Train drivers are expected to vote today in favour of strike action in the weeks ahead in a row over payment for past productivity.
Trade unions Siptu and the National Bus and Rail Union (NBRU) will announce the results of ballots of train drivers which have been under way for the past fortnight.
The two unions are expected to hold a joint meeting later this week to agree their strategy in the dispute.
Some informed sources have suggested any industrial action could involve stoppages on Dart, commuter and national rail services for short periods of time rather than all-out strikes.
The decision to ballot train drivers at Iarnród Éireann for industrial action follows the collapse of talks with management at the company at the Labour Relations Commission last month.
Unions maintained management refused to engage in discussions on past productivity despite this being part of an agreement reached in September 2014.
Iarnród Éireann said it was still losing more than €1 million a month and was not in a position to agree to past productivity pay claims.
