Minister for Transport Martin Cullen has turned the sod on the new Gorey bypass, a 22.9km stretch of dual carriageway due to be completed by late 2007.
Mr Cullen said the €179 million road would take up to 10,000 vehicles a day off the streets of Gorey as well as dramatically cutting journey times on the Dublin-Wexford route.
The local villages of Inch and Clogh would also benefit from the relief, he said.
The Minister was accompanied by chairman of the National Roads Authority Peter Malone, who promised the project would remove what was now "undoubtedly the most congested bottleneck" on the N11.
The last 12 months had seen traffic volumes on the road north of Gorey increase by almost 13 per cent, Mr Malone said, and the "east coast spine" would benefit from three further projects now bring planned.
A preferred route had been identified for the Enniscorthy bypass; plans were well advanced for a grade-separated interchange at Kilpeddar-Delgany; and An Bord Pleanála had cleared the Rathnew-Arklow dual-carriageway scheme for construction.