Trade union SIPTU has defended its decision to withdraw from DART discussions at the Workplace Relations Commissions.
Management and unions had been due to attend talks tomorrow aimed at averting industrial action over a new 10 minute service due to come in on April 10.
But SIPTU and the NBRU are refusing to attend negotiations - saying they won't discuss rosters without a discussion about pay too.
SIPTU's Paul Cullen says it's too soon for talks.
He said: "As far as we are concerned, the 10-minute DART service is part of productivity, and only yesterday, as part of a Labour court recommendation on this productivity, we met with a group set up to examine all of this and they wont be reporting back until June so we just feel this is premature on behalf of the company."
On March 2, SIPTU's members voted unanimously in favour of the strike action over Irish Rail's plans to introduce the new rosters for a 10-minute service at the company.