The company that operates the Luas is asked to explain a number of shutdowns and delays in the last two days.
A large part of the green line was shut down yesterday due to a power outage. There were no services at all between Balally and Brides Glen yesterday after a problem had arisen near Stillorgan on Friday.
Replacement bus services were installed, with Dublin Bus accepting Luas tickets on connecting routes.
Crews have since solved the problem.
Meanwhile, a signal error saw trams on the red line two days ago.
Services now work normally again.
However, Fine Gael Senator Neale Richmond said that problems occurred too often.
“For two days we have had three major disruptions in the green and red Luas lines, which, to be honest, have caused chaos in this really busy time of the year,” he said.
“There was a huge delay on the green line two days in a row – the line that serves Leopardstown, with its busy Christmas gathering, and also people who come to town for sale and others only during their daily commute.”