Motorways

In the Republic of Ireland, a motorway forms part of a national primary route, but is indicated by the prefix M instead of N. Motorways are the highest standard roads and certain drivers and vehicles are prohibited from using them. The motorway network has been expanded extensively since the 1990s, through construction of new motorways and redesignation of existing motorway-standard dual-carriageway sections of National Primary routes.

The first motorway section in the state was the M7 Naas by-pass, which opened in 1983. Since 2009, all motorways in Ireland are part of, or form, national primary roads. At the end of 2004 there were 192 km (119 mi) of motorway in the Republic and 286 km (178 mi) of dual-carriageway.^[12] This was extended, by the end of 2005, to 247 km (153 mi) of motorway and 297 km (185 mi) of dual-carriageway.^[13] By the end of December 2009 there were 667 km (414 mi) of motorway in Ireland, with 385 kilometres (239 mi) under construction at the time.^[14]

As of 2019, the following motorway routes are in operation:

• M1, part of the Dublin – Belfast route: from M50 J3 at Dublin Airport to Thistle Cross (just north of Dundalk), where it reverts to the N1 numbering as a dual carriageway up to the border with Northern Ireland, where it continues without interruption as the A1 dual carriageway to a junction with Northern Ireland's M1 and on to Belfast.
• M2, part of the Dublin – Derry/Letterkenny route: from just north of M50 J5 to just north of Ashbourne, County Meath, (where it reverts to a single-carriageway road (N2) as far as the border, then continues as the A5 to Derry or recrosses the border to become the N14 to Letterkenny).
• M3, part of the Dublin – Cavan/Enniskillen/Donegal route: from Clonee (on N3 from M50 J6) to Kells bypass. The route continues as the N3 as far as the border, then becomes the A509 to Enniskillen, whereupon it is renumbered the A46 to the border at Belleek and resumes its N3 identity as far as Ballyshannon on the N15 Sligo – Donegal road.
• M4, part of the Dublin – Sligo route: from Lucan (on N4 from M50 J7) to Kinnegad at which point it reverts to dual carriageway to (bypass) Mullingar.
• M6, part of the Dublin – Galway route: leaves M4 at J11 near Kinnegad, ending at the R381 crossing where it reverts to the N6 dual carriageway around Galway. The section around Athlone reverts to N6 status as it is an all-traffic dual carriageway. This was the first city-to-city motorway link in Ireland. Opened in January 2010.
• M7, part of the Dublin – Limerick route: begins at the Naas bypass at the end of the N7 Naas Road dual carriageway from M50 J9 and continues to Rossbrien outside Limerick where the motorway forms an interchange with the N18 & M20 routes at junction 30.
• M8, part of the Dublin – Cork route: branches off the M7 at junction 19 and continues to the Dunkettle interchange outside Cork where it forms an interchange with the N25 and N40 routes.
• M9, part of the Dublin – Waterford route: branches off the M7 at junction 11 and continues towards the Quarry Roundabout outside Waterford where it forms a junction with the N24.
• M11, two separate parts of the Dublin – Wexford route: the southern tip of the M50 to the west side of Bray and from Coyne's Cross to just north of Oilgate.
• M17, part of the Galway – Sligo route: begins at junction 18 on the M6 and continues to a terminus roundabout on the outskirts of Tuam. Continues northbound towards Sligo as the N17.
• M18, part of the Limerick – Ennis - Galway route: begins at junction 9 for Shannon Airport from the N18 dual carriageway from the Rossbrien Interchange in Limerick and continues to junction 18 with a junction on the M6 for Galway.
• M20, part of the Cork – Limerick route: branches off the M7 at junction 30 and the N18 at junction 1 at the Rossbrien interchange outside Limerick and continues for 10 km (6 miles) towards Attyflin near Patrickswell at junction 4. Here the route forms an interchange with the N20 towards Cork and the N21 to Tralee & Killarney. Both the N20 & N21 from here are single carriageway.
• M50, 45 km (28 miles) C – shaped ring road that forms a bypass of Dublin. The motorway connects to all the national primary routes from Dublin to the main cities and regions of Ireland as well as Dublin City centre.

