In Great Britain, there is a numbering scheme used to classify and identify all roads. Each road is given a single letter (representing a category) and a subsequent number (between one and four digits). Though this scheme was introduced merely to simplify funding allocations, it soon became used on maps and as a method of navigation. There are two sub-schemes in use: one for motorways, and another for non-motorway roads.
While some of Great Britain's major roads form part of the international E-road network, no E-routes are signposted in the United Kingdom. Due to changes in local road designation, in some cases roads are numbered out of zone. There are also instances where two unrelated roads have been given exactly the same number; for example, the Leicester Ring Road and a road in Cumbria are both designated A594.
This scheme applies only to England, Scotland and Wales; a separate system using similar conventions is used in Northern Ireland, as well as outside the United Kingdom in the Isle of Man, Jersey and British Overseas Territories.
Work on classification began in 1913. The Road Board had been established in 1909 to administer Vehicle Excise Duty [1] - money raised by taxation to pay for new road construction and for repair of damage done to existing roads by the growing number of motorists. [2] As the Board needed to work out which roads should be funded, upgraded or replaced, its secretary, William Rees Jeffreys, appointed Henry Maybury, one of the Board's senior engineers, to devise a classification system and then assign numbers to the highways for identification purposes. [3] The work was interrupted by the First World War.[ citation needed ] It did not resume until the Ministry of Transport was formed in 1919 and given authority to classify highways [4] and to allocate funding for road maintenance, authority for which was granted by section 17 (2) of the Ministry of Transport Act 1919.[ citation needed ] A classification system was created in 1922, [5] 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. [6] [ unreliable source? ][ citation needed ] Government funding towards the repairs of these roads were set at 60% for the former and 50% for the latter. [7]
Shortly after this, the numbers started to appear in road atlases and on signs on the roads themselves, making them a tool for motorists[ citation needed ] 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.[ citation needed ]
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).[ specify ] 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).
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.[ citation needed ] The exception is between Zones 1 and 2, where the River Thames defines the boundary so that all of Kent is in Zone 2.[ citation needed ]
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.[ citation needed ]
A few roads are anomalously numbered.
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.[ citation needed ] 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.[ citation needed ] 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.[ citation needed ] 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.[ citation needed ] 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.[ citation needed ] 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.[ citation needed ]
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:[ citation needed ]
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.
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 (such as the A38 (M)). 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.[ citation needed ] 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 Lowestoft) 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.[ specify ]
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.[ specify ] 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.[ specify ] 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. [9]
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.
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.[ citation needed ] These sections retain the same number but are suffixed with (M), for example the A1(M) and A404(M).[ citation needed ] 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).[ citation needed ]
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.[ citation needed ] 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.
B roads in the county of Devon have further sub-classifications according to their accessibility. [10] This is due to the rural nature of Devon's topology making some roads unsuitable for certain types of vehicle.
The classification is denoted by the colour of the sign border and direction arrow, and can be summarised as follows:
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;[ citation needed ] use of local numbers on signs in England is "not advised". [11] Exceptions to this are known in the forms of numbers on signs[ citation needed ] and past use of prefixes H and V on signs in Milton Keynes where main roads have a regular grid system. These designations are used when planning officers deal with certain planning applications, including the creation of a new vehicular access onto a highway. The letter Q is used for many important unclassified roads in Fife.
In London, Cycleways are using the C prefix and marked using pale green signs. There are also some CS prefixes for Cycle Superhighways, marked using magenta signs, but these are being phased out.
Despite numerous large roads in Great Britain being part of the International E-road network, no road that forms part of this network is signposted as such and only the road's national designation is shown. The same is true in Northern Ireland.
The M1 motorway connects London to Leeds, where it joins the A1(M) near Aberford, to connect to Newcastle. It was the first inter-urban motorway to be completed in the UK; the first motorway in the country was the Preston Bypass, which later became part of the M6.
