Originally Posted by James Shields
Running PPT trains to Docklands is problematic, as currently only the Midland line can serve that station. Either Glasnevin Junction would need to be redesigned to let PPT trains access the Midland line (which I believe is problematic), or the Drumcondra line would have to be linked to Docklands station somehow, which looks possible, at least to one platform, though would involve a fairly tight curve.
An obvious approch would be for both Maynooth and PPT trains to run into a greatly expanded Docklands station, the PPT trains via Drumcondra and North Strand Junction and Maynooth/M3 trains via Newcomen Junction. This would be a good operational solution as it would eliminate almost all of the existing traffic conflicts without the expense, disruption, compromises and impracticalities of DART underground. More radically the expanded Docklands station would be underground or at least have underground platforms with electric trains continuing in tunnel to Pearse.