R112

The R112 at Mount Merrion.

The R112 is a suburban secondary road in County Dublin, running from the R148 at Chapelizod, in the west of Dublin city, to the R138 at Mount Merrion in Dún Laoghaire - Rathdown, southeast of the capital, via Templeogue in the South Dublin County Council area.

Prior to the opening of the M50, this route was the signposted route from Dún Laoghaire port and the N11 to the N7. It was developed in the 1960s as suburbs were developed along its path and is typically surrounded by 1960s semi-detached housing, although there is also an attractive section along the River Dodder. It was noted that these roads were built to encourage traffic to use them as major arteries, marking a major difference in how south and north Dublin handled through traffic.

While generally S2, short sections have been improved near junctions and bus lanes have sometimes been added on one or other side approaching these.

'Ring road' signs were added to the road in 1977.

The section around Mount Merrion and Goatstown broadly follows the line which was reserved for the South East Motorway.