DfT rejects industry view on metric signs

The Department for Transport (DfT) has given in to anti-metric lobbying and backtracked on its earlier proposal that imperial-only height and width restriction signs should be replaced with dual metric/imperial signs within four years.  This climbdown is despite the responses to its own consultation, which revealed widespread support within the industry for the proposal.  It also flies in the face of its own cost assessment. The article concludes with a challenging question.

The DfT has just published amendments to the Traffic Sign Regulations and General Directions (TSRGD).  They contain some useful “tidying up” amendments but, as we reported in an earlier article, they fail to tackle some of the major issues that critics of UK road signage have been raising for years.  As the Local Government Technical Advisers Group commented in their consultation response1, “(we are) disappointed that the consultation is very narrowly defined and that the expected root and branch review of Traffic Sign Regulations has not been undertaken.”

Responses to the consultation¹

Phasing out imperial-only height and width restriction signs

When launching the consultation in 2009, the DfT published figures² showing that 10 – 12% of bridge strikes involved drivers of foreign lorries, which is “disproportionately high in terms of the number of foreign lorries on the road network.” From this it was inferred that the unfamiliarity of foreign drivers with the measurement units that appear on British traffic signs was a contributory factor, and that therefore the replacement of imperial-only signs with dual metric/imperial signs would have benefits.  A cost-benefit assessment showed that in England and Wales the one-off cost of the change would be £527 000, whereas the benefits over a ten year period would be at least £2 335 000 – a net gain of £1.8 million².

22 out of the 63 local authorities that responded¹ to the consultation said that the change would impose significant additional costs that could not be afforded from current budgets.  However, 24 local authorities indicated that a four year timescale would be sufficient, and the remaining 17 were ambivalent or made no comment. (The great majority of local authorities did not respond at all to the consultation).

Three local authorities and the Highways Agency pointed out that the DfT’s cost estimates were too low since they took insufficient account of the need for road closures in cases where signs attached to bridge arches need to be replaced.  However, 19 authorities agreed with the DfT’s figures while the rest made no comment.  A few authorities and individual respondents also pointed out that there were additional benefits not included in the DfT’s analysis.

Almost all the respondents who commented welcomed the principle of dual-unit signage even if they had reservations about financing it from their own resources.

Comments on the above:

  • As one Scottish authority (Dumfries and Galloway Council) pointed out, the costs of implementing the proposal would fall on local government, whereas the benefits (which far outweigh the costs) would accrue to Network Rail, the train operating companies, rail passengers, the police, the NHS, insurance companies, road hauliers (especially foreign ones), and motorists and society generally.
  • Most authorities appear to have assumed that they would have to make the changes within existing budgets.  Based on past experience, this may be a realistic assumption, but if Central Government is imposing a new policy on Local Government, it is reasonable to expect that Central Government should make the resources available within the overall Revenue Support Grant settlement.  One wonders whether the local authorities’ response would have been different if they had been offered a fair contribution toward any genuine increase in their costs.
  • It is therefore disingenuous of the DfT to use the reluctance of a minority of local authorities to finance the project from their own existing budgets as an excuse for cancelling it. What did they expect?

Having said all this, it is pleasing to see the positive response of Glasgow City Council:

“Although the changes to height and width restrictions will incur additional costs, Glasgow has already been undertaking sign replacement or refurbishment.”

It is 17 years since the Regulations permitted dual units on height and width restriction signs and 7 years since the DfT Traffic Signs Manual recommended that all new or replacement signs should be dual unit3.  If other highway authorities had followed Glasgow’s example, the problem would be well on the way to resolution by now.  What is barely credible and certainly unforgivable is that the DfT’s amended Regulations still permit local authorities to erect new or replacement imperial-only signs with an expected life of 10+ years.

