FourNorth - Quad Track Railway - North Dublin

Then you will have to inlcude Irish Rail in that cohort because it's their idea.

Connolly could easily be expanded if they weren't trying to use the land around it for development.

I don’t see any easy expansion of Connolly? At best some extra terminal platforms which would not raise the 12 tph DART limit but might allow extra intercity trains? It was examined as an option for DART+ but was ruled out on the basis of huge cost and disruption for very little benefit in terms of increasing capacity.

Spencer Dock is not operationally connected to the northern line and will be close to capacity anyway after DART+. The loop line will be at capacity post DART+ so the only way to fit in another northern DART will be by cancelling a S or SW DART.

The 2 track northern coastal will carry around 12 or so services per hour post DART+, yet the 2 tracks are capable of carrying 23 tph. So we’ll already have excess capacity on the 2 track northern coastal which cannot be used due to the lack of city center capacity so I can’t see adding more unusable capacity will pass any sort of CBA.

There is some room for Connolly to expand. The coach shed could go. It doesn't need to be in the city centre. The loco shed the same. There's no loco shed at any major railway station in Germany that I can think of. I don't see why Connolly needs one. It was built for the steam era.

However to me the more important aspect is that the mere fact of the existence of 4N and the quad tracked Kildare Route will build the pressure for DU. That alone is a good enough reason for me to see it proceed. It also adds operational flexibility to the northern line in case of an incident. If we are being imaginitive we could also envisage some DART+ SW trains arrive into Spencer Dock and immediately depart out towards Drogheda instead of returning to Hazelhatch. An "interim" DU if you will.

I don't think we should underestimate the benefit to Enterprise either. We want people to make the shift to rail. Expecting the Enterprise, which connects the two largest (by far) population centres on the island to wait behind DARTs is backward in 2025. It should be a flagship service with 200km/h running.

If we are feeling politically brave we could create a lot of capacity at Connolly by simplifying the network and eliminating most of the conflicting movements:

1. Run all Maynooth services to Bray via P6/7 at Connolly. Do not send them anywhere else. Terminate Rosslare trains at Bray. Build the relatively short cross country Maynooth-Adamstown link and send all Sligo etc. trains to Heuston. Finally sort out the level crossings on the DSER. Maynooth-Bray DARTs operate with no conflicts at very high frequency and capacity.
2. Run all DART+ SW trains to Spencer Dock only. Passengers bound for Tara, Pearse or GCD change at Glasnevin to metrolink or Bray bound DART. No conflicting movements here either as far as I can see as the DART+ SW lines are the northern pair and will just peel off into the PPT.
3. Terminate all northern line services at Connolly's 5! remaining plaforms. Passengers bound for Tara, Pearse or GCD change here to a Bray bound DART. If 5 platforms aren't enough to handle the load, demolish the coach shed and move those parked DMUs the hell out of there down to the docklands or out to Inchicore where space is readily available or could be made available by moving parked up stock that is rusting away at both locations. There is absolutely no reason to park all that rolling stock in the city centre. You could easily add another two platforms to Connolly in the given space. I refuse to accept that 7! platforms wouldn't be able to handle most of the massive capacity of 4N with relative ease.

Valeting plant/coach shed is due to become a maintenance shed. There’s also plans to build over it. But those plans seem stalled at the moment.
The loco shed is a protected structure. It might have been built for the steam era, but it’s still in use today.

We're going to have to get away from the idea that two changes is a no go. Having said that, with 4N in place they could actually revisit the Howth shuttle. Demolish Howth Junction station entirely and replace it with a GSJ and a new build station on the Howth branch as close as possible to the site of the old station. The vast majority of passengers using HJ are travelling into the city. Very few need to travel northbound.

Howth Junction Cottages is one of the few places where the land beside the embankment is in public ownership and does not back directly onto housing so there's room to taper the GSJ into the mainline there.

Timeframe doesn’t allow to build on a greenfield site. Dart+ is moving too slow as it is.

Or double track Newcommen Curve and bridge. The slow speed limit is not a problem as every train would be passing at that speed. It would just add 60s to the journey between Maynooth and Bray (in fact it would be a shorter journey time overall as the MGWR route is more direct more direct).

With the NDP monies signalled for the next number of years, do we actually know what the Irish Rail investment project priorities are ? Is the 4 tracking of the Northern DART / inter city lines confirmed as part of this, if indeed it has been confirmed ?

Newcomen is 10 mph. Not that fast, but a bit faster than 10 kph. 🤣

I don't think anyone suggested anything would be "rustled up". 4N is not happening anytime soon. It's not happening before DART+ and probably Metrolink are complete.