R Craven. Accepted that most pedestrian / traffic activity is in towns. This is why we need to view the problem of road danger from the pedestrian’s perspective. I have two issues with the statement “This is not because vehicles jump out of the road and onto the pavement but rather the other way round”. 1) That’s exactly what I observe vehicles increasingly doing and 2) We don’t blame the victim in other walks of life

    Pat. Given that the vast majority of casualties are on urban roads, that’s where I’d look to make the most savings. I’m glad that you separate the two problems of “what is the right speed” and “how to achieve”. Too many people conflate the two.

    I agree that it’s a complex problem . If removing road casualties were simple, we’d have solved it by now! 1) We have competing needs for the same road space (at lest in urban areas). 2) For >50 years we have designed our roads around motor vehicles not people – think bellmouth junctions which are great for cars and terrible for pedestrians. 3) Changing mindsets is THE most difficult thing to do.

    I sense that reducing the speed limit in urban areas can positively change behaviour, not least in setting driver expectations. Think about how you feel on a motorway if you can’t drive above 50mph. Now imagine you’re driving at 50mph on a country road. For me, the first is frustrating and the second is fine. Why is that? It’s because I set out with different expectations.

    Do I always wear a seat belt because of the scientific evidence about safety? Probably not. It’s mainly because of legislation.

    I was brought up to believe that driving at 30mph on urban roads is “normal”. It’s taken me a while to conclude that 20 really is plenty where there might be pedestrians and cyclists. I welcome the sign which ‘expects’ me to drive at 20mph or below. It’s strangely liberating.

    Adrian Berendt, Tunbridge Wells, 20's Plenty for Kent
    Agree (3) | Disagree (4)

    Adrian, my answers to your questions are:

    1. Yes, but the main problem is the priority system we use which dates back to the early 1930s
    2. No, speed limits didn’t work then and they still don’t work now, whether 30, 20, or whatever
    3. Unregulated junctions are inherently safe as they force traffic to slow down – the problem we see today was created by the priority system introduced on a whim, untried and untested, in the 1930s and exacerbated by attempts to ameliorate those problems (rather than abolish the dangerous priority system itself) ever since (using signals, signs, lines, roundabouts, speed limits, parking restrictions, etc.)
    4. Possibly, but the “small interventions” need to be evidence-based ones (i.e. not based on personal opinion of misrepresented or cherry-picked factoids) which have a track-record of working in practice, and not more of the same old failed ideas such as the tinkering with traffic light timings, speed limit signs, etc.

    Charles, London
    Agree (4) | Disagree (2)

    Lets imagine that the DfT after consultation with road danger professionals and public health decided that there were valid reasons why the 70mph limit should be cut to 60mph. Now imagine that the police say that although they agree with the benefits in road casualties, air quality, fuel consumption, etc they will not now routinely enforce the roads set at 60mph which previously they did enforce at 70mph. Even though that enforcement could be done with relatively little police manpower through the use of automatic enforcement technology.

    Imagine that after being implemented for 10 years the DfT spends £1m on a major study and concludes that the complete lack of enforcement has been a major factor in speeds not reducing as much as they could do.

    Now imagine that the benefits from that lower speed (20mph) accrue to the most vulnerable and neglected road users in our society. Imagine that NGOs and Public Health have been saying for years that the benefits from lower speeds in road safety and active travel terms are substantial and significant, but we simply cannot leave a speed limit that is the one that most protects vulnerable road users in the hands of driver benevolence.

    Maybe there is a systemic problem in the way that we look at health and transport but rely upon the Home Office for enforcement. Having brought Public Health into the local authority domain, maybe its time to bring community traffic policing in as well. Local authorities should be empowered to do the same enforcement that they do in other areas such as Trading Standards.

    As our briefing on Local Authorities being given powers for speed enforcement shows, it is possible. And the ability for local Road Safety Professionals to extend their involvement to speed awareness courses would provide an income stream that to pay for the enforcement that currently goes to the private sector. See See http://www.20splenty.org/las_could_enforce_20mph_limits

    Maybe it is time for a major re-think on how we manage and control our urban and village streets, but a safe speed of 20mph for those roads needs to be at the heart of it. And with it a full complement of measures to enable the potential benefits that are offered.

