The Taoiseach has turned the sod for the next phase of a planned motorway between Gort and Tuam in Co Galway.
The non-toll route, which is costing €550 million, will be open in 2018.
The road will be constructed as a Public Private Partnership and it is estimated that 450 jobs will be created.
It is the second largest motorway project undertaken by the NRA.
Enda Kenny said the infrastructure was much needed. He said both Ireland West and Shannon airports would benefit by enhanced connectivity.
He paid tribute to the previous Fianna Fáil-led administration for the work it had done on the motorway network.
The Taoiseach was joined at a ceremony in Gort this afternoon by Minister for Transport Leo Varadkar, representatives of the National Roads Authority and several local authority officials.
Minister Varadkar said the motorway would enhance the economic and social life of the region.