Stop Press Rod King of ’20 is Plenty for Us’ popped in to join in the debate below. Scroll down to ‘Postscript’ to check it out. We reproduce all his comments verbatim along with our replies. (He obviously knows us well … he thought he was talking to a place called Adcocks Green … )

Birmingham City Council have just run a Consultation: ’20 MPH is Plenty’. (Results not yet in.) Do you want 20 MPH speed limit signs on most Brum roads?

Sounds cool? Have a good look at these pictures.

Zones & Limits Collage for website

One well known, and slightly confused, Brummie social media pundit recently asked in surprise on Twitter ‘Don’t you support the 20 mile thing then?’ Do you know the difference between a 20 MPH speed limit and a 20 MPH zone?Does it really matter? It’s all an, um, ‘thing’ really? A ‘thing’ which is a ‘good thing’ (or a bad one depending on your point of view.)

An apple and an onion are both sort of spherical sort of food ‘things’ too. So only a real fusspot would bother about whether they were biting into a raw apple or a raw onion? Who cares? It’s all food? Of course that’s nonsense. Eating one of these raw will probably make you cry. It might turn out to be a bit the same with zones and limits as well.

What is the difference then between a zone and a limit?

The Royal Society for Prevention of Accidents site is very helpful here:

There are two distinct types of 20mph areas possible:

20mph zone

20mph zones, are designed to be “self-enforcing” due to traffic calming measures which are introduced along with the change in the speed limit. Speed humps, chicanes, road narrowing, planting and other measures are typically used to both physically and visually reinforce the shared nature of the road.

20mph limits

20mph limits, which consist of just a speed limit change but no physical measures to reduce vehicle speeds within the areas. Drivers are alerted to the speed limit with 20mph speed limit repeater signs.

Now have a look at this little look now at this set of stats.

Zones & Signs stats - auto contrast & crop(Transport Research Laboratory survey for Department for Transport, 1998)

What do you notice? That’s right – Traffic calming (zones) lowered speeds by an average of 9.3 mph and static signs by just 2.2 mph.

But that’s a long time ago, perhaps … ? Yes it is a long time ago. Let’s have a look at how things have been shaping up since. Have they changed? Both the National ‘Twenty is Plenty Campaign and Birmingham City Council is quite fond of quoting the findings of Portsmouth City Council, which installed across the board 20 MPH speed Limits in their city in 2007-8. This finally resulted in an overall lowered speed of just 1.3 MPH and according to one report (Atkins consultancy 2010) whilst casualty rates fell by 22% this did little more than reflect a national average fall in accidents at the time. The Department for Transport agree. In DFT Circular 2013: Setting Local Speed Limits they note:

Research into signed-only speed limits shows that they generally only lead to small reductions in traffic speeds […] 20 MPH speed limits without traffic calming reduce mean speeds by about 1 MPH on average. (p. 24, Paras 95-6.)

On the other hand, a forward-looking ‘zone‘ scheme in Hull set-up in 2003, concentrating on selected areas, shows a 56% decrease in accidents. (Birmingham City Council September 2013 Briefing Sheet)

Ah but zones are so expensive? You can get a far bigger area covered if you just put up signs?

Zones don’t have to cost a lot. Two of the most effective modern types of zone do not use humps or road narrowing at all, but still very effectively use physical and psychological measures to slow down traffic. In Broad Street in Birmingham wide centre strips called median strips help to slow traffic down by causing it to mainly stay in a confined area, although this can perfectly safely be crossed; simple but effective. Here is a median strip.

Median Strip

Median Strip

Median Strip - Walworth Road-cropped

This one is especially for Rod King of ”Twenty is Plenty for Us’. Patriotic Rod was upset that our last picture was not British. So, here you are Rod – a median strip that is British to its very core – Walworth Road, London. It comes fromManual for Streets 2(2010) – p. 105. This a work we have been very impressed with. Author Phil Jones gave Phil Jones gave us a very interesting presentation on MfS2 in 2010

Take a look at this video of Park Lane, Poynton. This traffic calming piece of road saves by not using a controlled pedestrian crossing which costs around £100,000 to install. Nothing much happens for twelve minutes; that’s the point. Wait until the camera pulls back at the end to show you the road design.

