The N81 road is a national secondary road in Ireland, from the M50 motorway to Tullow, County Carlow, north to south. The N81 continues past Tullow for another 8 km to terminate at the village of Closh, County Carlow, where it intersects the N80. The N81 is 76.784 km long (route map). The road is a dual carriageway between M50 motorway and west of Tallaght, known as the Tallaght Bypass or Blessington Road. It intersects with the M50 motorway at Junction 11. There are plans to extend the dual carriageway by 5 km to the urban boundary. The N81 is the only major national road emanating from Dublin that is a national secondary rather than national primary road. The official definition of the N81 from the Roads Act, 1993 (Declaration of National Roads) Order, 2012 states:

History

The route was previously known as the T42 (trunk road). The Dublin and Blessington Steam Tramway once took this route from Terenure to Blessington before it was closed in 1932 due to falling passenger numbers. In the 1990s when it was proposed to reestablish a tram system in Dublin due to chronic traffic congestion (see Luas), the old tram route from the city centre via Terenure to Tallaght was proposed. This route was later ruled out as a result of space constraints and the pipes under the N81 route seemingly being too old in the Terenure area, thus proving to be a great deal more expensive for utility diversion. The Luas instead was made to follow a less direct route from the City to Tallaght, following the Southern Canal ring and then moving south to Tallaght alongside the M50 Motorway.

Planned upgrade

In a Dáil Éireann debate dated 2 July 2019 it was mentioned that the N81 is one of the most dangerous roads in the State with twice the national average for single vehicle collisions and seven times the national average of head-on collisions. In 2021 Minister for Transport Eamon Ryan mentioned that the N81 Tallaght to Hollywood Cross road improvement scheme was not included in the projects to be developed during the current NDP period of 2018–2027, in effect pausing any work on the project until after this date.