A €550m contract has been signed to build a new motorway between Gort and Tuam in Co Galway, under a public private partnership.
The 57km M17/M18 motorway - which will not be tolled - will ease congestion by bypassing Clarinbridge, Claregalway and Tuam.
It aims to reduce journey times by up to 20 minutes, and is estimated to create up to 450 jobs during and after construction.
The motorway is the first project under the Government's new PPP stimulus programme. It is expected to open in late 2018.
The contract was signed off by the Transport Minister Leo Varadkar and the Minister for Public Expenditure Brendan Howlin.