HM Government looked at the case for and against the use of dual unit road signs as an intermediate step in the metrication of road signs in the second half of the 1960’s. Three different methods for dual unit sign conversion were evaluated and some technical issues related to dual unit signs were discussed. The findings and illustrations from the National Archive papers are presented here.
Method 1
A separate new sign indicating the speed limit in km/h can be mounted below the existing mph sign without any units as shown in the following diagram:
This method would be applicable to both terminal and repeater signs. After a suitable period of time had elapsed, the top sign could be dismounted and removed for scrap and the bottom sign could be moved up into position.
Three advantages were given for Method 1:
- During the changeover period, it would be clear that where one sign only was displayed, it meant mph and where two were displayed, the metric equivalent was shown below.
- No other additional plates would be required.
- Symbols would be very legible being the same height.
Two disadvantages were given for Method 2:
- Very expensive because all new signs would be required, and the only credit would be the scrap value of existing signs – some of which may be fairly new.
- At least three operations at the site of each sign would be required, i.e. (a) mount 50 sign below 30 (b) remove the 30 sign and (c) shift 50 sign to new position.
Method 2
An insert showing km/h could be made, either below the sign or within the sign. These two options in Method 2 were classified as 2(A) for a separate insert below the sign and 2(B) for an insert within the sign. In both cases, the insert could be made to fit existing signs showing the new figure in km/h.
Method 2(A)
A plate would be required below showing km/h to let motorists know the sign had been altered. Repeater signs could be treated in the same way. An example of Method 2(A) is shown here:
The advantage for Method 2(A) is that it is cheaper than Method 1 in materials. It requires a smaller, lighter disc and fittings would be required for one small plate only.
The disadvantages for Method 2(A) were:
- It requires three operations for each sign. These operations are fitting the new figure insert, fitting a supplementary plate and removing the supplementary plate.
- The cost of the supplementary plate is a complete loss except subsequent value for scrap.
Method 2(B)
The other option for the insert is to put in inside the sign as shown here:
The advantages of Method 2(B) are:
- It is cheaper than Methods 1 and 2(A).
- Only two operations are required. They are to fit the figure insert and subsequently to delete or remove the km/h symbol.
The disadvantage of Method 2(B) is that the km/h symbol might not be completely legible and might fail to indicate that the sign had been changed, especially on repeater signs.
Method 3
Method 3 inserts the km/h figure into the same sign as the mph figure. It was suggested that mph is the top figure and km/h is the bottom figure to indicate that it “was 30 mph and is now 50 km/h”. The specific numbers are just examples. It is possible for the numbers to be reversed but numbers are read from top to bottom. Subsequently, the plate could be salvaged and fitted with a sign face indicating the figure in km/h only. An example of such a dual sign with both figures on the same plate is shown below.
The advantage of Method 3 is that there should be no doubt at all that the sign has been altered.
The disadvantages of Method 3 are:
- The figures are smaller than normal.
- It is slightly dearer than Method 2(B).
- The method will not be really applicable to repeaters because the figure sizes in that case would be too small. Method 1 or Method 2 would need to be adopted for repeaters.
- It involves three operations. They are fitting the new 30/50 plate, removing the 30/50 plate and fitting the new 50 plate.
Technical Details
Further technical details on what is involved in practice for the metric conversion were provided in a paper published in February 1969, which is shown here.
Questions were asked about the adoption of the 24-hour clock for waiting restriction plates and confusion arising from the use of ‘m’ for metres and miles.
Conclusion
HM Government concluded that all methods cost a lot in terms of labour and materials. Some methods are more expensive than over in terms of materials and the amount of work involved. The government favoured Method 2(B) as the cheapest option in each respect. Adding km/h would indicate that the sign has been changed and remove any doubt that the speed limit is in km/h and not mph. It can fill all the available space. In case there is not enough room, alternatives suggested were using distinctive colours for the figures or for the whole background within the red border. A recommendation was made to investigate Method 2(B) in much greater detail as a firm basis for future action.
The government was open-minded about using dual units as an intermediate step for the metrication of road signs and suggested further investigation to examine the merits of this approach.
Metric Views 
To my mind the Labour government should look to what Ireland did to convert distance signs and speed limit signs and perhaps look at Canada as well. I suspect the method used by either country or a sensible blending of both (if applicable) would do the job quite nicely.
The missing ingredient is the political will to convert. The government could start by just converting “yards” to “m” and then gradually adding distance signs in “km” or “m” as appropriate to existing distance signs with a subsequent phase of removing the old distance signs showing “miles” so only the metric distance signs are displayed.
The final phase would be converting speed limit signs following the example of Ireland and/or Canada.
As Shakespeare wrote in “Measure for Measure”: The miserable have no other medicine but only hope.
