The T15 was part of a major trunk route running across Ireland from Galway to Belfast along with the A3.
It is unusual in that no comparable cross country route exists today, and the road has been renumbered to a wide variety of National and Regional roads. None of these, save perhaps a few sections of the N12, are particularly high quality compared to other modern single carriageway roads in Ireland and recent upgrades have been modest in ambition. Traffic between the two cities would today probably go via Dublin, which although a longer distance, can be travelled almost totally on grade separated dual carriageway, and predominantly on motorway.
