Public transport services face severe disruption on Monday, after a second CIÉ union decided yesterday to support a day of protest.
SIPTU said it would be asking members to take part in the action, affecting bus and rail services, announced on Thursday by the National Bus and Rail Union.
Although the NBRU said it would be available for talks over the weekend, the four-hour stoppage is expected to go ahead as planned.
Workers in Bus Éireann, Dublin Bus and Iarnród Éireann plan to leave their posts from 11 a.m. to 3 p.m., to take part in protest marches in the main urban centres.
Mainline bus and rail, DART and Dublin Bus services will all be affected.
The action is in protest at an alleged delay in getting talks started between the Department of Transport and unions on the future of public transport.
A chairman for those talks, Mr Kevin Foley of the Labour Relations Commission, was appointed yesterday.
As a result, the NBRU called off a one-day strike it had announced for Monday week, February 23rd. It declined, however, to cancel this Monday's protest.
The only concession made to the travelling public yesterday was a decision by SIPTU to request drivers on long haul and inter-city services which depart before 11 a.m. to complete their journeys.
Bus Éireann, however, said it expected to be unable to operate city and local services between 11 a.m. and 3 p.m.
On Expressway routes, any failure of services to depart from starting points between those times would result in continuing disruption to Expressway services for the rest of the day, it warned. "The company is not in a position to guarantee any services or forward connections in that event," it said.
Iarnród Éireann also anticipates disruption, but has said the extent of it is hard to predict. Bus services in Dublin are likely to stop for at least the duration of the four-hour protest.
Unions are opposed to plans by the Minister for Transport, Mr Brennan, to break up CIÉ and privatise a quarter of existing Dublin Bus routes. He also wants to increase competition on Bus Éireann routes.
Following a meeting of the its CIÉ strike committee yesterday, Mr Michael Halpenny of SIPTU said the union was willing to enter "intense discussions" with the Department.
If a satisfactory solution to members' concerns about job security and terms and conditions of employment was not forthcoming, the union would stage a one-day stoppage on March 18th, he said.