DfT holds back TfL from all-metric usage

Transport for London (TfL) uses metres and kilometres to express distances in its press releases with few exceptions and often uses metres elsewhere in public places. However, speeds are expressed in miles per hour, no doubt due to Department for Transport (DfT) regulations and usage. Tariffs for taxi fares are expressed in metres for short journeys and in miles for longer journeys and reflect current regulations. I praise TfL for using metric units wherever they can. It is a pity that DfT regulations and usage are holding back TfL from going fully metric.

In the TfL press releases, the speeds are all in miles per hour. This is unavoidable because DfT regulations require road speeds to mph so TfL cannot be blamed for using mph when all road speed limits are in mph.

However, distances in its press releases are all in metres and kilometres. It is nice to see TfL using modern measurement units. They face a limit to usage of metric units, namely road transport regulations. In the current environment, it is impossible to ignore the fact that imperial units dominate our road signs and road transport regulations.

I found one notable exception to the use of metric units of length – the tariff rate for longer taxi journeys, sometimes referred to as Tariff 4. For Tariffs 1-3, there are different tariff rates per mile for journeys of up to 6 miles and a single tariff rate for all journeys over 6 miles in the “Tariff rate for longer journeys” section. In the other sections, it is curious that Tariffs 1-3 contain minimum and additional charges based on a fixed number of metres or a fixed number of seconds, whichever is reached first. These fixed distances and times change once a journey exceeds a fixed number of metres in Tariffs 1-3.

The tariff rates change once a journey reaches 9591.4 metres in Tariff 1, 9643.2 metres in Tariff 2 and 9581.6 metres in Tariff 3. One interesting observation is that all these numbers of metres are all approximately 6 miles. For short journeys, Tariffs 1-3 apply at different times. For longer journeys, Tariff 4 always applies. Why can’t taxi fares and tariffs all be based on metres and kilometres?

This measurement muddle leads to mixed measurement usage in the same sentence, e.g.

  • “The new lower speed schemes are part of the TfL’s commitment to complete 20mph speed limits on 220km of the TfL road network by 2024.” (Source: “TfL to launch 13.77km of new lower speed limit schemes to cut road danger across the capital and save lives”, TfL press release on 9 February 2022)
  • “Reducing danger on the capital’s transport network is a top priority for TfL. In March 2020, TfL introduced a 20mph speed limit on all of its roads within the central London Congestion Charging zone as part of its Vision Zero commitment to eliminate death and serious injury on the capital’s roads by 2041, and 80km of its roads are now 20mph.” (ibid.)
  • “TfL recently launched local engagement on plans to introduce 28km of new 20mph speed limit on its roads within the boroughs of Camden, Islington, Hackney, Haringey and Tower Hamlets.” (Source: “New TfL data shows continued boom in walking and cycling, with almost twice as many now living near a high-quality cycle route”, TfL press release on 30 November 2022)
  • “To meet the PHV ZEC requirements a vehicle must: Emit no more than 50g/km CO2 and be capable of being operated with no (zero) exhaust emissions for a minimum range of 10 miles (16.093 km); or Emit no more than 75g/km CO2 exhaust emissions and be capable of being operated with no (zero) emissions for a minimum range of 20 miles (32.187 km)” (Source: “All private hire vehicles licensed for the first time in 2023 to be zero emission capable”, TfL press release on 30 December 2022)
  • “TfL recently launched local engagement on plans to introduce 28km of new 20mph speed limit on its roads within the boroughs of Camden, Islington, Hackney, Haringey and Tower Hamlets.” (Source: “TfL moves forward with plans for new cycle route through Nine Elms”, TfL press release on 25 January 2023)

The regulations require speed limits to be in multiples of 10 mph and there is no metric option for speed limits. So we can hardly blame TfL for using mph for speed limits. TfL mentions reductions in the speed limit to 20 mph in some parts of London in its press releases. TfL has no discretion to introduce a 30 km/h speed limit because this is not allowed by the regulations.

