Great Britain road numbering scheme

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 Great Britain (i.e. England, Scotland and Wales); similar systems are used in Northern Ireland, the Isle of Man, Jersey and British overseas territories. These other numbering schemes use similar conventions.

United Kingdom A road zones
The numbering zones for A & B roads in Great Britain


Work on classification began in 1913 by the government's Roads Board, with the aim of denoting the quality and usage of British roads. The work was interrupted by the First World War.[1] It did not resume until the Ministry of Transport was formed in 1919 and given authority to classify highways[2] and to allocate funding for road maintenance, authority for which was granted by section 17 (2) of the Ministry of Transport Act 1919.[3] A classification system was created, under which important routes connecting large population centres, or for through traffic, were designated as Class I, and roads of lesser importance were designated as Class II. The definitive list of those roads was published on 1 April 1923, following consultations with local authorities.[4][5] Government funding towards the repairs of these roads were set at 60% for the former and 50% for the latter.[6]

Shortly after this, the numbers started to appear in road atlases and on signs on the roads themselves, making them a tool for motorists[7] in addition to their use for determining funding. The numbers of the roads changed quite frequently during the early years of the system, because it was a period of rapid expansion of the network and some numbered routes did not follow the most usual routes taken.[8] The Trunk Roads Act 1936 gave the Ministry direct control of major routes and a new classification system was created to identify these routes. Originally, those numbers beginning in T were to be made public, but that was eventually deemed unnecessary.[1]

With the introduction of motorways in the late 1950s, a new classification of "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 the renumbering – some A roads retained their existing number as non-primary 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 was 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 that is the A1(M).[9]

Zoning system

Crouch Hill - - 1600248
This sign at Crouch Hill shows two road numbers in Zone 2.


In England and Wales the road numbering system for all-purpose (i.e. non-motorway) roads is based on a radial pattern centred on London. In Scotland the same scheme is centred on Edinburgh. In both cases the main single-digit roads normally define the zone boundaries.[3] The exception is between Zones 1 and 2, where the River Thames defines the boundary so that all of Kent is in Zone 2.[10]

The first digit in the number of any road should be the number of the furthest-anticlockwise zone entered by that road. For example, the A38 road, a trunk road running from Bodmin to Mansfield starts in Zone 3, and is therefore numbered with an A3x number, even though it passes through Zones 4 and 5 to end in Zone 6. Additionally, the A1 in Newcastle upon Tyne has moved twice. Originally along the Great North Road, it then moved to the Tyne Tunnel, causing some of the roads in Zone 1 to lie in Zone 6. The designated A1 later moved to the western bypass around the city, and roads between the two found themselves back in Zone 1. For the most part the roads affected retained their original numbers throughout.

Elsewhere when single-digit roads were bypassed, roads were often re-numbered in keeping with the original zone boundaries.[10]

In a limited number of cases road numbering does not necessarily follow the rules with some anomalously numbered.


Motorway number zones in England and Wales map
Motorway number zones of England and Wales

Motorways first came to Britain over three decades after the advent of the A-road numbering event, and as a result required a new numbering system. They were given an M prefix, and in England and Wales a numbering system of their own not coterminous with that of the A-road network, though based on the same principle of zones.[11] Running clockwise from the M1 the zones were defined for Zones 1 to 4 based on the proposed M2, M3 and M4 motorways. The M5 and M6 numbers were reserved for the other two planned long distance motorways.[12] The Preston Bypass, the UK's first motorway section, should have been numbered A6(M) under the scheme decided upon, but it was decided to keep the number M6 as had already been applied.[12] The first full length motorway in the UK was the M1 motorway.

Shorter motorways typically take their numbers from a parent motorway in contravention of the zone system, explaining the apparently anomalous numbers of the M48 and M49 motorways as spurs of the M4, and M271 and M275 motorways as those of the M27.[13] This numbering system was devised in 1958–59 by the then Ministry of Transport and Civil Aviation, and applied only in England and Wales. It was decided to reserve the numbers 7, 8 & 9 for Scotland.[14] In Scotland, where roads were the responsibility of the Scottish Office (Scottish Government after 1999), the decision was taken to adopt a scheme whereby motorways took the numbers of the all-purpose routes they replaced. As a result, there is no M7 (as no motorway follows the A7), and when the A90 was re-routed to replace the A85 south of Perth, the short M85 became part of the M90.[13]

