An Bord Pleanála has approved plans for a new €490 million dual carriageway linking Kilcullen, Co Kildare, to Powerstown, south of Carlow.
The route will form part of the €1 billion Kildare to Waterford dual carriageway.
Construction of the Kilcullen to Powerstown route will not begin until 2007 and is not expected to be completed until 2010.
The timetable has been confirmed by the Minister for Transport, Mr Brennan, at a meeting with members of the Southeast branch of the Irish Business and Employers' Confederation (IBEC).
Bord Pleanála has announced it has approved the compulsory purchase orders and environmental impact statement for phase one of the new N9 route, which is not to be designated a motorway but is instead officially described as a high-quality dual carriageway.
At 46km, the road works out at about €10.7 million per kilometre. This compares with a figure of about €8.1 million per kilometre for the 64km second section from Carlow to Waterford, which works out at an estimated total of €520 million.
The extra cost in phase one is attributed to a larger number of bridges and junctions.
The northern section of the road will include a specially constructed link to Athy, Co Carlow.
The 46km route will require four specially constructed interchanges, and 43 bridges or culverts.
Documentation relating to the statutory approval of the southern section, from Powerstown to Waterford, is expected to be published shortly.
Commenting on the planned route, the Kildare County Manager, Mr Niall Bradley, said that the new dual carriageway would carry "much of the long-distance traffic and heavy goods vehicles using the existing Dublin-Waterford route.
"This will substantially reduce congestion, noise and traffic pollution, and will improve road safety, travel times and air quality."
The Environmental Impact Statement can be viewed on the project website, at www. n9-n10kilcullen-waterford.ie
