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1922 Road Lists • 1935 Road numbering revision • 1977 Road Lists • Road numbering


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

The 9 all-purpose Zones as allocated in 1922

In Great 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 A1A6 radiating from London and A7A9 radiating from Edinburgh.

Route numbers can have from one to four digits in the case of "A" class roads (also known as Class I roads), and three or four digits in the case of "B" class (or class II) 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 (technically, Class III or Classified Unnumbered) roads may actually be allocated any letter code ("C", "D" or "U" being examples), and the numbers can be reused in different authorities.

In 2011, the Department for Transport consulted on reforming the administrative procedures in place regarding route numbering on the non-trunk network. These changes when implemented in 2012-13 will make it easier for local authorities to renumber roads to reflect strategic need. It is not yet known how extensive the safeguards to prevent any anomalies between local authorities will be, but it has been suggested that cross-boundary issues will be referred to the Department for a decision.


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

Road numbers are used less frequently for navigation in Northern Ireland compared to Britain. The roads don't follow a zone pattern, though some numbers can reflect allocation based on geography.

The A1 follows the historic Belfast - Dublin postal route, while the A2 follows the coast road around Ulster from Newry to Derry. The A3 to A6 inclusive then took the next 4 most important routes, increasing in number in a clockwise direction.

The A20 to A29 begin south/east of the A1-A3 axis, increasing in a clockwise-around- and distance-from-Belfast sequence. The A7 and the Cullaville version of the A37 are in this area. The A30 to A35 follow a similar pattern between the A3 and A6 and the A8, A36 and A37 north of the A6. The A38 and A39 took short links in the area between A3 and A6.

The A40 was an early addition, and the A42-A44, A45-A47, A48-A51 and A52-A54 form four sequences of very early additions. The A57 and A76 were numbered after the B roads that they were upgraded from. The A55 took the lowest available number when given a two-digit number.

The A500 and A501 were allocated to very short links in Belfast, joined later by other A50x routes. The A5xx sequence broke out of being Belfast with the A505, and they stopped being allocated sequentially.

B roads were given roughly sequential numbering, with B5xx numbers for Belfast and Derry. Later additions, after the B81, were added in sequential blocks heading away from Belfast.

Motorways in Northern Ireland were originally numbered with the two main routes being the M1 and M2, and subsequent motorways numbered as spurs off these (eg: M12, M22).

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, but these were generally not as well known as numbers in Great Britain, and did not receive official status from the government. The lower numbered T roads formed radials from Dublin to other major towns and cities, while subsequent numbers were allocated to other cross country routes, generally in order of decreasing importance.

A comprehensive review was undertaken in the late 1960s, and formally implemented as a major reclassification of roads in 1977, introducing the "N" system. Some of the "T" roads became the current "N" roads. For example, T1 is now the N1, and T2 is now the N2. Unlike "T" roads, "N" roads have legal standing and are formally recognised.

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 Naas 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, though this purely for signing convenience - it legally remains part of the N7.

The first primary "N" road classified after the original twenty-five was the N26 in County Mayo. The last "N" road classified so far in this sequence 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.

In 1994, regional "R" roads were recognised by the government. "R" roads tend to radiate anticlockwise from Dublin around the entire country in a similar fashion to National Roads, and grouped by county. The original allocation appears to have been R101 (central Dublin) through to R767 (northeast Co. Wicklow), though this is only a loose pattern. Roads from R801 upwards were allocated to local link roads in towns. Since then, new numbers have been added onto these lists, mostly being downgraded sections of National roads that have been rerouted onto bypasses or motorways.

"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

On the Isle of Man, there are A roads and B roads (and C, D, E, F, G and U roads). The Hierarchy is different to the rest of Britain as the classes are: Primary, District, Local, Access, and Unsurfaced, although these do not seem to relate to the prefix letter anymore. A map is available here: Isle of Man Government Map. The A1, A2, and A3 formed a triangle linking the largest towns on the island: Douglas, Peel and Ramsey, with the A4 forming a N-S route down the middle of the island, connecting the other town, Castletown. This has been changed, with the A3 and A4 swapping.

