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A metrication programme for the United Kingdom was announced by the government in 1965 at the behest of the engineering industry and received government approval on condition that its implementation was voluntary, that it was implemented on an industry-by-industry basis and that costs were absorbed where they fell. The metrication of transport related engineering and operational standards, including those used in vehicle design, took place over the following decades, though metrication of certain related sectors had already occurred before this. Not all of British transport operational standards have been metricated – in the railway industry, although metric units and distances are used on many new systems, most pre-existing systems have retained imperial units, especially for speed and distance. For roads, the engineering of new roads will be to metric standards, but all road signs except those related to vehicle weight limits, use imperial units only, or for those related to vehicle dimension limits may use dual imperial/metric units. Nautical and aviation operational practice is to retain the use the knot (unit) for speed, the nautical mile for distance and, in the case of aviation, the foot for altitude. ==Background== Historically, British industry opposed metrication on the ground that most of British exports went to countries that used the imperial or US customary systems of units. By the 1960s, changing trade patterns meant that this was no longer the case, and in 1965 the Federation of British Industry (now the Confederation of British Industry) initiated a change to the metric system. The government agreed on condition that the changeover was voluntary on a sector-by-sector basis, that costs would be absorbed where they fell and that there would be minimal legislation. In some cases it was appropriate to use ''hard metrication'' and in other cases ''soft metrication'' – soft metrication being defined as "the conversion of ... non-SI measurements to equivalent SI units, within the established measurement tolerances. In general, 'soft metric' products will not differ physically from analogous () products. Until 1969, when the Metrication Board was set up, the Royal Society and the British Standards Institution took the lead. When the Metrication Board was set up, much of the groundwork had been done, and metrication of many engineering sectors, including transport, was under way. From the early to mid-1970s, the lack of compulsion slowed the process of metrication, so a draft order was prepared to complete the process. However, the Government, which had a very small majority, declined to proceed with the order.〔(【引用サイトリンク】Historical Perspectives on Metrication by Jim Humble who was the last Director of the UK Metrication Board. )〕 When Britain joined the European Economic Community in 1973, it was obliged to adapt local law to accommodate EEC directives that were in place. One of these directives, 71/354/EEC, required a harmonisation of units of measure "for economic, public health, public safety or administrative purposes". By the late 1970s the British metrication programme had run out of steam and, at Britain's request, Directive 71/354/EEC was superseded by Directive 80/181/EEC, which among other things permitted the use of miles, yards, feet, inches and fathoms in the United Kingdom, and knots until 1989 (subsequently extended to 1994). As from 1 January 1990, the use of miles, yards, feet and inches was restricted to "Road traffic signs, distance and speed measurement()" only. The directive did not apply to areas of transport that were subject to governmental international agreements. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Metrication of British transport」の詳細全文を読む スポンサード リンク
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