The island of Ireland, comprising Northern Ireland and the Republic of Ireland, has an extensive network of tens of thousands of kilometres of public roads, usually surfaced. These roads have been developed and modernised over centuries, from trackways suitable only for walkers and horses, to surfaced roads including modern motorways. Driving is on the left-hand side of the road. The major routes were established before Irish independence and consequently take little cognisance of the border other than a change of identification number and street furniture. Northern Ireland has had motorways since 1962, and has a well-developed network of primary, secondary and local routes. The Republic started work on its motorway network in the early 1980s; and historically, the road network there was once somewhat less well developed. However, the Celtic Tiger economic boom and an influx of European Union structural funding, saw national roads and regional roads in the Republic come up to international standard quite quickly. In the mid-1990s, for example, the Republic went from having only a few short sections of motorway to a network of motorways, dual carriageways and other improvements on most major routes as part of a National Development Plan. Road construction in Northern Ireland now tends to proceed at a slower pace than in the Republic, although a number of important bypasses and upgrades to dual carriageway have recently been completed or are about to begin.
The N7 road is a national primary road in Ireland, connecting Limerick and Dublin. The majority of the route is motorway standard and is designated as the M7 motorway. At the Rosbrien interchange in Limerick the route continues as the N18 dual carriageway to Galway, Shannon and Ennis. The road passes through the midlands of Ireland, and acts as a trunk route out of Dublin for the N8 and N9 national primary routes to Cork and Waterford respectively. It forms part of European route E20.
The N18 road is a national primary road in Ireland, connecting the cities of Limerick and Galway. Ennis and Gort are two major towns on the route, and Shannon Airport is reached via the connecting N19. The west coast route continues on to Sligo as the N17. The section from Limerick to the N19 junction forms part of European route E20, and the entire route is part of the proposed Atlantic Corridor. The section of motorway from Shannon to Claregalway is designated the M18 motorway. The tolled Limerick Tunnel forms part of the route.
A regional road in the Republic of Ireland is a class of road not forming a major route, but nevertheless forming a link in the national route network. There are over 11,600 kilometres of regional roads. Regional roads are numbered with three-digit route numbers, prefixed by "R". The equivalent road category in Northern Ireland are B roads.
The R509 road, the Childers Road, is a regional road in Ireland, running through the southeastern side of Limerick City. It forms what is somewhat akin to an inner ring road.
The R518 road is a regional road in Ireland which runs from Kilmallock via Rathkeale, to Askeaton, all in County Limerick.
The R512 road is a regional road in Ireland which runs from Limerick city to Fermoy, County Cork. At one time it was part of the main route between the cities of Limerick and Cork.
The N20 road is a national primary road in Ireland, connecting the cities of Cork and Limerick. Buttevant, Croom, Charleville, Mallow and Blarney are major towns along the route. A short section of the route is motorway standard and is designated as the M20 Motorway.
The R445 road is a regional road in Ireland. The route is a non-motorway alternative route to the N7/M7 motorway between Naas and Limerick, and at 170 km it is one of the longest regional roads in Ireland. Indeed, much of the route comprises roads that were formerly part of the N7 between the cities, prior to motorway and other bypasses. Some of the R445 route also comprises local link roads to new N7/M7 route sections.
The N24 road is a national primary road in Ireland forming a route from Limerick to Waterford, running through County Tipperary and passing Tipperary town, Cahir, Carrick-on-Suir and Clonmel. The route begins at its junction with the Limerick Southern M7 ring road.
The N23 road is a national primary road in Ireland, and is located entirely in County Kerry. The route is one of the shorter national primary routes, merely forming a link road between the N21 Limerick – Tralee route at Castleisland to the N22 Tralee – Killarney – Cork route at Farranfore. This facilitates traffic passing in the Limerick – Killarney direction or vice versa, allowing it to avoid detouring into Tralee.
The R421 road is a regional road in Ireland which runs southwest-northeast from the R445 south of Roscrea to the N52 north of Tullamore. The route also passes through Clareen, Kinnitty and Killurin. The bulk of the route is in County Offaly with small sections in counties Tipperary and Laois. The route is 50 km (31 mi) long.
The R503 road is a regional road in Ireland which runs east–west from Thurles, County Tipperary to the N7 west of Limerick City. The entire route is in County Tipperary and is 55 km (34 mi) long.
The R505 road is a regional road in Ireland which runs east-west from Cashel, County Tipperary to the N24 southeast of Limerick City. En route it passes through Dundrum and Cappawhite in County Tipperary and Doon and Cappamore in County Limerick. The road is 45 km (28 mi) long.
The R522 road is a regional road in Ireland which runs 51 kilometres from Newcastlewest in County Limerick to the N73 national secondary road near Doneraile in County Cork, passing through Dromcolliher and Buttevant.
The R506 road is a regional road in the east of County Limerick, Ireland which runs west-east from its junction with the R445 regional road at Garraunykee, Annacotty and its junction with the R505 regional road in the townland of Dromsally on the outskirts of the village of Cappamore. En route it passes through the village of Murroe. The road is 18 km (11 mi) long.
The R507 road is a regional road in the east of County Limerick, Ireland which runs south-north from its junction with the N24 national road at Cluggin Cross and its junction with the R505 regional road in the village of Doon.
The R523 road is a regional road in Ireland, located in County Kerry and County Limerick.
The R510 road is a regional road in Ireland which links the N69 road and the R526 regional road in County Limerick.
The R526 is a regional road in County Limerick, Ireland which follows the former route of the N20 that is now classified as the M20 Motorway, from Junction 5 of the M20 to a junction with the R445 in Limerick city centre.
R445 at Caherdavin 
M7 at Ballysimon