The A5 forms the main route from Douglas to the south east corner of the island. The A6 formed a branch to Douglas' docks (now diverted and extended to form a loop around Douglas), the A7 and A8 being two spurs into Castletown - one from Port Erin, the other from Ballasalla. The A5 has since been rerouted via Castletown and the Ballasalla to Port Erin route has become a recycled A7. The A8 has been recycled as a short road in Douglas town centre.

The A9 is at the north end of the island, between Ramsey and Andreas - near the A1x series.

2-digit A roads cluster together, though there are some exceptions:

  • A1x: North of the Island (A12 is, however, on the south coast)
  • A2x: Middle of the Island
  • A3x: South of the Island (A35, A38, A39 in Onchan, A33 recycled in Douglas)
  • A4x: Douglas (A40 in St Johns, A48 and A49 don't exist)

B Roads are numbered roughly north to south with higher numbers used for newer routes - most of which are in Douglas.


The earliest reference to classified roads on the island is the Government Circular 1131 of 25/2/1926, which details the A1 to A10 and B1 to B26. This is reflected by the Michelin Map from around the same time, which has the same A and B roads marked (although some short routes are omitted). Interestingly, while the A1-A8 and B1-B23 can be said to have been assigned in a logical manner, the A9, A10 and B24-26 look less logical, particularly the B26 which is one of the most northerly B roads. This suggests that by 1926 there had already been additions to the numbering system, although it could be that they were late additions and there was no identified need to juggle numbers around to maintain a numeric progression from north to south.

No evidence has yet been found of exactly when the routes were classified, and it is interesting to note that as late as 1937 the classified routes did not appear to enter the towns, as they are often described as starting at the boundary, with the section of the route inside the towns listed separately as a Town Road. By 1937, the number of classified routes had been increased, with the A11 and A12 added to the A roads and B roads now extending to the B37, with the B32 number having been re-used following the original line becoming the A12.

At some point between 1937 and 1963, when the OS One Inch Map first shows road numbers on the island, there was a major reassessment of the classified road network. The core A roads were retained with only minor changes - the A10 was extended to Ballaugh for example, but many of the B roads were upgraded to give a total of over 40 routes. The A36 is the highest number marked, but the lines of most of the A4x routes in Douglas are shown as unnumbered A roads. However, it looks as though this may have happened in more than one phase, with the A13-A33 loosely being assigned from north to south, while subsequent numbers appear to have been assigned in smaller batches later.

B road numbering was not added to in the same way, but instead the B roads appear to have been renumbered from scratch, certainly none of the routes have retained their number since 1937. Again, numbers seem to have been assigned from the north to the south, but perhaps more haphazardly, unless there have been changes not yet identified. For instance, the B1, B11 and B12 are in and around Laxey, while the B2 - B9 and B13-B17 are scattered around the north of the island. If there was any form of logic, it appears that the B47 may have been the highest number allocated in the first batch, and all subsequent numbers came as later additions. In particular, the B6x and B7x numbers predominate in and around Douglas, suggesting they were all assigned at a similar time.

Channel Islands


The 1960 map of Jersey shown on SABRE Maps includes road classifications

Jersey's road numbering system is fairly straightforward, but can sometimes be a confusing mess. In Jersey, some roads (main roads) are owned by the States and maintained by the Government, while all other public highways are owned by the administrations of the 12 parishes, who manage their respective networks through their Road Committees. All main roads have a number and two classes (A, B, C: representing the importance of the route in movement; and I to IV: representing the quality of the route). The numbers rise inversely with importance, 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.

It is unknown when the road numbering first came about, but it was before 1960, and likely after the Occupation. We will use 1960 as the reference point for the original numbers, since SABRE Maps has a map showing route numbers from that year. Despite large changes in the road network, especially in St Helier, since 1960 (for example the construction of the Tunnel in the late 60s, which transformed traffic movement through the town, as well as a number of minor changes, the road number classifications have not really been updated since then, leading to many confusing situations where road numbering does not make sense.