In June 2007, it was announced that around 800 kilometres (500 miles) of 'new' motorway would be created; however, much of this resulted from the re-classification of most of the country's high-quality dual carriageways to motorway regulations rather than the construction of purpose-built motorways. This affected most of the major inter-urban routes between Dublin and various towns and cities and some of the Atlantic Corridor along the Western seaboard.^[15]

National primary roads

National Primary routes form the main cross country roads in Ireland and include all motorways. This category of road is numbered from 1–50 with the prefix "N" (or "M" for motorway sections). The routes numbered N1-N11 radiate anti-clockwise from Dublin, with those in the range N12-N26 being cross-country roads and N27-N33 being newer short link roads. The N40 is the Cork Ring Road and the N50 is the Dublin Ring Road. National secondary roads (see next section) are numbered under the same scheme with higher numbers. On road signage, destinations served but not on the route in question are listed in brackets, with the connecting route also listed (see thumbnail).

Northern Ireland route sections (which are classified separately according to NI schemes) are in some cases included in a theoretical complete cross-border route – for example the N3 route, which re-enters the Republic. These are listed here in brackets for completeness (and are present on southern road signage).

Naas Road (N7), non-motorway high-grade dual carriageway

Non-motorway National Route sign in Ireland

This list ignores the sections of route reclassified as motorway (see previous section).

National secondary roads

Local road route marker at the junction of the L8282 with R747 regional road at Lackareagh, County Wicklow.

A directional sign with Local Road number indicated.

National secondary roads fill in the rest of the main cross country routes in Ireland. They connect large towns (such as Birr) which are not served by National Primary routes, and some routes (such as N59) follow long coastal route connecting many towns. They are indicated with a "N" prefix followed by a number from 51 to 99 (N87 is currently the highest).

There are 2683.974 km (1668 miles) of national secondary roads in Ireland, making up slightly less than 50% of the entire national route (national primary and national secondary) network.^[20] National secondary routes are generally more poorly maintained than primary routes (although their quality can vary widely), but often carry more traffic than regional roads. Almost the entire network of national secondary roads is single carriageway, although there are some short sections of dual carriageway on the Tallaght bypass section of the N81, on the N52 at Dundalk, on the N85 at Ennis, on the N62 at Athlone and on the N71 between Cork and Bandon. Typically, national secondary roads are of a similar standard or higher than regional roads although some are of lower quality than the better sections of regional roads. Many of them have been resurfaced with higher quality pavements in recent years with relatively smooth surfaces and good road markings and signposting. However, road widths and alignments are often inadequate, with many narrow and winding sections.

National secondary roads generally do not bypass towns on their routes although there are a number of exceptions: the N52 bypasses Nenagh, Mullingar and the centre of Dundalk (as a relief road) with a further N52 bypass of Tullamore planned, the N55 (along with the N3) bypasses Cavan, the N56 forms part of the Donegal bypass, the N61 and the N63 bypass Roscommon, the N71 bypasses Halfway and Skibbereen, the N74 bypasses Cashel, the N76 bypasses Callan, the N77 forms the northern part of the Kilkenny ring road, the N80 bypasses Carlow and the N85 bypasses Ennis. When the Fermoy (Moorepark) to Kilbehenny section of the M8 was completed, the former N8 bypass of Mitchelstown was re-classified as the N73.

Examples of national secondary roads are:

• N52 Dundalk via Mullingar and Birr to Nenagh joining M7 to Limerick
• N59 Galway – Clifden – Westport – Bangor Erris – Ballina – Ballysadare
• N62 Athlone – Horse and Jockey
• N74 Cashel – Golden – Tipperary Town
• N81 Dublin – Tullow
• N86 Tralee – Dingle via Lispole

Alternative National roads

Alternative National roads are regional roads which provide an alternative route to a national route. A large amount of national primary routes have been replaced by motorways, which certain drivers and vehicles are prohibited from using. These regional roads provide an alternative route to the motorway for these drivers. They are usually the former national road which was downgraded following the opening of the motorway. In 2010 new signage was introduced for alternative routes. They are signposted in black on a yellow background, instead of black on a white background for other regional roads.^[21] This new signage has been installed on most roads, being included when signage was replaced. Roads where the new signage has been installed include the R132 in Swords (alternative to M1), the R147 in Dunshaughlin (alternative to M3), the entire length of the R448 (alternative to M9), the R712 in Paulstown (alternative to N10) and the R772 from Rathnew to Arklow (alternative to M11).

