Great Britain road numbering system

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 in Northern Ireland (see Roads in Northern Ireland), the Isle of Man (see Roads in the Isle of Man), Jersey and British overseas territories. These other numbering schemes use identical basic conventions and road-sign designs.

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 was published on 1 April 1923 following consultations with local authorities. Government funding towards the repairs of these roads were set at 60% for the former and 50% for the latter.

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