Luas tests on the Tallaght to Connolly Station line are to intensify from today in an effort to combat delays in opening the "Red Line", the Railway Procurement Agency (RPA) has said.
The second Luas line had been expected to start operating in August. However, a spokesman said there was a possibility that that target would not be met.
"It is possible that there will be delays. We want to put the line into operation as soon as possible, and we will be pulling out all the stops to bring it on track as quickly as we can," said RPA spokesman Mr Tom Manning.
From this morning, Luas would be conducting "intensified tests" on the line, running trams up to every 10 minutes until the service was ready to go.
Suggestions that the line had been delayed because of the construction of a ramp at Connolly Station were "not true", said Mr Manning.
"We always said that the end of August was a target. There are 14kms of track running through streets for the most part. It's a very difficult line."
Testing on the Green Line from Sandyford to St Stephen's Green had taken six weeks, and Connex, the company contracted to run Luas, told the RPA on Friday that this was sufficient test time.
However, Mr Manning said he would not give a new proposed start date.
"When we give a date we want to be able to stick to it, and we can give no absolute date at this time."
A slight derailment of a tram on route to Sandyford Station on Saturday evening was "a very minor incident", and not a safety worry, said Mr Manning.
The tram was heading from a local depot to Sandyford just after 6 p.m. when its front wheels left the track. No passengers were on board at the time.
The Luas service from Balally to Sandyford had to be suspended for a short time, and passengers were transported between the stops by a shuttle-bus.
"This sort of thing is common enough in light rail systems, and in rail systems in general. We don't know what caused it yet, but it will be investigated."
The incident would have "no impact" on the official opening of the new cable-stay Dundrum Luas bridge this evening.
The William Dargan Bridge has been named in honour of "the father of Irish railways".
Father Daniel Dargan, a Jesuit priest, descended from Mr Dargan, will officially open and name the award-winning bridge.
The Minister for Transport, Mr Brennan, is due to attend the ceremony, which starts at 6.30 p.m. at the Dundrum Luas stop.
William Dargan (1799-1867) was responsible for building the Harcourt Street Line, which has now become the Luas Green Line. He lived nearby at Mount Anville, and was a regular user of Dundrum Station.
RPA accepted the recommendation of the selection committee that naming the new bridge in honour of Mr Dargan would be a fitting tribute to a pioneer of public transport in Ireland.
Asked about the number of passengers using the Green Line, Mr Manning said that the company was very pleased that more than 140,000 had used the service in its first commercial week.
He said that figures to date were "40 per cent ahead of target".