Regional roads

Regional Roads fill in the rest of the main roads in Ireland. They connect many small towns to each other and to the national road network. There are over 11,600 kilometres (7200 miles) of regional roads.^[22] Regional roads are numbered with three digit route numbers, prefixed by "R" (e.g. R105). Route numbers range from R1xx in the north-east to R7xx in the south-east of the country, with newer short urban roads numbered R8xx and R9xx. They are signposted in black with a white background. Some of the more important regional roads such as the R136 Outer Orbital, Dublin and the R710 Waterford Outer Ring Road are dual-carriageway in whole or part. Most regional roads are however single carriageway roads, and many are rather narrow country roads.

Regional roads are subject to a general speed limit of 80 km/h (50 mph) or 50 km/h (30 mph) in built-up areas.

While funding for national primary roads is administered centrally by Transport Infrastructure Ireland (TII), regional and local roads are less well funded (although funding has increased in the 2000s). Local councils are responsible for these roads, as opposed to TII.

Local roads

Local Road (boreen) in County Mayo with a speed limit of 80 km/h (50 mph).

All public roads which are not motorways, national roads or regional roads are local roads: "a public road, other than a national road or a regional road, shall be a local road".^[23]

Local roads vary greatly in quality, from wide urban streets to very narrow, rural lanes, known as boreens in Ireland. There are three types of Local road: Local Primary (local roads wider than 4 metres (13')), Local Secondary (local roads narrower than 4 metres (13')) and Local Tertiary (cul-de-sacs and other minor roads).

Local roads are subject to a general speed limit of 80 km/h (50 mph) or 50 km/h (30 mph) in built-up areas. While this is the maximum speed allowed, drivers must adhere to the Road Traffic Act and drive with due care and attention and with regard to the road conditions.

Local roads are not generally referred to by number, but are registered with a four- or five-digit "L" number, taking the form Lxxxx. It used to be rare to see these numbers on signposts (and these numbers do not appear on Ordnance Survey maps), but in 2006 the Department of the Environment, Heritage and Local Government began a programme of new signage for regional roads that incorporates local road numbers on directional signage (see thumbnails).^[24]

Old system

Old style Fingerpost with old Link Road number on it

The Republic of Ireland had a different road numbering system prior to the introduction of the National Route numbering system.

Major roads were marked with "T" for Trunk Road, less important roads were marked with "L" for Link Road.

The first nine Trunk Roads (T1, T2, T3, T4, T4a, T5, T6, T7, T8) radiated out from Dublin (with the T8 branching off the T7 at Enniscorthy) and followed an anti-clockwise pattern. This pattern was similar to the existing anti-clockwise pattern which the routes radiating out of Dublin follow.

Unlike the present system, where each road (whether N- or R-) has a unique number, under the Trunk/Link system, the L-roads were numbered separately beginning with L1. These L (for Link Road) classifications are not related to the current Lxxxx numbers for Local Roads. Confusingly, some old road signs still show the former (now obsolete) road numbers.

Trunk Roads were broadly equivalent to the present National Roads, and Link Roads to the present Regional Roads. Most of the National Primary and National Secondary routes had been Trunk Roads and generally they followed the routes of these Trunk roads, albeit with a different numbering system. However, some National Primary and Secondary roads also incorporated Link Roads and unclassified roads into their routes. Furthermore, many Trunk Roads were downgraded to Regional roads, effectively 'de-trunked'. Some newer National Primary routes were built as new roads in the 1990s and therefore did not incorporate former Trunk, Link or unclassified roads into their routes.