A roads

Single-digit A roads

In England and Wales, the six single-digit numbers reflect the traditionally most important radial routes coming out of London. Starting with the A1 which heads due north, numbers were allocated sequentially in a clockwise direction, thus:[3]

  • A1 London to Edinburgh, (Also known as the Great North Road)
  • A2 London to Dover, (The southern part of Watling Street, also known as the Dover Road), however, the A2 beyond Rochester has been replaced by the M2.
  • A3 London to Portsmouth, (Also known as the Portsmouth Road)
  • A4 London to Avonmouth, (Also known as the Great West Road or the Bath Road), although this route is not used as a long distance road since the completion of the M4.
  • A5 London to Holyhead, (The Northern part of Watling Street)
  • A6 Luton to Carlisle (The A6 originally started in Barnet on the old A1. When the A1 was moved onto the Barnet Bypass in the 1950s, the A6 was cut back to the A1/A1(M) junction (later A1/M25 junction). Further renumbering in the St Albans area means that it now starts in Luton town centre. The old route is numbered as A1081).

Similarly, in Scotland, important roads radiating from Edinburgh have single-digit numbers, thus:

While these routes remain the basis for the numbering of the A road network, they are no longer necessarily major roads, having been bypassed by motorways or other changes to the road network.

Other A roads

These radials are supplemented by two-digit codes which are routes that may be slightly less important, but may still be classified as trunk routes, although many of these routes have lost a lot of their significance due to motorway bypasses, or the upgrading of other A-roads. These routes are not all centred on London, but as far as possible follow the general principle that their number locates them radially clockwise from the associated single digit route.[15] For example, the A10 (London to King's Lynn) is the first main route clockwise from the A1, the A11 (London to Norwich) is the next, then the A12 (London to Great Yarmouth) and the A13 (London to Shoeburyness); the next radial is the A2, followed by the A20 (London to Dover), and so on. These roads have been numbered either outwards from or clockwise around their respective hubs, depending on their alignment.

The system continues to three and four digit numbers which further split and criss-cross the radials. Lower numbers originate closer to London than higher numbered ones. As roads have been improved since the scheme commenced, some roads with 3 or 4 digit numbers have increased in significance, for example the A127, A1079 and A414. New routes have also been allocated 3 or 4 digit numbers, for example the Edinburgh City Bypass is the A720.

The Major Road Network is a proposed classification of major local-authority controlled A roads that the government committed to implementing in 2017, with the aim of better targeting road funding.[16]

Lists of A roads

Trunk roads and primary routes

Some A roads are designated trunk roads, which implies that central government rather than local government has responsibility for them. A more recent classification is that of primary routes, the category of recommended routes for long distance traffic. Primary routes include both trunk and non-trunk roads.

Motorway sections

Some sections of A roads have been improved to the same standard as motorways, but do not completely replace the existing road; they form a higher standard part of the route for those which are not excluded.[9] These sections retain the same number but are suffixed with (M), for example the A1(M) and A404(M).[9] There have been occasions where this designation has been used to indicate motorway bypasses of an existing road, but the original retains the A road designation, for example A3(M), A329(M), A38(M), A48(M) and A627(M).[9]

Other classifications

B roads are numbered distributor roads, which have lower traffic densities than the main trunk roads, or A roads. This classification has nothing to do with the width or quality of the physical road, and B roads can range from dual carriageways to single track roads with passing places. B roads follow the same numbering scheme as A roads, but almost always have 3- and 4-digit designations.[17] Many 3-digit B roads outside the London area are former A roads which have been downgraded owing to new road construction; others may link smaller settlements to A roads.

Lists of B roads

Minor roads

C32 Rare C road sign in Ribblesdale - - 260339
C road sign in Ribblesdale, North Yorkshire

Roads and lanes with yet lower traffic densities are designated as unclassified roads commonly using C, D and U prefixes but, while these are numbered, in general this is done for use by the local authorities who are responsible for maintaining them and the non-unique numbering is in a local series which usually does not appear on road signs;[18] use of local numbers on signs in England is "not advised".[19] Exceptions to this are known however both in the form of numbers on signs[20][21] and past use of prefixes H and V on signs in Milton Keynes where main roads have a regular grid system. These designations are however used when planning officers deal with certain planning applications, including the creation of a new vehicular access onto a highway.


