Road numbering in NI is a mess

Any outsider trying to get from A to B in Northern Ireland would be best advised to invest in a satnav. People who regularly commute from Craigavon to Belfast are well accustomed to seeing cars with Dublin license plates barrelling westward on the M1 with panicked-looking drivers inside. This is because in the Republic, the powers that be have (sensibly) decided that a motorway should have the same number as the route that it replaces, which then reverts to a regional road with a different number. The concept of an M1 and an A1 going in completely different directions therefore takes people by complete surprise.

But that’s not all. Travelling from Belfast to Derry, one takes the M2, which is inexplicably renamed to the M22 shortly before downgrading to the A6*. One end of the M1 becomes the A4, but the other end becomes the A12. When driving from Derry to Coleraine one should not stay on the A2 for the full distance unless a scenic detour is desired. And nobody in their right mind would drive from Armagh to Newtownhamilton using the A29 via Keady. Then there are several routes that fork so that they have three or more ends (A2 in Derry, B2 in Lurgan, B3 in Gilford, B95 every half a mile…) and two that share the same number (A37 at Coleraine and also at Crossmaglen). It’s almost as if the person who was dishing out the numbers came in with a hangover one morning and forgot what he’d done the night before.

Several decades ago, the Republic completely renumbered all of its roads. The new system is consistent, logical and future proof. I would propose a limited renumbering of NI’s trunk routes on a similar basis, with the primary aim of making life easier for drivers of strategic traffic, who may not be familiar with the idiosyncrasies of the current system.

  • The renumbering would initially apply only to motorways, primary strategic routes and a few other border-crossing roads that connect to the Republic’s N routes.
  • Where routes cross the border they would have the same number on both sides.
  • Routes would use the same number for their entire length, the only change being an M to indicate a motorway.
  • The ultimate destination of each route would be clearly signposted, even if it was on the other side of the border (with one exception).
  • Route numbers would not need to be unique across the island, but would be chosen to minimise confusion and represent the relative importance of the routes.

The last point is important – this is an NI-specific scheme, and would be defined independently of the Republic’s system (making it easier to implement both logistically and politically). It would however be coordinated on a best effort basis, in the same way that neighbouring counties in the U.S. often coordinate the numbers of their border-crossing county roads while freely duplicating others. Strategic routes in NI would use a novel prefix (S for “strategic”, say) to avoid any ambiguity.

This scheme would entail significant costs, so would probably only happen as part of a larger project, perhaps including bilingual signage and/or metrication.

The new routes would be:

Primary Strategic Routes

  • S1 – A1 Sprucefield to Dublin (=N1)
  • S2 – A5 Derry to Dublin (=N2)
  • S3 – A509, A46 Dublin to Ballyshannon (via Enniskillen) (=N3)
  • M10, S10 – M2, M22, A6, A514 Belfast to Derry
  • M11, S11 – A8(M), A8 Glengormley to Larne
  • M12, S12 – M12, A3 Craigavon to Monaghan (=N12)
  • M13, S13 – A26, M2, A26, A37(N), A2, A515, A2 Antrim to Letterkenny (via Coleraine and Derry) (=N13)
  • M16, S16 – A12, M1, A4 Belfast to Sligo (=N16)
  • M31, S31 – M5, A2 Belfast to Carrick
  • M32, S32 – M3, A2 Belfast to Bangor

Concession Routes

These short (<5km each) border-crossing sections are not considered strategic routes by NI but are by the Republic and should have consistent signage (and quality) within NI for driver convenience (and safety). It might be best if any signs on the NI side showed only the Republic’s N designations, to avoid unnecessary confusion.

  • S14 – A38 Strabane to Letterkenny (=N14)
  • S53 – A37(S) Dundalk to Castleblayney (=N53)
  • S54 – A3 Monaghan to Cavan (=N54)

S15 is reserved. The N15 joins the N14 immediately on the Republic side of the border, and so may also be signposted from within NI.

All the numbers above match those used in the Republic apart from:

  • N10 is a short route in Kilkenny that arguably doesn’t justify a low number now that the M9 exists.
  • N11 is used for the Dublin to Rosslare route, but both N11 and S11 are part of the greater Larne to Rosslare strategic route, so the numbers do not conflict.
  • N31 is a short route used for access to the port of Dun Laoghaire.
  • N32 was once used for a very short section of road near Malahide that has since been detrunked.

The numbers have been chosen so that major strategic routes have satisfyingly low numbers (fortunately the Republic numbers roads from north to south so all border-crossing roads have low numbers already) and also so as not to use a number that the Republic might choose in the future for a road close to the border (it hasn’t yet reused a deallocated number).