    Rod King, Warrington
    Agree (3) | Disagree (9)

    I admit to being a complete amateur in road design and I try not to comment on it directly. Would be good to hear from a professional on the following observations:

    1) Is it right that we still employ road designs from the 1980s, which focus on speeding up cars at the expense of pedestrian and cyclist safety?

    2) Is the 30mph default speed which came in during the 1930s when there were many fewer cars on the road, still fit for purpose on our crowded urban roads?

    3) Although junctions are the places where there are most collisions, is there a sufficient concentration of such places to make cluster analysis useful? Yet, this is what highway authorities often focus on?

    4) As with other walks of life, would the prevention paradox – small interventions over large populations – bring greater benefit that large interventions on small populations?

    Adrian Berendt, Tunbridge Wells, 20's Plenty for Us
    Agree (0) | Disagree (2)

    Adrian has commented, “lowering the speeds at which we all drive, particularly in urban areas, would save many, many casualties” – well that may be a bit optimistic but saving some casualties at least .

    However getting enough people TO ACTUALLY DO IT is another matter entirely and where the majority of disagreements on 20s schemes are played out. The Atkins report does not contain a cast iron solution to this problem, but neither does any other report I have read (or scheme I have had experience of) have a realistic and workable solution.

    Pat, Wales
    Agree (8) | Disagree (0)

    Adrian. I find no fault with your figure but one must put them into context and understand that in the main the maximum speed limit in most urban areas is 30 mph and these roads are by far the busiest in the country as opposed to being urban residential areas that maybe have as little as 1 to 5% of traffic on them at the best or worst of times. Main roads also carry the greatest volume of not only vehicles but of pedestrians also and as a result one can easily see that there is nothing new in your statements. Where we have most vehicles and most pedestrians we end up having more incidents and collisions and pedestrian casualties. This is not because vehicles jump out of the road and onto the pavement but rather the other way round. We have inappropriate behaviour on the part of pedestrians placing themselves and others in greater danger by not obeying simple rules as outlined in the Highway Code and taught at most if not all infant and junior schools.

    As a lot of traffic travelling in and around town centres do so at or below the 30 mph limit and becomes a congestion then drivers are advised by the DVSA to stay at least the Thinking distance away from the rear of another vehicle and this gives rise to tailgating with insufficient space between vehicle. In order to save valuable road space they are advised to forget for the moment the safer full stopping distances. The 20 is plenty scheme will do nothing the reduce this dangerous trend of tailgating but will only make it worse.The benefit therefore will be nil.

    Agree (5) | Disagree (0)

    I’ve been resisting the temptation to reply until now but it is apparent from regular comments that commenters here have never carried out highway design or collision investigation in a real world environment.

    It appears that they consider it merely to be a purely academic exercise which can be undertaken by laymen without any professional expertise or experience.

    Unfortunately in the real world it isn’t like that. But hey ho they are entitled to your opinions as to where we have all been going wrong in the past.

    Michael Bell, Norwich
    Agree (7) | Disagree (1)

    64% of casualties occur on urban road and 78% of those were on 30mph roads. Those two %ages rise to 80% for vulnerable road users. We could spend a lot of money on re-engineering our urban roads to give more protection for pedestrians, motor cyclists and cyclists (and I wouldn’t disagree) but simple physics tell us that lowering the speeds at which we all drive, particularly in urban areas, would save many, many casualties.

    Adrian Berendt, Tunbridge Wells, 20's Plenty for Kent
    Agree (5) | Disagree (2)

    Hugh, you must be misunderstanding “road characteristics”. Let’s change the term to “self-explaining roads”. Is that better? Motorways are definitely not “as good as they can be”, and not really comparable with mixed-mode public highways anyway. And besides, motorways still say “go as fast as you can”, despite not now being safe for the levels of traffic they are expected to handle, and not having segregation between the incompatibility different sized vehicle types they have to handle.

