A 2+2 road is a specific type of dual-carriageway being built in Ireland and in Sweden and in Finland, consisting of two lanes in each direction separated by a steel cable barrier.
These roads do not have hard shoulders and therefore they cannot be designated as Motorway at some future date. The Irish variant,however, has 3.5m lanes where there are a number of Swedish variants some with 3.25m wide lanes.
Junctions are generally at-grade roundabouts and minor roads cross under or over the mainline without connecting. They are also known as "Type 2 dual-carriageways" by the Irish National Roads Authority. These roads look similar to expressways, except that expressways often have interchanges, large medians or concrete barriers between traffic. The United States has 80,000 km of roads that fit this description.
2+2 road Wikipedia
The first road of this type opened in December 2007 as a new greenfield section of the N4 national primary route which joins Dublin to Sligo.