DfT cost claims busted

The UK Department for Transport (DfT) now puts forward cost as the principal reason for the failure to convert road traffic signs to metric. Ronnie Cohen reports on a major study he has recently carried out, using the Freedom of Information Act, to find out the actual costs of replacing and installing traffic signs. He finds that the DfT estimate of cost, published in 2006, bears little relation to reality.

In 2006, the UK Metric Association published the “Metric Signs Ahead” report on the metrication of British road signs. (Source: UKMA, http://www.ukma.org.uk/sites/default/files/MSA.pdf) This report estimated that the cost of amending or replacing half a million road signs would be in the range £41 – 160 million, with a “most probable” figure of £80 million, some of which would be absorbed within annual revenue budgets. This is equivalent to £82 – £320 per sign with a “most probable” figure of £160 per sign.

In response to the UKMA report, the DfT published its own report, “Estimating the cost of conversion of road traffic signs to metric units”, on the cost of replacing around half a million signs. (Source: The National Archives, http://tinyurl.com/7bqczxa) It was estimated that the cost of amending or replacing around half a million signs would be in the range £680 – 760 million. This is equivalent to £1360 – £1520 per sign. In a FOI request, I asked the DfT whether they have done any further research into the cost of the metrication of road signs. The DfT admitted that they have not.

The DfT and UK Transport Ministers are now the main obstacles to the completion of the metric changeover in the UK. The justification that the DfT now uses to defend the status quo is that a metric conversion programme costs too much, and it bases this claim on its own figures for the metrication of road signs. I noticed that UKMA only had information about the cost of Irish road signs, Portsmouth road signs, driver location signs and changes to Spanish speed limit signs. I felt that we need a lot more information about road sign costs to make a convincing case for the Metric Signs Ahead report and to demolish the DfT cost claims and disprove the DfT claims that the costs of change are too prohibitive.

I have made FOI requests with a total of 37 councils, including all 32 London Boroughs. The other councils I contacted were the City of London, Leeds, Liverpool, Manchester and Reading councils. I also made enquiries with road sign suppliers and did some web searches for news reports that contain information about road sign costs. Of all these councils, 34 replied (excluding automated acknowledgements and requests for clarifications and more information). From the ones that replied, 8 provided inadequate information, 6 refused to provide information on cost grounds, 4 said that they had no information and 16 provided adequate information. This article contains information from councils, which provided adequate information about road sign costs, from Portsmouth, which provided information to Robin Paice, chairman of UKMA, and from Wiltshire, which provides information about road sign costs on its website. Here are my findings.

Actual Costs of New Road Signs for Local Councils

Council Total costs Quantity Average costs
Barking and Dagenham £16 000 244 £66
Ealing £130 000 2167 £60
Enfield £84 162 265 £318
Hounslow £360 280 6824 £53
Islington £295 490 745 £397
Kensington and Chelsea3 £9 533 152 £63
Lambeth4 £8 689 57 £152
Portsmouth5 £313 000 3128 £100
Reading6 £370 000 450 £822
Redbridge7 £59 699 652 £92
Southwark £25 900 47 £551

Actual Costs of Changed Road Signs for Local Councils

NOTE: “Changed Road Signs” refers to replacement signs and amended signs.

Council Total costs Quantity Average costs
Camden1 £23 333 59 £395
City of London2 £41 183 51 £808
Ealing £33 000 455 £73
Enfield £8 390 55 £153
Havering £65 000 420 £155
Hounslow £17 125 682 £25
Kensington and Chelsea3 £81 466 1320 £62
Lambeth4 £25 588 193 £133
Southwark £40 400 473 £85
Waltham Forest8 £50 240 427 £118

Overall Average Costs of Road Signs for Local Councils

From the two tables above, the overall average costs of road signs for local councils can be calculated. The overall average costs are:

Barking and Dagenham (£66), Camden1 (£395), City of London2 (£808), Ealing (£62), Enfield (£289), Havering (£155), Hounslow (£50), Islington (£397), Kensington and Chelsea3 (£62), Lambeth4 (£137), Portsmouth5 (£100), Reading6 (£822), Redbridge7 (£92), Southwark (£128), Waltham Forest8 (£118)

Cost Figures from Other Councils

Sutton Council was unable to provide actual cost figures but provided cost estimates for various types of road sign instead. Here are their estimates:

New illuminated speed limit sign, including electricity supply (£1200), Replace exiting sign plate for an externally illuminated sign (£100), Replace existing internally illuminated sign (£400), Replace existing internally illuminated sign with externally illuminated sign, including post extension (£350).

Sutton Council added the following comments to their figures for new illuminated speed limit signs: “Speed limit signs have to be internally or externally illuminated and therefore this would increase the cost of installation. A new sign, including electricity supply, would therefore cost approx. £1200.”, “In a number of locations, signs may be able to be replaced on existing posts and the other costs shown above would apply.”