Next point: do we really need limits everywhere? Is everywhere equally dangerous? Of course it is not. Just about everyone knows this is rubbish. So why not concentrate designed traffic calming where it is really needed, rather than take the money that was being used for this to scattergun the whole city with signs? Ask the people of Sampson Road, Sparkbrook what they think about this idea. Sampson Road has recently suffered two road fatalities. They already have a prominent ‘slow’ sign on the road which is obviously doing nothing. They have asked for a ‘zone’. They are told they can only have a sign, because that is now City-wide policy. How confident and happy would you feel about that, and feel about knowing that the money that could have gone to pay for your safe zone is paying for signs in 90% of Brum instead?

Now, what’s the most dangerous part of Acocks Green? Where do most accidents happen on the Warwick Road? Take a little looksie at this screenshot of an accident map for the years 2005-12 from (Which is used by Birmingham City Council.) Notice the Warwick Road: the bit between roughly Dudley Park Road and Oxford Road. That’s our shopping area – where we were promised a Zone, before the promise was withdrawn. That’s our most accident prone area.

Crash Map - Acocks Green Centre

Crash Map – Acocks Green Centre

Acocks Green was told it was going to have a zone in Acocks Green village on the Warwick Road in July: safer, more attractive, more pedestrian friendly and good for increasing footfall and getting people to use local shops. We were going to be a model village for Birmingham – a showcase village. Then in November we found out that we were not going to get a zone after all – just a Limit, because the Council is not ‘doing’ Zones anymore. Just picture how excited we were when we found at that we were getting a Limit not a Zone. (Or maybe don’t try that at home … ) No parties to celebrate that the average drop in speed on the Warwick Road through Acocks Green village is likely to be around 2.2 mph (on the optimistic side – Portsmouth 1.3) as opposed to 9.3 mph?

But signs everywhere will reinforce the idea that there is a rule, and everyone will go more slowly, so it’s still a good idea? Oh yeah? Remember Portsmouth – that magic area which introduced across the board limits signs … and achieved an overall 1.3 MPH drop in speed. Why so low? Many people don’t decrease their speed when they don’t have to. Whether they do it by more old fashioned physical methods or more modern psychological methods zones have a very good record in reducing speeds where we need speeds to be reduced. Sure they cost more than signs. That’s why they are not put everywhere, but where they are needed. Don’t ask Portsmouth. Ask Hull. Ask Sparkbrook. Ask Acocks Green.

Why not tell the Council that you are not taking signs for wonders? Tell them ‘Please don’t zap the zone. The consultation is now closed, but you could always drop a line


How flattering – our little blog page has upset Mr Rod King of the ubiquitous and well-funded ‘Twenty is Plenty for Us’ national movement. Let’s see what he has to say. Our responses in red.

I would be pleased for 20’s Plenty for Us to engage with this group and discuss the relative benefits of zones and limits. However, it must be noted that many of the assertions and information given above are actually incorrect. The 20mph limit sign shown is a US sign and is not legal in the UK. Yes – we were aware of that. We needed a picture of a sign to make a visual point, and could find no British ones. However, we do realise that we need to get these things right because foreign pictures could drastically alter the entire content of the argument. It is possible that the apple is Canadian – perhaps Mr King could be good enough to check that for us as well? The 20mph limits in Portsmouth did record a 22% reduction in casualties against a 14% over the same period on all UK roads. That’s a 50% greater reduction in casualties. In addition it must be remembered that national average was across all types of roads and is hardly comparable with Portsmouth which is the most densely populated city in Europe.A whole 8% reduction – blimey – it is almost the same as the reduction achieved by zones in Hull (56%) … or perhaps not? In Warrington the 20mph pilots in residential areas resulted in a drop in casualties that was 27% higher than the rest of the town over the same period.The British Medical Journal (2009) made a study of zones in which they found that the average reduction of accidents in zone areas was 41%
Poynton is effective but the cost was £3.5m. Hardly replicable. What is more, just 200m away in residential roads motorists are encouraged to accelerate to 30mph. You are confusing the main Poynton scheme with Park Lane, which is a side road. Did you get around to watching the video? Did you really think that what has been done here could cost £3.5 million? We accept that physically calmed zones are more effective than limits, but when you take the 50x cost into account they are 7 times less cost effective in speed reduction. You have completely failed to grasp the cost arguments. Portsmouth appears to basing its somewhat dramatic comparisons upon humps. In Acocks Green (An area which initially – apology accepted – you turned into Adcocks Green demonstrating you are clearly unfamiliar with it ) the cost would be very considerably less because we would not require pedestrian controlled crossings (£100,000 per crossing) if we had the type of crossing shown in Park Lane Poynton. In fact isolated small 20mph physically calmed zones endorse travelling faster wherever there is not physical calming. Evidence? The comment about average speeds reducing by 1.5 mph does not take into account that the speed reduction is variable. In wide-area 20mph limits you always get the largest reduction on the faster roads. Many roads stay at the same speed because they are already low. But they reinforce the idea that 20 is plenty where people are. In Portsmouth the reduction on the faster 20mph roads was 6.7 mph. Still less than the reduction which can be achieved in a zone, but the real issue is clearly comparative numbers of accidents, We have had some nasty accidents and it is those we are concerned about. Whilst I can understand the concern that Adcocks Green may have lost its opportunity to get a highly effective small 20mph zone. But the realisation by Birmingham City Council that it wants an effective and economic methodfor speed reduction across the whole city should really be seen as an opportunity rather than a threat. Within its plans BCC has already accepted that there could be some physical calming at appropriate places. Hallo: Try telling that to Acocks Green or Sparkbrook – both have been told they cannot have a zone. Two recent fatalities in Sparkbrook apparently mean nothing. Have you tried the Birmingham September briefing on speed limits. It makes informative reading in this respect:

