Review of The Official Highway Code 2015 Edition

Ronnie Cohen reviews the 2015 Edition of the The Official Highway Code to comment on what has changed since the last edition and what has remained the same.

This review includes comments on the use of measurement units within the guide and how they relate to official traffic signs.


In June 2015, the Driver and Vehicle Licensing Agency (DVLA), an executive agency of the Department for Transport (DfT), published the sixteenth edition of The Official Highway Code, to celebrate 80 years of the driving test, which was introduced in 1935. The previous edition of The Official Highway Code was published in 2007.

My overall impression of The Official Highway Code is that it is printed on high quality paper, contains excellent colourful graphics and makes good use of sections, paragraphs, headings, fonts, bold text and colour. It is thinner than the last edition because it uses thinner paper, the kind of paper used for some good-quality magazines. The use of bold red capital letters for “MUST” and “MUST NOT” is excellent for alerting drivers to rules where punishable offences apply for breaking them.

So what has changed since the last edition?

Not a great deal. Here I summarise all the important changes I could find compared to the previous edition of the Code.

Some changes reflect devolution of some transport issues and it was essential that drivers know where rules differ between parts of the United Kingdom. On page 29, the Code tells readers about Scotland’s lower legal limits for alcohol and drugs compared to England & Wales. Anyone driving to Scotland must know about them. On page 30, the vastly expanded section on alcohol and drugs is welcome. The information on drugs includes both illegal drugs and medicines. On page 40, there are two rows that show different speed limits for goods vehicles with a laden weight exceeding 7.5 tonnes, one for England & Wales and one for Scotland.

On page 48, the words, “MUST NOT”, in bold red capital letters, were added for throwing objects out of a vehicle, indicating that this is now a punishable offence. Annex 2, called “Motorcycle licence requirements”, has been rewritten with better information about licence categories for mopeds and motorcycles. Annex 3 includes changes to subsections on Vehicle Excise Duty (VED) and Statutory Off-Road Notification (SORN) vehicles. Annex 7, called “First aid on the road”, has been rewritten with extra useful information. These changes are clear, concise and well-structured.

There was one change where I found a mistake. The sentence in the MOT subsection of Annex 3 was OK except for the tense. On page 121, the Code states, “From November 2012, motor vehicles manufactured before 1960 will be exempted from an MOT requirement, although they can still be submitted for a test voluntarily.” (my emphasis). This appears in a guide published in 2015!

So what has NOT changed since the last edition?

There is no change in measurement usage since the last edition.

Most places in the booklet express speeds in miles per hour followed by kilometres per hour in brackets. However, there are several exceptions. On page 90, the booklet says that, “On leaving the motorway or using a link road between motorways, your speed may be higher than you realise – 50 mph may feel like 30 mph.”. Curiously, no equivalent is given in km/h. Annex 2, called “Motorcycle licence requirements”, shows speeds in km/h followed by mph in brackets. No metric conversions are shown in descriptions of any imperial speed and distance signs in the Traffic Signs section (pages 106-113).

Most references to short distances use metres followed by feet in brackets. However, there are numerous exceptions and inconsistencies.

The Vision section about ability to read number plates in good daylight expresses the reading distance in metres only. The “Seat belt requirements” table on page 32 shows two rows with a child’s height expresed in metres, one with no imperial conversion and the other showing the equivalent in feet and inches. The next section expresses height in metres followed by feet and inches in brackets.

The Speed Limits table shows speed limits for buses, coaches and minibuses not exceeding 12 metres in overall length. Again, no imperial conversion is given. Also, only metres are used for vehicle and overhang lengths in Vehicle Markings section (page 117). However, the DfT does not allow any metric-only vehicle length dimension sign unless it is accompanied by an imperial vehicle length dimension sign. However, the DfT allows imperial-only vehicle dimension signs with no metric equivalent.

The section on Typical Stopping Distances uses metres and feet. This is also the only section in the booklet that also gives conversions in car lengths based on a notional average car length of 4 metres. On the same page, drivers are told, “If you have to stop in a tunnel, leave at least a 5-metre gap between you and the vehicle in front.”. No imperial conversion is given there.