I quote him because I feel miserable about how previous governments have been so useless when it comes to metrication. But metricating road signs would be a way for Starmer to show some rapprochement with the EU (which he wants to do) without trying to rejoin the Single Market and the Customs Union (which I personally favour, however).
Ezra aka punditgi
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An interesting historic document. Although hindsight might be a wonderful thing, it is still worth critically analysing this document.
The first thing that I noticed was confusion as to how “kilometres per hour” should be represented, even though the matter had already been decided at the ninth CGPM (1948).
The second thing that I noticed was that Methods 1 and 2A were not “fail-safe” – if half of the sign was “lost”, then the sign could change its meaning – for example if the plate displaying “kmph” [sic] in Method 2A was removed, speed limits would go up by 60% which would be an open invitation to vandals!
The third thing that I noticed was that a high-level strategy for rolling out road signs that display metric units had not been formulated. Furthermore the document gave no indication of how speedometers on new cars would display during the transition period, nor how motorists who had older cars that only displayed mph on their speedometers would cope with the new signs.
What has happened in practice?
I was in South Africa during the change-over in the early 1970’s. They had the advantage of a total change of design of speed limit signs. There were no dual speedometers nor were there dual speed limit signs. People coped. Moreover, the Yom Kippur War (1973) resulted in a fuel shortage which in turn gave way to speed restrictions (given in km/h only) and heavy fines for those who transgressed these restrictions.
I was in Mauritius in 1978 and they adopted a variation of Method 3 on the roads (the dividing line was at 45°, not horizontal). Cars in Mauritius did not have dual units – it was the speed limits that had dual units during the change-over period.
In 2005 Ireland went for Method 2B. In order to overcome the problem of the “km/h” becoming hidden, changed their signs over one weekend.
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It seems that the government of the day envisaged a phasing over of old imperial to new metric speed limits. What we need to do here is more cost-effective and similar to Ireland – phase over the distance signs piecemeal and set a date to change over the speed limits on one weekend. I suggest that unlike Ireland, where the speed limits were changed near the end of the change-over period, we change the speed limits early on. A lead time of about three years would give sufficient time for publicity, change of vehicle construction and use regulations, etc.
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Metricmac,
Unlike everywhere else in the Commonwealth and former colonies, Eire decided to take 30 years to convert road distance signs. This sort of worked because they didn’t forbid metric on signs and didn’t have any organised resistance that switched new metric signs back to imperial. The conversion to metric speeds went quite quickly. But, in reality, Eire’s metrication of roads should have followed the same path as Australia, Canada, New Zealand, South Africa, etc.
England can’t and should never follow Eire’s example as it would first require changing the law to allow metric signs, which is something that should never have been forbidden. In addition, would anyone want to wait 30 long years for road signs to change?
What I’ll never understand is how the entire Commonwealth and former colonies were able to metricate quickly in a few short years and the “mother” country and the US with claims to greatness can’t seem make it happen.
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For more on the UK’s bungled attempt to metricate speed limits go to:
https://ukma.org.uk/the-case-for-change/policy-areas/road-signs-policy/#speed-limits
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@Daniel
Thanks for your response. You apparently favour a rapid change to metric of both speed limits and distance indicators in the space of a few months, as Australia and other Commonwealth countries did.
I am inclined to agree with you in principle. The problem is that many people are under the misconception that this would cost a small fortune. When I contacted my MP on this subject a few years ago, the response from the DFT included reference to the cost, for which it had no budget.
Ireland did the job cost effectively by updating distance signage on a piecemeal basis. “Would anyone want to wait 30 long years for road signs to change?” you ask. We are actually in a worse situation than that. The change in the UK was proposed more than 50 years ago, but nothing has happened and there isn’t even a plan yet. If our government had have followed Ireland’s example, the metrication of all signs would have been complete by now.
For this reason, I believe that UKMA should campaign for a programme similar to that of Ireland, because a scheme that costs less has a better chance of acceptance. The government would start by repealing the law that makes metric signage illegal, then enable the piecemeal changing of distance signs to take place, and plan a change of speed limits about three years ahead. The cost of changing speed limits would thereby be deferred while the government brought more-urgent financial matters into order.
Why can’t UK and USA make this happen? As has been stated before there is not the political will. You will recall that during the previous government, Boris & Co arranged the public consultation over increasing the exhibiting of imperial weights and measures on retail pricing. The preface heralded the British tradition, but the results were not what they expected or wanted. We are still up against this type of opposition.
I imagine that in the USA there is a similar lack of political will. Again, the cost of change is not an issue as I see it. A nation that can send umpteen space probes all over the Solar System can afford to metricate road signs. A lot of the lack of progress in the USA relates to international trading. The USA is self-sufficient for much of its regular marketing, thus when one enters an American supermarket one will see for sale in imperial weights and measures many food and other items that are normally sold in metric in the UK. There are some exceptions, e.g. wine is sold in 750 mm bottles just like everywhere else. Of course the Californian wine market has a huge international penetration.
