Table of contents
1 Roads in the Republic of Ireland
2 Roads in Northern Ireland

Roads in the Republic of Ireland

Motorways

In the
Republic of Ireland, the most important roads are a small number of motorways, indicated by the prefix “M” followed by one or two digits. The motorway network is focused on Dublin.

M1 Dublin – Newry (several sections)
M4 Dublin – N4
M7 Naas – Portlaoise (two sections)
M9 Portlaoise – N9
M11 Dublin – Bray
M50 Dublin bypass

"N" roads

The second category of road has the prefix “N” followed by one or two digits. Roads N1 to N11 radiate anti-clockwise from Dublin:

N1 Dublin – A1 south of Newry
N2 Dublin – A5 north of Monaghan
N3 Dublin – Northern Irish border north of Cavan
N4 Dublin – Sligo
N5 Longford – Westport
N6 Kinnegad – Galway
N7 Dublin – Limerick
N8 PortlaoiseCork
N9 Kilcullen – Waterford
N10 Paulstown – Ballyhale via Kilkenny
N11 Dublin – Wexford

The most important cross-country roads are numbered in the range N13 - N30, with less important roads having higher numbers. Less important roads still are indicated with an “R” prefix and a three-digit number, ranging from R1xx in the north-east to R7xx in the south-east of the country.

Roads in Northern Ireland

Motorways

Although the roads in the north connect well with the roads in the south, their numbering follows the British system. The most important roads are
motorways, many with the same designation as those in the Republic or mainland Britain. The motorway network is focused on Belfast.

M1 Belfast – Dungannon
M2 Belfast – Ballymena
M3 Short spur in Belfast
M5 Belfast – Newtownabbey
M22 Antrim – Randalstown

"A" roads

The next most important roads are designated with the prefix “A” and a one-, two- or three-digit number. Some of the most important are:

A1 Belfast – N1 north of Dundalk
A2 DerryNewry coastal road
A3 Belfast – Armagh
A5 Derry – N2 north of Monaghan
A6 Belfast – Derry
A7 Belfast – Downpatrick
A8 Belfast – Larne

"B" roads

Less important roads are indicated with the prefix “B” and a one-, two- or three- digit number.