Tower Hamlets Council provided a schedule of fixed rates for road signs as the basis for their road sign costs. The rates quoted here include the cost of the replacement signs and installation costs but do not include costs for removal of existing signs and posts or for the provision of new posts. These rates are based on the size of the signs.

Replacement costs for Tower Hamlets road signs are: Sign Face of 0.25 m² (£90), Sign Face of 0.5 m² (£140), Sign Face of 1 m² (£235), Sign Face of 3 m² (£252)

Wiltshire Council provides information about the costs of road signs on its website. Here is a quote from a page on its website (Source: http://www.wiltshire.gov.uk/parkingtransportandstreets/roadshighwayspavements/roadmaintenance/costwiltshighwaysworks.htm):

“To erect a warning or regulatory sign on a new post costs £150 – £500 dependant [sic] on size. Direction signs on new posts typically cost between £200 – £1,000 dependant [sic] on their size. (If any sign requires external illumination then a further £500 – £1,000 can be added to the cost for connection to the electricity supply). A village nameplate on two new posts costs up to £350. If a road safety message is required this costs an additional £150.”

Significance of Council Figures

No figures, whether estimated or actual, have been adjusted for inflation. Despite the fact that there is a difference of several years between the UKMA and DfT cost estimates of road sign costs and the councils’ figures and thus takes no account of inflation since the UKMA and DfT reports, it is significant that eight councils’ figures fall within the UKMA range of £82 – £320 per sign. The UKMA figures are supported by figures from Enfield, Havering, Lambeth, Portsmouth, Redbridge, Southwark, Tower Hamlets and Waltham Forest councils. By contrast, not a single council supports the DfT figures of £1400 per sign despite the fact that several dozen councils were contacted and 16 of them provided adequate information. I was also unable to find a single road sign supplier or road contractor that supported the DfT figures.

Surprisingly, despite the fact that the UKMA Metric Signs Ahead report was published in 2006 and that inflation since then was bound to have an impact on road sign costs, four councils provided figures that were below UKMA’s lower range. Of the two highest figures, the average of £808 per sign for the City of London relates to illuminated signs only and the average of £822 per sign for Reading relates to motorway signs. Their figures are still far below the DfT’s estimate of £1400 per sign.

The real significance of the council figures is that these are the actual costs of road signs in the real world rather than the fantasy figures provided by the DfT. The DfT figures have also been discredited by news reports and ministerial replies (see below for more information). These news reports and ministerial replies also refer to the actual costs of road signs in the real world.

The Sales Manager at Viewtec Signs described the DfT’s figure of £1400 per sign as “massively excessive” and “that if metric conversion went ahead, many of the existing posts could be re-used and it would only be a matter of swapping the sign plate for the majority of locations”.

Evidence from News Reports

Occasionally, there are reports that relate to the installation of road signs and provide information about road sign costs. Here are a few that I have found:

The link, http://www.mirror.co.uk/news/uk-news/cirencester-highway-has-71-road-signs-380464, contains a report with the headline, “Cirencester highway has 71 road signs in half a mile”. The amount quoted for total spending on these signs is £8500, equivalent to £120 per sign.

The link, http://www.dailymail.co.uk/news/article-382842/Excessive-road-signs-branded-waste-money.html, contains a report with the headline, “Excessive road signs branded waste of money”. The report says that £9000 was spent on more than 100 road signs. That works out at less than £90 per sign.

The link, http://news.bbc.co.uk/1/hi/england/gloucestershire/7920372.stm, contains the report, “‘Excessive’ road signage reviewed”, appeared on the BBC News website on 3 March 2009. Here are a couple of quotes from this report, one of which gives the cost of the road signs:

  • “The installation of 35 No U-turn signs on a half mile stretch of the A419 in Gloucestershire is under review.”
  • “Some drivers and local residents had complained there were too many of the signs, which cost £120 each.”

Evidence from Ministerial Replies

The link, http://www.theyworkforyou.com/wrans/?id=2009-06-12c.278813.h, contains the following question by Robert Goodwill, Shadow Minister for Transport:

“what estimate he has made of the cost to the public purse of installing overhead line warning signs on roads for which the Highways Agency is responsible in each of the last three years; and how many such signs have been installed;”

Chris Mole, Parliamentary Under-Secretary of State for Transport, provided a table of cost estimates that worked out at £33 per sign for 2007-8 and at £74 per sign for 2008-9.

In 2009 in response to a parliamentary question, the Minister of Transport, Chris Mole, said “Driver Location Signs were introduced in 2003 and approximately 16 000 signs have been installed on 80% of the motorway network at a cost of £5.9 million. ….”. Thus, the average cost of driver location signs was £370 each. (Source: House of Commons Hansard http://tinyurl.com/6ohjtsp)


How much more evidence does the DfT need before it admits that its estimate of £1400 per sign is grossly inflated and not credible? If it had asked councils and the Highways Agency, which actually do the work, and road sign suppliers and contractors about road sign costs when it produced its report about the costs of the metrication of UK road signs, it would have got more sensible figures. Even replies of transport ministers do not support the DfT figures. Unlike the DfT figures, all the figures from councils, news reports and ministers in this article are actual costs of real road signs in the real world.

