Symbols understood by everyone, everywhere (unlike abbreviations)

Do British road signs have symbols on them or abbreviations? (Martin Vlietstra asks a rhetorical question).

The EU directive on metrication lists the symbols that should be used to represent the various units of measure, but many British publications such as the The Traffic Signs Regulations and General Directions 2002â (see use symbols and abbreviations interchangeably.  What then is the difference?

The difference is that an abbreviation consists of letters that form an ordered subset of the word itself, while a symbol consists of arbitrary characters that may or may not be part of the text they represent.  However symbols are consistent across linguistic boundaries, abbreviations are not.

Perhaps the best way to compare the two is by example. A typical abbreviation is VAT. The table below shows how ‘VAT’ and ‘Value added tax’ are translated in other European languages:

English  VAT Value added tax

Dutch  BTW  Belasting over de toegevoegde waarde
French  TV  Taxe sur la valeur ajoute
German MwSt Mehrwertsteuer
Greek  Î¦Î Î  Î¦Ï?Ï?οÏ? Ï?Ï?οÏ?Ï?ιθέμενηÏ? αξίαÏ?
Spanish  IVA  Impuesto sobre el valor a adido

Now consider ‘kilometres per hour’.  The text below illustrates that the symbol ‘km/h’ is universal across Europe, even though the local word meaning ‘kilometre’ might not contain a ‘k’ or the local word meaning ‘hour’ might not contain a ‘h’.
Language      Symbol          Text

English          km/h             kilometres per hour
(The Republic of Ireland now has metric road signage)
French           km/h             kilomètres par heure
German         km/h             Kilometer pro Stunde
Greek            km/h             Ï?ιλιÏ?μεÏ?Ï?α ανά Ï?Ï?α
Italian            km/h             Chilometri allâ??ora
Polish            km/h             kilometrów na godzinÄ?Â
Portuguese    km/h             quilómetros por hora
Spanish         km/h             kilómetros por hora

These tables should make it clear why symbols are of great use on road signs, but abbreviations are not.

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11 Responses to Symbols understood by everyone, everywhere (unlike abbreviations)

  1. Alex Bailey says:

    It's interesting you mention the Traffic Signs Regulations and General Directions... which incorrectly uses "m" for miles and "T" for tonnes (the latter for those who don't know should be "t"). Over the years the DfT and it's predecessors have admitted that they are wrong about these, but so far only the "t" issue has been resolved (it is now allowed in TSRGD Section 17 Para 10 as a variation of "T") but the issue of "m" has not.

    No matter how hard I try, I still do a double take when I see a signs saying "Services 2m" on the motorway and have no idea which of " and ' are feet or inches!

  2. George Carty says:

    What's the best spoken abbreviation for kilometres per hour, given that I don't think "kay-pee-aitch" is allowed?

  3. Dave Brown says:

    George, I would have thought the best spoken form of the unit would be "kilometres per hour". Why abbreviate it? You wouldn't say "em-pee-aitch" currently; you either say "miles per hour", or "mile(s) an hour". In fact there should be no need to state the unit. As soon as the UK catches up with the rest of the world you will only need to state "50". If the context is vehicle speed then everyone will know that you mean 50 km/h because that's the unit that the human race uses to measure vehicle speed. (The only exception will be when communicating with residents of the USA - but I don't think they'll stay in the past forever.)

  4. Markus Kuhn says:

    Once every speed-limit sign on this planet uses km/h, the "red circle on white background" will become the international standard symbol for "speed limit in km/h". Additional unit symbols such as "km/h" or "mph" are only needed for as long as two different units are used on speed-limit signs. Ultimately, a unit symbol just clutters the view and should be dropped if the type of sign already unambiguously represents both the quantity ("speed limit") and unit ("km/h") shown.

    Unit symbols make more sense on distance signs, for two reasons:

    1) Distance signs come in many different shapes, therefore adding "km" to a number clarifies that this is a distance (rather than a road number, exit number, etc.).

