Proposed Re-numbering of Northern Ireland

Motorway and Junction Numbers



Northern Ireland boasts the oldest integrated motorway system in Ireland, amongst the earliest motorways in the UK, and what was for many years the widest motorway in the UK. Yet, as they were never completed as intended, our motorway numbering system seems illogical to outsiders and is often confusing for drivers who live here. Plans for future junctions will put further pressure on a numbering system now over 40 years old. The current Westlink upgrade provides a rare opportunity for a review of motorway numbering in Northern Ireland: to re-number the motorways and their junctions in a more logical and future-proof manner.

Rationale for Change

Northern Ireland's motorway numbering system was based on the plans of 1964 which were never completed. So while they made sense at the time, we are now in a situation where the motorway numbers are confusing. For example:

  • The M2 becomes the M22 at Antrim giving the appearance of two junction 1's on the route, and an arbitrary number change; a situation which makes no sense to most drivers.
  • Short spurs such as the M5 have single-digit numbers while the much longer M12 and M22 have two-digit numbers.
  • Numbers of abandoned motorways are missing, such as the M11 and M21.
  • There is too much use of 'A' and 'B' designations to clarify junction numbers, most obviously the first three junctions on the M2 which are numbered 1A, 1B and 1. Planned junctions between j4 and j5 on the M2 and j8 and j9 on the M1 will compound this issue.

With the A12 Westlink currently (Jan 06) being upgraded to fullly grade-separated standard, it will soon flow directly onto and off the M1. It seems very clear to the public that it is, for all practical purposes, part of the M1. Given the fact that the M3 was built to urban motorway standard with reduced hard shoulders and tighter curves, and given that some motorways in Britain have no hard shoulders at all, there is no real argument against doing this with the Westlink.

Numbering Strategies

In England and Wales five principal motorways leave London radially and are designated, clockwise from the north, M1, M2, M3, M4 and M6. The M5 runs further west than London. These six motorways then form the edges of "zones" of numbering. Anything within a zone has that number as a prefix. So, for example, the other motorways in zone 4 are called the M40, M42, M48 and M49. These numbers are logical and help road users to unconsciously know where a given motorway should be in the country. Also, the secondary motorway often leads to the primary motorway (although in quite a few cases it does not).

In Scotland and the Republic of Ireland, by contrast, motorways are designated by the number of the primary route that they replace, or bypass. So the M8 in Glasgow replaces the A8 route, and the M3 in the Republic of Ireland replaces the N3 road. The motorways either in existance or being planned in the Republic of Ireland are the M1, M3, M4, M6, M7, M8, M9, M11 and M50.

The original numbering strategy in Northern Ireland was for the principal routes to be designated M1-M4 clockwise from the west. The addition of proposals for the M5-M8 muddied this simplicity as they were interspersed between the first four. The plan was that spur motorways would come off these and be numbered the same as the parent motorway but with an additional number, hence M11, M12, M21, M22 and M23. This is how the Northern Ireland system got its current motorway designations. While this system made sense at the time, it makes little sense now that most of the original plan has been abandoned. In addition, our insistance that spurs should be numbered sequentially without gaps (eg M21, M22, M23 etc) is a degree of strictness not found anywhere else in the UK, where any two-digit number within a zone is available for use (witness M40, M42, M48, M49 but not the other 6 possibilities). This requires less long-term planning.

A Strategy for Northern Ireland

There is a good case for numbering our motorways in conjunction with the authorities in the Republic of Ireland because we all share an island and motorists see less significance to the border than politicans do. However, it is also recognised that this is a contentious issue that deals with much more than just road numbering. So what is proposed is a "future proof" numbering system, one that is designed for Northern Ireland as a self-contained entity, but which could relatively easily be converted to an all-Ireland numbering system if that is what the two governments decide.

A new numbering strategy should therefore:

  • Be based on a small number of strategic motorways with secondary spurs.
  • Number motorways the way drivers see and use them.
  • Have a single geographic location as the point of origin for the whole system.
  • Eliminate 'A' and 'B' junction numbers.
  • Future proof, ie able to be integrated into an all-Ireland numbering system.
  • Take into account, within reason, the possible future addition of junctions.