The 1960s route numbers seem to follow a generally simple pattern:

  • The A1 is the most important road in the island, linking the two historic towns of Jersey: St Helier and St Aubin together. The A2 is given to Victoria Avenue, the longest dual carriageway in the Channel Islands. The A3 is the main road from the town centre to Mont Orgeuil Castle and the village of Gorey.
  • The remainder of the routes 1-13 branch from the town and St Aubin's Bay in an anti-clockwise / east-to-west direction, all terminating at either the A1 or A3 starting with the A4 (St Clement coast) round to the A9 (St John's road), then continuing west along the coast to the A13 (St Brelade's Road).
  • Apart from the A11 (St Peter's Valley) and A7 (St Saviour's Hill), all the A roads in this part are named 'Grande Routes' for at least some of their length.
  • The A14 and A15 provide link roads. The A14 stretches across the north of town, linking the A9 with the A7, and the A15 linking the A4 with the A6.
  • Roads 20-91 are B roads. These generally decrease in importance with higher numbers, but that's not a hard and fast rule.

Since 1960, two new A roads have been classed: the A16 linking the town centre to the industrial estate at La Collette (presumably classified when the reclamation was done) and the A17 being La Route du Fort, a new road opened in the late 60s, including the well-known Tunnel (oft featured in Bergerac).

Back in 1960, movement around the town was governed by these A roads, which would all have been two-way into the town centre. For example, traffic travelling from Trinity Church to the Esplanade would travel down New Street, and traffic arriving from the east would use Hill Street. Since then, traffic around the town has moved towards a 'Ring Road' model, with such traffic instead encouraged to loop around the town. Many former main routes are now parts of one-way systems or no longer hold their former importance. The opening of La Route du Fort has also meant that the A17 is now the main road to travel out east.

Therefore, many road classifications no longer make sense when looked at purely in a modern sense. The A3 has been split by one-way systems and pedestrianisations, making it impossible to drive along its length. The A1 has been rerouted since land reclamation took place, meaning part of the Esplanade, depsite still being a main road, lacks a number. Furthermore, a bus gate installed half way along the A1's length means it is not possible to drive along the whole length of the road. The A8 no longer links to the A1, having been cut off by one-way systems and precinctisation (it is no longer officially numbered in its southern part). Numerous gyratories installed as part of the ring road scheme mean that you cannot drive north on the A9 or A7, and you cannot drive west on parts of the A14 and A6, instead being directed along B roads and X roads. Seemingly unimportant town streets are in fact A roads, while wide main roads part of the St Helier Ring Road are B roads.

Essentially, while the system was initially designed such that you can drive from wherever you are to town using one or two A roads, now the system is much more haphazard and this is not possible. For example, from Gorey into St Helier you would have initally taken the A3 into town, however, to do this now, you would have to take the A3 and A17, before turning onto the A15 to reach the A3 once again, but then turn left onto a B road, eventually reaching the A3 again to make its way into town.

Route number Origin Destination Notes
A1 Weighbridge, St Helier St Aubin No longer driveable. Must use A2
A2 West Park, St Helier Bel Royal Main route for cars to St Aubin
A3 Weighbridge, St Helier Gorey Cut off by pedestrianisation and one-way schemes.
A4 A3, St Helier Grouville
A5 St Clement Grouville
A6 A3, St Helier St Martin One-way system in town centre
A7 A3, St Helier St Saviour One-way system in town centre
A8 B76, St Helier Trinity Originally longer
A9 A1, St Helier St John
A10 Millbrook St John
A11 Bel Royal St Peter's Valley
A12 Beaumont St Ouen
A13 St Aubin La Moye
A14 A9, St Helier A7, St Helier
A15 A4, St Helier A3, St Helier
A16 Weighbridge, St Helier A4, St Helier
A17 Weighbridge, St Helier Georgetown


The roads of Guernsey are all unclassified, however a heirachy of quality exists - map, description

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