Since the DfT published its report, it has done no further research into the costs of metrication and made no effort to find out how it can be done cheaper. Instead, it has used its own erroneous figures as the basis of its argument that a conversion programme would cost too much.

There is no point in deluding themselves about the costs of metrication. The more that it is put off, the more the eventual costs will be as any new imperial signs will need to be amended or replaced. It should now abandon its cost claims, admit that they are ridiculous and stop using them as an excuse to postpone metrication and to justify the status quo.


1 Camden Council spent £23 332.73 replacing 59 lit sign posts as part of its structural testing programme for the lighting team.

2 Replacement of illuminated signs only. All issues concerning non-illuminated signs are included as part of a much larger contract with CoL’s highways contractor F.M.Conway.

3 £2200 spent on new signs, £18 800 spent on existing signs. No breakdown of £70 000 installation costs, assumption of proportional amounts spent on new and existing signs.

4 The number of replacement signs includes all missing signs.

5 Information obtained by Robin Paice, chairman of UKMA, under FoI request. Figures are for 2007/2008 financial year.

6 The traffic signs were installed as part of the M4 Junction 11 and Mereoak Improvement Scheme.

7 Redbridge Council only gives total costs of installation. Total signs = 652, new signs = 522. Thus existing signs = 130. No breakdown of installation costs for new and existing signs is given. Signs supply cost~£112.50 per square metre (also provided)

8 Approximate number of replaced signs

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33 Responses to DfT cost claims busted

  1. John Frewen-Lord says:

    It appears obvious from the above figures that a new sign plate on an existing post can be installed for no more than £100. If the highly successful Canadian solution were to be adopted (a new stick-on sign on top of the existing one), it could be done for half that (and that is in line with my own estimate when I was a QS doing some consulting work for a contractor, and I found that a new 600 mm speed limit vinyl sign cost £35 to buy and 20 minutes of £30 an hour labour to install). When some discounts are applied relating to the massive quantities involved, the £100 per sign is way more than enough.

    The point that never seems to be mentioned is whether any cost-benefit analysis has been done. I remember seeing somewhere that the current government is conscious of ensuring that in any government expenditure benefits at least equal (and preferably exceed) costs. I find it illuminating that no C-B analysis has been performed in relation to metricating road signs. Why is that I wonder? Would the government be embarrassed to find that benefits exceed costs and that the program of conversion should therefore go ahead?

    I have mentioned on these pages before about one company that lost an export order because the foreign client, in visiting Britain during his undertaking of due diligence, gained the impression that Britain was not metric, and this declined to award the order to this company - the client wasn't prepared to risk an imperial-metric mix-up. One can only wonder how many times this happens year in year out. In 2010 the UK had about £430 billion of exports. If even 100th of 1% (one 10 thousandth) of those were lost to the perception that Britain was not metric (due to the imperial road signs), that amounts to £43 million of lost export business, each and every year. The £43 million is around the bottom end of the estimates to replace all signs, as stated in Ronnie's article above. I personally think that the 100th of 1% of lost exports is probably rather conservative, in which case there is no question that the benefits of conversion greatly exceed the costs.

    However you look at it - from the real costs as stated in this article, to the benefits to be expected - the DfT has absolutely no leg to stand on at all.

  2. Tim Bentley says:

    They wouldn't need to replace any signs. They would apply vinyl stickers over a weekend to existing signs. Modern vinyl is extremely strong and durable. A lot of buses and lorries and even some cars are covered with it instead of paint.

  3. RonJ says:

    One way to recover some of the costs is to make ARM pay for all of the signs they defaced over the years and as punishment, make them pay a fine to cover additional signs equal to those they defaced. That should at least cover the costs of the signs that were already metric but are no more.

    Truthfully, though, it can´t be that expensive if they are able to do it with their own funds.

  4. Richard Ational says:

    It would seem a great shame, given the time and effort that Ronnie has put into this report, if it were simply sit on the shelf. However, I’m sorry to say that whatever else they concede, the DfT will still claim that any expenditure on such a project during this time of fiscal austerity cannot be justified. Of course into this can also be read fear of the media, a.k.a. trial by The Mail and the other similar publications that are so adept at appealing to the prejudices of their readership in order to maintain their circulation figures. Evidence for this was reported recently from the Leveson Enquiry; a certain A Blair was extremely wary of The Mail (http://www.levesoninquiry.org.uk/wp-content/uploads/2012/05/Witness-Statement-of-Tony-Blair1.pdf) whilst Vince Cable was unsettled by the media implying that his party would suffer if he pursued a certain course of action (http://www.levesoninquiry.org.uk/wp-content/uploads/2012/05/Witness-Statement-of-Tony-Blair1.pdf clause 64(b) ).