Based on experiences elsewhere, guidance and clear benefits it is recommended that on 90%+ of all adopted roads in Birmingham the default should be 20 mph introduced through a ‘limit’ rather than ‘zones’. The following type of roads should be included as 20 mph limits: all residential roads those with a designated high street function – defined as ‘primary shopping frontages’; roads designated as ‘secondary shopping frontages’; ‘B’ and ‘A’ roads with school entrances or schools;and roads with other local trip attracters such as parks/ leisure facilities, Health Centres and hospitals, and public transport hubs and interchanges;

(In other words pretty much everything.)

Hence Adcocks Green residents may do better by working with BCC for the wide-area adoption of 20mph limits rather than opposing plans. Wide-area 20mph limits are being adopted in most of our conurbations and this is an intervention that bodes well for the future liveability of the whole Birmingham community. In your opinion … some of us remain rather less than convinced and rather more worried. Rod King – 20’s Plenty for Us

7 Responses to “DON’T ZAP THE ZONE!”

  1. Graham Hankins says:

    I think it is ridiculous to apply a 20mph limit to EVERY residential road (ie 90% of Birmingham’s roads) as stated in the BCC Consultation documents. You CAN use the on-line survey but that is mostly a ‘select an answer’ exercise. You can respond direct to one of the Lead Officers for this, but today IS the final day of the Consultation.

  2. Rod King says:


    I didn’t realise that “moderation of my comment” would include editing it with contradictions.

    I note you started off your postscript by mentioning how well-funded our campaign is. Our funding is really quite small and mostly comes from individuals. Also from thousands of individuals is their time which they voluntarily give (just like myself) in campaigning to make their places better places to be. And if my role in that seems “ubiquitous” then so be it.

    I think I can say that I am as much in favour of lower speeds throughout communities as anyone. My comments were not about your campaign for a 20mph zone for Acocks Green but about your criticism of 20mph limits and inaccuracies in your comparison with zones.

    In fact 20mph zones and limits have far less differentiation. A zone now only requires a minimum of 1 physical calming device. The rest may be repeaters or carriageway roundels, or other devices. However I don’t think “median strips” are officially accepted as traffic calming devices. In fact I think your picture is of a cycle path in the Netherlands so it really wrong to suggest that these could be used as the “traffic calming devices” in a 20mph zone.

    Also remember that a major cost of the Poynton scheme was the paving used on Park Lane. Incidentally I don’t think this is even a 20mph zone.

    I accept that physically calmed zones are more effective at reducing speeds than limits, but for £100,000 you can either treat 250 people living on a street with physical calming or 12,500 people living in a community with non-physical calming (ie signs and engagement).

    I equally see the benefits of wide-area 20mph limits with specific physical calming in some places. Indeed the flexibility on having zones with mainly signage rather than physical calming allows this. And I think that this should be your objective to get wide-area 20mph limits accepted as the societal norm across Birmingham and then selectively add more calming (additional signage or physical) where required. I would be pleased to assist your group in achieving this.

    But if you solely implement 20mph with isolated physically calmed zones then you create inconsistent limits, and with every isolated zone have a large sign saying that drivers should go back up to 30mph.

