The ATGWU, the union representing striking train drivers, has said it is now more optimistic about a breakthrough in the row.
Spokesman Mick O'Reilly said that while he did not want to pre-empt the process required to resolve the issue, progress had been made.
He added that he was now more positive about the chances of an imminent settlement following the intervention of the Labour Court.
The Court is to investigate Iarnrod Eireann's disciplinary procedures and inter-union relations within the company.
The dispute, which is now in its third day, has left tens of thousands of passengers stranded.