| Road |
From |
To |
Notes |
| A1 |
Belfast |
Dublin |
Via Lisburn and Newry. Becoming the N1 at the border, joining on to the Southern Irish M1 before Dundalk. |
| A2 |
Derry |
Newry |
Northern Irish coastal road. Including routes such as Belfast-Bangor, Belfast-Carrickfergus, Newry-Warrenpoint and Derry-Limavady |
| A3 |
Lisburn |
Cavan |
Becomes the N12 at Middletownn until Monaghan, then the N54 to Cavan via southern Fermanagh. |
| A4 |
Portadown |
Sligo |
Via Enniskillen. Becomes the N16 at the border village of Belcoo. |
| A5 |
Derry |
Dublin |
Via Omagh and Strabane. Becomes the N2 after the Aughnacloy at the border. |
| A6 |
Derry |
Belfast |
|
| A7 |
Belfast |
Downpatrick |
Stemming from the A24 at Carryduff. |
| A8 |
Belfast |
Larne |
Stemming from the A2 at Glengormley. |
| A11 |
|
|
Belfast Inner Ring Road |
| A12 |
Broadway |
York Street |
Westlink dual-carriageway in Belfast |
| A20 |
Belfast |
Portaferry |
Via Newtownards |
| A21 |
Bangor |
Ballynahinch |
Via Newtownards and Comber. |
| A22 |
Dundonald |
Downpatrick |
Via Comber. |
| A23 |
Belfast |
Ballygowan |
|
| A24 |
Belfast |
Clogh |
Forms the greater part of the route from Belfast to Castlewellan, Newcastle, and Kilkeel. |
| A25 |
Downpatrick |
Castleblayney |
Becomes the R182 at the border. |
| A26 |
Banbridge |
Coleraine |
Via Lurgan, Antrim and Ballymena. |
| A27 |
Newry |
Portadown |
|
| A28 |
Newry |
Augher |
Via Armagh |
| A29 |
Portrush |
Dundalk |
Via Maghera, Cookstown, Dungannon, and Armagh. At the border it becomes the R177. |
| A30 |
Lisburn |
Glenavy |
|
| A31 |
Moneymore |
Castledawson |
Form part of the route connecting Cookstown to Belfast. |
| A32 |
Omagh |
Swanlinbar |
Becomes the N87 at the border |
| A34 |
Maguiresbridge |
Clones |
|
| A35 |
Irvinestown |
Donegal town |
Becomes the R234 in Pettigo at the border. |
| A36 |
Ballymena |
Larne |
|
| A37 (North) |
Coleraine |
Limavady |
Part of the Coleraine to Derry route. |
| A37 (South) |
Dundalk |
Castleblayney |
Only a short stretch of this route actually lies within Northern Ireland. The rest of the route being called the N53. |
| A40 |
Derry City Centre |
St Johnston |
Goes southwest along the River Foyle to the border, where it becomes the R236 towards Raphoe |
| A42 |
Maghera |
Carnlough |
Via Ballymena. |
| A43 |
Ballymena |
Glenarriff |
|
| A44 |
Ballycastle |
A26 north of Cloughmills |
|
| A45 |
Granville |
Tamnamore |
Via Dungannon and Coalisland |
| A46 |
Enniskillen |
Ballyshannon |
Becomes the N3 in Belleek on the border |
| A47 |
Kesh |
Belleek |
|
| A48 |
Newtownards |
Donaghadee |
|
| A49 |
Lisburn |
Ballynahinch |
|
| A50 |
Portadown |
Newcastle |
|
| A51 |
Gilford |
Armagh |
|
| A52 |
Belfast |
Crumlin |
|
| A54 |
Castledawson |
Coleraine |
|
| A55 |
|
|
Belfast Outer Ring Road |
| A57 |
Belfast International Airport |
Ballynure |
Forms part of the main route connecting the airport with Belfast City and Larne. |
| A76 |
M1 |
Lurgan |
|
| A101 |
M1 |
Sprucefield, near Lisburn |
|
| A211 |
|
|
Bridge Street and Newtownards Road in Comber, designated when the A21 Comber Bypass was opened in 2004 |
| A371 |
|
|
Various roads in Limavady town centre, designated when the A37 Limavady Bypass was opened in 2004 |
| A501 |
Belfast |
A30 just east of Glenavy |
|
| A505 |
Omagh |
Cookstown |
|
| A509 |
Enniskillen |
Dublin |
Becomes the N3 road at the border after Derrylin. |
| A512 |
|
|
Old Golf Course link road in West Belfast and North Lisburn |
| A514 |
|
|
Derry Ring Road (Crescent Link) |
| A515 |
|
|
Derry Ring Road (Foyle Bridge and Skeoge Link Road) |