    By all means criticise me for not knowing Acocks Green, but at the same time I think I do have a very detailed understanding of the issues around 20mph zones and limits, both technically and as regards behaviour change. If that can be used to assist in getting slower vehicle speeds across Acocks Green and Birmingham in general then I will help if I can.

    Best regards

    Rod King

    • Julia says:

      Hi Rod

      Firstly may we point your mind at rest that we have not ‘edited’ your previous comments (Or these new ones.) They are all reproduced verbatim, down to your rather charming attempt to render the name ‘Acocks Green’. The only editing we have ever done of anyone’s comments is to diplomatically tidy up spelling, grammar and punctuation where needed – none of this was necessary in your case. We did reply to your comments within your own text. That is a different matter and the red font was to make very clear which were your comments and which were ours.

      Our Comments in response as follows:

      (1)I notice that you are no longer querying most of the figures and statistics here, re relative safety of zones and limits, but pottering around looking for something else to pick on!
      (2) We are less concerned with measuring precisely what percentage traffic calming work needs to be done in order for an area to qualify as a zone and more concerned with having safe, effective and pedestrian friendly traffic calming in Acocks Green. What we are asking for is not vaguely ‘a zone please’ but for some quite precise work to be done – we have a proposed list.
      (3) Median strips are detailed as an effective way of traffic calming in Manual for Streets 2 (2010) which was sponsored by the Government and written for traffic engineers. They were also recommended to me when I consulted one of the authors of MfS2 for traffic calming ideas for Acocks Green which did not involve the much hated humps or pinch points (We don’t like those either!) It is sad that so much of the work which ‘Twenty is Plenty for Us’ is now doing seems in effect aimed at unpicking the people friendly, uncluttered, traffic calmed environments being worked towards in MfS2 and by the Shared Space movement – Acocks Green have been working with both for many years now.
      (4) Likewise, I am aware that Park Lane has not been legally defined as a ‘zone’ However what it does entail is clear, psychological, highly effective, traffic calming measures. It was also pointed out to me by the same MfS2 author is something which Acocks Green could possibly think about. We are impressed. We are not terribly interested in having exactly the same sort of as paving as Park Lane – oddly enough this is not the point of what we are seeking. In principle we have already accepted the much cheaper grey blocks suggested by Birmingham City Council. And, just for interest, BCCs current beef with our suggestions appears to be principally that they are now doing limits and not zones everywhere, not that what we are asking for cannot be defined as a zone.
      (5) Yes – you can get something you CALL 20 MPH all over the City: job done – hurray – everyone is going to go at 20 MPH ‘cos the sign says so – sorry but findings don’t bear that out. It is far cheaper to slap up signs … and how many lives do you then lose in the areas where the dangers is greatest by paying money to stick up signs in lots of areas which are not so dangerous?
      (6) I see you are continuing your campaign for all British imagery with none of that foreign contamination! The image I am using of a median strip is from the Netherlands yes – and the picture is about the bit in the middle. I don’t think you are intended to cycle mainly on that! I selected it after doing an image search on the phrase ‘median strip’. I found many others which were similar (including some in Brum) but chose this one because I thought it came out most clearly on the blog. However, just to make you happy I have now added an image of a British median strip as well, so you can compare.
      (7) Your offer of help … sorry Rod. I can see you care about what you do, but I have looked you up, and the end of the day you would appear to be an amateur like us – an IT specialist not a traffic engineer. You have been campaigning since 2007. We have been campaigning – and studying, and learning from many people who work in this field – since 2004. (For example I urged the Hull example in my piece because it’s main originator came to and gave us a PowerPoint talk and led a group of us around Acocks Green in 2005.) Sure you might catch us in the odd slip because we are not experts … and come on, you have been caught just now in quite a few yourself. So perhaps a little less high horsing and ‘I carry the true word which I will explain to you ordinary mortals’ would not go amiss? And yes, probably at some time soon there SHOULD be a proper debate between zone – and MfS2 and Shared Space People like us, and the ‘Put up a sign and it is sorted’ people like you. That looks to me as though it might be on the cards fairly soon now. Whether or not we can reach any sort of agreement I don’t know, but I do agree that it would be nice if we could. Meantime, sorry but I think you are just going to have to live with it … we’d like to see fewer deaths on the roads too, that far we agree. We are not saying there should never be a ‘Limit’ and I don’t think you are saying there should never be a ‘Zone’. I agree that is a good start, but I think you do need to accept that there are two slightly differing philosophies going on here and simply offering to go and ‘explain’ things to the other ‘camp’ and to put them straight is not really where it is at just yet!