One of the motorway rules expressed near the bottom of page 91 states, “try to stop near an emergency telephone (situated at approximately one-mile intervals along the hard shoulder)” (no metric conversion given). The use of “one-mile intervals” in the DfT’s advice is not consistent with the use of metres in the rest of the booklet nor with the kilometre-based driver location signs used on motorways.

All short distances in the booklet are given in metres, feet or both. However, neither of these measurement units are authorised on distance signs, which must be expressed in yards, miles and fractions or a mile.

One subsection called “Overhead electric lines” under the Level Crossings section expresses clearance in metres followed by feet and inches in brackets yet in another subsection called “Overhead electric lines” under the Tramways section, clearance is in metres only. However, the DfT does not allow metric vehicle height signs without an imperial one alongside them but allows imperial vehicle height signs to appear alone. They also allow dual height signs. The overhead electric cable warning sign shown on page 109 is in feet and inches only.

The measurement anomalies in the latest edition of The Official Highway Code remain. The measurement disconnection between The Official Highway Code and the Traffic Signs Regulations and General Directions (TSRGD), which regulates official traffic signs, remains. Clearly, there is a lack of joined-up thinking at the DfT on measurement units. Apparently, when it comes to measurement usage, confusion reigns at the DfT.

23 thoughts on “Review of The Official Highway Code 2015 Edition”

  1. The Highway Code makes it clear that readers (and hence road users) MUST have to know both imperial and metric measures. In which case, why bother with imperial? It is redundant, as well as potentially confusing to have to read two sets of measurements in one section, imperial-only in another, metric-only somewhere else – and for what purpose? Time to get rid of the imperial for good.

    Interestingly, when Canada and Australia converted their roads to metric units, few people back then had been educated in school on the metric system, yet we all coped, and coped very easily and well. Today in the UK, people have been educated in metric units for 40 years, the HC assumes they know metric, and so conversion should be a doddle. So what’s holding us back? (A rhetorical question I know.)


  2. Can someone post word for word for word from the law that states metric signs are illegal?


  3. #Daniel
    I don’t think metric signs are illegal as the /speed limits states that we have speed limit of 30 miles per hour (mph) or 48 kilometres per hour (km/h) usually applies, unless you see signs showing otherwise.
    ( Note the or) however there are not many km/h signs to see, the only km/h sign that I have seen is a mph to km/h information sign situated on the A2 going inland from Dover port, for the benefit of foreign truck drivers. hope this helps more than confuses!


  4. Readers may like to see my post (word limited) to the your letters page of a local south east England newspaper –

    Speeding foreign drivers and unpaid speeding tickets

    Speeding foreign drivers well used to km/h have little or no regard for our mph road speed limits from a bygone age.
    As a first step our government should move with the times like 99% of the world and go metric.
    One only has to look at the latest edition of the Highway Code to see the metric/imperial halfway house muddle .
    On the spot fines, paid of course with metric money need to be collected at the roadside or ports before they leave the country.

    I have to say the above short letter has yet to be published. There appears to be a reluctance by the mainstream press to publish pro metric articles or metric information.


  5. I have to admit I can’t currently find anything that says specifically that metric signs are illegal (except in the Road Signs manual which is not actually law but uses the phrase “not permitted”).

    It seems more the case that all the relevant laws state that, as far as roads are concerned anyway, only signs in TSRGD can be used unless an exception is sought from the relevant minister; where metric-only signs appear in that it is usually with a disclaimer that states that it may only be used in conjunction with an identical sign with imperial units. With the exception of weight limit signs which are probably the only ones which are, truly, 100% metric (despite the fact that I can to this day name several places within 30 minutes drive of my house with signs that use the word “ton”).

    I don’t think anybody will disagree with me that it probably wouldn’t take much (and certainly wouldn’t cost anything) for somebody to say “Ok, so let’s allow the use of the metre in place of the yard” while also banning the use of “m” to mean “metre” on all new signs.


  6. It is a pity that this booklet was published when a new version of the TSRGD (Traffic Signs Regulations and General Directions) was awaiting publication as many of the illustrations refer to 2002 version of the TSRGD (maximum lengths of vehicles in feet only, the use of “T” for tonnes and many other points that Ronnie has pointed out).

    For the record, the TSRGD 2016 is a statutory instrument which will be “laid upon the table” in Parliament for a specified period. If no-one forces a debate, it will become law without debate.


