An estimated 6,000 cars a day will be taken out of Kilkenny's medieval centre following the opening of a new section of the city's ring road yesterday.
The €34.5 million project took two years to complete and links the N10 main Dublin road to the N77 Castlecomer road.
Minister of State John McGuinness said it was "evidence of this Government's commitment, under the ambitious framework of the National Development Plan and Transport 21, to the continuing transformation of Ireland's transport infrastructure.
"This will prove to be of immense value to the future economic growth and development of this thriving city" and that "all road users will benefit", he said.
Peter Malone, National Roads Authority chairman, said the road would "create a safer and more pleasant environment for locals and the thousands of tourists who flock to this historic city" .
He said the NRA was committed to improving the national road network in the southeast resulting in shorter travel times, certainty of journey duration and safer road conditions.
The 4.2 km of single carriageway road, which incorporates a new bridge over the Dublin-Kilkenny railway line, was blessed by the new Bishop of Ossory, Dr Séamus Freeman, who apologised for his late arrival at the opening ceremony. The Minister and the bishop then drove along the new road in the first car registered in Ireland.
The 1901 French-built "De Dion-Bouton" model has the Wexford number plate MI-1. Its owner, Ossie Bennett of Johnstown, Co Kilkenny, said the car valued at "around €250,000" had a "top speed of 20 miles per hour".