Other signs

A number of other comments by the majority of respondents to the consultation have also been rejected by the DfT:

  • 6 respondents (including the Institute of Highway Engineers) drew attention to the anomaly whereby vehicle length restrictions (sign 629.1) could continue to be imperial-only and suggested they should also be phased out in favour of dual unit signs.
  • Ditto for ford depth signs.
  • A few respondents requested that in-cab indications of vehicle height (required for high vehicles) should be dual metric/imperial.  No response from the DfT.
  • It was pointed out that the DfT proposal appeared not to include temporary width restrictions at road works (e.g. at motorway contraflows) – potentially a major hazard.
  • 11 out of 12 respondents opposed allowing journey times rather than distances on cycle/pedestrian direction signs – e.g. “It is nonsense to put an arbitrary time for a journey when a precise distance can be given.” Nevertheless the DfT is going ahead with this sign as an option. (Fortunately, in the light of the overwhelming opposition to it, there is unlikely to be much take up).

On the positive side, many respondents argued for a dual-unit advance warning sign (red triangle) for height restrictions rather than the current option of a separate metric sign (not to be used in isolation). This has now been included in the new Regulations.

Finally, it is welcome news that the DfT has at last conceded that the current symbol “T” for “tonne” is incorrect and will no longer be permitted on new or replacement signs.  The correct SI symbol “t” must be used instead.  However, existing signs will still be legal until they wear out and need replacement.

But – are dual unit signs the right answer?

This question is posed in the hope of starting a debate, and MetricViews would welcome readers’ views.

Along with other supporters of completing metrication in the UK – and despite serious reservations – the UK Metric Association has hitherto accepted the principle of dual-unit signage for height and width restrictions.  Faced with implacable opposition from the DfT, it was felt that dual-unit signs would be the only way of making any progress and getting metric units on to UK road signs.  This latest setback raises the question whether dual units are the best answer – especially in the longer term.

The experience in the retail industry is that permitting both metric and imperial units in labelling and pricing has simply enabled people to ignore the unit they are not familiar with and to continue using the old unit.  No progress is made in encouraging or persuading the public to adapt to metric units, and so, despite over 40 years of metrication, the UK is still split between two incompatible systems.  For this reason, metric campaigners have therefore sought (alas unsuccessfully) to phase out “supplementary indications” from pricing and labelling.

As a result of this experience, metric campaigners have been opposed to signing road distances in both kilometres and miles.  Quite apart from requiring larger signs (meaning that they would all have to be completely replaced rather than amended with overlays), they would perpetuate the problem that many motorists (and the media) would ignore the metric distance and continue to “think imperial.”  Again, no progress would be made.

Moreover, it would be quite unthinkable to sign speed limits in dual units.  Even if you could overcome the problem of equating rounded mph values with rounded km/h values, the possibility of catastrophic error if a driver mistakes a metric speed limit for an imperial one is too awful to contemplate.

So why then do we accept dual units on height and width restriction signs?  It may have appeared at one time to be an expedient step in the right direction, but given the refusal of the DfT to set even a modest timetable for phasing out imperial-only signs, should we be considering a different approach to the signing of height and width restrictions?

I was struck recently by reading the following proposal that I came across in the blog of Hughster at


What Hughster suggests is that instead of supporting a transitional phase of dual unit signage, leading eventually to metric-only signage (which of course may continue to be postponed indefinitely), we should be advocating a full and direct changeover from imperial to metric .  The steps would go like this:

  1. The Road Vehicles (Construction and Use) Regulations would be amended to require in-cab height indications (in vehicles over 3.66 m high) to be dual metric/imperial.
  2. The TSRGD would be amended to require all new signage to be metric-only – that is, no new or replacement imperial-only or dual-unit signs would be permitted.  Existing signs would continue to be legal for a transitional period.
  3. The TSRGD would also be amended to require any remaining imperial-only signs to be replaced within 10 years at the latest (the expected life of a sign).  Whether remaining dual-unit signs should remain is debatable.
  4. At the end of this period, the requirement that in-cab indications should also show imperial units would then be removed.

One of the advantages of this neat solution is that it involves no public expenditure – thus removing the principal stated objection of the DfT to metric signs.

Is this proposal one that UKMA should be supporting?