    2) While speed limits fall roughly within a single decade (20-200 km/h), distances posted on road signs can cover at least five decades (5-500000 m). A unit symbol helps here to resolve any ambiguity that might remain.

  5. Daniel Jackson says:


    ' means minutes as applied to angles and " means seconds as applied to angles.

    Did you know that in the US the number symbol # is called a pound sign and is suppose to mean pounds of weight. As in handwritten signs showing the weight of goods using this symbol.

    Tomatoes: $1.99 #

    On a telephone, an automatic operator may cue you to use the "pound sign", meaning the # symbol after entering numbers.

  6. Alex Bailey says:


    I know what ' and " are supposed to mean... I was merely pointing out that their normal use in the UK is much more confusing than the continuing use of "m = mile".

    To be brutally honest, from the viewpoint of getting metric used here in the UK I am quite happy to tolerate "T" for tonnes or KM where km should be used (outside of "official" signage and documentation) because at least it means that somebody is trying. I just can't abide the fact that a government department who admitted that "m" and "M" shouldn't be used for miles 18 years ago has done nothing to fix it - and it almost looks intentional!

    (Oh... and I work for an American IT company and have spent some time in North America so have had much experience of the # - which interestingly occupies the same key on a US keyboard as the British £ does on the UK keyboard!)

  7. Seares says:

    The one I find obscure sometimes is l for litre. It can be mistaken in many fonts for a 1, especially if written without a space. If there is a space it can look like an I. Maybe that's why you often see ltr or litre used to avoid confusion.

  8. Martin Vlietstra says:

    According to the CGPM standard, symnols for units of measure that are named after people start with an uppercase letter (eg W, Pa, Hz etc), others start with a lower case letter (eg m, s, g). They have made an exception in the case of the litre with may be written as either upper case or lower case.

    For more information, please visit the BIPM website. The entire SI brouchure can be accessed from Rules regarding the use of upper and lower case letters can be found in Chapter 5 of the brochure.

    My own preference is to use lower case if there is a prefix (eg 100 ml), but to use upper case if there is no prefix (eg 5 L).

  9. Joe Oakley says:

    Um... do the people who enjoy using the mile get a look in? Whilst the mile is still the official unit of road length, I'm sure the symbol/abbreviation 'm' will do fine. If any motorist driving along the motorway sees a sign for services in 2m and then turns off two metres later, then they should go see an optician.

  10. Alex Bailey says:

    Joe... it's not a matter of needing optical correction. It should not be necessary to know the context when using a measure - metric, unlike imperial, does not need context (i.e. type of liquid when using barrels, whether US or UK when using gallons, fl oz, etc). I know that when I see "m" on a road sign it means "metres" in height and width and "miles" in distance but this should not be necessary - all children since the 1970's have been educated to think "m=metre" and this just confuses matters. Even my 10 year old son thinks it's all some sort of joke!

    The DfT (well, it's predecessor) have recognised for many years that "m" isn't being used correctly but still choose to do nothing about it.

  11. Clifford Dudley says:

    Seares: this is why Unicode gives us a special symbol for litres. The code point is U+2113, and it looks like a script lower case letter 'l'. It is not included in all fonts, but it is, for example, in Arial. I'm not sure if this forum software will cope with it, but I'll try anyway: â„“

    Here in Germany you'll see "kmh" as often as "km/h", and it usually pronounced "ka-em-ha" (not "ka-em-pro-ha" or "ka-em-strich-ha").

    In English, it should, in theory, be either "km/h" or "kmph" (the p replacing the /, like in "mph"). However, you just as often see "kmh".

    As for saying it out loud, the problem is that, like it or not, "miles an hour" rolls more smoothly off the tongue than does "kilometres an hour" (whether you stress the 'i' or the 'o'), which, to my ears, is all the more reason for allowing "kay-em-(h)aitch".


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