The Metro North rail link in Dublin is to go underground through Ballymun.
The decision follows local opposition to a proposal from the Railway Procurement Agency to put the rail line on stilts through the area.
Metro North is due to be completed in 2013 and will run from St Stephen's Green to Swords going through Dublin Airport.
The city centre section will be a deep bore tunnel and it was originally proposed to run the line overland from Dublin City University onwards.
But following protests by Ballymun residents, there will now be 'cut and cover' line through the area, which is less costly than a tunnel.