The Government is finalising details of a €20 billion, 10-year transport plan that will include a metro to Dublin airport and an underground rail link between Heuston Station and the Dublin Docklands.
The plan, which is expected to be brought to Cabinet next month, will include a new "western corridor" linking Cork by dual carriageway to Sligo via Limerick and Galway.
Detailed planning on both rail projects is expected to get under way almost immediately, once a decision is made by Cabinet, although both are not expected to go into construction phase at the same time.
Officials from the Department of Transport and the Department of Finance are currently discussing the final details of the plan, including the total costs, budget of the plan, and the phasing of the major construction projects.
There is general agreement on the broad outline of the plan within the Cabinet subcommittee on transport, which includes the Minister for Transport, Martin Cullen, the Taoiseach, Bertie Ahern, the Tánaiste, Mary Harney, and the Minister for Finance, Brian Cowen.
The committee has held a number of discussions on the plan since March, when Mr Cullen presented it to the committee. It is expected to have further discussions before the final plan, is agreed.
Mr Cullen, who will bring the plan to Cabinet, is understood to favour a metro route that would extend from Dublin city centre to the airport and on to Swords.
The final decision on the route and extent of the metro will depend on the final budget for the project to be agreed with the Department of Finance over the coming weeks.
The Rail Procurement Agency has provided estimates ranging from €2 billion to nearly €5 billion for the project. The €1.2 billion "interconnector" is expected to be built by 2012 and would link a new station at Spencer Dock to Heuston station, with stations at St Stephen's Green and Christchurch. Spencer Dock will in turn link back to Connolly station.
Under the plans by Iarnród Éireann, double-decker trains would be able to use the line, travelling directly from Drogheda through to Kildare. It would also free up capacity on northern routes allowing for increased commuter services, with the extension of the Dart line to Maynooth.
Iarnród Éireann has claimed that unless the interconnector is built, commuter rail services in Dublin will be seriously overcrowded from 2012, with projected population increases of 300,000 in the region.
The cost of the whole plan is believed to be in the region of €20 billion, although this could be further increased, if parts of the plan are extended beyond 2015, as is currently being proposed by the Department of Transport.
The plan is to be divided in two sections, one for Dublin and another for the rest of the country.
The completion of all motorways and dual carriageways between Dublin and the main Irish cities, which has already been committed to, will also be included in the plan.
The main road project is the western corridor dual carriageway linking Cork to Limerick, Galway and Sligo.
Other projects expected to be included in the plan will be commuter rail links for the Cork area, a new commuter line for Dunboyne, Co Meath, upgrade programmes for local and inter-regional roads around the country, bus and "green corridors", and park and ride facilities on the outskirts of major cities.