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|Motorway • Classification|
In the UK, it is typical for motorways to have numbered junctions. In the earliest days of motorways, junctions were not numbered. Some strip maps of motorways produced by the AA used numbers or letters to refer to the junctions, but these were entirely unofficial. Official junction numbering was introduced in 1966 or thereabouts for most motorways in Great Britain. Junctions on some shorter motorways and Ax(M) motorways initially remained numberless; some of these were given numbers later. Numbering in the UK and Ireland typically is numerical and incremental in counting the number of junctions since the start point, e.g. 1, 2, 3...
Junctions are normally numbered consecutively. Gaps (unused numbers) may be left for planned future junctions. New junctions not provided for in the numbering can be indicated by numbers with appended letters A, B etc. - but appended letters can also be sometimes used for junctions on spurs, or in other ways, as in the case of the A55.
On the A55, the numbering suggests that consecutive numbers were first assigned to those junctions which allow all movements, so that numbers with appended letters then had to be used for limited-movements junctions.
Junction numbering on a route normally starts from 1. Sometimes, as with the M62, it starts at a higher number. This is an indication that an extension of the road was planned at the low-numbered end.
Junction numbers are shown on direction signage addressed to traffic already on the road in question. In a few cases, junction numbers are also shown on signage seen when joining the road in question.
Junction numbers are normally shown on road maps, though some maps such as OS Landranger show only those on motorways.
A potential problem with junction numbers is that in some areas a journey may involve short stretches on two or three different motorways, leading to forward and backward jumps in the junction numbering,or a switch between increasing and decreasing numbers.
In several cases, the junction numbering on a stretch of road has been changed at some time. In some cases, such as the M74, this has happened twice.
The M62 Stretford-Eccles Bypass was unusual in that although it had no official junction numbers (shown on signs) until 1971 when most of it became the M63, maps by several mapmakers showed its junctions as numbered 1 to 6 from south to north. It is now part of the M60, junction 7 to junction 13.
On the A1(M), junction numbering was introduced in the 1990s, first for the southernmost section, later for the rest. Gaps were left in the numbering to allow for possible future upgrade of the intervening sections of all purpose A1. However junction numbers for all-purpose sections were not shown on maps or signs until about 2014, and then only on Tyneside, where the numbering was extended to Seaton Burn. With the upgrade of some intermediate sections of the A1 to motorway it has become apparent that on some stretches too many or too few junctions were originally allowed for.
Junction numbers were later assigned for some long-distance all purpose trunk roads. These include the A14 and A55, the trunk section of the A12, and selected sections of the A45, A50 and A483. The numbering on the M25 was extended onto the A282, and that on the M42 was extended onto the A42.
Some urban areas also have junction numbers applied to central ring roads to aid navigation. These include Birmingham, Blackburn, Coventry, Derby, Dublin, Leeds, Redditch and Sheffield. In Peterborough there is a junction numbering system that applies to several major roads in the city, equipping main junctions with numbers which are unique over the city area rather than just along a particular road.
Non-motorway roads with junction numbers
- A1 Newcastle-Gateshead Western Bypass
- A12 M25 - A14
- A14 whole route
- A15 Peterborough
- A42 whole route
- A45 east Northamptonshire
- A47 Peterborough
- A50 Derby Southern Bypass
- A55 whole route
- A61 Sheffield ring road
- A282 whole route
- A483 Wrexham area
- A601 Derby ring road
- A1139 Peterborough
- A1260 Peterborough
- A4053 Coventry ring road
- A4540 Birmingham Middle Ring
- A6078 Blackburn ring road
- B4160 Redditch ring road
- Cork City Inner Orbital Route
- Dublin Inner Orbital Route
- Dublin Outer Orbital Route
- Leeds City Centre Loop
- N1 Dundalk - border
- N2 M50 - M2
- N3 M50 - M3
- N4 M50 - M4
- N4 M4 - Mullingar
- N4 Collooney - Sligo (junction numbers prefixed with 'S')
- N6 Athlone bypass
- N7 M50 - M7
- N11 Bray - Wicklow
- N18 Limerick - Shannon
- N22 Ballincollig bypass
- N25 Cork - Carrigtwohill
- N25 Waterford bypass (junction numbers prefixed with 'W')
- N40 Cork South Ring
Routes that do not start with Junction 1
This list ignores spur junctions, named off a main route, and situations like Peterborough where several routes share a single junction numbering system. It also ignores routes that count from an unsigned 'junction 0'.
- M11 (GB) (Junction 4)
- M11 (RoI) (Junction 3)
- M23 (Junction 7)
- M62 (Junction 4)
- A12 (Junction 11)
- A45 (Junction 10)
'Skipped' Junction numbers
This ignores routes that don't start with 1, places where junction numbers are shared with other route and places where there's gaps in the route.
- M1 (GB) J3 - unfinished junction
- M1 (NI) J4 - junction renumbered as junction 3 which was to be an unbuilt junction.
- M1 (NI) J5 - unbuilt junction
- M2 (NI) J3 - unbuilt junction
- M4 (GB) J31 - unbuilt junction
- M7 (RoI) J20 - unbuilt junction
- M8 (RoI) J2 - unbuilt junction
- M27 J6 - unbuilt junction
- M50 (RoI) J8 - unbuilt junction
- M55 J2 - unbuilt junction
- M56 J13 - unbuilt junction?
- M58 J2 - unbuilt junction
- M61 J7 - unbuilt junction
- A1(M) J54, J55 - numbers not required (plans for where junctions were changed)
- A14 J48 - junction replaced with the A14 realigned
There are two main competing systems for junction identification, wich are not mutually exlusive
This system was principally adopted in Germany, although motorways in the UK also use junction names, which are sometimes singposted, in addition to numbering. Every junction in Germany has a name, and is referred to as such on signposts and traffic reports. In the last 20 years, junction numbers have also been assigned to many motorways in Germany.
Junctions using km (miles) markers
In some countries, junctions are numbered by their km or mile markers. This is the case on Spain's Autovias and in America. This has the advantage that a junction can simply be added between two others, without having to append a suffix (e.g. A) and that it is always apparent how far the next junction is. It has the disadvantage that multiple junctions in a short space are not easily signed (these may need to use a suffix). Note that parts of Spain and some US states still use consecutive junction numbering on some routes, though they are planned to be converted.
In some countries, the junction suffix, rather than being an alphabetic character appended is a numeric, e.g junction numbers like 12.1 are sometimes used.
The distinction between 'exit' and 'interchange' is common in continental Europe, marked with different symbols. Several countries (eg France, Belgium, The Netherlands) only typically give numbers to junctions that allow one to exit the motorway network (though exceptions exist). This can be confusing for the Brit, as, for instance, the A26 in France has, heading south, this sequence of junctions: exit 7 for the N17, the interchange with the A1, exit 8 for the D939, the interchange with the A2, exit 9 for the D917, exit 10 for the A1029, the interchange with the A29, exit 11 for the D1. One might feel that, after exit 7, exit 11 would be the 4th junction, not the 7th.
Germany numbers its interchanges and exits alike, but interchanges may not be with an Autobahn, making the difference between the two not clear from a map.