The official description of the R129 from the Roads Act 1993 (Classification of Regional Roads) Order 2012[1] reads:
R129: Coldwinters - Wyanstown, County Dublin
Between its junction with R132 at Coldwinters and its junction with R122 at Wyanstown via Thomondstown, Grange, Ballyboghill, Murragh and Leastown all in the county of Fingal..