Traffic signs and speed limits to be devolved to Scotland

The Smith Commission on further devolution to Scotland has recommended that speed limits and traffic signs should be devolved to the Scottish Parliament.

On 27 November the Commission on further devolution to Scotland (known as the “Smith Commission” after its Chairman, Lord Smith) published the unanimous report of its 11 members (two from each main Scottish political party, plus Lord Smith).

Most attention has been focused on the Commission’s  recommendations on devolving income tax and some welfare benefits, but paragraph 66 of the Report states:

“Remaining powers to change speed limits will be devolved to the Scottish Parliament. Powers over all road traffic signs in Scotland will also be devolved.”

Assuming that these recommendations are implemented in full, this should mean that a future Scottish Government could decide to convert traffic signs and speed limits to metres, kilometres and km/h even if the rest of the UK clings to obsolete imperial measures. This is much as recommended by the UK Metric Association in its submission to the Smith Commission.

However, the Report makes no specific mention of Weights and Measures powers generally – although paragraph 72 recommends that “Consumer advocacy and advice will be devolved to the Scottish Parliament.”

A slight doubt therefore remains over the power to convert speed limits and traffic signs. It has been found in the past that although the Northern Ireland devolved Government has control over traffic signs, legal advice has been obtained that  Weights and Measures law trumps traffic signs, and therefore the NI Assembly cannot match its southern neighbour and convert to km/h speed limits without UK consent.  That said, and given the current mood of Scottish voters, it is inconceivable that a future UK Government would dare to veto a Scottish decision to modernise its road signs.

(See also Metric Views article at

13 thoughts on “Traffic signs and speed limits to be devolved to Scotland”

  1. Weights and Measures legislation only permits the UK to continue to use yards, miles and mph for road traffic measurement. It doesn’t mandate their use. Therefore, imho, the Scottish Government can amend the traffic sign legislation to have signs displaying metric.


  2. That’s good news, anything which reduces the DfT’s stranglehold raises the possibility of steps in the right direction. Maybe not km/h any time soon, but perhaps authorisation of such things as metric pedestrian signs, removal of imperial on width or length signs, metres on tunnel escape signs are reasonable ambitions to start with. 

    And there may be fewer unionists in governmemt in Scotland than in Northern Ireland…


  3. I would challenge the argument: “That said, and given the current mood of Scottish voters, it is inconceivable that a future UK Government would dare to veto a Scottish decision to modernise its road signs.”

    Considering the referendum is won, I think there’s definitely a chance of the UK government vetoing a Scotland decision like that. I imagine the situation would be parallel to that in the north of Ireland where it’s incredibly limited devolution which wouldn’t permit the appearance of metric units except in those places we already see them in the UK, unfortunately.


  4. I am not totally convinced that Weights and Measure legislation “trumps” traffic signs. A large part of weights and measures legislation complies with EU directives. In particular, the EU has published directives that:
    • Catalogue the units of measure that may be used for activities that come under the “Internal Market”, including, but not restricted to trade, health and safety, public administration.
    • Require that member states set up regimes to verify that weighting and measuring devices which come under the umbrella of the “Internal Market” are properly calibrated. There are two parts to such regimes – the calibration organisations (often private firms) and the authorising organisations (who act on behalf of the government). This structure is much like the MoT structure where the Department of Transport authorises garages to do MoTs.
    • Require that member states recognise calibrations done within other member states.

    The EU directives are vague as to how governments should implement their structures and even more vague as to how they should be enforced – that is a matter of national legislation.

    In the case of Scotland having control over its own road signs – the Scots will have to comply with EU regulations. They will also be well advised to comply with the Vienna Convention on road signs. Both of these do, in my view, leave the Scots with the freedom to continue using imperial units or to convert to metric units, but does not permit them to use pre-1707 Scots units. It also leaves the Scots free to set whatever speed limits they like, but again, only using mph or km/h. It is not clear what freedom they will have on how to enforce the law, nor how they relate to organisations such as the National Physical Laboratory.


