The General Secretary of the National Bus and Rail Union has said it is highly likely that a planned strike by NBRU and SIPTU drivers at Iarnród Éireann this Friday will go ahead.
Dermot O'Leary said the only way to avoid the stoppage, planned to take place from 6am to 9am, was for the company to sit down with unions and discuss the problems.
The action follows a dispute over payment for past productivity improvements.
About 40,000 passengers were affected by a previous strike over the issue, on 23 October.
Speaking on RTÉ's Morning Ireland, Mr O'Leary said there were no proposals to put to workers.
"I suppose at this stage we're at Tuesday morning now and we're heading into a second dispute on Friday into a place where no worker wants to be unfortunately.
"Certainly it's going to discommode the travelling public but unfortunately, I suppose, the only way we're going to avoid that is for the company to sit down around the table and discuss the issues that to date they have not been discussing."