  5. Wild Bill says:

    In reply to John Frewen-Lord (above), I agree that a cost-benefit analysis would be the obvious way to go, and maybe Lord Howe could be persuaded to table a question in the Lords sometime asking if such a thing has ever been seriously done, and if not, why not. As a side-effect, it might be nice if anyone can find a reliable citation to J. F-L's story about the company that allegedly lost a contract because the buyer wasn't convinced Britain could be trusted to design things properly in metric. It's a great story, and not in the interest of the UKMA to find that it is false, but if you want to use it as "evidence" of a problem, verify it properly first!

    I would also suggest to the UKMA that an F.O.I request to the D.f.T might be in order, asking how much taxpayers' money was spent designing the new dual-units height-warning triangle only for it not to be mandated by the latest TSRGD, which still permits the old imperial-only triangle to be erected as a brand-new installation. It strikes me as a waste of our money to create a new, better sign yet allow the old one still to be used - how can they waste money like that whilst using the "we can't waste money in a recession" argument to justify not metricating the whole lot properly?

    It seems to me that during a recession is an ideal time to initiate projects like fixing the roadsigns, so that by the time the recession is over the conversion job would be a distant memory and our workforce would be more familiar with distances in km and speeds in km/h then they are now. And the country therefore would have a bigger metaphorical "We're as modern as anyone - come and do business with Britain" sign on it.

  6. Tony W says:

    Excellent work. So the question is, is the DfT completely out of touch with costs, have a succession of ministers from both parties told the DfT pad the numbers, or is the DfT misleading ministers for its own purposes, to block the longstanding government policy of metrication?

    The most generous answer is that the DfT got it badly wrong, rather than to lie to ministers, MPs and the public about the costs, although I fear the truth is one of the latter possibilities.

    More importantly, as mentioned above, is for the DfT to approach it from the perspective of establishing just how cheaply it could be done, rather than make a grand assumption that just about every sign in the country would need to be changed overnight for a brand new sign on a new post. There are not many internally illuminated signs these days so the vinyl option has significant potential, and remember it is only speed limits which need the overnight or 2-day switchover, other signs can be done over a period of time.

  7. Richard Ational says:

    Referring to my earlier post. The link to Vince Cable’s statement to the Leveson enquiry is corrected to http://www.levesoninquiry.org.uk/wp-content/uploads/2012/05/Witness-Statement-of-Vince-Cable-MP.pdf

  8. Martin Clutterbuck says:

    I agree with Richard Ational's view that in spite of Ronnie's excellent work disproving the DfT's figures on costs of road sign conversion, 'DfT will still claim that any expenditure on such a project during this time of fiscal austerity cannot be justified'.
    Even if the cost was zero, I don't think that anything would be done because of politics.
    It would be interesting to investigate the prejudices that Richard refers to that give rise to the political pressures preventing the DfT from performing what we think is the logical and obvious course of action.
    These prejudices are reflected by the media of course, not only by newspapers referring to imperial measures in articles but also by TV through the language of reporters, etc.
    The question I would ask is how could these prejudices be eliminated?
    Logic may not be the solution.

  9. Ezra Steinberg says:

    Logic is definitely not the solution.

    As cognitive psychology has uncovered, we make decisions in the non-rational part of our brain first and then in a split second invent a rational justification for our position. Only with much training (and some basic innate talent) can one learn to at least partially reverse this process at least some of the time.

    And in the political realm it is virtually always about the emotional or primitive message. In some cases it's a plus ("Love they neighbour as thyself.") and in some cases it's a minus ("Those bossy Brussels bureaucrats aren't going to tell us what to do! Remember that the sun never used to set on OUR empire! Can THEY say that????")

    So, working the emotional side of the argument, such as modernisation of the UK economy, competitiveness with other countries, better business opportunities if seen as a fully metric country, pride in the English origins of the metric system thanks to John Wilkins, etc. is the way as I see it.

  10. derekp says:

    The DfT and the politicians are like two drunks, just about upright but relying upon each other for support. The DfT has been reluctant for forty years to divert funds from highway construction to the sign changeover, and needs to keep politicians on side as the implications for the wider economy of its narrow vision become ever more apparent. The politicians, on the other hand, require the DfT to provide justification for a popular policy that defies logic. And so, as we watch, the pair stagger off down the street together.

    I suspect if we ask the DfT alone to sober up, it will just follow the lead of its partner and carry on drinking.

  11. Alex Bailey says:

    I seem to recall reading somewhere, must have been a year or so ago, of somebody who had seen some new road signs back in the 1970s there the imperial units seemed to have been plated onto the signs on a new motorway, almost as if the metric information was actually underneath and waiting to be uncovered.

    There might have been another reason for it but it would be interesting to see if this had in fact been done and if so how much it had cost at the time.

