A new report says the LUAS won't cause further delays at the busiest roundabout in the country - the Red Cow roundabout linking the M50 and the Naas Road.
The roundabout carries 80,000 vehicles a day.
However, Minister for Transport, Séamus Brennan, isn't ruling out the prospect of building an elevated track over the junction.
The report says building a track on stilts could cost €40m, twice the figure estimated previously.
It's not certain whether the bridge would require a new public inquiry, which could delay completion of the line to Tallaght by up to nine months.
With construction continuing at a fast pace, Minister Brennan says he needs to decide whether a bridge is needed within the next few weeks - before it's too late to change his mind.