Everything we do costs money, so it is easy for someone opposed to something to argue that it costs too much. Around 2003 the DFT issued a statement that cost to metricating our highways would cost around £680 million. This represents the cost to metricate ALL road signs over a short period, and was used as an excuse not to go ahead. It represents about £10 for every UK inhabitant. If they really were prepared to do it this way they could happily have my £10.
So overall it is a case of do we campaign for what would be ideal, or do we campaign for something that would take a long time but would have a better chance to achieve our end eventually?
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@metricmac
Here in the USA we have loads of uneducated and illiterate people who cannot do elementary school math or even read at that level. They are like the Roman masses after the fall of the Republic who cheered the gladiators in the Coliseum. Bread and circuses are all they want but soon there will be only very expensive and not very good bread after the Trump trade wars are in full swing.
Still, they cling to the halcyon days of American preeminence (much as some Britons still cling nostalgically to the glory days under Queen Victoria when the sun never set on the British Empire). Consequently, these deplorable folks cling to whatever vestiges remain of our status as a great power, including the American version of Imperial. Just like their guns, future generations will have to pry the US version of Imperial out of their cold, dead hands.
Sic transit ignorantia. 😦
Ezra aka punditgi
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Punditgi gives a very excellent analysis of the American situation. Those loads of uneducated and illiterate masses who can’t do simple elementary maths or even read at that level are collectively known as ‘muritards.
But it is worse than what anyone can even imagine. The American elites also fall into this group, they are not exempt. Forget the fact that Americans who feel they are superior to all in the world and that these said Americans who feel the rest of the world who are beneath them were able to make the change.
Now realising that the whole world has passed the point of adopting the metric units, the American masses fear that if metrication were to ever happen in the future a whole two or more generations will struggle such that not one person would be able to measure or even understand any measurement as they all grope to learn to use the metric system and forsake the present set of unit collections. Americans will never let themselves appear in this state even if it means that they will forever be disconnected from the measurement standards, technology and scientific and engineering development experienced by the rest of the world.
As the world adopts English as the world language there will be a huge communication gap and struggles increase as battles are waged between the world speaking and demanding metric be used and Americans insisting they be communicated to in ‘muritard units.
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@punditgi – a small point of correction, the sun still does not set on the British Empire. At any moment in time, it is shining on one or more of the United Kingdom, Pitcairn Island (population 35) or the British Indian Ocean Territory (mainly the Changos Archipelago) (population 3500 US and UK military personel). Also, the sun is always shining on at least one of the King’s domains which include the United Kingdom, Canada, Australia and New Zealand
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Here is the reply from Tom Wade of Ireland in response to my email to him about my recollection that he helped push the Irish government to metricate road signs there:
“I may have played a small part, but I can’t claim to have brought it about. It had stalled since the 90’s, because the Dept of Industry & Commerce were responsible for the metric transition, but the Dept of Environment were responsible for the road legislation. The former kept setting deadlines, and the latter kept ignoring them and applying for extensions. The situation was that distance signs had mostly been converted to km & m, petrol [gas] was sold by the liter, but speed signs were in MPH. I wrote letters to the national papers, pointing out this absurdity (which was echoed by others). I also got our local TD [Congressman/MP] to table a Parliamentary Query to the minister asking when this anomaly would be resolved.
Eventually, there was a government reshuffle and responsibility for roads (including metrication) was moved to a new Dept of Transport; a proactive minister there finally set a real deadline within a few months. There was some grumbling from the car industry as they still had cars in stock with the old speedometers but most people were unopposed. In the end, the changeover took about 5 days to replace the speed limit signs. There was a publicity campaign, and — uniquely — our speed limit signs now explicitly have “km/h” on them so there would be no confusion.
It’s interesting that there was pretty much no opposition to the idea whereas in the UK this would be seen as a contentious issue. This was for a number of reasons. Everyone who started high school since 1970 was educated solely in metric units. There is also no cultural attachment to “Imperial” measurements; if anything, the name is somewhat negative here, but mainly because of the fact that the attitude to the EU here is overwhelmingly positive whereas in the UK this is not the case.
In both countries metrication would be seen largely as an EU led initiative. However, this is not entirely accurate in the UK as their decision to go metric predated their membership and was made as part of a British Commonwealth decision in the 60’s, but I doubt if most people are aware of that.”
From Ezra aka punditgi
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The difference between the UK and Ireland is that Ireland never forbid metric signs but rather they were a hangover from British rule which made it easy to phase them in for things like distances over time. Which then only left the issue of speed limit signs that couldn’t have been phased in for safety and practicality reasons. So were eventually done in one go.
