CIE is believed likely to settle a £11 million (€14 million) claim by a rail signalling contractor for £1.5 million today.
The claim by the French multinational Alstom arose from work it carried out on a signalling project that went £36 million over budget between 1997 and June of this year, when CI╔ ended the contract.
The overrun is the subject of an Oireachtas inquiry that opened on Monday, although yesterday's hearing was adjourned as a mark of respect to those killed in terrorist attacks in the US.
Alstom's partner in the Mini-CTC rail project was a Dublin firm, Modern Networks Ltd (MNL), which went into liquidation last month claiming CI╔ owed it up to £2 million.
CI╔ disputed that and it is understood the designated project engineer said the State transport group had no such liability.
The £1.5 million payment to Alstom is in addition to transfers of up to £11 million to it and MNL in respect of work on the signalling network.
CI╔'s alternative was to go to arbitration, it is understood.
A subcommittee of the Oireachtas Joint Committee on Public Enterprise and Transport wants to find out why the cost of completing the programme has risen to £50 million from the £14 million projected in 1997.
Designed to reduce costs and enhance safety, the system is still incomplete.
The subcommittee also wants to investigate CI╔'s connections with Esat Telecom, the company which constructed a telecoms network parallel to the signalling system.
PricewaterhouseCoopers reports commissioned last year by CI╔ linked work on the Esat system, which is complete, to delays in the construction of the signalling system.
However, both Alstom and three figures who left CI╔'s rail company Iarnr≤d ╔ireann to join MNL, have expressed reservations about PwC's findings.
Counsel acting for both parties have sought the right to cross-examine two senior PwC figures before the inquiry continues.
The accountants gave evidence to the inquiry on Tuesday morning.
However, PwC sought, through its counsel, to block any move to change the arrangements.
The inquiry's chairman, Mr Seβn Doherty TD, is expected to make a ruling this morning when the inquiry sits again.
Some observers believe either PwC, Alstom or the former MNL executives will move a High Court action if their applications are unsuccessful.