Irish Rail has invited bids for the €2.5bn ($3.43bn) project to design, build and operate two rail tunnels beneath Dublin, part of the Dublin Area Rapid Transit (Dart).

The proposed twin tunnels will run 24m below the surface and will allow the DART trains to run underground from the Docklands to Inchicore.

The new 7.6km underground line will run through Dublin covering underground stations at Heuston, Christchurch, St Stephen’s Green, Westland Row and Spencer Dock, in addition to a surface level station in Inchicore, according to

Expected to be complete by 2016, the tunnels will have 20 trains running in each direction every hour carrying a total of 64,000 passengers.