CIÉ unions are to go ahead with tomorrow's "no-fares day" in spite of a call by Iarnród Éireann yesterday for it to be abandoned.
The rail company said it had no dispute with the unions, and asked them to reconsider their "ill-advised" protest given the problems that could arise.
Workers in Iarnród Éireann, Bus Éireann and Dublin Bus will refuse to collect fares to highlight union opposition to a shake-up planned by the Minister for Transport.
Mr Brennan intends to dismantle CIÉ, and open 25 per cent of the Dublin bus market to competition by early next year.
Tomorrow's action means that all train and bus services operated by the three CIÉ companies will be free for all customers who have not already paid for their tickets.
Iarnród Éireann yesterday appealed to customers to travel only if their journey is necessary.
"Any increase in the number of people travelling over and above the normal levels of demand will result in capacity issues and difficulty in continuing to provide a service. It will not be possible to guarantee accommodation for everybody who may wish to travel in this situation."
A similar appeal was issued by Bus Éireann. Both companies said "control procedures" may have to be implemented to accommodate people with pre-paid tickets.
The general secretary of one of the main unions involved claimed yesterday that Mr Brennan was not being asked "hard questions" about his plans.
Mr Liam Tobin, of the National Bus and Rail Union, said nobody was asking the Minister for the research informing his decisions.
"How, for instance, does he intend dealing with the vexed question of the joint CIÉ pension fund when the company is broken up? How will employees' pension rights be protected? Or why is he trying to force Dublin Bus down the failed privatisation model pursued in London?"