  7. Daniel says: 2016-01-21 at 02:55
    Can someone post word for word for word from the law that states metric signs are illegal?

    Probably not.
    However in the TSRGD 2016 draft pdf, ( ) this little gem appears on page 196 : –

    Diagram 976
    Maximum speed limit for
    tramcars in kilometres
    per hour

    I presume this is not new, and would suggest that metric speed limit signs on roads in UK are de-facto, not illegal!
    Now we have also metric height, width and length signs on public UK roads.
    Many, if not most or all of UK motorways also trunk roads, have metric wayside markers at 400m (aka 1/4 mile) intervals.

    Some (or many?) UK waterways also use km and km/h as these were never covered by the EU derogation. (

    As of (Oct) 2013 the UK rail network started metric conversion ( ) covered in metric Views (Metrication of the rail network Posted on 2014-08-29 by Erithacus).

    So, far from metric being illegal “in public view”, or whatever, it is very much a de-facto practice. Laws of England as I understand them, are mostly based on what is considered normal and reasonable by a jury of 13 individuals.

    This leaves me totally perplexed as to how ARM can ever claim them to be illegal, even more how they can claim this to have been legally proven, and how DfT can claim that metric signs are not permitted.

    The stupid muddle continues.


  8. Daniel says: “Can someone post word for word for word from the law that states metric signs are illegal?”

    AIUI, the regulations say what the units for each individual road sign type must be, and not what they must not be. For most signs where units are involved, the units are required to be specific imperial units only.


  9. The older the vehicle, the less stringent the safety checks, which obviously includes emissions. So what else is new in the UK?
    I experienced the same when I was handling ‘grey’ imports from Japan. Over 10 years old and only the MOT applied. Under 10 years and an enhanced (and more expensive) test applied. So I had to get the speedometer re-calibrated to mph.


  10. Charlie P:

    Even though you didn’t answer my question as I asked it with a word for word stating of the supposed law, you did make it clear that metric units are in no way illegal on signs.

    A law that states “must be” does not in any way exclude other units. If it didn’t meant to include other units then it would have to include the word “only” as in “must only be”. Without the word “only” it can be interpreted that dual signs are perfectly legal. The signs must show at least imperial but can show metric as options. This is why dual height/width signs are legal without a change in the wording of the law.

    Even though imperial is required it doesn’t mean that if metric is included that imperial has to be the primary units.

    Thanks for clearing this up. The UKMA can now campaign to have metric added to all measurement signs.


  11. @Daniel

    You misunderstand the way the regulations work. There is no single “law” applying to all signs in general, stating what the units must, or must not be. What there is is a specification for each and every individual sign giving the form and design and stating what the units must be. For dual measurement signs the specification explicitly states how they must be portrayed and what secondary unit is allowed or mandated. If a sign does not comply exactly with its specification (eg if it has units or even unit symols that are not explicitly allowed) then the sign is illegal.


  12. @Daniel

    I wish having our road distance and speed signs converted to (kilo-)metres were as easy as just adding metric to signs. The change is long overdue and I’m beginning to despair that I will not live long enough to see it happen – and I’m only 41 years old!

    Unfortunately, Charlie P is right. The Traffic Signs Regulations are a Statutory Instrument (=secondary legislation) and they specify which units may appear on signs and thus (by omission) which units may not, since signs that do not comply with the specifications are unlawful. The law is prescriptive, not permissive.

    The current Statutory Instrument is about 500 pages long and there are too many instances to quote every part where imperial units are mandated. By way of example, though, from Schedule 16:

    “(1) Numerals indicating distance may be varied with—
    (a) distances of over 3 miles being expressed in miles to the nearest mile;
    (b) distances of 1?2 mile or more but less than 3 miles being expressed to the nearest 1?4 mile with the fractions 3?4, 1?2 and 1?4 being used; and
    (c) distances of less than 1?2 mile being expressed in yards to the nearest 10 yards; other than on the signs shown in diagrams 7012 and 7015, “yards” or the abbreviation “yds” may be used interchangeably.”


    “Distances may be expressed as “yards”, “yds”, “mile”, “miles”, “m”, “YARDS”, “YDS”, “MILE”, “MILES”, or “M”.”

    I shan’t quote any more. It’s depressing reading.