      Best wishes


      • Rod King says:

        Our answers inset below:


        1) I have already queried the figures and pointed to the fact that across wide areas the 20mph limits with engagement offer better cost effectiveness in speed reduction than isolated physically calmed zones.

        It all depends what you mean by ‘cost effectiveness’ Zones in selected areas where there is danger result in a greater drop in speed and fewer accidents.

        2) If you want traffic calming then that is fine by me, but a default 20mph limit for residential roads in Birmingham is surely a separate intervention. It may have created a new “context” for how to treat Warwick Road, but do you not support such a wide area implementation?

        The ‘default’ is costing 7 million to deliver, currently alienating lots of people who probably won’t obey the signs – and is more importantly is taking money from more concentrated efforts where they are needed.

        3) The key question is whether median strips are classed as “traffic calming devices” for the purpose of 20mph zones. As I understand it whilst they may calm traffic they are not classified as such for 20mph zone purposes.

        Sorry – that is not the ‘key question’ for us. We are most interested in crossings and Shared Space areas, but for what it is worth, Bexleyheath and Bishopsgate zones schemes in London both involve median strips. However, I think this is becoming a rather desperate argument about semantics. The main argument is about whether you use engineered methods or stick signs up.

        4) I think you will find that as the detail gets added to the BCC plans for wide area 20mph limits then different treatments will be used in particular areas. You may well end up with some physical calming within limits or zones.

        Perhaps you could be good enough to share with us the privy information BCC have given you that makes you think that! They have certainly not given people who live there any such impression, but rather the contrary.

        5) Its never been a case of putting up signage alone and forgetting. The whole process of debate (even this) is an important aspect of setting new norms for residential and community streets. Its all about engagement with the whole community about what they want for the public spaces between buildings. Its about maximising the number of people who get the benefit of 20mph limits on their home streets so that it becomes an accepted norm in other people’s streets and high streets as well.

        That’s sounds wonderful – almost like you have been reading Manual for Streets 2. It might be that your
        vision is not so very different from ours, but sorry: you have not sat in on any of the debates that have been going on recently in er, that area that you know so well, Adcocks Green, or in Sparkbrook. If you had then let me assure you you would not be talking like this.

        6) I am easy about that.

        7) I have been campaigning for better conditions for pedestrians and cycling since 2000, but set up 20’s Plenty for Us in 2007. We don’t claim to be Traffic Engineers, but we do work with 216 local 20’s Plenty for Us campaigns and have been involved with most of the Total 20 implementations in the UK.

        Hmm – so mainly you have been campaigning and implementing. That’s part of it. What you clearly have not done is to engage with, and studying, the approach which has convinced us. Not saying you should have done, but as I said before, I think you need to beware of evangelising to a different camp as though only you have the true word!

        But this really is not an argument about whether 20mph limits are better than 20mph zones. Each is appropriate and we would say that Birmingham should have 20mph limits on all its residential roads and have additional measures where required. These may be zones or limits with additional measures. The argument about where those measures are required should be focused on making the case for those specific roads and not directed at the wide area implementation of what most people agree is a sensible speed limit.

        Yes, you keep on telling us that all these ‘additional measures’ are going to be available. Maybe you have a personal hot line to Albert Bore? Perhaps you could tell him to get his skates on and organise some ‘addtional measures’ then, because he sure ‘aint listening to us … and as long as he is pouring potential zone money into limits then I don’t think he is going to.

        Overall I suspect that we agree on many more things than we differ on.

        Think we’d better let others decide that!

        Best regards


  3. richard says:

    60-90 mins to get into work 10 miles 20mph another costly mistake for buisness

  4. richard says:

    the roads are full of pot holes but the they keep wasting our money on on stupid traffic calming try going through stirchley

    • Julia says:

      Hi Richard I don’t think there is any traffic-calming going on through Stirchley though? I think you are thinking of the limits lollipops? Traffic calming means actually doing work on the road – can be humps, or tables, can be narrowing the road, can be painting markings on the road in order to guide where cars go. (Not counting 20 mph signs painted on the road, they don’t guide.) Traffic calming means a zone, and there are no new zones being introduced in Birmingham at present, as far as we know. Agree though that the lollipops are worse than useless (They slow traffic by on average 1 to 1.5 mph) The money would be far better spent on fixing the pot holes!

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