Patrick Logue looks what Luas may mean for motorists, particularly with changes on St Stephen's Green.
While Luas will be greeted today with a generally warm welcome from those who live live near a Luas stop, the coming weeks will reveal just how successful the first phase is, and what the effect on other traffic will be.
It is clear that that driving space will not be reclaimed as the system is finished, and that those who dare to get behind the wheel will have to give way to the "superior" public transport at major junctions.
As a Luas train approaches a junction it triggers a request for priority, which in reality means traffic lights will change in its favour. If the tram is running late, the driver can manually request priority.
Dublin City Council's Director of Traffic, Owen Keegan, says the council retains control over whether Luas gets priority at key junctions in the city, "but we would endeavour to give Luas maximum priority".
Ger Hannon of the Rail Procurement Agency (RPA), responsible for implementing the Luas system, says trams should get maximum priority: "If you have 300 people coming in from Sandyford, you have to try to keep it attractive for these people who may otherwise be in cars. To our mind they deserve priority."
All very well if the system is working properly. But a malfunctioning of the software last week led to major traffic disruption in Dublin city centre during testing.
The issue led to a public row between Dublin Bus, Dublin City Council and the RPA. Both the bus company and Dublin City Council blamed the Luas testing for the problem.
"There was a particular problem last Tuesday caused by a software glitch which meant lights were not functioning the way it was agreed. The software error was the responsibility of the RPA," Keegan adds.
The RPA responded by assuring motorists and bus users that any glitches in traffic management would be ironed out by today. It was a "bit rich", Hannon says, that Luas was blamed for the congestion.
"We have been running trams on a shadow timetable for six weeks. Occasionally drivers were driving over-cautiously during testing and lost the signal and had to re-call it. We are fine tuning, and by Wednesday that will be complete."
Motorists have more immediate worries, however.
While Luas begins today, new traffic arrangements on St Stephen's Green to accommodate take effect early on Sunday morning. Besides having to deal with some traffic problems in the intervening number of days, motorists will have deal with a radical, new and possibly permanent traffic system next weekend.
The west side of the Green, near the St Stephen's Green shopping centre, needs to be completely reconstructed, partly due to the Luas works, and will be closed to traffic for the foreseeable future.
The south side of St Stephen's Green, outside the Department of Foreign Affairs, will become two-way, while the traffic direction on the east side will reverse, meaning that motorists entering the Green from Leeson Street will have to turn right.
They will then be allowed to proceed around St Stephen's Green and turn right down Dawson Street.
The Council is adopting an ominous wait-and-see approach and says a permanent change may be needed to accommodate Luas. "We're going to look at how it works. Some elements may be permanent. It is possible traffic flow might be much better," a spokeswoman said.
New signs are to be erected before the implementation of the change at 5 a.m. next Sunday. Gardaí on point duty will be deployed to assist potentially confused motorists.