DfT continues to drag its feet on metrication and is to blame for the continuing measurement muddle. DfT is the chief culprit for holding back TfL from full metric usage.

You can find the TfL’s taxi tariffs at:

Here are some TfL press releases that contain measurements:

11 thoughts on “DfT holds back TfL from all-metric usage”

  1. Ronnie has overlooked one exception: London Trams speed limits are shown in km/h, e.g. a diamond with ‘50’ indicating a 50km/h limit ≈30mph.


  2. QUOTE: “DfT continues to drag its feet on metrication and is to blame for the continuing measurement muddle. DfT is the chief culprit for holding back TfL from full metric usage.”
    I could not agree more, Ronnie. Your closing comment sums things up utterly. In my working life as an engineer, it would have been sheer madness to mix up units like this. But then politicians do not perform analysis; they just bandy figures around.

    Liked by 2 people

  3. I’m just curious of how it happened that for 50 years and more, every person in power who ran the DfT all had and continue to have an anti-metric attitude. I’m sure the person responsible for keeping metric out in the beginning was hoping every other agency and industry would follow their lead and rebel against metrication. It’s also amazing though that the employees at the DfT were allowed and encouraged to use metric behind the scenes.

    Maybe the person(s) at the DfT who held out all these decades are gleeful that they may have helped promote the push-back towards FFU coming from the political elite.


  4. It is a farcical situation that everything else has moved onto metric but the DFT refuses to update the road signs to reflect that. I find it bizarre that people can not see it and seem content on continuing with this absurdity. They literally measure out 800 m on the road and put a sign saying “humps for 1/2 miles” when they could simply write “800m” and save a lot of room as well as being better understood by British drivers, never mind foreign drivers whose cars can not even read the units sign posted.

    It is easy to point the finger at the DFT but ultimately how many people are asking for the road signs to be put in metric units? The DFT is ultimately an arm of the government and they are held accountable to it. As such a major change like this needs to come from the top. Political inertia is a thing and politicians don’t like making significant changes, that are potentially quite controversial unless there is pressure for them to do so. Which is why this situation has lasted as long as it did when in reality they should have stuck with their original 1973 deadline and got it done and dusted then.

    Liked by 1 person

  5. Alex M said: “It is a farcical situation that everything else has moved onto metric but the DFT refuses to update the road signs to reflect that.”.

    Seeing that the DfT is not a sentient being and of itself can not make a decision on the matter, a person or group of people in charge make the decisions that determine the status of road signs. How many directors has the DfT had since 1973, that being the past 50 years and how is it that each one of them has been anti-metric in such a manner to assure that road signs stay in yards and miles?

    How did it work out that each person who ran the DfT in the past 50 years has had an anti-metric attitude and were responsible for preventing metrication of the road signs? How is it also possible that even though each of these directors made an effort to keep metric off the road signs they didn’t interfere with the engineering and actual usage of metric units in design, construction and maintenance, possibly even encouraging metric behind the scenes and including driver location signs to be metric? Even requiring that signs stating miles and yards be hidden metric values.


  6. The continued use of imperial units has little to do with the DfT, but a lot to do with our politicians. With our first-past-the-post system, politicians must take care to antagonise as few voters as possible and an announcement that Britain intends switching to the metric system will antagonise a certain number of voters ss it will be exploited by opposition parties. If this causes just 1% of the voters to change from supporting the government of the day to supporting the opposition of the day, this could well mean that the government of the day will lose the next election.

    I know that most thinking people will not be swayed by single issues such as this, but I am reminded of a conversation that allegedly took place between Adlai Stevenson II and one of his supporters when he was running for the presidency against Eisenhower:

    Sporter: Mr Stevenson, every thinking American supports you.

    Stevenson: I know, but in order to be elected, I also need the votes of those who don’t think.

