The Gorey bypass on the N11 Dublin to Wexford road was partially opened yesterday - four months ahead of schedule.
A 13.5 km (8.3 miles) stretch of dual-carriageway will allow an estimated 10,000 cars a day to avoid the town centre which had become one of the country's most notorious congestion blackspots.
The remainder of the 22km (13.6 miles) bypass is expected to be officially opened in September.
Peter Malone, chairman of the National Roads Authority, said "the bypass will improve the quality of life for the people of Gorey . . . and provide an incentive for jobs and development as well as a boost for tourism along the east coast".
Visitors will have easier access to the holiday resorts of Courtown, Ardamine and Ballymoney.
Motorists on the N11 had been experiencing delays of up to half an hour trying to pass through the town.
Gorey is one of the fastest-growing towns in the State and has become a major commuter town. Local officials estimate that almost 50 per cent of people in employment commute to work - usually to Dublin - and most drive, despite the rail and bus alternatives.
Minister for Transport Noel Dempsey described the opening as "great news" which "will improve journey times" and "free up the streets of Gorey".
The people of Gorey would "reclaim the streets", said town clerk Bernard Lawless. He said the bypass would give the town back to the people, the businesses and the tourists.
There was "celebrations on the streets" with music, street theatre and activities for children.
