A Cabinet committee is to hear a presentation from the head of Madrid's metro company on how it built a metro for nine times less than the projected cost for Dublin.
Prof Manuel Melis will outline how the Metro de Madrid company, which opened a new 40-kilometre line last month, managed to keep the cost to €46 million per kilometre.
A proposed rail link between Swords and Dublin city centre, serving the airport, is projected to cost €417 million a kilometre, or more than €4.5 billion in total.
The Minister for Transport, Mr Brennan, claims the link could be built in the lifetime of the present Government in the event of a significant cost reduction.
Prof Melis, who is president of Metro de Madrid, will outline how this might be achieved to the Cabinet committee on housing, infrastructure and private-public partnerships, which is chaired by the Taoiseach.
It is understood his presentation, planned for next month, will be the first by an outside party to a Cabinet committee.
Mr Brennan has made the Swords rail link, which would be underground through the city centre, a priority, but acknowledges it cannot be built at current cost projections.
Among the measures planned to reduce costs are the establishment of a special section of the High Court to deal with planning issues concerning major infrastructural projects.
This is to be included in a proposed "critical infrastructure Bill", which Mr Brennan has said is to be introduced.
His intention, he has told The Irish Times, is to address the delays at planning and design stages of major projects, such as motorways, which add hugely to the cost.
Mr Brennan and a team of officials visited Madrid recently, where he held discussions with his Spanish counterpart, Mr Francisco Alvarez-Casco, about the different approach to such projects in Spain.
A technical team from the Department and the Railway Procurement Agency have been back to Madrid in the past fortnight to further analyse the costs of building the metro there.
A spokesman for Mr Brennan said Spanish and Irish construction costs might not be directly comparable, but the Madrid experience could still be relevant in some respects.
Spain had a shorter planning process, he said.
"While they do compensate people, they also set deadlines which shorten the time-frame compared to here".
One of the purposes of the proposed Bill would be to ensure that people's right to compensation and right to object to projects would be upheld, but court hearings would have to adhere to tight deadlines.
Preparation of the new legislation is at an early stage, and consultations are currently taking place with relevant agencies such as the National Roads Authority and the Railyway Procurement Agency.