The Minister for Transport, Noel Dempsey, has forecast that some 10,000 vehicles will be removed each day from a section of the Galway-Dublin road that had been one of the country's most notorious bottle-necks.
Mr Dempsey was speaking at the opening of a dual-carriageway resulting in Kilbeggan, Horseleap and Moate being by-passed by motorists commuting between Galway and Dublin.
The new dual-carriageway commences near Kilbeggan at the western end of the completed N6 Kinnegad to Kilbeggan scheme and connects to the eastern end of the existing Athlone by-pass.
Travel times between Dublin and Galway are expected to be reduced significantly as motorists had previously experienced delays of up to 45 minutes in Moate at peak times.
Mr Dempsey said: 'The opening of the N6 Kilbeggan to Athlone scheme is fantastic news for local people and other road users.
'It will improve the quality of life for those living in these areas and make their local roads safer while at the same time cutting driving times on the Dublin to Galway route.'
The entire route from Dublin to Galway will be complete by 2010.
The schemes currently under construction are the N6 Athlone to Ballinasloe scheme, which is due for completion next year, the 56km N6 Ballinasloe East to Galway project will be completed in 2010 and the N4 Lucan Bypass Upgrade scheme will be finished in 2009.