The S1 does not extend the entire way to Belfast but terminates on the M16. The M12 also violates the rule of thumb that side branches should have higher numbers than the parent route. I consider this preferable to having motorways change number partway down their length. The S13 is not the preferred route between its end points (and so should not be signposted end to end), however it is the preferred route between any other two significant towns along its length.**

Future application to other trunk routes

This scheme could easily be extended to all other trunk routes in NI. If so, then they might be assigned numbers greater than 100, as south of the border these are reserved for minor roads. Currently trunk roads in NI are defined chronologically rather than geographically, and follow some bizarre routes which appear designed to use the fewest route numbers rather than define routes that a driver would find useful. Fortunately these trunk numbers are not used on signage, but it would be sensible to redefine trunk roads using the new numbering to minimise the number of different schemes in use. The 15 additional trunk routes would then be (roughly anti-clockwise around Belfast):

  • S100 – A55 Outer Ring
  • S101 – A44 Ballymena to Ballycastle
  • S102 – A36 Ballymena to Larne
  • S103 – A57 Larne to Aldergrove
  • S104 – A26 Antrim to Moira
  • S105 – A31, A29, A505, A32 Castledawson to Enniskillen
  • S106 – A29 Coleraine to Armagh
  • S107 – A28 Aughnacloy to Newry
  • S108 – A27 Portadown to Newry
  • S109 – A2 Newry to Warrenpoint
  • S110 – A24, A2 Belfast to Newcastle
  • S111 – A7 Belfast to Downpatrick
  • S112 – A22 Belfast to Comber
  • S113 – A20 Belfast to Newtownards
  • S114 – A21 Bangor to Comber

Trunk roads leading into Belfast (other than the three main motorways) would terminate on the Outer Ring. There are also several roads that use green signage (such as the A11 Belfast Inner Ring) but which are not legally defined as trunk roads. To minimise confusion, this practice should be discontinued.

Minor routes

The inconsistencies with minor routes could be individually addressed. There is little justification for a costly wholesale renumbering of non-trunk routes. The division into A, B and C classes is broadly sensible as it reflects the importance of a route and thereby implies the standard of road a driver should expect. Usually.

Some suggestions:

  • Renumber the B32 to A29 so that the A29 runs straight up the high street of Keady and out the Castleblayney road. The old A29 from Keady to Newtownhamilton could then be an extension of the B132, and the B31 would continue on the mainline from Armagh to Dundalk (no need for an A classification as the preferred route goes via Newry).
  • The Tandragee-Keady-Monaghan, Lurgan-Scarva and Loughbrickland-Rathfriland branches of the B3 should get separate numbers. The Scarva-Loughbrickland section is of such poor quality that it should probably be downgraded.
  • The B2 is a shattered mess. There are several identifiable sections: 1. a sensible section from Downpatrick to Lurgan. 2. a hairpin shaped section from Lurgan to Portadown via Charlestown. This should be renumbered. 3. A section from Lurgan to Tandragee which never matched the signposted route between the two towns and has anyway since been partially overbuilt. This should be both renumbered and rerouted so that it uses the Tandragee Road to go to Tandragee. 4. The Clare Road beyond Tandragee should be renumbered as an extension of the B131.
  • The B95 also has several distinct branches: 1. Antrim to Ballyclare 2. Antrim to M2 J6 3. Templepatrick to Glengormley. 4. Scullions Road, Mayfield Link, Upper Hightown Road 5. Hightown Road (due for demotion once Mayfield Link is complete?). Each of these should have a distinct number.

One would think numbers were a scarce resource, observing the absurdities that the Roads Service creates in trying to avoid assigning new ones. Bypass schemes have historically resulted in the bypassed sections being awkwardly renumbered as extensions of other, unrelated roads. There does seem to be an emerging standard whereby downgraded sections of road are given new codes by appending digits to the old ones but this is not consistently applied. It should be.

(*) there is a good historical reason for this, which will never be relevant again

(**) A good general principle for route numbering would be to adopt the notion of a geodesic from geometry, thereby ensuring that a numbered route will travel in a broadly consistent direction along its entire length (which is obviously not always the case at the moment). We could define a “geodesic condition” so that a numbered route should describe a best path across the landscape that cannot be improved by incremental detours along roads of similar quality. For example, the B3 between Gilford and Loughbrickland is not a geodesic, as it does not follow the the signposted “best” route between those towns. A geodesic road may not always be the preferred route between its end points, as the existence of a high quality road does not negate the need for a parallel minor road. A ring road may be a geodesic, if it beats driving through the centre of town.

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