A line through Clondalkin has been chosen as the preferred route for the Dublin's Metro West, winning out over neighbouring Lucan.
The preferred option was announced today for the line, which is due to completed by 2014.
The new line will go from Tallaght through Clondalkin, Liffey Valley and Blanchardstown, and link up with the planned Metro North line to end at the airport.
Metro West is being hailed as the rail equivalent of the M50.
It is understood Clondalkin was chosen for the route as a LUAS link is already planned for Lucan.
Metro West is expected to carry 20 million passengers a year and make it possible to travel from Tallaght to the Airport in under an hour.
Bridges and tunnels will allow it to cross three national routes and the design for a bridge over the River Liffey is expected to go for international competition.