Two men have been arrested after an Irish Rail signalling station was vandalised and equipment destroyed on Saturday evening, causing severe delays at Heuston station.
Gardaí arrested two men aged in their 30s and 40s, questioned them and later released them without charge.
The men were held at 5:30pm on Saturday in relation to the criminal damage, and detained at Ronanstown Garda station.
A signalling centre was broken into at an unused train station at Kishoge, south Dublin. Equipment there was destroyed, causing "major signalling difficulties at Heuston Station", a spokeswoman for Irish Rail said. Services were disrupted for a number of hours, from 5:20pm until after 8pm on Saturday.
Normal service had resumed by Sunday morning, a spokeswoman said.
Investigations into the incident are ongoing, a Garda spokesman said.