  5. Let’s hope the Scots test the waters by going ahead with a plan to convert to metric only road signs to see what happens.,

    I should note that to the best of my knowledge one single person in Ireland whom I know of via email exchanges persisted in encouraging the Irish equivalent of the Minister for Transport for some time before that minister finally agreed to complete conversion of road signs in Ireland. (In that case the Irish had committed to conversion but were just dragging their feet.)

    I think there is a decent chance that the right combination of encouragement and persuasion could result in Scotland seeking to convert road signs for a variety of political and social reasons.

    Definitely worth a shot (as we say over here 🙂


  6. Given that weights and measurements are not devolved, I can’t see that the devolution of road signs will change anything.

    In any case, whilst I absolutely support the change to metric road signs, I think this should be done UK-wide. I don’t think it’s sensible for one part of the country to use metric signs whilst the rest uses imperial.

    Yes, it’s more difficult to push for metric signs for the UK as a whole, but it will come eventually. We just need to keep up the campaign.


  7. The 1986 Units of Measurement Regulations state that the mile, yard, foot and inch MAY be used on road signs, NOT MUST be used. This is in line with the EU directive 80/181/EEC (See page 11 of the amended text at Provided that the Scottish road signs remain within the scope of this directive ands also that they remain within the scope of the Vienna Convention on road signs (for example using yellow rather than white backgrounds for warning signs as is done in Sweden and other northern countries) there is scope for the Scots to go their own way. For the record, yellow is used so that a motorist can see whether or not part of the signs is covered with snow. (See


  8. Interesting comment from Martin (above).
    I think weather records will show – snow is more common in Scotland than in other parts of the UK, so perhaps if the Scottish Government wants another way to increase safety on its roads then it needs to think about adopting (and phasing in) warning signs with yellow backgrounds.
    On today’s news:
    Lower drink-drive alcohol limit


  9. I’m wondering how devolution in Scotland would allow the Scottish government to do such things as enforce kilogram-only weighing scales in medical facilities, reporting newborn weights in grams, or fully enforce metric-dominant signage and advertising for goods and services offered in Scotland.

    Anyone have any ideas or information?


  10. Kilogram-only weighing devices are standard in United Kingdom medical facilities. (See This is certainly the case at my own doctor’s surgery. Unfortunately all medical staff have a conversion chart to hand so that if patients ask “How much is that in old units”, they gat an answer. Ideally they should give the patient a print-out of a conversion chart for the patient to work it out themselves.


  11. The latest newsletter from the UKMA mentions the devolution of road signs to the Scottish Parliament (repeating the essentials of this post on Metric Views).

    The newsletter also points out (correctly, I believe) that Westminster would be unlikely to veto a move by Scotland to switch road signs to metric (even if legally they had the power to do so) in order to not anger the Scots by appearing to renege on the promised devolved powers and thus strengthen the hand of those who favour independence.

    That could very well become the tipping point to push the next UK government to agree to convert road signs to metric in England, Wales, and Northern Ireland.

    In the case of NI such a move on the part of Scotland might even give the folks over there the idea that they should also convert in order to harmonize road signs with the Republic of Ireland. (On the other hand, the Unionists might oppose this in order to maintain as much psychological distance between NI and the Republic as they can.) The outcome of such an eventuality remains to be seen, but it could create some interesting momentum in favour of metricating road signs in NI. And if that happens, how long can England and Wales go it alone?

    Here’s to metric optimism to ring in the New Year! 🙂


  12. @ Ezra;

    I do hate to be a “glass half-empty” kind of person (but having lived 21 years in this muddle, who can blame me) – but let’s not forget the Scottish Government’s White Paper on independence indicated regarding weights and measures that “the existing system will continue on independence” – I think chances of change are minimal, but I do admire your optimism!


  13. It was announced today that the setting of speed limits in Wales will be devolved to the Welsh Assembly. So where does that leave speed limits in England?


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