DART underground - options

With the level of immigration, they need a massive amount of housing, way more than we are building and way more, than we have the capacity to build

It's possible. Our commuter line in to Berlin which also happens to be the mainline to Hamburg is being completely closed down for 9 months starting in August. It's gonna be hellish.

Both are needed for their own reasons, and they are far from dependent on each other, although I do believe the two projects will be at their greatest when they are both delivered.

4North by itself will be massively benificial to the IC and outer commuter networks, allowing them to speed into Connolly on the four-tracked section rather than being stuck behind DARTs. It can additionally open track capacity for additional IC and even allow for express commuter services. Even if it doesn't allow for additional DART capacity, the overall fast-line improvements are more than needed for the future of the network. Also while not part of 4N, the project is what will make the airport link possible, as currently even if built there wouldn't be the track capacity.

DU will just add a large amount of DART capacity and connectivity to the network, by adding a high capacity corridor through some of the busiest areas of the city. Also, while I don't think potentially using it for outer commuters is the best use of the capacity, if that is the direciton IE go it would free a decent amount of space at Heuston and Connolly for additional IC services. However I don't think it depends on 4N either as it would instead be replacing the various SD terminating services (assuming the route picked is the SD route, not another option).

While I don't think that either project is dependent on the other, imo if they are I think its the otherway around. DU is dependent on 4N because of track capacity limitations that could limit the number of services capable of using the tunnel.

We are building basically no infrastructure. Just houses/apartments.

Houses/apartments are not immune to court action and judicial reviews but some is getting through.

Absolutely no infrastructure seems to get through without being fought from all sides.

Partly because the business case for Dart U has become a lot poorer since they've reopened the PPT

Unclear as to why this should be heavy rail though.

It's been discussed fairly frequently but look at what we're doing with Metrolink, with high capacity segregated rail that doesn't have to share track with slower intercity services. If we want to develop a high capacity connection between the two stations it probably should be done like that?

Besides you could probably count less than 100 people who are travelling each day from Heuston to Connolly each day from one intercity service to another.

This craic of Dart Underground trying to be both an intercity and Dart tunnel seems to be trying to be too much of both and failing at both as a result. This is ignoring how massively costly it's going to be, for the addition of likely as not only 2 new stations.

Don't forget the Stammstrecke in Munich, possibly the first "Interconnector" type project in Europe. It's such a no brainer to do it. In Munich they are building a second parallel one for heaven's sake.

All of the commuters will benefit from DU.

Dart+ will leave all of the dart west and dart north trains fighting for space heading towards connolly platforms 5 to 7.

Dart U will take all of the Dart north trains out of that equation, relieving the bulk of the congestion between connolly and ossary road junction. Thus relieving the biggest congestion point in the network, and therefore opening up every branch to its full potential.

Both Dart West and Dart North can go to Spencer Dock after the changes though? A lot of the Belfast services can also terminate in Spencer Dock. It's not just going to be the two platforms.

If you put IC trains through this tunnel, then they cannot stop at an intermediate location - there simply is not space to build an inter-city rail station anywhere along the proposed route - it's not just platforms, it's the additional space for passengers, plus luggage to wait, board and disembark needed for a longer-distance service.

The other problem with an IC Tunnel that there is no feasible routing for the tunnel that would connect with Connolly station. Even if there were, a direct connection between Heuston and Connolly would end up overloading Connolly, thanks to that station being closer to the business centre of the city. (Putting this IC stop at Pearse would be even worse on this score) So, if the Inter City tunnel effectively makes Connolly a dead-end spur, then Inter City services would only call at Heuston over time, with a changeover to DART provided at, say, Clongriffin, on the northern approach, or Maynooth on the Western.

Now, that might not be a bad option, and it could be achieved with a centre pair of "fast" tracks through the tunnel that do not stop at any DART station, but it does make both the stations and the mainline tunnel (or tunnels) more expensive.

DU brings rail to vast numbers of commuters who presently couldn't really dream of it, but it requires us to change modes. Just look at a map of west and north Dublin. Plenty of orbital roads with continuous bus lanes or the space to build them, which could easily funnel vast numbers of passengers in to the DART network, but the capacity needs to be there in the DART network to take them. DU unlocks that enormous capacity. It multiplies the investment in the quad tracking and station facilities already made and likely yet to be made. Look at the likes of Adamstown station. It's massive. It handles far fewer passengers than it could, because there are hardly any trains stopping there because there's no onward capacity in Heuston and no capacity to terminate and turn trains around in Heuston anyway. DU solves all these problems.

Compulsory purchases on Ossory Road combined with building platforms at grade could allow for an interchange with Connolly for far less than DU and allow Dart West and Dart SouthWest to terminate at Spencer Dock all the time.