The A1, also known as the Great North Road, is the longest numbered road in the United Kingdom, at 410 miles (660 km). It connects London, the capital of England, with Edinburgh, the capital of Scotland. The numbering system for A-roads, devised in the early 1920s, was based around patterns of roads radiating from two hubs at London and Edinburgh. The first number in the system, A1, was given to the most important part of that system: the road from London to Edinburgh, joining the two central points of the system and linking the UK's (then) two mainland capital cities. It passes through or near north London, Hatfield, Stevenage, Baldock, Biggleswade, Peterborough, Stamford, Grantham, Newark-on-Trent, Retford, Doncaster, Pontefract, York, Wetherby, Ripon, Darlington, Durham, Gateshead, Newcastle upon Tyne, Morpeth, Alnwick, Berwick-upon-Tweed, Dunbar, Haddington, Musselburgh, and east Edinburgh.
The A7 is a major road, partly a trunk road, that connects Edinburgh in Central Scotland to Carlisle in North West England. The A7 meets the M6 motorway close to Carlisle, which connects to the English motorway network.
The A90 road is a major north-to-south road in eastern Scotland, running from Edinburgh to Fraserburgh, through Dundee and Aberdeen. Along with the A9 and the A82 it is one of the three major north–south trunk roads connecting the Central Belt to northern destinations. The A90 is not continuous, separated between Dalmeny and Perth by the M90.
The A74(M) and M74 form a major motorway in Scotland, connecting it to England. The routes connect the M8 motorway in central Glasgow to the Scottish-English border at Gretna. They are part of the unsigned international E-road network E05. Although the entire route is colloquially referred to as the M74, for more than half its length, south of Abington, the road is officially the A74(M); see naming confusion below.
The A66 is a major road in Northern England, which in part follows the course of the Roman road from Scotch Corner to Penrith. It runs from east of Middlesbrough in North Yorkshire to Workington in Cumbria. The road has been progressively improved with dual carriageway sections, but with stretches of single carriageway road. The road is set to be completely dualled between Scotch Corner and Penrith, with a £1.3 billion scheme being announced in March 2024.
The A14 is a major trunk road in England, running 127 miles (204 km) from Catthorpe Interchange, a major intersection at the southern end of the M6 and junction 19 of the M1 in Leicestershire to the Port of Felixstowe, Suffolk. The road forms part of the unsigned Euroroutes E24 and E30. It is the busiest shipping lane in East Anglia carrying anything from cars to large amounts of cargo between the UK and Mainland Europe.
The A12 is a major road in Eastern England. It runs north-east/south-west between London and the coastal town of Lowestoft in the north-eastern corner of Suffolk, following a similar route to the Great Eastern Main Line until Ipswich. A section of the road between Lowestoft and Great Yarmouth became part of the A47 in 2017. Between the junctions with the M25 and the A14, the A12 forms part of the unsigned Euroroute E30. Unlike most A roads, this section of the A12, together with the A14 and the A55, has junction numbers as if it were a motorway.
The island of Ireland, comprising Northern Ireland and the Republic of Ireland, has an extensive network of tens of thousands of kilometres of public roads, usually surfaced. These roads have been developed and modernised over centuries, from trackways suitable only for walkers and horses, to surfaced roads including modern motorways. Driving is on the left-hand side of the road. The major routes were established before Irish independence and consequently take little cognisance of the border other than a change of identification number and street furniture. Northern Ireland has had motorways since 1962, and has a well-developed network of primary, secondary and local routes. The Republic started work on its motorway network in the early 1980s; and historically, the road network there was once somewhat less well developed. However, the Celtic Tiger economic boom and an influx of European Union structural funding, saw national roads and regional roads in the Republic come up to international standard quite quickly. In the mid-1990s, for example, the Republic went from having only a few short sections of motorway to a network of motorways, dual carriageways and other improvements on most major routes as part of a National Development Plan. Road construction in Northern Ireland now tends to proceed at a slower pace than in the Republic, although a number of important bypasses and upgrades to dual carriageway have recently been completed or are about to begin.
A trunk road is a major highway with a specific legal classification in some jurisdictions, notably the United Kingdom, Sweden and formerly Ireland. Trunk roads are planned and managed at the national-level, distinguishing them from non-trunk roads which are managed by local authorities. Trunk roads are important routes usually connecting two or more cities, ports, airports and other places, which is the recommended route for long-distance and freight traffic. Many trunk roads have segregated lanes in a dual carriageway, or are of motorway standard.
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The A167 and A167(M) is a road in North East England. It is partially a trunk road and partially a motorway, where it is commonly referred to as Newcastle Central Motorway. Most of the road’s route was formerly that of the A1, until it was re-routed with the opening of the A1(M) in the 1960s.
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