  1. ^ a b Marshall, Chris. "In Depth – Road Numbers – How it happened". CBRD. Archived from the original on 24 July 2011. Retrieved 28 December 2007.
  2. ^ "FOI Request – Road numbering" (PDF). Department for Transport. 5 August 2005. Archived from the original (PDF) on 12 May 2009. Retrieved 27 December 2007.
  3. ^ a b c "Road Numbering". The Vauxhall Motorist. Vauxhall Motors. January 1935. Retrieved 29 December 2007.
  4. ^ "List Of Class I and Class II Roads and Numbers (transcription)". HMSO and National Archives files MT39/241 and MT39/246.
  5. ^ "In Depth – Road Numbers – How it happened". Letter to editor of Encyclopædia Britannica from Ministry of Transport. 6 March 1941. Archived from the original on 24 July 2011. Retrieved 28 December 2007.
  6. ^ Porter, John; Bridle, Ron (2002). The Motorway Achievement. Thomas Telford. p. 27. ISBN 0-7277-3196-3.
  7. ^ Wykes, C. H. (7 July 1959). "How the Motorways were Numbered". Ministry of Transport Memorandum. Pathetic Motorways. Retrieved 28 December 2007. Professional drivers make great use of the system and I do not think that it is a matter of very great moment that some private motorists prefer to work on names alone.
  8. ^ "1920s Renumbering".
  9. ^ a b c d Wykes, C. H. (30 September 1959). "How the Motorways were numbered". Ministry of Transport Memorandum. Pathetic Motorways. Retrieved 28 December 2007. Where, however, a motorway is merely a by-pass along an existing route such as the Doncaster Bypass along Route A.1, it will not be given a separate M number, but in order to make it clear that it is a motorway and that motorway Regulations apply to it, the letter M will be added in brackets to the existing route-number – e.g. A1(M) for the Doncaster Bypass. This will preserve the continuity of the route-number of long-distance all-purpose roads. Generally speaking by-passes that are eventually linked to form a continuous motorway will preserve the existing route-number (plus M in brackets) until they are so linked.
  10. ^ a b "Numbers for A and B-roads". Retrieved 25 January 2015.
  11. ^ "How the Motorways were numbered". Ministry of Transport memorandum. Pathetic Motorways. November 1961. Retrieved 28 December 2007. Mr Usborne explained that his proposal followed the principle of the sector system on which trunk and classified roads were already numbered, although the sectors themselves, which were six in number, were somewhat different.
  12. ^ a b Wykes, C. H. (7 July 1959). "How the Motorways were Numbered". Ministry of Transport Memorandum. Pathetic Motorways. Retrieved 28 December 2007. The result of applying such a system to current plans would be the appropriate numbering of the London – Yorkshire Motorway as M.1, with provision for extension still further north as required. M.2 would be reserved for any possible Channel Ports Motorway, the Medway Towns Bypass meanwhile becoming A.2(M) and the Maidstone Bypass A.20(M). M3 would be reserved for a motorway in the direction of Portsmouth – Southampton, starting with the Exeter Radial. M.4 would be applied to the South Wales Radial. The remaining single figure numbers would not be required for radials and could therefore, continuing clockwise, be applied to the Bristol – Birmingham Motorway – M.5 and the Penrith – Birmingham plus Dunchurch Bypass – M.6. The Preston Bypass was numbered M.6 in advance and although under these proposals it should initially have been A.6(M), I see no reason to make any change from M.6 pending the ultimate completion of the whole route.
  13. ^ a b "Numbers for motorways". 25 January 2015.
  14. ^ Payne, B. A. (10 July 1959). "How the Motorways were Numbered". Ministry of Transport Memorandum. Pathetic Motorways. Retrieved 28 December 2007. 1. The numbers 7, 8 and 9 which were used in Scotland should be reserved for the use of Scottish Motorways.
  15. ^ "CBRD » British Roads FAQ".
  16. ^ "Proposals for the Creation of a Major Road Network: Consultation" (PDF). Department for Transport. Retrieved 5 February 2018.
  17. ^ "CBRD » British Roads FAQ".
  18. ^ Marshall, Chris. "What is a C-road?". CBRD. Retrieved 29 December 2007.
  19. ^ DfT - Guidance on Road Classification and the Primary Route Network
  20. ^ - C roads
  21. ^ Marshall, Chris. "C-Roads". CBRD. Retrieved 14 September 2016.

