The Luas service to Tallaght, known as the Red Line, has been officially opened by the Taoiseach, Tánaiste, and the Minister for Transport this morning.
Trams will run initially every 10 minutes from 5.30 a.m. to 12.30 a.m., Monday to Friday, with services starting at 6.30 a.m. on Saturdays and 7.30 a.m. on Sundays.
After a trial period, there will be one tram every five minutes in each direction at peak periods, falling back to one every 7½ minutes between 10 a. m. and 4 p.m., and every 10 minutes after 7 p.m.
The service will be open to the public from 3 p.m. and will be free-of-charge for six days. The Green Line from Sandyford to Stephen's Green opened earlier this year.
The Taoiseach, Mr Ahern
Speaking at the launch, Mr Ahern said it was an "historic day for Tallaght, for Dublin and for Ireland".
"The opening of the Luas Red Line marks another significant step in the provision of modern, world-class infrastructure for the city and country.
"This line will change our perception of the city, linking Connolly Station and the IFSC on an east-west axis with Smithfield, the National Museum and the new Heuston Station.
It will open up new areas of the city and county, as well as helping the regeneration and development of existing areas.
"In particular, it will provide Tallaght with the quality transport service it needs and deserves," he added.
Traffic signals at the notorious Red Cow interchange on the M50 have been altered to facilitate the Luas Red Line.
The change is expected to cause further delays for motorists at the interchange, which handles almost 90,000 vehicles a day on the M50 and about 60,000 on the N7, the Dublin-to-Limerick road.
Earlier this year Mr Brennan asked the Railway Procurement Agency "to look again" at the prospect of Luas getting through three level crossings safely and on time as it crosses the interchange.
The Minister suggested the tram system might have to be put "on stilts" as it was not to have priority at the lights.
Testing of the light rail route in recent weeks has revealed that trams are negotiating the junction in just 70 seconds. However, other traffic at the interchange is frequently delayed by up to half an hour as it negotiates the move from one road to the other.