¹    The responses to the consultation were obtained from the DfT as a result of a Freedom of Information Request and can be seen at this link (676 pages).  However, the DfT refused to disclose its own analysis of the responses, which have therefore been analysed by UKMA.  See this link.

²   See pages 2-3  and page 11 of Annex D to the DfT’s consultation document, available at this link.

³    UKMA’s summary of the  evolution of metric height and width signs (and the DfT recommendations) can be read at this link.

21 thoughts on “DfT rejects industry view on metric signs”

  1. I am glad that dual signing will become easier with the new regulations (although ideally I agree with the straight metric switch proposed above; I just think it’s too sensible for the luddites in the DfT to contemplate). However, it is absolutely essential that highway authorities are compelled to use metres, because some stubbornly refuse to do so even when required to by the Traffic Signs Manual.

    For example, at road works “Dual unit signs should be used wherever possible,” states the Traffic Signs Manual: http://assets.dft.gov.uk/publications/traffic-signs-manual/traffic-signs-manual-chapter-08-part-01.pdf

    I struggle to think of any circumstances in which it is not possible to use the dual unit signs, and therefore arguably imperial-only temporary signs are not compliant with the Traffic Signs Manual, yet this guidance which is widely flouted, even by the Highways Agency, whose roads of course carry a high percentage of foreign HGVs.

    Authorities must be obliged to start eliminating imperial-only signs to ensure that they are brought into line with international norms (and indeed, in line with the Vienna Convention, with which our current height, width and length signs do not comply).


  2. Whenever I’ve hired a large vehicle (in the UK) I’ve always found the vehicle dimensions are given somewhere near the driver’s sun visor and in metric only. Thus imperial dimensions on road signs are useless and dangerous, necessitating the driver to open the cab window and check visually there is sufficient clearance under low bridges. Clearly maximum dimension warning signs in imperial should be replaced with metric signs as a matter of urgency. To have a mix of imperial and metric would be a confusing mess, so all the remaining signs would need to be changed to metric as soon as possible. Then at last road signs would speak the same language as maps and sat-navs.


  3. It is my understanding that UKMA campaigned for compulsory dual signs as a possible path to full metrication (albeit a non-commital undertaking for the DfT) in the hope that it would be taken up immediately in response to urgent safety concerns.

    The refusal by the DfT to do so leads me to the conclusion that no progress will be made until we overcome the irrational governmet opposition to the idea of full metrication. So we might as well hold out for a decisive change over a sensible period. That is not to say that we should now oppose dual indications for height, width or length restriction/warnings, but we should insist that they be on separate signs. I’m also inclined to agree with article with regard to distance and speed limits.

    I sincerely doubt that there are genuine cases where HGV drivers would not cope with metric only signs, were they to be required immediately for all new installations. All they would need is a metric indication of vehicle height width and length in the cab – which could be remedied quicky, cheaply and easily (assuming that is even necessary – see Robert’s comment above). If there are lorry drivers who steadfastly ignore metric then their experience must be limited to driving only in the UK and are quite likely to drive on regular routes which they already know are passable.

    So I say let’s get back to the original campaign as set out in Metric Signs Ahead.


  4. The conversion of speed and distance signage (but not height and width restrictions) received a thorough public airing in 2006. Alistair Darling, then Transport Minister, gave cost as a principal reason for not proceeding, and the DfT, true to form, provided an inflated estimate of cost in support.

    There were some of us at that time who thought that cost was just an excuse for inaction. Even if a way could be found to do the job at no cost, we believed the government would still find a way to avoid making the change. Now there is evidence to support that view. For height and width restrictions, the benefits of conversion outweigh costs, indeed there is an opportunity to save almost two million pounds over ten years, and the consultation reveals opinion almost evenly divided. But still the government avoids commitment.

    At the same time as the Roads Minister, Norman Baker, was signing off the TSRGD 2011, the Sports Minister, Hugh Robertson, was agreeing to a doubling of the Olympic Budget for ‘ceremonies’ from £40 million to £81 million. This was described by London Mayor, Boris Johnson, as a “small sum of money”. Clearly one cost criterion applies to road signs and another to firework displays.