Further reading

  • Bancroft, Peter; Andrew Emmerson (May 2007). A, B, C and M: Road Numbering Revealed. Capital Transport Publishing. ISBN 978-1-85414-307-5.

External links

A1 in London

The A1 in London is the southern part of the A1 road. It starts at Aldersgate in the City of London, passing through the capital to Borehamwood on the northern fringe of Greater London, before continuing to Edinburgh. The road travels through the City and three London boroughs: Islington, Haringey and Barnet, which include the districts of Islington, Holloway, Highgate, Hendon and Mill Hill, and travels along Upper Street and Holloway Road, crossing the North Circular Road in Hendon, a district in the London Borough of Barnet.

The A1 is the most recent in a series of routes north out of London to York and beyond. It was designated in 1921 by the Ministry of Transport under the Great Britain road numbering scheme, comprising existing roads and streets, mostly historic, and later using stretches of purpose-built new roads in what is now the outer London borough of Barnet. The Archway Road section was built by Thomas Telford using Roman cement and gravel, an innovative technique that was used there for the first time, and is the basis for modern road building. The route closely follows the historic route of the Great North Road, though from 1954 it has diverted round the congested suburbs of Finchley and High Barnet along modern roads constructed in the 1920s and 1930s.

The A1 is one of London's main roads, providing a link to the M1 and the A1(M) motorways, and on to the Midlands, Northern England and Scotland. Despite this, its main use is to connect a number of neighbourhoods within north London; less than 5% of its vehicles are through traffic – the bulk is local. The roads along which the A1 route travels are the shared responsibility of the local boroughs, the Greater London Authority, and the British Government via the Department for Transport.

A2020 road

The A2020 is a previous road in Kent but has been renumbered to A20 following the construction of the M20 motorway.

Between 1960 and 1961, two sections of (what is now known as) the M20 motorway were built between junctions 5 and 8. This was known as the Maidstone Bypass and was renumbered the A20(M) as it bypassed the stretch of the A20 through Maidstone. The A20 road was then renumbered as the A2020, which is the source of the name of the 20/20 Business Park, situated close to junction 5 of the present M20.

However, during 1971 and later in 1977, the A20(M) was extended westwards towards London and was renamed the M20 motorway, and as a result the A2020 reverted to being the A20. The 20/20 Business Park has kept its name, however.

A500 road

D road can also apply as a road designation under the Great Britain road numbering schemeThe A500 is a major primary A road in Staffordshire and Cheshire, England. It is dual carriageway for most of its length and connects Nantwich, junctions 16 and 15 of the M6 motorway with the city of Stoke-on-Trent. It is known locally as the D-Road (D is also the Roman numeral representing the number 500). In 2004 the road was stated as carrying 60,000 vehicles a day through Stoke.It was built to provide links between Stoke-on-Trent and the M6, before being extended to Nantwich. Construction has taken place over several stages, beginning in 1962, with the final section of the original route being completed similar to the original plans in 2006. As a trunk road it is maintained by the Highways Agency.

A6023 road

The A6023 road runs from Conisbrough to Rotherham via Mexborough and Denaby Main. It passes Conisbrough Castle.

A6079 road

The A6079 is a road in Northumberland, northern England, that runs eight miles (13 km) from Hexham to the A68 road. The road begins off the A69 road to the north of Hexham, before passing the villages of Acomb and Wall before meeting the B6318 road just to the south of Chollerford - unusually, traffic on the A6079 must give way to the traffic on the B6318, despite the fact that "A"-roads are more important than "B"-roads. The A6079 continues through the village of Chollerton, and terminates at its junction with the A68 road to Edinburgh, nine miles (14 km) north-west of Corbridge.

A60 road

The A60 is a road linking Loughborough in Leicestershire, England, with Doncaster in South Yorkshire, via Nottingham.It takes the following route:








West Bridgford






Market Warsop


Carlton in Lindrick




A62 road

The A62 is a major road in Northern England that runs between the two major cities of Manchester and Leeds, covering a distance of 38.5 miles (62.0 km).

