Classification
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Introduction
The classification of roads varies throughout the British Isles. Although originally done as a means of recognising the level of funding for maintenance of a road, it is more commonly used for ease of navigation, and is an important component of direction signs.
Great Britain
All-purpose roads
In Britain, the all-purpose roads are grouped into nine Zones, with the majority of the boundaries being the single digit roads. The exception is the boundary between zones 1 and 2, which is the River Thames rather than the A2. There are two hubs to the system, with A1–A6 radiating from London and A7–A9 radiating from Edinburgh.
Route numbers can have from one to four digits in the case of "A" class roads, and three or four digits in the case of "B" class roads. These roads form one system across Great Britain, and there should be no duplicates. This is, however, not always the case and some duplicates do exist. In addition, numbers can be recycled and can be applied to a different route from the original – usually with a time delay between one use and another.
The classification of the roads in Britain was first completed in 1922, although there have been many changes over the years, and there was a major revision in 1935. The A1 formerly used part of the present route of the A19, whilst the A66 had a route that headed into York. The first renumbering due to a building of a bypass is believed to be the first Dartford Bypass, built in 1924 which became part of the A2.
In 1964, Primary routes were introduced, being recommended routes between places "of major traffic importance", usually large towns. Primary routes have direction signs with green backgrounds and white lettering, whereas all other non-motorway roads have direction signs with white backgrounds and black lettering. Individual A-class roads may be partially primary and partially non-primary.
Other important routes within Highway Authorities are given internal classifications within each authority which are not meant to appear on signage. These so-called "C" class roads may actually be allocated any letter code ("C", "D" or "U" being examples), and the numbers can be reused in different authorities.
Motorways
In 1958, the Preston Bypass opened and the motorway era began, although the numbering system was not finalised until the 1960s.
Motorways also follow a zonal system, which is different between Scotland and England & Wales, and are given a number either prefixed with M, or suffixed with (M). Direction signs on motorways have a blue background with white lettering.
Scottish motorways are numbered according to the number of the "A" road that they replace, hence the reason there is no M7 – it has not been necessary to build a motorway along the line of the A7.
In England and Wales the motorway zones are different, though they again use the single digit motorways (plus theoretical extensions thereof). The boundary between the motorway zones 2 and 3 consists of the M3 to junction 8, then a theoretical straight-line extension southwest from J8 to the coast of Cornwall. The M3 south of junction 8 was not part of the originally planned motorway, and so does not form the zone boundary.
Motorways can also be given a suffix of (M). These roads, whilst being full motorways, are used for shorter bypasses of sections of "A" class roads and are so numbered in order to preserve the long-distance route number.
Changes to zones
It is unknown as to whether the zone boundaries move when a single digit road is rerouted. Some renumberings (such as those regarding the A1 in the Tyneside area have caused a mass of other renumberings (for example, from A1(M) to A6127(M) to A167(M) as the zone boundaries moved.
Other renumberings of single digit roads have not seen such wholesale changes.
Northern Ireland
There seems to be no system at all here. The A2 is a case in point. It follows the coast and goes from primary to non-primary very often. Similarly, the numbering of motorways has no obvious pattern.
Republic of Ireland
In the Republic of Ireland, road classification happened just after partition and their original classification was very different to that of the UK. Originally the roads were designated "T" for trunk roads and "L" for link roads. The some of the "T" roads became the current "N" roads. For example, T1 is now the N1, and T2 is now the N2. It was much like Northern Ireland in that there was no particular system. In the late 1970s, a major reclassification of the roads took place. The "T" and "L" system was swept way and the current "N" and "R" system was introduced. This new classification was much more ordered. All the "N" roads are numbered in a anti-clockwise fashion from Dublin. So N1 is at the top, N11 at the bottom. Then it starts again in the same way. There were originally only 25 Primary "N" roads. When the Nass bypass opened in 1983, that became the first motorway in the Republic of Ireland. Motorways in Ireland are part of the N-Road system so as the Naas Bypass was part of the N7, it became the M7.
The first primary "N" road classified after the original twenty-five was the N26 in County Mayo. The last "N" road classified so far was the N33 in 2004 which supposes that next number in the scheme will be N34. However there are some oddities, the biggest being the N50 being numbered the N50. As it all motorway, it is signed M50.
Non-primary "N" roads have numbers over fifty. As in the UK, primary routes have green background signs, motorways have blue background signs and all other routes have white background signs.
"R" roads on the other hand are randomly numbered, though mostly grouped together within the first digit, eg. all the R1xx roads are all near to each other.
"L" road numbers were revived in 2005 but for a different purpose to the original scheme. "L" roads are all the remaining roads in the Republic of Ireland that are not "N" roads or "R" roads. Many "L" roads have numbers five digits long.
Isle of Man
Channel Islands
Jersey
Jersey roads all have a unique number, with lower numbers (1-17) being A roads, then the next numbers (21-92) being B roads and higher numbers (93-125) being C roads.
There seems to be a pattern in numbering the A roads with the A4 to A13 increasing in number in an anti-clockwise direction. However the other A roads don't follow this pattern.
Guernsey
The roads of Guernsey are all unclassified.
See Also
Links
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