    So, would it help if hughster’s ‘no cost’ plan were adopted? I think not. Some politicians may realise that it is in the national interest for the UK to have a single system of measurement for all purposes. But as long as they see completion of the changeover as unpopular, they will be reluctant to argue and persuade, and will allow lame excuses from government to go unchallenged.

    As a Dutch politician said about the Euro crisis, “We know what needs to be done. We just don’t know how to get re-elected when we have done it.”


  5. All the comments above are spot on. In particular, the observations of derekp@ are shown to be precisely correct when DfT advocates the use of time intervals in place of actual distances on certain signs. Exactly how does posting time intervals save any money? It seems to be just a (foolish) way of trying to avoid posting any metric signage whatsoever.

    Clearly, all of the opposition to metric is irrational and cloaked in fabricated “justification” of inflated cost estimates and similar rubbish.

    Given the fact that the majority of all UK residents have now been educated in metric and that in a few more years nearly two-thirds of the realm will share that characteristic, together with the other consistency arguments of in-cab dimension signage, units displayed by sat-nav devices, the existing posting of height restriction signs at petrol stations and other locations (garages, etc.) in metric only, the need to save money from repairing needless bridge strikes, safety issues, etc., I find it more than appropriate for UKMA to advocate adoption of the 4 points given in the posting.

    In addition I would suggest advocating for metrication of all distance signs to approaching road works, hazards, etc. (in other words, replacing “XX yards” signs with “XX m” for meters).


  6. As much as I agree with Ezra on the whole thing of changing yards to m the only stumbling block is the continued use of m to mean miles. While it’s likely that in 99.9% of cases anybody seeing such a sign will understand the context it was recognised in DfT memo (IIRC as far back as the 1980s) which stated that use of m in this context would be discontinued in a future change to TSRGD. However no change seems to have taken place – all uses of m for miles could have been all but removed by now at no cost whatsoever to the tax payer at which point another simple change to TSRGD could have happened stating simply that m for metres should now be used and yards and it’s variants were no longer permitted, again at no cost whatsoever to the taxpayer.

    To prove that such simple changes can have an effect, several days ago I saw several weight restriction signs in Northamptonshire that use “t” instead of “T”; what would it have cost the DfT to have changed TSRGD to make this mandatory instead of optional?


  7. To pick up on what both Derek and Ezra say, what is it about the education our children are receiving (or have received) in our schools that makes then so anti-metric when they become adults? I was educated in the 1940s/1950s, when most (but not all) education was in imperial units. There was some metric – but it was treated as a simple matter-of-fact, and certainly not in any way as something to be avoided, or ‘not used in real life’, or any other negative ways.

    Until we get someone in government who is not, for whatever reason, anti-metric, then nothing will change. It’s interesting to note that when I returned to living in this country after 30 years in Canada, and saw how incongruous it was to be still using Imperial measurements on the UK’s roads, after having used metric units on Canada’s roads for decades, I predicted that such a situation couldn’t last more than ten years, if that. That was in 1999 – how wrong I was.


  8. John Frewen-Lord was wrong about predicting that the UK would change to metric road signs no later than ten years after his return in 1999 …. but he would have been right about Ireland! 🙂

    Speaking of Ireland, I read in the UKMA newsletter that there are automobiles sold in Ireland that default to metric only speedometers (km/h), which creates a hazard for Irish drivers who cross into Northern Ireland or take the ferry to Great Britain. Isn’t it time DfT thought not only about UK safety but the safety of others as well?


  9. The article above claims:

    “…rejected by the DfT:

    * 6 respondents (including the Institute of Highway Engineers) drew attention to the anomaly whereby vehicle length restrictions (sign 629.1) could continue to be imperial-only and suggested they should also be phased out in favour of dual unit signs.”

    Er – see page 30 of part 2 of the amendment regs folks. No, there is no dual-units sign permitted (too cluttered I suspect), but there is a new metric-only vehicle length sign permitted which *may* be used (as long as the imperial one is there too). Sign 629.1

    So not ideal, but better than nothing.