A643 road

The A643 is a main road in West Yorkshire, England.

It starts at the Armley Gyratory and ends at junction 23 of the M62 Motorway (Mount Roundabout, Outlane, Huddersfield) and is approximately 18 miles (29 km) long.

The road goes through Morley, Birstall, Gomersal, Cleckheaton, Brighouse, Rastrick to the north of Huddersfield (Ainley Top and Mount).

The Leeds United AFC football stadium is named after the road part of the A643 that passes it, Elland Road. This road is so called because the A643 originally ended in town of Elland near Halifax.

A647 road

The A647 is an A road in West Yorkshire, England that begins in Leeds and ends in Halifax. The road is 17 miles (27 km) long.

A661 road

The A661 is an A road running between Wetherby and Harrogate (via Spofforth) in West and North Yorkshire, England. The road is 8.4 miles (14 km) in length.

The A661 begins in West Yorkshire at the South Wetherby roundabout (adjacent to the Ramada Jarvis Hotel) where it intersects with the A58 (St Helens to Wetherby via Leeds, Bradford and Halifax) and slip roads for the A1.

The A661 finishes at the Empress roundabout in Harrogate, where it intersects with the A6040 towards the town centre, and A59, towards Knaresborough and York in one direction and Skipton in the other.

A949 road

The A949 is a major road in Sutherland, in the Highland area of Scotland. It has staggered junctions with the A9. From the A949 the A9 runs (1) generally north to Thurso and (2) generally south to Tain, Inverness, Perth, Stirling and Falkirk.

From the A9, just north of Tain and the Dornoch Firth, the A949 runs (1) west to the A836 at Bonar Bridge and (2) east to Dornoch. The junctions are about 1 mile (2 km) apart. The section of the A949 between Bonar Bridge and the first junction on the A9 on the north side of the Dornoch Firth was part of the A9 until the opening of the Dornoch Firth Bridge in 1991.Bonar Bridge is about 10 miles (16 km) west of the A9, at the neck of the Kyle of Sutherland. Dornoch is about 2 miles (3 km) east, at the mouth of the Dornoch Firth.

Within Dornoch the A949 has a junction with the B9168.

The A949 road goes west of the A9 road at a roundabout, merging into Zone 8 of the Great Britain road numbering scheme. It is one of the few Zone 9 roads to go west of the A9.

Anomalously numbered roads in Great Britain

In the Great Britain road numbering scheme, the country is divided into numbered zones, the boundaries of which are usually defined by single-digit roads. The first digit of a road's number should be the number of the zone it occupies. If the road occupies multiple zones, then the furthest-anticlockwise zone is the correct one. The following tables list all British roads which are anomalously numbered. Roads in bold lie completely outside their "correct" zone; all other roads run for some length in their "correct" zones but trespass into zones anticlockwise of this zone. A further table lists duplicated road numbers.

B roads in Zone 2 of the Great Britain numbering scheme

B roads are numbered routes in Great Britain of lesser importance than A roads. See the article Great Britain road numbering scheme for the rationale behind the numbers allocated.

B roads in Zone 7 of the Great Britain numbering scheme

B roads are numbered routes in Great Britain of lesser importance than A roads. See the article Great Britain road numbering scheme for the rationale behind the numbers allocated.

B roads in Zone 8 of the Great Britain numbering scheme

B roads are numbered routes in Great Britain of lesser importance than A roads. See the article Great Britain road numbering scheme for the rationale behind the numbers allocated.

B roads in Zone 9 of the Great Britain numbering scheme

B roads are numbered routes in Great Britain of lesser importance than A roads. See the article Great Britain road numbering scheme for the rationale behind the numbers allocated.

C road

C road may refer to:

In Malaysia, Malaysian State Roads system, in Pahang

In Great Britain, Great Britain road numbering scheme#Other classifications

In the Isle of Man, List of roads on the Isle of Man#"C" roads

In the United States:

C-Road, California, a census-designated place in Plumas County

Colorado State Highway 470, the only Colorado route to use the label

County-designated highways in zone C in Michigan

Corridor C, part of the Appalachian Development Highway System

Marsham Street

Marsham Street is a street in the City of Westminster in London, England. It is approximately a mile in length and runs south from Great Peter Street, near Victoria Street and Parliament Square.

Other lists

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