More than 1,000 jobs are to be created in two new road projects with the last major traffic bottleneck between Dublin and Cork being removed.
Some 282 million euro is to be spent upgrading the N7 Newlands cross junction into a traffic light free flyover and turning the N11 between Arklow and Rathnew in Wicklow into a dual carriageway.
Transport Minister Leo Varadkar said the projects were milestones and will improve safety and journeys in and out of the capital.
"These projects will make a huge difference to road users and will finally remove two bottlenecks which were not addressed during the boom," he said.
"The N11 will improve safety standards the minute it's opened, while the Newlands Cross fly-over will remove the last traffic light between Cork, Limerick and Waterford and the border."
The deals are the first transport public private partnerships to be signed since the wheels came off the economy in 2007.
The N7 project, where 80,000 vehicles pass through each day, will mean drivers can go from Belfast to Cork, Limerick and Waterford without facing a traffic light.
The flyover will replace the junction of the Naas Road and the R113 Fonthill/Belgard Roads at Newlands Cross. West and southbound traffic will be taken up and over the minor road reducing the impact on local road users.
The N11 upgrade, to be finished within two years, will improve safety on a notoriously dangerous stretch of road and will also include the first on-line service station on the route at Gorey, Co Wexford.
The new carriageway will be 16.5km connecting the Arklow bypass with the existing Rathnew/Ashford bypass bringing motorway or dual carriageway along the east coast from Dublin to Gorey.