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The Great Britain road numbering scheme is a numbering scheme used to classify and identify all roads in Great Britain. Each road is given a single letter, which represents the road's category, and a subsequent number, of 1 to 4 digits. Introduced to arrange funding allocations, the numbers soon became used on maps and as a method of navigation. Two sub-schemes exist: one for motorways, and another for non-motorway roads. The scheme applies only to England, Scotland and Wales. Similar systems are used, though, in Northern Ireland (see Roads in Northern Ireland), the Isle of Man (see Roads in the Isle of Man), Jersey, Guernsey, and British overseas territories. All of these numbering schemes use identical basic conventions and road-sign designs. == History == Work on classification began in 1913 by the government's Roads Board to determine the quality and usage of British roads. This work was interrupted by the First World War 〔 and did not resume until the Ministry of Transport was formed in 1919, given authority to classify highways,〔 〕 and to allocate funding for road maintenance - authority for which was granted by section 17 (2) of the Ministry of Transport Act 1919. It created a classification system for the important routes connecting large population centres or for through traffic, which were designated as Class I, and roads of lesser importance, which were designated as Class II. The definitive list of these roads published on 1 April 1923 following consultations with local authorities.〔(【引用サイトリンク】title=List Of Class I and Class II Roads and Numbers (transcription) )〕 Government funding towards the repairs of these roads were set at 60% for the former and 50% for the latter. Shortly after this, the numbers started to appear in road atlases and on signs on the roads themselves, converting them into a tool for motorists in addition to their use for determining funding. The numbers of the roads changed quite frequently during the early years of the system as it was a period of heavy expansion of the network and some numbered routes did not follow the most usual routes taken. The Trunk Roads Act 1936 gave the Ministry direct control of the major routes and a new classification system was created to identify these routes. Originally these numbers beginning in T were to be made public, however this was eventually deemed unnecessary. With the introduction of motorways in the late 1950s, a new classification M was introduced. In many cases the motorways duplicated existing stretches of A-road, which therefore lost much of their significance and were in some cases renumbered. There was no consistent approach to this renumbering – some retained their existing number as non-primary A roads (e.g. the A40 running alongside the M40), others were given 'less significant' numbers (e.g. the A34 in Warwickshire became the A3400 after the M40 was built) and the remainder were downgraded to B or unclassified roads (e.g. the A38, which has been replaced by the M5 between Tiverton and Exeter). Occasionally the new motorway would take the name of the old A-road rather than having its own number. The most notable example of this is the A1(M).〔 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「Great Britain road numbering scheme」の詳細全文を読む スポンサード リンク
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