IARNRÓD ÉIREANN is under "huge pressure" from the Department of Transport and politicians to make rapid progress in delivering an underground rail link between Dublin's Heuston and Docklands stations.
Project manager Peter Muldoon also said there was "not a peep that the project is being targeted for cuts" by the Government to trim public expenditure - even though it carries an estimated price tag of €2 billion.
Omagh-born Mr Muldoon, who spent most of his working life in the private sector, told The Irish Times he had made a full presentation of the "Dart underground" project to Minister for Transport Noel Dempsey last month.
"The Minister has told us that this is Iarnród Éireann's number one priority, because he wants to get it done," said the company's spokesman, Barry Kenny. "Every aspect of it is being pushed as well as being scrutinised by the department."
The latest plan is now out for public consultation, with meetings taking place over the next week. Tenders are also being prepared with a view to engaging a multidisciplinary team of consultants to take it forward as a public-private partnership (PPP) project.
Consultants are expected to be appointed later this month to prepare an environmental impact statement on the 5.2km (three miles) route, including the excavation of underground stations at Heuston, Christ Church Cathedral, St Stephen's Green, Pearse Station and Docklands.
At Christ Church, the intention is to excavate the amphitheatre of the Civic Offices to install a station there and also a green area on Cook Street just north of St Audoen's Catholic Church, to provide a second means of access to and from the station.
Mr Muldoon said four tunnel boring machines would be used to dig twin tunnels through limestone bedrock, with two starting from Docklands in the direction of St Stephen's Green while the other two would work their way from Heuston towards the Green.
The average depth of the tunnels would be 25 to 30 metres, each with an internal diameter of six metres - sufficiently wide to accommodate an eight-carriage Dart-type commuter train and the overhead 1,500-volt electricity wires.
Some of the tunnelling work, particularly for stations, would involve substantial cut-and-cover excavations and/or "mining" from the surface to minimise the impact at ground level. But Mr Muldoon conceded that there was bound to be some disruption to traffic.
At Heuston Station, two options are being considered. One would involve excavating an underground station beneath the old station hall, necessitating the closure of four platforms, or alternatively excavating part of the vast Guinness transport yard nearby.
Diageo plc, which owns Guinness, has serious concerns about the impact on its freight movements if the latter option was to be chosen.
But given that the company is rationalising its brewery at St James's Gate, Iarnród Éireann expects a "positive outcome". Mr Muldoon said the Civic Offices amphitheatre had been chosen to excavate the Christ Church station because it had already been "archaeologically resolved"; alternative locations in High Street were ruled out because the "risks were too great". He said the excavation would stop short of the old Viking city wall on Wood Quay, just three metres to the south. "We'll be carrying out an archaeological excavation in these areas [on the Civic Offices site and Cook Street] to make sure there are no surprises".
The Dart station at St Stephen's Green would be slotted in beneath the station planned by the Railway Procurement Agency (RPA) for Metro North, which would require the excavation of the north-western corner of the Green, including removal of the Fusiliers Arch.
After starting out separately, Iarnród Éireann and the RPA have been holding bi-weekly project meetings over the past year to co- ordinate planning of this multi-level station. It is also likely that tracks for a Luas city centre link will be laid within the enclosure.
Mr Muldoon conceded that Iarnród Éireann's works would have a negative impact on the north side of the Green, facing Dawson Street and Kildare Street, and also on the north of Merrion Square, where an entrance/exit is planned for the station serving Pearse.
He emphasised that the huge cut-and-cover excavation for the Docklands underground station would have no impact on traffic that will be using a new bridge linking Macken Street with Guild Street, as it would all be done on vacant land to the east.
The twin tunnels would be bored some five metres beneath the bed of the river Liffey to take the underground trains to and from Docklands station, where there would also be a direct connection with the Luas extension from Connolly to the Point on Mayor Street.
Mr Muldoon said electrification of the rail lines to Maynooth and Hazelhatch (on the Kildare line) was "fundamental" to the project, though it is not included in the cost estimate. However, he stressed that there was "no fat in this programme whatsoever".