  12. Bob says:

    Excellent work. Great research. Great use of Freedom of Information. Fantastic.

    I have the following comments:
    * The DfT have added "optimism bias" in their figures. If we want them to accept our figures, we need to address that point.
    * The Irish government changed the location of speed limit signs. That increased costs attributed to metrication. We need to be ready to address that point.
    * The cost-benefit argument is important. No government has given a monetary figure for metrication of roads. All pro-metric people should be keenly aware that cost of change, no matter how small, is a valid argument for not changing. Can anyone think of ways of getting financial figures for benefit?
    * When figures are disputed, it's sometimes the ones that get quoted most often that become regarded as the truth. Can anyone think of ways of getting our figures more widely quoted?

  13. Erithacus says:

    @ Bob

    We did refer to the "optimism bias" surcharge in an addendum to "Metric Signs Ahead", which can be read at http://ukma.org.uk/sites/default/files/msaupdate.pdf.

    The point is that some degree of "optimism bias" surcharge is appropriate in the case of ill-defined major projects where you don't know at the outset the full nature of the project, what problems you might hit, what changes might be made in the brief, what the rate of interest or exchange rate or inflation will be in 5 years' time etc. Examples would be the Channel Tunnel, Scottish Parliament, Olympic Games. None of these are relevant to amending 500 000 road signs, since the exact nature of the work can be precisely specified, and it would probably be done on a fixed price "schedule of rates" type contract, with little chance of the outturn exceeding the estimate.

    We also did an article in MetricViews at http://metricviews.org.uk/2010/11/optimism-bias-falls-from-favour/

    However, I don't think there is any chance of the DfT accepting our figures. They just don't want to do it - however little it might cost.

    BTW there is no question of having to move signs because of metrication. They don't have to be positioned at rounded values of kilometres (if that is what you meant). 1/2 mile converts to 8oo m, and indeed the quite frequently found 1/3 mile is 500 m (within the 10% tolerance allowed). The situation in Ireland was different. They decided to cease using the "Default speed limit applies" sign (i.e. the white disc with a diagonal line through it) and instead to sign every change in speed limit. Hence, for example, every motorway slip road is signed with the appropriate limit (normally 120 km/h). That is why they installed 23 000 signs on new posts (out of a total of 58 000 signs). Even so, for the speed limit sign changeover, the cost was only €11 million, including publicity. You can read more on pp. 55-7 of "Metric signs ahead" at http://ukma.org.uk/sites/default/files/MSA.pdf.

  14. Martin Vlietstra says:

    I turned up an old report in the Daily Express in which the then Minister for Transport Philip Hammond required that "From today, all briefings, submissions and external communications must use the imperial format to describe road, traffic and freight distances, rail and aviation statistics and bus reliability." (http://www.express.co.uk/posts/view/179560/This-U-turn-on-metric-is-miles-better- It seems that Hammond was quite happy to demand that reports which, in accordance with OECD procedures, used metric units, be "translated" into imperial units, even if it cost money, but was not prepared to spend money on improving road safety when he cancelled their previous government's proposal to make dual units on height warning signs mandatory. How did this benefit the nation - Hammond scored a few brownie points in the eyes of certain sectors of society by getting a headline in the Daily Express, but how many accidents will happen when Polish drivers are confused by feet and inches (which are displayed unlawfully anyway)? Was Hammond's currency ego point or pounds sterling?

    Maybe he wasn't taught metric units at school (OK, he is one of the oldest ministers in cabinet and one of the few for whom metric units was an "inconvenience" in the science class). Hopefully his successor (who is young enough to be his daughter and who therefore did use the metric system in all part of her education) is not pushing his policy.

  15. Bob says:

    Erithacus says:
    >We did refer to the “optimism bias”

    Yes, I remember. That's partly why I mention it. I just wanted to make sure we can be two logical steps ahead in order to persuade the persuadable. It sounds like we are.

    >BTW there is no question of having to move signs because of metrication.

    Well, I'm raising the question so we have the answer just in case somebody else raises it. The location of speed limit signs isn't entirely arbitrary, there are engineering calculations. Some are located to enable speed reduction before a specific hazard like a junction, a sharp bend, a school, or another speed limit. If you increase the difference between initial and final speed limits, you may need to move the sign to allow more distance for speed reduction. This is one reason why metrication of railway speed limits requires relocation of signals.

    I'm aware the Irish replaced 'Default limit' signs with 'Specific limit' signs and they quote a number of signs for that. I wasn't talking about that. They also took the opportunity to review existing limit values and zones. I couldn't find any reference on an Irish website that distinguished between modification of existing signs versus installing a new one at the same location versus at a new location. My hypothesis is that the location of speed limit signs is dependent on the speed limit changes in a section of road: change the limits and the optimum sign location changes.

