The latest section of the M1 motorway between Dublin and the border is due to open in Co Louth today, four months ahead of schedule.
The 11km Dundalk western bypass has been built at a cost of €120m and is the penultimate stage of the Dublin-to-Belfast road.
The final stage, which is due to open in two years, is a 14km dual carriageway linking the end of the bypass at Ballmascanlon with the Clohogue roundabout south of Newry.
The bypass being opened today is expected to take 10,000 vehicles away from Dundalk and reduce peak-time travel by around half an hour.
It has been constructed as part of a public-private partnership and is being paid for by tolls collected on the Drogheda bypass, which was built by the same company.