Crayonism alert: I've been reading here and elsewhere of the difficulty of trying to run a Metro style system (a.k.a the DART) while also running increasing volumes of Intercity and Commuter traffic down the twin-track lines that run from the Conolly side of the network.
So far, this problem appears to have added unacceptable - indeed semi-fatal - delays to both the Rosslare and Belfast lines. Sligo, I fear is next, when Maynooth/Dunboyne gets the DART service that it requires, and is quite entitled to.
So I've been thinking of a possibility, of adding passing loops in the Suburban Area, in the style of 2+1 roads. Basically, for about 500M, at about 3 points on each line (Maynooth, HJ&D and Balbriggan, and Bray/Greystones) the twin line arrangement should be replaced with 3 tracks, one track in each direction, plus a centre line for passing.
So that, basically, if a Outer Commuter or Intercity train were to be stuck behind a DART, the DART would stop in the loop and the long distance train would "overtake" it down the centre line. It would cost the DART about 2 minutes, but save the IC/Commuter, I figure, an average of 10. Of course the ideal place to do this would be stations, but new stations have been built to twin line only spec
I've attached a quick sketch of what I had in mind.
Would this work? Could it be feasable?