    It may be that it's more of a theoretical issue than an actual issue. A speed increase doesn't need a new location for safety reasons although the signs will be in the wrong location in engineering terms. Many speed limit signs are located in advance of diffuse hazards so the engineering tolerance will be so large it's not of much concern. Some signs are ahead of a transition (e.g. entrance to a motorway) where the location is fixed anyway. It may be that most speed reductions are within engineering tolerance. I may be totally off my rocker, if so then disregard my rambling. I'm just raising it so it can be addressed and/or dismissed as appropriate.

  16. John Steele says:


    First, you need a "map" of what each MPH speed limit will map to in kilometers per hour. I'm not familiar with UK rules, but a US speed limit MUST be a multiple of 5 MPH or 10 km/h. If you simply round to the closest allowed value, the actual change is pretty small.

    You may have a few cases where you want to re-study what the limit should be, and there appropriate warning distances may need review too. In the case of simple rounding, I doubt there would be a major problem.

    But keep in mind the rounding will be a problem. To have a rounded value, each speed limit will have to be rounded up or down slightly and you can expect division and argument about wwhether to round up or down.

  17. John Frewen-Lord says:

    To Bob and others:

    I think the biggest'problems' that detractors are going to raise will be:

    1. Some speed limits will be increased slightly (mostly the current 96 km/h will default to 100 km/h and the current 48 km/h will default to 50 km/h. I can just hear the so-called road safety experts howling at how that is going to cause 'carnage' on our roads, forgetting of course that some limits will go down (e.g. the current 64 km/h will likely go down to 60 km/h), while the 10 km/h increments will permit much better correlation of speed limits to road conditions (there are 11 increments between 30 km/h and 130 km/h - the new proposed motorway maximum speed - compared to 7 currently within that range).

    2. Also likely to get touted as causing 'carnage' will be drivers getting confused, and mistakenly reading km/h as mph. The ACTUAL experience of countries such as Australia, Canada, South Africa, ROI and others is that simply does not happen - it didn't happen back then (and that was when few cars had supplementary km/h speedometer displays), and, with proper education and publicity, it will not happen now - unless of course British drivers are somehow less capable as drivers than their counterparts in those other countries, which is certainly not the case.

    These are the issues we must be ready to counter.

  18. Alex Bailey says:

    On the question of rounding speed limits I think that the argument about wether it goes up or down is actually less valid when you consider the way speed limits are enforced in Britain.

    The law allows for up to 10% over-read (but no under-read) on speedometers in new cars hence at the current 70MPH speed limit you could actually be doing as little as 63. In addition to this it seems to be accepted that speed limits are enforced on a "10+2" basis meaning that enforcement starts at 10% plus 2MPH over the speed limit.

    Given that many drivers compensate for both of these things a few km/h either side of the existing speed limits will make little or no difference to actual driving speeds... and to my mind little or no difference in the positioning of speed limit signs (unless a changeover is also used to do a wholesale review of limits which in itself has an underlaying cost).

  19. Wild Bill says:

    As Alex Bailey just pointed out, most existing British speed limits would just change to the "obvious" km/h equivalent with little real effect. Indeed, you can I think pander to both th "won't someone think of the children" brigade *and* the Jeremy Clarkson petrolhead fraternity at the same time:

    20MPH (outside primary schools) becomes 30km/h, a *lower* limit thus showing that pro-metric folk care about the kids.
    30MPH (normal urban limit) becomes 50km/h, a slightly *higher* limit which will appeal to petrolheads, and also have the practical effect of being aimed at keeping urban traffic moving better.
    40MPH. See below.
    50MPH (occasional out-of-town limit, occasional urban elevated motorway limit). Becomes 80km/h, almost identical. No effect either way.
    60MPH (rare) becomes 100km/h (a slight increase), and therefore an improvement from the point of view of petrolheads.
    70MPH (national limit). Could become 120km/h (a modest increase) but actually even the D.f.T have mooted upping it to 80MPH which would be pretty much the same as 130km/h.

    This latter point proves that the D.f.T are not obviously swayed by the "speed kills" lobby, though the subject does seem to have gone quiet lately.

    I left the question of 40MPH out of the list above because I believe that almost for sure the other conversions could be done with no reason to consider moving signs - the real changes in velocity aren't enough to merit it.

    But 40MPH (urban fast-road limit) is a bit of a misfit. Councils should probably be encouraged to consider whether the change is to 60km/h or 70km/h on a case-by-case basis. Maybe the rules could be drafted with the idea that 40MPH -> 60km/h (a decrease) can be done with no moves to signage required, but that 40MPH -> 70km/h (an increase) means that the signs have to be checked and maybe moved.

    Notice also that there is scope for a council that fitted a 20MPH sign just to protect a secondary school should be encouraged to ask themselves if 40km/h would be more appropriate then 30km/h. Again, being a significant increase in the limit, the signs probably should be reviewed.