  13. Except that all of the miles to the nearest mile are measured to a rounded metric distance and just an approximated conversion of an actually measured rounded metric value appears. Yards are really exact metres. Right distance wrong word on the signs.

    You forgot the part about the tolerances that allow them to vary enough so that the signs can be placed at the closest rounded metric values. The law wants to see the words but allows the real units to be hidden.


  14. @Daniel 2016-04-02 at 00:57

    Can you quote and/or provide a link for the forgotten “part about the tolerances that allow them to vary enough so that the signs can be placed at the closest rounded metric values.” please.


  15. I agree with Daniel. At least one of the Traffic Signs Manuals (not law but published by the DfT in order to assist the folks who actually make and use signage get it right) actually states in several places (I’m paraphrasing) that, given the allowed tollerance of 10%, it is perfectly acceptible to place signage at the same metre distance as the number of yards stated on the sign (in fact, I’m sure I remember in one place it is actually encouraged with a comment added that under no circumstances though must you use “metre” on the sign itself)

    In fact you only need to be on a dual carrageway or motorway approaching road works to see that the “800 yard” “400 yard” and “200 yard” signs are always alligned almost precicely where the 100 metre markers are on the side of the road.


  16. @Charlie P I looked this up specially for you.

    There is a great example of the allowed 10% variance in Chapter 8 of the Road Signs Manual published by the government at

    You will find what you’re looking for there at the bottom of pages 83 and 272. The latter of these sums it up quite well:

    “The siting distance of the first sign is given in metres or miles. However, to comply with the Regulations the distances on supplementary plates must be shown in imperial dimensions. Tables and plans show the placing of road works signs in equivalent metric dimensions; this utilises part of the permitted 10% tolerance on the placing of signs (paragraph D4.4.8), e.g. signs showing 400 yards being placed at 400 m.”


  17. @Charlie P

    See Alex’s response. This is exactly what I was referring to. Even though this bit of knowledge has been revealed, there will still be those who insist it isn’t true.

    Oh dear! Let’s hope they don’t go out and measure “yard” signs to see how metric their placement is, then find one that isn’t and from it claim none are.


  18. @Alex Bailey
    That is good news about the metric placement of signs with “yards” printed on them. That means a simple overlay of “m” (with some opaque white stuff following the “m”) will nicely cover up the word “yards” once road signs finally get metricated … and the signs won’t have to be moved! Huzzah!


  19. @Alex Bailey 2016-04-07 at 17:50

    No, that’s from the Traffic Signs Manual (merely confirming what we already know – that UK engineering is fully metricated) and not from the Statutory Instrument regulating signs that was the subject of the query.

    Daniel had suggested, in response to quotes from the SIs by Peter Collier, that in them was a forgotten “part about the tolerances that allow them to vary enough so that the signs can be placed at the closest rounded metric values.” I was hoping to find that part, in those terms.


  20. @Daniel & Ezra this is the thing with the 10% variance, it actually gives a LOT of leeway and would likely allow most distance signs to be re-labeled in metric with little or no remeasuring.

    I’ve also suspected for a long time that speed limits would be much the same, 10% variance is allowed on speedometers on new cars (though they are only allowed to under-read) hence a brand new car off the forecourt with a speedo reading 70 mph could legally be doing anything between 63 and 70 (my own experience is that manufacturers err on the side of caution). I’ve determined my own car, a 5 year old Astra, actually reads 120 km/h when I’m doing 70 mph. The wide variance of speedometer accuracy means that whether speed limits effectively go up or down by a couple of km/h would make very little difference to vehicle speeds which would likely still be within their previous imperial limits (assuming people stick to the limit in the first place).

    In my view, all the reasons we’re given for not changing are nothing more than excuses.


  21. @Daniel 2016-04-09 at 12:57

    You said “This is exactly what I was referring to.” Well you confused us because this is from the “Traffic Signs Manual” (and we all know that UK road engineering was metricate decades ago) and not from the Traffic Signs Regulations Statutory Instruments (which specify the units for use on road signs and which are still largely imperial) as you implied in your earlier remark. No-one will be surprised to know that people who work in metric use metric measures, especially as 100 metres is less than 10 yards longer than 100 yards (the allowable tolerance for sign placement) – will they?


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