More than 200 passengers on the Iarnród Éireann Sligo to Dublin rail service were stuck at the station in Clonsilla after a signal fault this morning.
The train left Longford at 10.15am but was delayed initially in Edgeworthstown for 35 minutes and came to a halt again in Clonsilla.
Passengers were told that power failure was responsible for the delay.
An ambulance was called to attend a person who fell ill on a second train travelling from Dublin to Sligo which was delayed at Coolmine.
A spokeswoman for Iarnród Éireann said Maynooth commuter services are not expected to be disrupted this evening.