  20. Martin Clutterbuck says:

    The trend over the last few years has been the decision by the motor manufacturers to install speedometers in cars only showing a mph main dial with km/h indications tucked away in a separate digital display. I included an example of this in the latest newsletter.

    Previous speedometers with dual scales, although messy in appearance, could be used relatively easily if a change in road signing were to be made in the UK. Now, with the new speedometers however, car owners would have to change the instruments. A further deterrent to change! Why did the manufacturers take the decision to go down this design route? Did they consult with the DfT over the possibility of changes to road signs and get the response that it will never happen?

    I would be interested to know when motor manufacturers first fitted metric-only speedometers and odometers to vehicles delivered to Irish customers. How was this change-over managed by the Irish equivalent of the DfT?

  21. Erithacus says:

    @ Martin

    As I indicated in my response to Bob, the Irish changeover was described in "Metric signs ahead" at http://ukma.org.uk/sites/default/files/MSA.pdf (pp. 55-7). Quote:

    "Perhaps the biggest issue was that most vehicle speedometers did not
    have easily legible km/h on the dial. It was decided that it was not
    practical to require speedometers to be “retrofitted” with new km/h dials,
    and the emphasis was therefore on familiarising drivers with the
    approximate conversions (e.g. 50 km/h = 31 mph). Every household
    received leaflets with conversion charts which could be kept in the car.
    All newly registered cars are required to be metric-only or metric-predominant."


    "The key to a successful changeover was believed to be a very rapid
    conversion of the actual signs preceded by a blitz of information and
    publicity in the two weeks preceding the change. Drivers were therefore
    left in no doubt as to what was happening and were warned that
    ignorance or confusion about the new limits would not be accepted by the police as an excuse for breaking the new limits."

  22. Michael Glass says:

    When Australia changed to the metric system, many if not most cars had mph only speedometers. Nevertheless we coped with the change and there was no rise in the road toll. The change was quick and permanent. All the signs were changed at once, including distance signs, though I believe that there was some dual signage on low bridges for a while. Based on the Australian experience I would advise changing all the road signs at once, including distance markers.

  23. John Frewen-Lord says:

    To add to Michael's description of the Australian experience, Canada's was very similer, although there were differences. The changeover for speed limits was the Saturday night on the Labour Day weekend, 1977 - Sunday morning every single sign in the country was in km/h. All new cars from January 1st that year were permitted to have metric-only or metric-predominant speedometers, with this becoming mandatory on April 1st (and there were of course the obligatory April's fools jokes).

    In February that year I bought a new Saab 99, which had a metric-only speedometer (even though it was over six months to the changeover). I remember going into the US in it to visit a project I was working on, and the contractor I was working with couldn't believe his eyes when he saw my speedometer go up to 200. When I explained that these were kilometres, he became very confused - I may have been no more than 500 km from the Canadian border, but I might as well have been in a different galaxy.

    Few existing cars had supplementary km/h back then. Canadian Tire (a chain of motor stores similar to Halfords in the UK) sold kits that were little gearboxes between the speedometer head and the cable (nothing digital in those days), that made 60 mph read as 60 km/h, etc. Other solutions used stick on numbers on the speedometer face. The thing about all these solutions is that they worked - there was no change at all in the accident rate, and, as with the Irish change, ignorance of the changeover, and how to accomodate it, was no excuse.

    All the new speed limit stick on signs had a little km/h (contrasting white letters on black background) under the numerical value. Drivers had no trouble coping with them, accident rates didn't change, and the police found little reason to 'go soft' on enforcing the new km/h limits. If all these countries can do it quite successfully, so can the UK.

  24. Wild Bill says:

    In response to Martin Clutterbuck, I can't see a big problem with km/h in a separate display. It's better than the situation in my car which does the MPH in white figures on a black background, and km/h in *red* figures on the same black background in a smaller font size! Utterly unreadable without reading glasses, with which of course you can't drive!

    I've seen a number of examples of cars these days where the entire instrument panel is digital, and not just that, but switchable metric/imperial on a menu setting. It would be interesting to know what proportion of the cars on British roads are switchable like that.

    Certainly more than at any other time in our history - and making any changeover all the easier when it comes.

  25. Wild Bill says:

    Y'know - I reckon that the biggest costs to be incurred when the speed limits switch over to metric are going to be the re-painting of the reminder roundels on the roads ("20" and "30" being common on urban roads round here) and the reprogramming of all the radar activated speed-limit reminder signs and radar-activated variable speed limit signs.

    Some of these speed limit signs have big LCD displays which can probably be fixed at the side of the road by sliding a switch, but others light up to mimic a "30" (or "20") in a red roundel. Those are going to be a problem - and the longer the DfT procrastinates, the worse it is going to be.

    Quite honestly, sticking a reflective vinyl "50km/h" over an existing "30" roundel is going to be easy in comparison. Especially the on-road roundels. They just had to close a narrow road for most of a day to repaint it near here.

