Minister for Transport Martin Cullen has made a railway order allowing Iarnród Éireann to proceed with plans to double the number of tracks on the Kildare line between Heuston Station and Hazelhatch, near Celbridge.
The order will permit the railway company to acquire some 30 hectares (75 acres) of land along the 13km (eight-mile) stretch for the Kildare Route Project, which is designed to separate inter-city and commuter services, greatly increasing their frequency.
Existing commuter services on the route have a capacity of 11,050 passengers. Completion of the project, now costed at €400 million, will steadily increase this to a potential capacity of 36,400 passengers a day in each direction.
Iarnród Éireann has said the project has the potential to generate up to seven million additional passenger journeys on the route every year. It also envisages that the line will be electrified as far as Hazelhatch to allow Dart-type trains to operate.
New stations are to be built at Kishogue and Adamstown in west Dublin, while Hazelhatch station will be upgraded. The existing station at Cherry Orchard is to be relocated to Parkwest and the station at Clondalkin relocated to Fonthill Road.
This new station will include a bus interchange and will also allow for integration with the proposed Metro West line between Tallaght and Ballymun.
Provision is also being made for park-and-ride sites at key stations along the Kildare route.
Several stone bridges are to be demolished and replaced with structures to enable the number of tracks to be increased to four. On completion in 2009, two tracks will cater for commuter services and the other two for inter-city and regional services.
This will double the frequency of trains between Hazelhatch to Heuston, serving all stations, and also the service frequency between Heuston and Kildare, as well as providing more trains to serve "outer commuter towns" such as Portlaoise, Athlone and Carlow.
The announcement made no reference to the fact that work on the project will involve extensive road closures along the route for periods of up to six months as well as speed restrictions and reductions in service during the three-year construction period.
The €400 million bill will be largely met by the Exchequer, but some contributions are expected to be raised from local authorities and property developers donating land to facilitate the project, as well as funding the construction of new rail stations.
According to the Minister, the project would significantly enhance the reliability and accessibility of rail services between Heuston and commuter destinations in the greater Dublin area as well as inter-city services for Cork, Limerick, Galway and Waterford.
It would complement other improvements in the railway network, including the upgrading of capacity and facilities at Heuston, expanding inter-city and commuter fleets, and developing a new station at Spencer Dock and a train depot in Portlaoise.
In making his decision to grant the railway order, Mr Cullen said he had considered all "relevant documentation" as required under the 2001 Railway Infrastructure Act, including the report of Pat Butler SC, the inspector who presided at a public inquiry into the project.
However, the order makes no reference to a case made at the inquiry - and accepted by the inspector - that there will be a peak hour deficit in onward public transport services at Heuston until the proposed rail tunnel to Spencer Dock is completed in 2015.
Seán Giblin, on behalf of the Lucan-based "Deliver It Right" campaign, estimated that 3,000 passengers would be left with no onward connection to the city centre - even after Luas trams are lengthened to 40 metres and the number of buses is doubled. Mr Giblin said he was "astonished" that this point had been ignored.
Platform 11, the rail campaign group, said yesterday: "We are extremely frustrated and angry that once again a positive step to deal with a public transport issue in Dublin has been blocked by a politician who appears to have very little grasp of the situation."