The final section of the new Dublin to Cork motorway has opened in Co Laois - bypassing the towns of Abbeyleix, Durrow and Cullahill.
Motorists will face tolls on journeys that could be shortened by up to 45 minutes at peak times.
It has been under construction for three years and has cost almost €500m to build.
The new M7-M8 motorway opened to traffic four months ahead of schedule.
The Limerick end will not be finished until later in the year but today's opening means the bypassing of one of the most lethal stretches of road in the country between Mountrath and Borris-on-Ossory where more than 30 people have died.
The toll for cars is €1.80, bringing in expected daily revenue of over €30,000.