Dear Editor, In the Irish Times, last Friday December 24, you reported that:
'Conversion to kilometres will mean a reduction in speed limits' in an article by Martin Wall. This article contained an error of style and several errors of fact. I will deal with the error of style first. 'The use of k.p.h. is not the correct style for kilometres per hour. The correct symbol for kilometres per hour is km/h and when this is used in conjunction with a number (as it usually is) it is written as (say) 60�km/h with a narrow non-breaking space between the number and the unit symbol. The International System of Units does not use abbreviations but symbols; km/h works as an abbreviation in English but it does not work so well in Chinese where km/h is also the symbol for kilometres per hour. The expression k.p.h. seems to be an orphan form of 'The Irish Times' own devising, and as an orphan it definitely has not come from any reputable institution. I know that the Irish Department of Transport use the correct unit, km/h as does the National Standards Commission in Australia. I have referred to the 'International System of Units (SI) 7th Edition 1998', and the website of the Bureau Internationale de Poids et Mesures (BIPM), and they use km/h. To make sure, I also checked with the National Institute of Standards and Technology in the USA; they use km/h. All of these sources recommend km/h as the correct international symbol for kilometres per hour. The unit symbol, km/h, is correct because it demonstrates how the value was obtained. If I drive 120 kilometres in 2 hours, I then calculate my speed as 120 divided by 2 to get 60 km/h. The fact that I divided one number by another is included in the solidus (or slash) contained within the unit, km/h. Your travesty of an abbreviation, k.p.h, is quite meaningless in any international or mathematical context. You are wrong in using k.p.h as an abbreviation for kilometres per hour. You are wrong because you are ignoring all international agreements and standards. You are also wrong because what you write, in the abbreviation k.p.h, is simply wrong internationally and wrong mathematically. And now for the errors of fact. My reference is the official Irish Government website at: http://www.gometric.ie/faq.html You say: >The changeover to metric road signs from January 20th is expected to cost >around EUR 30 million. The sum quoted officially is EUR 9 million, plus EUR 2 million for a publicity campaign. You say: > The move will mean the installation of up to 35,000 new signs across the > country. The number of signs is 58 000 new or replacement signs.. These will comprise 23�000 new signs and 35�000 modified signs. When you check these facts on the official Irish Government website at: http://www.gometric.ie/faq.html where you will also see that the Irish Government has designed the new signs to use the correct international symbol for kilometres per hour, km/h, for Irish road signs. Cheers, Pat Naughtin ASM (NSAA), LCAMS (USMA)* PO Box 305, Belmont, Geelong, Australia Phone 61 3 5241 2008 Pat Naughtin is the editor of the free online monthly newsletter, 'Metrication matters'. You can subscribe by going to http://www.metricationmatters.com and clicking on 'Newsletter'. * Pat is the editor of the 'Numbers and measurement' chapter of the Australian Government Publishing Service 'Style manual � for writers, editors and printers', he is an Accredited Speaking Member (ASM) with the National Speakers Association of Australia, and a Lifetime Certified Advanced Metrication Specialist (LCAMS) with the United States Metric Association.
