Motorway

A motorway (in the United Kingdom, Ireland, New Zealand and some Commonwealth nations) is both a type of road and a classification. Motorways may also be regarded as highways designed to carry a large volume of traffic where a normal road would not suffice or would be unsafe, usually between cities. In the UK they are predominantly dual-carriageway roads, usually with three lanes in each direction although four-lane and two-lane carriageways are also common, and all have grade-separated access.

Route numbering

In the United Kingdom, motorways usually adopt the number of the nearest "A" road. The A road usually continues to also use that number, thus allowing both an "A1" road and "M1" motorway to exist as full complementary routes.

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In the Republic of Ireland, motorway and national route numbering does not follow the same convention. As of 2005, all motorways in the Republic are part of, or form, National Primary Routes. These routes are numbered in series, using numbers from 1 to 33 (and separately from the series - 50), which apart from on motorways, carry an "N" prefix.

Related Topics:
2005 - National Primary Route

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In the Republic of Ireland, motorways use this route number (of the national route they form part of), albeit with the M prefix rather than N. In most cases, the motorway has been built as a bypass of a road previously forming the national route (e.g. M7 bypassing roads previously forming the N7) - the bypassed roads are reclassified as Regional Roads, although updated signposting may not be provided for some time, and adherence to signage colour conventions is lax (regional roads have black-on-white directional signage, national routes use white-on-green).

Related Topics:
N7 - Regional Road

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The M50, an entirely new national route, is an exception to the normal inheritance process - as it does not replace a road previously carrying an "N" number. The M50 was nevertheless legislated as the "N50" route (despite having no non-motorway sections). The M50's designation was chosen as a recognisable unique number (As of 2005 N34 is the next unused National Primary Route designation).

Related Topics:
M50 - As of 2005

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