    [What the IHE said was :”For consistency, the vehicle length limit should be amongst those for which a new diagram is provided showing, alongside each other, signs with imperial and metric units, with the option to position them vertically.” In fact sign 629.1 is not new, although it had not previously been illustrated (it was just a verbal reference). The DFT have rejected the suggestion of a dual unit sign, and of course the metric variant may still be omitted. So no change there. – Editor”]

    And (re: Alex Bailey’s comment above) looks like the symbol “t” for tonnes *is* mandatory for new signs. As you asked Alex, what would it cost? Nothing! And they appear to have gone for it.


  10. To follow up on Ezra’s comment about speedos above – he’s right that Irish vehicles’ speedos now have km/h scales only. But that’s a recent development. We’ve got German, French, Spanish, Polish, Czech, You-Name-It-Land vehicles on British roads too, and they have all had speedos with just km/h scales for ever! And their drivers only know their vehicle heights, widths and lengths in metres, and only ever have.

    The DfT’s been turning a blind eye to all that for years – don’t expect a miracle change of heart.


  11. It is ironic that the metrication process in the UK was initiated by trade and industry requirements, now however requests from trade and industry are being ignored, presumably in the name of short-term political expedience.


  12. Is not the “who was educated in metric” argument a bit of a red herring?

    I’m 67 and I received some metric education in math and science classes in high school. I went on to a career where I used the metric and many of my classmates didn’t and have forgotten. Younger people have been better educated in metric, but to the degree they don’t use it in “real life” they forget it (and the rest of their school lessons) pretty quickly.

    Do you really need to understand metric while driving? Are those not trained in metric forbidden to drive on the Continent? Let me explain speedos: The number on the speedo better not be bigger than the number on the sign or the cop will get you. Doesn’t matter how long a mile or kilometer is. All that matters is that the speedo use the same units as the sign.

    Let me explain bridge heights: The height number on your dash (or the actual height of your vehicle) better not be bigger than the number on the bridge sign. That is true regardless of whether you can demonstrate with your arms how big a foot, yard, or meter is. It is easier to do the math in one unit, meters, than in mixed base, feet and inches.

    Distance: Look at the number, look at your speedo, divide in your head. Pretty simple.

    A little education helps (a newspaper article would sufffice) but education doesn’t give feeling. The only way to get a feeling for metric is to use it. The education issue is a cop-out. The real issue (applies to US too) is the politicians are afraid of unpopular change, specifically the fear they won’t get reelected.

    Dual units may help with the transition from one unit system to another. However, if the end date is not pre-announced people make no effort to get onboard with the new unit. They HAVE to understand it is a limited duration crutch.


  13. Mr. J. Steel:
    Do not be insensitive whatever view on dual sings. If a speedometer is calibrated to miles and one is driving in a km zone one is driving over the limit. If a speedometer is calibrated to km and driving in a mile zone one is driving too slow.


  14. Although dual signs and labels should be avoided, I concur with the 4 step process suggested by hughster. Dual signs and labels are the reason that metrication is slow and voluntary. However when road distance and speed signs are changed to metric units there will be no dual signs. This would be the time to change height, width, length, etc, signs to metric only. Metrication of road signs will not be voluntary it will be forced. there will be no alternative to metric.
    My understanding of the term “who was educated in metric” refers to people who where educated in the UK post 1965. (ie the under 52 year olds) I dont believe that many of this group are “metric haters” rather that most of them are in the “hybrid zone” thay are both pro-imperial and pro-metric. Most are in transit from the imperial corner to the metric corner. Exposure to metric is important for them be able to use metric units and “think metric”. That is why the metrication of road signs is so important for the process of metrication in the UK.


  15. @ed
    In a world with only one measurement system, this isn’t a problem. Otherwise, the units should be marked on the speedo (and are under US law). If you drive in both zones, you can either convert yourself or use the secondary ring if you have it. Except for the secondary font being a little small and hard to read, I have no real trouble driving in Canada, because I know Canada is metric.

