| Road |
From |
To |
Notes |
 A1 road |
Belfast |
Killeen |
Via Lisburn and Newry. Forming part of the main route from Belfast to Dublin. Becoming the N1 at the border, joining onto the Southern Irish M1 before Dundalk. |
 A2 road |
Derry |
Newry |
Northern Irish coastal road. Including routes such as Belfast-Bangor, Belfast-Carrickfergus, Newry-Warrenpoint and Derry-Limavady |
 A3 road |
Lisburn |
Cavan |
Via Craigavon and Armagh. Becomes the N12 at Middletownn until Monaghan, then the N54 to Cavan via southern Fermanagh. |
 A4 road |
Craigavon (Portadown) |
Belcoo |
Via Dungannon and Enniskillen. Becomes the N16 at the border towards Sligo. |
 A5 road |
Derry |
Aughnacloy |
Via Strabane and Omagh. Becomes the N2 after the Aughnacloy at the border towards Dublin. |
 A6 road |
Derry |
Belfast |
Via Dungiven, Antrim and Glengormley. |
 A7 road |
Carryduff |
Downpatrick |
Via Saintfield. Stemming off the A24, it forms most of the main road from Belfast to Downpatrick. |
 A8 road |
Glengormley |
Larne |
Via Ballynure. Stemming from the A6. |
 A11 road |
|
|
Belfast Inner Ring Road |
 A12 road |
Belfast (Broadway) |
Belfast (York Street) |
Westlink dual-carriageway in Belfast |
 A20 road |
Belfast (Bridge End) |
Portaferry |
Via Dundonald and Newtownards |
 A21 road |
Bangor |
Ballynahinch |
Via Newtownards and Comber. |
 A22 road |
Dundonald |
Downpatrick |
Via Comber, Killinchy and Killyleagh. |
 A23 road |
Belfast |
Ballygowan |
Via Moneyreagh. |
 A24 road |
Belfast (Cromac Street) |
Clough |
Via Carryduff and Ballynahinch. Forms the greater part of the route from Belfast to Newcastle, and Kilkeel. |
 A25 road |
Strangford |
Altnamackan |
Via Downpatrick, Clogh, Rathfriland, Newry and Newtownhamilton. Becomes the R182 at the border and carries on towards Castleblaney. |
 A26 road |
Coleraine |
Banbridge |
Via Coleraine, Ballymena, Antrim, Moira, Craigavon (Lurgan) and Warringstown. |
 A27 road |
Newry |
Craigavon (Portadown) |
|
 A28 road |
Newry (Sheepsbridge) |
Aughnacloy |
Via Markethill, Armagh and Caledon. |
 A29 road |
Portrush |
Ballymaclosha |
Via Maghera, Cookstown, Dungannon, Armagh, Keady and Newtownhamilton. At the border it becomes the R177 and carries on towards Dundalk. |
 A30 road |
Lisburn |
Glenavy |
|
 A31 road |
Moneymore |
Castledawson |
Form part of the route connecting Cookstown to Belfast. |
 A32 road |
Omagh |
Swanlinbar |
Via Enniskillan. Becomes the N87 at the border. |
 A34 road |
Maguiresbridge |
Clones |
Via Lisnaskea and Newtownbutler. Becomes the R183 road at the border |
 A35 road |
Irvinestown |
Pettigo |
Via Kesh. Becomes the R234 at the border. |
 A36 road |
Ballykeel |
Ballyrickard |
Via Moorfields and Killwaughter. Forms the main route from Larne to Ballymena. |
 A37 road (Co. Londonderry) |
Macosquin |
Limavady |
Part of the Coleraine to Derry route.(North) |
| A37 road (Co. Armagh) |
Dundalk |
Castleblayney |
Only a short stretch of this route actually lies within Northern Ireland. The rest of the route being called the N53.(South) |
 A38 road |
Strabane |
Lifford |
Less than a mile lies in Northern Ireland crossing the River Foyle and divides into the N14 to Letterkenny and N15 to Sligo. |
 A40 road |
Derry city centre |
Carrigans |
West of the River Foyle, becomes the R236 at the border which carries on towards Raphoe. |
 A42 road |
Maghera |
Carnlough |
Via Portglenone, Ahoghill, Galgorm, Ballymena and Broughshane. |
 A43 road |
Ballymena |
Glenarriff |
Via Martinstown. |
 A44 road |
Ballycastle |
A26 north of Cloughmills |
Via Armoy. |
 A45 road |
Granville |
Tamnamore |
Via Dungannon and Coalisland |
 A46 road |
Enniskillen |
Belleek |
Becomes the N3 at the border which carries on towards Ballyshannon. |
 A47 road |
Enniskillen (Trory) |
Belleek |
Via Killadeas, Lisnarick, Kesh, Boa Island and Leggs. |
 A48 road |
Newtownards |
Donaghadee |
Via Six Road Ends. |
 A49 road |
Lisburn |
Ballynahinch |
|
 A50 road |
Craigavon (Portadown) |
Newcastle |
Via Gilford, Banbridge, Katesbridge and Castlewellan. |
 A51 road |
Gilford |
Armagh |
Via Tandragee and Hamiltonsbawn. |
 A52 road |
Belfast (Carlisle Circus) |
Crumlin |
Via Nutt's Corner. |
 A54 road |
Castledawson |
Coleraine |
Via Bellaghy and Kilrea. |
 A55 road |
|
|
Belfast Outer Ring Road |
 A57 road |
Belfast International Airport |
Ballynure |
Via Templepatrick and Ballyclare.Forms part of the main route connecting the airport with Belfast City and Larne. |
 A76 |
M1 |
Craigavon (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 |
Via Mountfield. |
 A509 |
Enniskillen |
Belturbet |
Becomes the N3 road at the border after Derrylin. |
 A510 |
Belfast (Cromac Street) |
Ballymacarrett (Albertbridge Road) |
Formerly numbered as A20. |
 A512 |
|
|
Old Golf Course link road in West Belfast and North Lisburn |
 A513 |
Ballymacash |
Derriaghy |
Lisburn Feeder Road |
 A514 |
|
|
Derry Ring Road (Crescent Link) |
 A515 |
|
|
Derry Ring Road (Foyle Bridge and Skeoge Link Road) |
 A519 |
Tonagh |
Ballymacash |
Distributor road in western Lisburn |
 A520 |
Ballymacash |
Knockmore |
Link between the A3 and the A519 in Western Lisburn |
 A522 |
Dublin Road, Antrim |
Belmont Road, Antrim |
Former route of the A6 through Antrim town centre. |
 A523 |
Ballymena Town Centre |
Ballee Roundabout, Ballymena |
Former route of the A26 through Ballymena. |