In the UK, the road traffic regulations specify that these signs need to be in yards, miles or fractions of a mile, with there being guidelines in regards to placement. Signs that use metric units are not officially authorised for this purpose. Therefore those signs are considered “illegal” and they are supposed to be taken down. Certain groups have gotten blamed for this but in reality, it is the fault of government legislation. Small vigilante groups can fairly easily be disregarded.
I also don’t think there is a huge amount of opposition in the UK to it; it is more apathy. The public is used to it and doesn’t see much point in change, so it isn’t considered a political priority. People generally don’t like change, so there is the issue of short-term opposition to overcome, and politicians don’t want to push for something that is seen as unpopular in the short term with little political benefit.
I don’t believe cost was ever a serious problem but rather a convenient excuse; everything costs money, so they can easily dismiss any suggestions as costing too much and simply bring up an exaggerated estimate based on assumptions in order to try and stifle any further debate.
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“In both countries metrication would be seen largely as an EU led initiative. However, this is not entirely accurate in the UK as their decision to go metric predated their membership and was made as part of a British Commonwealth decision in the 60’s, but I doubt if most people are aware of that.”
Thanks, Ezra. And well done on getting that reply from Ireland. I’ve often thought the Irish talk much more sense than we do on certain issues. It was a very interesting read. But I wonder if we in UKMA can use it to our advantage at all?
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Alex M,
I can’t help think that the resistance of the managers of the DfT fought off metrication efforts in the early days not only because of a personal hatred of the metric system, but an unfounded hope that their actions would spread to other sectors of the economy. They were hoping that they would be a strong force to creating an anti-metric uprising across the economy and insuring that imperial units would never be replaced by metric units.
This is sort of what happened in the US. It was a small amount of resistance in some sectors that spooked the government to cancel metrication and the government’s support for it. However, even though metrication never happened in sectors involving the general population it did happen in major industries and to avoid having to deal with an anti-metric workforce, many good paying company jobs were lost as companies closed their operations in the US and exported the work to metric countries or made efforts towards automation where people were replaced by machines.
As a result, those Americans were forced to switch from high paying manufacturing jobs to lower paying service jobs with a heavy reliance on credit cards and debt to keep themselves in the middle class. Due to the US dollars world position as a reserve currency, American debt is serviced from a world-wide base, so the average American can continue to incur high debt without hyper-inflation or an economic collapse. England, Eire and other countries do not have this luxury following and American example would never work. Things will change though as economic blocks like BRICS gain more influence and decrease the use of the dollar in trade thus weakening the US dollars power and eventually ending the needed support to keep American debts financed.
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One hope I have is that Labour will do the right thing and support youth mobility to allow young people from the UK to spend time on the Continent. My own experience living in France is that once I got used to the metric system I realized that Imperial had to be consigned to the dustbin of history. Over time those folks will influence others in the UK and a large percentage of the population will eventually push for metrication in the UK.
Eza aka punditgi
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punditgi,
I’m confused as to why you think members of the Labour party will support of completion of metrication any more than members of other parties? Is it because the Labour party was in power in metrication’s heyday some 50 years ago? If so, your in error as the members of the Labour party 50 years ago were a different group of people with different feelings and goals than the members today. There are about two generations of differences.
This is found everywhere in life, not just with the Labour party, where the grandchildren have totally different ideas and goals than their grandparents. Also, people today are more self-absorbed than their grandparents and feel that change and improvements require efforts that aren’t worth to them to make. Laziness, ignorance, procrastination, etc abound today.
England today is at least 80 % metric and the young English are completely functional in metric units (with the possible exception of kilometres) that living in a metric country will not bring about some epiphany. I’m sure exposure to kilometres will be so minimal that almost no one will feel a strange new need to want to change road signs. I’d almost feel certain that the young English pay very little attention to the miles on road signs. I would doubt many even own a car where paying attention to the speed and odometer are a necessity of driving.
I really don’t have an answer as to what it would take to convince the English that completing the last vestige of imperial exposure would be in their best interest. I’m sure no one does. I can’t even venture to guess what it would take to complete the last 20 %. But hoping on some action from members of the Labour party isn’t going to bring about any further change.
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@Daniel
Well, “hope’ by definition is … well, you can look it for yourself. 😉
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@Alex M:
You wrote: “The difference between the UK and Ireland is that Ireland never forbid metric signs but rather they were a hangover from British rule which made it easy to phase them in for things like distances over time…” I noticed the same attitude in South Africa. It was probably also evident elsewhere in the Commonwealth.
When Cecil John Rhodes set up the Rhodes Scholarship scheme in his will, the underlying object was to educate future leaders in the colonies so that the colonies would not be dependant upon Britain for their leadership. As a result such leaders had a primary allegience to their own colony and a secondary allegience to the UK. This is something that has never been understood in the UK with the result that there is a reluctance in the British political classes to look beyond the British Isles for inspiration.
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