    Another minor problem is that neither Canadian nor US speed signs typically show the unit. If the sign says “Speed Limit” you are in the US and it is miles. If it says “Maximum,” you are in Canada, and it is km/h. Generally, the border crossing is a clue too. There may be more potential for confusion in Europe. UK speed signs and Continental speed signs look alike, as I recall, but are different units.

    Note: The US does allow metric speed signs, but they are VERY rare. The numeric limit must be in a circle with km/h under the circle, and “Speed Limit” above the circle. Dual speed signs are not really possible as the limit must be a multiple of 5 MPH or 10 km/h. Only a few speeds (25 MPH / 40 km/h, and its integer multiples) qualify as close enough for dual signing.


  16. To John Steele:

    When Canada converted its speed limit signs (overnight), using adhesive vinyl overlays, the km/h designation was added (in contrasting while letters on black background) under the numerical value. You see very few of those today, as of course most speed limit signs have been replaced over the years.

    As regards your point about how US speed limit signs must be displayed, I HAVE seen (and even have pictures of) metric signs in the US, displayed underneath the imperial ones, and in the same format – rectangular sign, black border, but with the km/h designation underneath (but unlike in Canada, black letters on white background).

    A point was made elsewhere (in the recently issued UKMA newsletter?) about Canadian cars having to have supplementary mph markings. I am not sure if that is true – or if it is, it must be very recent. I (or my family) had a number of cars in Canada with km/h-only speedometers – 1979 VW Rabbit, 1984 VW Jetta, 1988 SAAB 900, 1989 VW Golf, 1990 Jeep Cherokee (a surprise that one, and this only lasted a couple of model years), and 1991 SAAB (900 or 9-3, cannot quite remember). A colleague, who I visited last year, has a 2007 SAAB 9-5, which also has a km/h-only speedometer. That said, most cars in Canada (and certainly all cars from US and far-eastern manufacturers) are dual marked.


  17. @John Frewen-Lord

    You are correct. Neither CMVSS 101 nor FMVSS 101 currently require (and haven’t since at least 1995) the secondary speedo, but both allow it. Manufacturers seem to feel it is a “customer requirement” as it is nearly universal.

    I was not familiar with “km/h” plate you mentioned. I believe the current one is black on a yellow background. It is optional, not required, but tends to be used near border areas.


  18. Perhaps this is one way to help convince Westminster to finally metricate road signs:


    If Scotland does break away, it could be ripe for converting its road signs. Once that happens, the pressure will be even greater on England to convert, which will bring along Wales and Northern Ireland!

    Saor Alba! 😉


  19. I think that UKMA should support Hughster’s proposal as it is a good plan and removes the DfT’s principal objection to the metrication of road signs, namely cost. The main appeal of this proposal is that it involves no public expenditure. It would be interesting to see what the DfT says about Hughster’s proposal. If they still object, it would show that cost is just being used as an excuse to resist change and that cost is not the real reason for their opposition to metric road signs.

    We know that the DfT’s objection is ideological because they will not even allow amendments to the TSRGD to allow metric road signs as an alternative to imperial, even when there are no cost implications from such changes.


  20. I agree with Ronnie, I think Hughster’s proposal is a very good plan, and I certainly support it. Personally, I am not too keen on dual-unit restriction signs (even though dual unit height/width restriction signs would have been better than nothing) and of course I oppose dual unit signs in principle (who doesn’t).

    It’s good that the DfT finally realised, even though it’s only been a few decades, that “t” is the right symbol for tonnes. I hope they will also realise that “m” to mean miles is also wrong, when this should be a reserved symbol for metres – something which was noted in 1989, but has still not been corrected to this day.

    But I still wonder what the DfT is hoping to achieve by not doing what needs to be done (a full conversion to metric-only signs). And all in the name of short-term political expediency, protecting budgets, avoiding negative headlines in the tabloids, etc.

    I wonder who exactly is benefitting from the status quo anyway.


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