Principal Numbering Proposals

The primary proposal of this document is to base the entire system at a single location, the York Street junction, and designate this "junction 1". This would provide a single, recognisable point of origin for Northern Ireland's entire motorway system. All three motorways that leave this point would have single digits. All remaining motorways would be designated secondary to these three. Such a system would quickly become familiar to the travelling public who would unconsciously know roughly how far any junction was from York Street by its number.

The implication of this for the Westlink leads to proposal number two, that the A12 Westlink be incorporated as part of the M1 once the current upgrade is completed. The result of this relatively simple move would be that the existing M1, M2 and M3 would all meet at this single location. The junction would be junction 1 of the entire system.

With future integration with the Republic of Ireland's motorway numbering system in mind, we note that the M1 in the south is designated as the main route towards Belfast. Therefore, no matter what happened in the future, the M1 at the Belfast end would in all likelihood retain the M1 label. The M2, however, is one of only two primary numbers that not used in the Republic, so it would make little sense at this late stage for the Irish NRA to create a duplicate M2. This leads to the third proposal, that the Irish National Roads Authority avoids using the designation M2 which should be reserved for its existing use in Northern Ireland. Future use of the label M3 is discussed in more detail below.

Secondary Numbering Proposals

The numbering of the secondary motorways, then, should be based on the primary motorways M1, M2 and M3. Adopting the British system of "zones" would give us three numbering zones, as shown below. Zone 1 would include everything south and west of Belfast, zone 2 everything north and west, and zone 3 everything east of Belfast. All secondary motorways in each zone would be two-digit and use the zone number followed by a second digit. This system has the advantage that it allows most of the motorway system to retain its current numbering, minimising disruption, while still providing a more logical framework for numbering. Detailed proposals for each zone are given below.

Zone 1 Proposals

The current motorways in zone 1 are as follows:

  • M1 motorway from Broadway to Dungannon
  • The existing M12 spur to Craigavon
  • The Westlink from York Street to Broadway

The main proposal is to subsume the Westlink into the M1 since most drivers do not see a distinction even before the upgrade, and this will be even less once it is fully grade-separated. Other than this, there seems to be no good case for changing the designations of the M1 and M12, as the M1 is already the primary motorway, and the M12 is correctly numbered for a secondary motorway in zone 1. In any case, the M11 number is already used in the Republic of Ireland.

The proposed motorways in zone 1 are therefore:

  • M1 motorway from York Street to Dungannon
  • M12 spur to Craigavon

Zone 2 Proposals

The current motorways in zone 2 are as follows:

  • M2 motorway (main section) from York Street to Antrim
  • M5 spur to Whiteabbey
  • A8(M) spur to Corr's Corner
  • M2 motorway Ballymena bypass section
  • M22 motorway as the continuation of main section of M2 on to Randalstown

The numbering system here was originally highly logical when the M2 was intended to go to Coleraine, the M5 to Carrickfergus and the M22 to Castledawson. However, with the abandonment of these plans, the numbers are confusing to motorists and a source of derision to those living outside the province. The motorways should be united around a simplified M2 with the others designated with two digits. The fourth proposal of this document is therefore to combine the existing main section of the M2 and the M22 into a larger M2, and redesignate the M5 and M2 Ballymena bypass as the M20 and M21 respectively. The A8(M) is a different class of motorway, numbered this way as it is really the A8 with motorway restrictions. This designation should not change. The M22 number would cease to exist which would prevent the confusion which would occur were it to be used elsewhere.


Zone 3 Proposals

The M3 Lagan Bridge is the only motorway in zone 3, but as it is a primary route leading to Bangor and east Belfast and coming from York Street, it should have a single-digit number. There is an opportunity when the Sydenham Bypass is widened and the Dee Street junction closed, to upgrade the route to a motorway standard as far as the City Airport, and possibly as far as Knocknagoney. Therefore, the M3 may expand in future. Comments on what would happen to zone 3 in an all-Ireland numbering system are discussed below. These proposals allow the M3 to retain its current designation.

Summary of Numbering Proposals

The proposed re-numbering above is summarised in map form below:

Proposed Junction Numbering

The M1 would have to be re-numbered if it was subsuming the Westlink, and given that similar numbering problems exist on the M2, the opportunity could be taken to re-number all the motorway junctions at the same time, in order to minimise confusion for road users. Doing this when the Westlink upgrade is completed would be an ideal opportunity when people's minds will be focused on the new road, and it will be easy to publicise the changes all at one time.

