Bus passengers are likely to be severely disrupted by the industrial action after Siptu voted by 91pc to strike. Members of the National Bus and Rail Union (NBRU) had already agreed to stoppages.
Workers were balloted after Bus Eireann management wrote directly to staff before Christmas to tell them the company would be implementing a number of money saving measures from this Sunday.
Among those likely to be worst affected are people living in the commuter towns around Dublin who need to travel into the capital for work.
Unless an agreement can be reached in the meantime, Siptu staff will mount pickets on Thursday and the trade union has warned the unrest could spread to the CIE's other companies, Iarnrod Eireann and Dublin Bus.
Fianna Fail's Darragh O'Brien today called on the parties involved to resolve their differences. "I think all of us want it sorted out. Strikes don't solve anything. I want management and staff and the unions to engage and solve the issues," the Dublin senator said.
"The worrying thing is if it spreads to other parts of the transport network. If that happens, it would be a disaster not only for commuters but also for businesses," Mr O'Brien said.
NBRU says its members will implement action from this Sunday, although Bus Eireann insisted any strike at the weekend would be unofficial as the company is entitled to seven days notice under the law.
A spokesman for the semi-State told the Herald today the cuts will be implemented.
"We have been in talks with the trade unions since June last year, over six months ago. There has been no progress because the unions will not negotiate with us on the substantive issues. We asked for a Labour Court hearing but they refused to go in," he told the Herald.
He said the NBRU has not informed the company what action its workers intend to take on Sunday.
"We don't know what will happen on Sunday. That's the problem we're facing," the spokesman said.
Siptu organiser Willie Noone said: "Our members have always been willing to change working conditions and practices within reason but are not prepared to have changes unilaterally imposed on them.
"This decision is a direct response to the threat by management to dictate change and cut the pay of our members."