Metrolink south of Charlemont

How would that work? Unless they've already decided on and designed the upgrade, there certainly will be more tunnelling required.

The options include everything from a connection north of Dunville to somewhere around Alex. There is no way to tunnell in advance of picking one of the options.

To be clear, I'm not talking about stupid stuff like veering off toward UCD or Terenure - just the options to upgrade the Green line.

The "feck it just build what they'll let us go ahead with" response feels like desperation and worse I completely understand it. "Let's not think about the hard problem we're creating for the future because even drawing attention to it may jeopardise the bit we can probably get support to build."

On the other hand, it's disappointing to have such an immature approach to infrastructure development even if it is understandable given how starved of funding rail based PT has been historically.

Even if you're not going to do the entire Sandford to Swords line in one go, surely you should actually have a plan on how you are going to do it so that the bit you do first will fit into the overall plan.

I find the idea that once the north of Charlemont section is done, the rest of the upgrade will just happen as a matter of course almost naively optimistic.

To the extend that I'm will to bet - using one of those "long bet" escrow sites - anything to a thousand hard earned euro that there will still be trams running south of Charlemont 10 years after the northern section of ML starts operations.

This will not be a cheap or easy upgrade - in fact the cost could be astronomical. A TBM will have to be employed to construct a few KM of tunnels, a significant amount of CPOing will be required and maybe even one or two stations have to be expensively mined. The disruption will be horrendous. This is why I'd favour stopping at SSG until there is a realistic plan for the rest of the upgrade. The current approach is ostrich head in the sand stuff.

I guess I'd like to see the earlier option of a north of the canal/peter place link up (involving some cut n' cover on Earlsford terrace) remaining a possibility as I feel it's one of the few cost-effective options left. This option was included before the sewer issue became know but was dropped in favour of the just-south-of-Charlemont option in that evaluation. When the latter was found to be impossible due to the sewer, the former doesn't seem to have been reconsidered. But tunnelling to an underground station in Charlemont effectively precludes any option except continuing to tunnel at least to Dunville if not almost to Milltown.

The original plan was not to go through the church but through the housing just west of it. But I think we went through this before - I know you prefer CPOing and a portal near Dunville Av.

The reason the just-past-the-canal link-up (scuppered by the sewer discovery) was preferred initially was because of concerns about disruption on Earlsford Terrace. There was a large commercial block between Dartmouth Road and the canal that would have provided a perfect location for handling the construction of a portal with minimal disruption to traffic or business had the sewer not been there.

The Peter Place option was ruled inferior at the time because the works would have to occur on a public street - Earlsford Terrace. No other technical obstacles were identified at the time - although the fact that they didn't know about the canal sewer at the time suggests the evaluation was fairly shallow.

To be honest, I'm not convinced it's the best option. But I would like to see it re-evaluated in light of how much more engineering studies have been done since the first evaluation.

We're building the northern section without having planned the southern section upgrade. I'd like to know what they have in mind as honestly terminating a newly constructed metro line in the city centre these days seems daft. But I fear that's what we'll be left with for a generation or more. It took 13 years for the original Green line to be extended through the centre of the city.

Your claims are at odd with the engineering report - none of these objections were raised as issues.

The Peter Place link-up made it through to a short-list of feasible options but it failed in comparison with locating the portal south of Charlemont on the grounds of increased disruption and a more difficult works environment.

I'm not talking about any of the options 2?

It's option 3(C) on page 43:

"From the north, NMN tunnels will be bored to Earlsfort Terrace, at a suitable location between the Conrad Hotel/NCH and Hatch Street junction, where the road is approximately 22m wide. The tunnel portal and TBM receiving shaft will be formed in cut and cover within the public road space, with limited impact on surrounding buildings. During construction, the road will be closed to traffic in both directions and the footpaths will have to be temporarily accommodated within the NCH grounds.

The tracks will then rise in a cut and cover section beneath the Earlsfort Terrace, Hatch Street and Adelaide Road junctions, to then rise in open retained cut, immediately south of Adelaide Road, on the west side of the Adelaide Road Presbyterian Church, tying in to the existing Luas Green Line ramp, immediately north of Charlemont Stop."

They explicitly state the church would be avoided. The curvature is not an issue as you can see from the technical drawings.

What Sam means, I'm guessing, is that there would be a natural (future) extension of the on-street tram system (the green Luas) along Adelaide road - maybe to a terminus in Irishtown or somewhere like that. The 3C option described a turn-back facility just around the corner from the Harcourt St stop on Adelaide Road with a configuration similar to the old SSG stop. Integration between metro and the Green Luas would be provided at SSG.

Linking ML to the southern section south of Cowper is going to leave us with a Green line tram terminus in a quiet suburban cul-de-sac with no scope for further extension and little scope in the immediate vicinity for densification.

It will also mean no metro stop between Charlemont and the portal between Cowper and Milltown - maybe a 2km gap, while linking at Peter Place means Ranelagh, Beechwood and Cowper will all have metro stops.

And immediately after that in the Conclusions it says;

It merely considered that option to be "potentially feasible" but that it had "significant environmental and logistical challenges" which were considered so great that the option was then discounted.

I don't think it goes into the level of detail to say that the church can definitely be avoided or that the curvature or gradient would not be issues, rather that if they are possible, the level of difficulty would be so great that it just isn't practical.

The report then was fairly high level. The fact that Option 4(B) was identified as the preferred option and the sewer issue then came to light which meant that wasn't possible shows that no option should automatically be considered possible. 4(B) was considered impractical at best and possibly would have been found to be impossible with further assessment. I don't think it solves any problems, likely only creating more.

I don't really see the point in extending it 1-2km to Rathmines or Harolds Cross. How does that fit into the transport network for the city? It's not nearly long enough to replace a BusConnects spine, doesn't unlock new TOD, and both areas are a short cycle or walk from the South City centre. If you extended it 2km South West, people 5-10km south west would also want it extended there.

A connection to GCD enhances the PT network but duplicates the O bus route.

On the future Green Line, it should continue east towards GCD and on to the Glass Bottle Site at Poolbeg. I know there is a basic plan to extend the Red Line from The Point over to there but that would require an extremely expensive opening bridge at the widest end of the Liffey.

That permission is conditioned on the private developer building the retaining wall that is necessary to construct the metro station in future.