The €85 million dual carriageway between Kilmacanogue and the Glen of the Downs on the N11 Dublin-to-Wexford route has been officially opened this afternoon by the Minister for Transport.
Mr Brennan said the road, which overran its initial cost estimate by more than 70 per cent, completes a "missing link" by connecting the existing continuous motorway/dual carriageway from Dublin to the Newtownmountkennedy bypass in Wicklow.
Motorists long accustomed to miles of traffic tailbacks will now travel on 35 kilometres of continuous motorway/dual carriageway from Donnybrook, South Dublin, to the end of the Newtownmountkennedy bypass.
Some 30,000 vehicles travel through the Glen of the Downs each day and Mr Brennan said the new road would improve travel times and bring down the accident rates experienced on the old road by offering "free-flow" traffic conditions and a footbridge for the safety of pedestrians.
Mr Brennan said he has authorised an independent assessment of the huge cost over-run on the Glen of the Downs project - the final cost was €85 million rather than the estimated cost of €49.2 million at the tender stage in June 2000.
He said the increased cost has been attributed to a delayed start, very difficult site conditions, the relocation of significant utilities and the cost of an additional median barrier.
Mr Brennan paid tribute to the National Roads Authority and Wicklow County Council for what he said was the sensitivity shown in constructing a road at a unique environmental location.
Six thousand oak trees have been propagated from acorns collected in the Glen and so far 600 of these have been planted in the area to replace the 150 mature trees which had to be removed. Access has been provided for small mammals - along with fish ladders and culverts - and Kilmacanogue Marsh has been moved.
The controversial Glen of the Downs road was held up initially by court challenges and protests against its construction through such a sensitive landscape and ecosystem. So-called ecowarriors occupied the site for three years before construction began in 2002.