  26. WJG says:

    Well done UKMA. Its important to assess the costs of road sign metrication. This is valuable research.
    John Frewen-Lord says "Also likely to get touted as causing ‘carnage’ will be drivers getting confused, and mistakenly reading km/h as mph." To support John's comment, I would like to add that we must remember that generally speeds will not change. For example: drivers that make regular trips, on routes through speed zones they are familiar with, to shops, supermarket, schools, etc, will still drive at the same speed that they always have. A driver will still drive at 30MPH through a speed zone that was 30MPH but is now designated as 50 km/h. The speed does not change only the unit of speed measurement. This is one of the key reasons why there will be no "carnage" on the roads when the metrication of speed signs occurs.

  27. Wild Bill says:

    There won't be any carnage anyway - that's just the standard FUD that's routinely rolled out by the Luddites any time this subject comes up. Ireland switched their speed limit signs about seven years ago and I think you'll find the carnage was conspicuous by its complete absence.

    The Luddites should be made to explain why they assume the British driving public are mysteriously so stupid compared with their Irish equivalents.

  28. Ronnie Cohen says:

    I have received a very late response to my FOI request from Barnet Council today.

    Barnet Council provided the following figures for road sign costs:
    1) New road signs – None
    2) Replacing existing signs £11 991
    3) How many new signs were installed – None
    4) How many existing signs were changed or replaced = 52

    Therefore, the average cost of replacing existing signs is £231 per sign. This figure is within the UKMA range of £82 – £320 per sign for replacing road signs.

  29. derekp says:

    By way of explanation for his change of heart on the proposed third runway at Heathrow, Tim Yeo MP wrote this in the Telegraph last week:
    "In 2008 China's economy was barely two-thirds of its present size, and other Asian tigers were much smaller, too. Now not only are our competitors stealing a march on us, but we also need to modernise our transport infrastructure ..."
    Having just returned from a visit to one of the Asian tigers, I share Mr Yeo's concerns. But those tigers do not handicap themselves by working with two systems of measurement, nor do they send out this mixed message to visitors and potential customers: "We are not sure if we are in the 19th or the 21st century."

    In an attempt to kick start investment in infrastructure, the Chancellor is now looking for "shovel ready" projects that are nationally significant, financially credible, good value for taxpayers and ready to start within 12 months. Bringing the UK's road traffic signs into the 21st century certainly meets all those criteria - Ronnie's article shows that the DfT's estimates for the job are not financially credible, but there are other estimates available that are, including those in UKMA's 2006 report "Metric signs ahead". However, past experience suggests that blinkered thinking at the DfT will ensure that this project, significant not just for transport but for the whole UK economy, will not receive serious consideration.

  30. Mark Swain says:

    Vinyl stickers? The material used needs to satisfy standards based on colour, durability, reflectorisation etc. You cannot ask the shop round the corner to produce traffic signs. Local authorities have lower costs to replace signs because unlike the Highways Agency, they do not need to close roads and send out special crews with large machinery. The cost to replace gantry signs on motorways probably includes these costs. The cost to replace a sign is not simply the cost to produce a replacement sign!

  31. John Steele says:


    In the US, when the national speed limit of 55 mph was abandoned, and states returned to their prior speed limits (and for other speed limit changes) sticky labels have been used. They are made of 3M reflective material, just like the applique to a new sign, and have proved quite durable, holding up until the rest of the sign needs to be replaced. Over time, both the original sign and the sticky labels fail to meet the reflectance standard. Then it is time for a new sign. Indeed they are not printed by the corner shop and they have to meet standards, but both the patch and the installation are cheaper than an all-new sign. The patch size has to be chosen to cover all outdated info and hold all the revised info with some tolerance for application error. As a result, a patch may not work for every situation.

  32. Wild Bill says:

    Mark: as you see from John Steele, vinyl stickers are used in the U.S. and it's the same here if you look. Our local authorities modify signs with these stickers all the time. John Steele is right - they're not going to be printed by just anyone, but someone does them and they last well. You can probably get 10 years out of them, which is often quoted as the mean-time-to-failure for the underlying steel(*) sign plate.

    So - stickering the signs to deal with the conversion from miles to kilometres would be the obvious way to go. Spain did a similar thing recently when they decided to change the country's national speed limit. That involved stickering thousands of signs (Spain apparently doesn't use a "national speed limit" sign like we do). They just got on with it - job done over a single weekend I believe.

    (*) The underlying sign plates are I believe quite often plastic these days to deter metal thieves.

  33. John Frewen-Lord says:

    This was Canada's country-wide solution when it converted overnight in 1977, when reflective vinyl stickers were just coming into use. It worked extremely well - some of those signs were around 20 years or more, until the sign needed replacing for other reasons.

    I've always maintained this is the best solution for the UK's standard speed limit and distance signs. Of course, there are lots of other signs as well - illuminated gantry signs, painted signs in the road, etc, and these will need some sort of equally fast and cost-effective solution.


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