Ireland's Iarnród Éireann may reintroduce a fleet of withdrawn inter-city carriages to improve an hourly service on the Dublin to Belfast Enterprise service.
The railway operator withdrew a number of unused Mark III inter-city carriage sets after the arrival of new trains several years ago.
The Enterprise service, jointly operated by Iarnród Éireann and Translink, runs eight return trains on weekdays.
The service is facing competition from the newly completed Dublin to Belfast road.
The rail journey takes over two hours and was described as the worst-performing inter-city route in a recent punctuality survey, according to Irishtimes.
Business groups have demanded a non-stop hourly service, with journey times of under two hours.