The proposed re-numbering, which takes account of foreseeable future junctions, is as follows:

M1 Motorway
M2 Motorway
M2/M3 interchange York Street  
M1/M3 interchange York Street
Clifton Street, Belfast  
Dock Street, Belfast
Divis Street, Belfast  
Fortwilliam, Belfast
Grosvenor Road, Belfast  
M20 and Greencastle, Belfast
Mulhouse Road, Belfast  
A8(M) and Sandyknowes, N'abbey
Broadway, Belfast  
<reserved for future use>
Stockman's Lane, Belfast  
<reserved for future use>
Black's Road, Belfast  
<reserved for future use>  
Rathbeg, Antrim
<reserved for future use>  
Crosskennan, Antrim
Saintfield Road, Lisburn  
Dunsilly, Antrim
Sprucefield, Lisburn  
Blaris, Lisburn  
Terminates as A6 dual-carriageway
<reserved for future use>      
M20 Motorway
Lurgan   Begins at M2 junction 4
M12 interchange  
The Birches  
Terminates as A2 dual-carriageway
M21 Motorway
Larne Road Link, Ballymena
  Terminates as A4 dual-carriageway  
Broughshane Road, Ballymena
Teeshan, Ballymena
M12 Motorway
    Terminates as A26 road
Roundabout south of M1      
Carn, Portadown  
M3 Motorway
M1/M2 interchange
Bridge End

M1 junctions 9 and 10 are reserved for a future southern junction between Belfast and Lisburn and possible service area, while junction 14 is reserved for a possible junction for the National Stadium. M2 junction 6 is reserved for the proposed Sandyknowes relief junction and junction 7 for a proposed motorway service area. (Most service areas in Britain do not have junction numbers, but it would be prudent to reserve these numbers in case of policy change.) It seems implausible that an M2 junction will be built at the Antrim Road in Newtownabbey now, so that number is no longer reserved as it currently is (jn 3). The M3 motorway could be extended onto the Sydenham Bypass when it is upgraded in a few years' time with junction 3 for the new Harbour Estate interchange, 4 for the City Airport and 5 for Tillysburn. This final section can be summarised as proposal five - that a review be undertaken of all junction numbers, centred on the new unified junction 1 at York Street.


The five key recommendations of this document are:

  1. To base the entire system at a single location, the York Street junction, and designate this "junction 1".
  2. That the A12 Westlink be incorporated as part of the M1 once the current upgrade is completed.
  3. The Irish National Roads Authority avoids using the designation M2, which should be reserved for its existing use in Northern Ireland.
  4. To combine the main section of the existing M2 and the M22 into a larger M2, and redesignate the M5 and M2 Ballymena bypass as the M20 and M21 respectively.
  5. That a review be undertaken of all junction numbers, centred on the new unified junction 1 at York Street.

Appendix - An all-Ireland Numbering System

The above numbering scheme would not only greatly simplify the motorway system for drivers in Northern Ireland, but it would also be relatively easy to change it to an all-Ireland numbering system if the two authorities decided this was the right course of action to take. On such a small island, this makes sense from a traffic management point of view, but it is clear that the issue is more complex than this! The discussion below is from a purely traffic management perspective.

In such a scenario, the only duplicate motorway numbers are the M1 and M3 which are used for different motorways north and south of the border. As the M3 in Northern Ireland is so small, it should be subsumed into zone 1 and designated M13. This would be easy for motorists to handle, as it simply requires the insertion of a '1' into the existing number. This would solve one of the two duplication problems.

The two M1's could remain in co-existance for a longer time than this but, with a possible upgrade of the A1 in mind, there could come a point when the M1 would run from Belfast to Lisburn, then south along the A1 and on to Dublin. In this scenario, the portion of the existing Northern M1 from Lisburn to Dungannon would be re-designated the M10, itself quite a prestigious number. As Ireland's first motorway, the Northern M1 has already secured its place in history.

It is thus proposed that under an all-Ireland numbering system, the M3 at Belfast become the M13, the M1 from Belfast be redirected south along the A1 and the remainder of the northern M1 become the M10. This would create a fully integrated all-island numbering system with no duplication and with minimal confusion to travellers. No numbers at all would have to change in the Republic, unless the NRA ignored proposal 4 above, and except for a possible renumbering of junctions on the Irish M1.