    Liked by 1 person

  7. I’ve tried replying to some of these emails, but my reply seems to be absorbed into the æther.

    One point that I’ve tried to make is that London Trams signaling is definitely metric. Their speed limits ( a number, such as “50”, on a white diamond ) are in km/h, for example.


  8. @Daniel. The DFT is a government agency and not a power into themselves, it exists in order to reflect government policy. It is not so much that they have a strong anti-metric agenda but rather any decision to switch over needs to come from government themselves rather than expecting the DFT to act independently of that.

    The reason for the continuation of imperial on road signage is because of politicians and there being a lack of political will to change it. As I have mentioned in my post above politicians don’t like making significant and potentially controversial changes unless there is significant pressure for them to do so. Which lets face it, over the last several decades there hasn’t been. With there being about a 20 year timespan between the disbanding of the metrication board and founding of the UKMA where there wasn’t really a dedicated organisation campaigning on this issue. It also wasn’t helped by certain groups, conflated with hostilities towards EU membership and certain parts of the British press not being favourable to it.

    Human beings are naturally resistant to change and without proper guidance they quite often don’t see the need to change things. Politicians are also concerned that switching over might alienate certain voters who they need to win over. Although, I think in reality that it is quite a minor single issue that once is done people would quickly get use to it and quickly move on.

    Liked by 1 person

  9. Alex M,

    If I remember correctly when the politicians were deciding on the course of metrication in the 1960s and 70s, the then head of the DfT told them that the DfT was going to keep the signs in miles and yards and it was agreed to give them this exception. I’m sure the reason had something to with waiting for enough people to be educated in metric.

    We can blame the politicians only as far as not insisting that the signs be metricated along with everything else at the time. No exceptions to anyone should be granted. As it was in the Commonwealth countries.

    The politicians did play an active role by changing laws (the WMA) to make the metric system the legal and only to be used system in the majority of incidences. The only other exception being pints of beer. The changes that did occur that we can thank the politicians of the time for, include requiring that retail scales be converted in 1999, and abolishing the acre, the gallon, and requiring prepackaged goods to be in metric, etc.

    It seems that in most cases, the politicians did the right thing by bringing about reforms to the WMA to make metrication a reality. Why they granted an exception for road signs makes no sense. but, by doing so it has added fuel to the fire of those salivating at a possible full return to imperial.

    If the protests of recent days are a sign of the collapse of the British economy just think how much further the economy will collapse and the protests increase if full demetrication occurs.

    Liked by 1 person

  10. Daniel. My understanding is that Ted Heath’s Conservative government indefinitely postponed the original 1973 target date after taking power in 1970 and there hasn’t been political will to complete it since. It seems odd to me why you are so adamant at putting so much blame on a government agency who have don’t have much to do with it. Sure they can make excuses for not wanting to do it but at the end of the day their job is to reflect government policy and are subservient to it.

    The mistake made in the UK was that it was done on a sector to sector basis with the brunt of it being placed on them as opposed to recognising it as a all encompassing program of national importance, like it was in other Commonwealth countries. Which is why it has been such a drawn out farcical mess while other countries largely completed it in a decade timespan without any of this fuss.

    Also changing road signage is different from changing legalisation. Legalisation can be easily amended while road signage is a fairly significant change that requires time, money and resources to ensure that it happens. While I agree doing so is highly beneficial and the objections to it are baseless. Politicians need to be convinced of that and they are too concerned about annoying potential voters who they need if they want to maintain power.

    Liked by 1 person

  11. Of course what drives the government is the will of the people (in theory at least), and the media.
    My perception here is that recently there has been quite a shift to the use of SI by the mainstream media. Even hectares are used occasionally, everything but those miles in fact, which pretty much closes the circle.
    The hope is that this will increase as they realise this is what most of us use and it is no longer the geeky subject they perceive. More nature related programmes are getting there, now if only those overseas property ones would stop pretending everything is in miles and pounds sterling we may just start connecting to the rest of the world.

    Liked by 1 person

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