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Revision as of 17:32, 29 March 2004 by Mark Richards (talk | contribs) (=Metrication in Europe= As of 2004 link)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)Metrication, or metrification, is the process of converting from the various older systems of units used throughout the world (especially the "Imperial" or "American" systems that derived from the United Kingdom), to the metric or SI (Système International) system.
Introduction
All countries in the world use the metric system to a greater or lesser extent, and most have abolished the use of non-metric units for almost all purposes; notable exceptions are the time units from second to year and mile as a unit of distance. Apart from the US, Liberia and Myanmar have also not officially adopted the system.
In addition, in a few more specific areas, non-metric measures retain worldwide dominance. These are notably air and sea transport, where the knot remains the prime unit of velocity for maritime navigation, and for safety and flexibility reasons aircraft flying heights are universally calculated in feet rather than metres.
With the ever increasing importance of global trade, increasing harmonization of units of measurement and standards has taken place. Metrication generally requires legislative action to overcome resistance and inertia among populations familiar with another system, i.e. legal requirements to use metric units in commerce, and the eventual prohibition of the use of nonmetric units. Businesses which convert to metric standards frequently cannot compete with those which do not, due to the preference of consumers for the familiar. Those countries which have attempted to engineer a voluntary conversion to the metric system, such as the United States, have been largely unsucessful compared to those which have made the metric system legally compulsory.
Use of multiple standards of units was a contributing factor in the loss the Mars Climate Orbiter in its crash on Mars. The manufacturer of the spacecraft had designed the navigation system to be programmed in Imperial measurements, whereas the navigation team at NASA's Jet Propulsion Laboratory in Pasadena, California incorrectly assumed the spacecraft required metric units.
Often, metrication involves not only changing the units with which quantities are measured, but also redesigning standards to use metric sizes. For example, 1 inch is a rational size for a bolt if the bolt is to be measured in inches, but the metric equivalent of 25.40 mm is not a rational size, and thus the metric size of 25 mm is substituted. This requires the redesign not only of the bolt, but also of many other products and structures that would contain the bolt.
Metrication in the United States
The main exception to standardised metrication is the United States. Although metrication is the official policy of the United States, the progress of metrication has been much slower in the United States than in the rest of the world. The nonmetric units continue to be frequently used in everyday life, and in commerce and engineering. However, change has happened; with most products within the U.S. now labelled with both metric and nonmetric units, and a number of companies and government agencies switching to metric standards. The U.S. (along with other countries) continues to use only miles for road distance signs. Originally U.S. legislation set October 2000 as a deadline by which states must undertake construction work and statistics in metric for states to be eligible for Federal funding, but that requirement has since been rescinded. Some states, such as California, have experimented with metric road signs, but there are as yet no plans for large-scale conversion. Metric units are generally used in scientific applications in the USA with some few exceptions like BTUs and calories.
Metrication in Europe
Europe generally uses metric units for almost all purposes, and uses metric standards. Some nonmetric units are still popularly used in some countries, including the pint in the UK.
Metrication was first begun in France during the French Revolution, although many of these revolutionary efforts were abandonned. The metrication of units of time was originally a part of the plan, but this failed to receive popular support. Until about 1900, metrication had spread over much of continental Europe.
Metrication for all EU member states is required under EU law, with a target date of 2009 by which all products in Europe must be sold only by metric units, with some limited exceptions.
The United Kingdom and Ireland are the main exceptions; these countries are in the process of phasing out the legal status of most nonmetric units. Thus they use a mixture of metric and nonmetric units for different purposes. The United Kingdom is currently in the process of abolishing the use of most nonmetric units; as of 2000, all loose goods sold by mass must be sold using metric units, a process that has been resisted by some so-called 'metric martyrs', leading both to legal appeals and to acts of vandalism such as the defacing of metric road signs. UK policy is to eliminate almost all nonmetric units by 2009, except for road signs.
Ireland generally uses metric measurements more than the United Kingdom, but still less than the rest of Europe. Confusingly, road distance signs were progressively converted to kilometres during the 1990s, but to date speed limit signs (and the associated road traffic legislation) are still in mph.
Metrication in Canada
Canada has converted to the metric system for most purposes, including temperature in weather reports, speed limits, road signs, and sizes of most products. However there is still significant use of nonmetric units and standards in some sectors of the Canadian economy, mainly due to the close proximity to the United States. Notable among these are stationery and construction lumber and gyproc. Retrofitting metric sized wallboard on old 16" spaced studs can be significantly difficult.
Also, many Canadians still use nonmetric units for common informal measurements. A person's height and weight are normally calculated using the US units foot and pound while area (for reasonably small areas such as floorspace) is measured in square feet. Fahrenheit is used for cooking as are US cooking measurements. Grocery stores advertise products sold by weight in both price per pound and per kilogram but the pound is prominent mainly because the price per pound appears cheaper than the price per kilogram.
Metrication in Australia and New Zealand
Australia and New Zealand have largely converted to the metric system, but nonmetric units are still sometimes used in popular conversation, especially to measure body height or mass. (Many Australians know their height in feet and inches but their mass in kilograms.)
See also: anti-metrication, conversion of units, decimalization