The Luas is back in action after Storm Ophelia damaged the roof of a technical room at the Red Cow depot.
It houses vital systems which operate the trams, and meant the Red and Green lines were both out of action until 9pm yesterday.
Transport Infrastructure Ireland has told 98FM News the only back-up room is at the same location, so it couldn't be used to keep services going while repairs were carried out.
Around 90,000 passengers were affected by the outage.
Chair of Dublin City Council's Transport Committee, the Green Party's Ciaran Cuffe, is surprised that two crucial pieces of infrastructure would be kept in the same place:
"It does seem odd that both lines were both controlled from one location and they didn't gave a back up plan. To have a hole in one roof knock out an entire network is pretty unforgivable in 2017."
It's believed Luas operators Transdev will have to examine whether to locate a back-up room at a different station, in case there's ever an emergency like this again.