    Charles, England
    Agree (3) | Disagree (2)

    How do you explain crashes on motorways then Charles, as their physical characteristics are as good as they can be.

    It’s the same explanation as with any other road – it’s the ‘characteristics’ of the person behind the wheel – not the road!

    Hugh Jones
    Agree (4) | Disagree (4)

    Hugh, that is the reason why road characteristics trump speed limits in controlling the speeds that drivers choose to adopt. That they work at a subconscious level, rather that relying on drivers spotting them, recognising them, registering them as needing attention and then making a conscious decision to actually comply with them regardless of how ludicrous they might seem.

    Look at the crash maps and ask yourself what it is about the zones where there are never any serious crashes, and I don’t think you’ll conclude that it is because they are all perfectly regulated and it is only the most conscientious of drivers that ever use them (or that random chance has yet to visit them!). I think you’ll find it is because their physical characteristics render them inherently safe. The challenge for the road safety community is to replicate those characteristics elsewhere, and not to try and kid themselves that regulation, no matter how draconian, is ever going to suddenly start working, at least not until all human drivers are written out of the equation by the total adoption of autonomous vehicles.

    Charles, England
    Agree (6) | Disagree (2)

    The report states in residential areas :-
    1. that there is insufficient evidence to conclude that there has been a reduction in collisions and casualties resulting from the introduction of 20mph signed only limits
    2. less than 1mph reduction achieved in average speed .
    3. lack of speed limit compliance was the most common concern across all user groups and stronger enforcement measures would be needed if 20s are to be effective.
    4. that a substantial proportion of drivers in the scheme areas were already travelling at less than 20mph prior to the scheme implementation (what chance of success with higher speeds then?)
    5. National guidance DfT Circular 01/2013 remains broadly valid.

    In view of the above it seems to me that it is perfectly reasonable to continue with the current policy of making evidence based decisions on road casualty reductions by introducing the majority of new 20mph schemes in specific locations with speed reducing engineering features as required – i.e. in most schemes where drivers are not already travelling at speeds close to 20mph.

    Pat, Wales
    Agree (16) | Disagree (3)

    “… road characteristics have a much larger impact on the speeds that drivers choose to adopt..” unfortunately it’s not the same speed! Whilst road characteristics (including the speed limit) will give a range of speeds (hence the 85th%ile as a reference), the problem is that individuals have a different idea of what is ‘appropriate’ for the same particular characteristics – some I’m sure, give it no thought at all.

    Hugh Jones
    Agree (3) | Disagree (7)

    I don’t think that’s how most readers will interpret the full report, Charles, although most will fully agree with the need to design roads for slower speeds.

    I noted:

    “There may therefore be broader reasons for strengthening the [DfT] guidance [on setting local speed limits] whilst recognising that authorities retain the responsibility for setting speed limits on their roads.”

    It’s my experience when dealing with certain LAs that their interpretation of the guidance on 20mph is, er, not rigorous, and the DfT wording needs clarifying.


    “51% [of drivers] complied with the new 20mph limit… with the majority travelling at less than 24mph: 70% in residential areas and 85% in city centre areas.”

    That contrasts with the Daily Mail dogwhistle headline of “80% of drivers don’t obey 20mph speed limits”

    At first glance, it would also seem that there has been a significant reduction in casualties on 20mph roads. The 20mph road network has more than tripled in the 2010-15 survey period (3.25x), but casualties rose by 2.8x – equating to a saving of 850 casualties (per DfT stats)

    Adrian Berendt, Tunbridge Wells, 20's Plenty for Kent
    Agree (5) | Disagree (29)

    So they stopped short of saying the 20s are worthless, but were struggling to find any road safety benefits for them. The telling paragraph for me is this one:
    “The results suggest that road characteristics have a much larger impact on the speeds that drivers choose to adopt than whether the road has a 30mph or 20mph limit. The differences in speed between the different road categories are far larger than the changes brought about by lowering the speed limit.”

    Road system design is the key to sustainable road safety, without the use of regulations, signals, signs, lines & so on, clearly.

    Charles, England
    Agree (35) | Disagree (7)

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