Iarnrod Éireann has said that passengers will be required to pre-book their tickets if they want to travel on intercity rail services from between Friday 18 December and Wednesday 6 January.
The company says that, with the easing of travel restrictions over Christmas and New Year, only 50% of seats will be available on trains.
It says the measure will ensure that capacity is managed effectively. 
It will also provide “rail customers with a safe and sanitary travelling environment over the Christmas and New Year period”, the company added. 
Tickets can be pre-booked on the Iarnrod Éireann website.