Metrolink south of Charlemont

The point of "30tph plan" is getting the infrastructure upgrades needed to be able to run at such a high frequency. Additional turnbacks at Charlemont and and SSG, increased priority at Dunville Ave, and grade separation at St Rapheala's Road are what is listed in the 2019 report. However I imagine if they were to to try it today they would likely also eliminate the Dunville ave crossing.

Ah I forgot about the OHLE works. It is exactly what you say they need to be lowered. Thankfully though it is considered as being a short closure, needing less than 4 weeks like the platform upgrades. In theory they would both be things that could be done duirng the extended closure for the tie-in, of course depending on how long the final connection takes, though I can't imagine it would be shorter than a month closure.

It’s a different voltage and higher current draw so substations may need to be altered also?

I understand the difficulty with Dunville Ave but there likely isn't a choice if we want to see increased capacity. At least with green line 30tph it doesn't require full closure, but I believe full priority for the luas at the intersection. Though at that point It think there is barely a difference during peak hours.

Yea it varies. Supposedly an off-line tie in between Charlemont and Ranelagh could be around 3 months, however they want to avoid an off-line tie-in because it results in more road closures, CPOing, etc. In this case it requires the closure of Northbrook road, however I don't think they have a choice if its closing one road versus shutting down the best mode of transport in the city.

The on-line tie in between Charlemont and Ranelagh would need a 1-2 year closure, which is already bad. But the one the 2019 construction report suggested, the on-line tie in between Beechwood and Cowper would require either a minimum or 3 or 4 years depending on scheduling of enabling works. So I don't think there is any world in which that recieves approval. However to be clear, that specific option needs such a long time because it needs an additional underground ML station at Beechwood which for the entire of its construction needs the green line to be closed. The whole portal construction also needs the green line closed however I think that is common to many of the on-line options.

Honestly I get the feeling that all the reports they have done didn't consider closure time, given the "two best options" as suggested in the tie in report noted problems with costs, environmental, or historical impacts, but barely(if at all) mentioned the impact of the green line being closed for mutliple years.

Why are we not running the TBM to somewhere between beechwood and Cowper and have the portal there where there seems to be a bit more space?

A lot of the options still leave the options for a link between the GL and Sandyford depot. I don't know how that would work or what that would look like, but it sounds like it's at least possible. I would hope that if they actually create that link they build a new depot, ideally also on the green line, but especially if the metro upgrade happens before a second alignment is built, that might not be an option right away. And that doesn't even consider if the new depot would be ready in time for the closure.

Additionally, the link could still be required for before a second alignment to allow trams to reach the Sandyford-Brides Glen seciton of the green line if it isn't upgraded to ML at the same time as Charlemont-Sandyford.

The residents of Dartmouth Square and Michael McDowell are preparing legal action as we speak

Because it doesn't really. They did the 2019 closure consultation for the "viable" Beechwood option, as it does require the least amount of CPOing of any option and no road closures. However while it does technically have the space, its because it was using all of the space taken up by the existing GL and Beechwood station. Which sounds fine, but in reality I think it makes it one of the worst options, or at least worst than either Ranelagh option. As while they require more CPOing and road closures, in particular as off-line option which needs more houses and the closure of Northbrook road in addition to Dunville Ave, they need a far shorter closure time and are both much cheaper. The Ranelagh on-line and off-line tie ins are estimated to be 70 and 80 million cheaper than the estimated 250 million for the Beechwood tie in, and needs much less time of 1 year and 3 months, compared to the estimated 3 years or 4 years for Beechwood.

There has been a push to get ML to go south-west towards Rathfarnham (I think by Eamon Ryan?), and while that direction definitely needs more, it somewhat ignores why the GL was being upgraded. The green line is along a very high demand corridor and it needs more capacity. It is predicted that while 30tph will be a massive upgrade, it will only be enough until 2040-2050 before another major capacity upgrade is needed, at which point a GL metro upgrade will be needed. And 2040-2050 is when the next capacity upgrade would need to be complete, which means that 2040-2050 really isn't very far away.

Looking at the constructability report for the Beechwood option, it seems 29 of the 33 months would require the closure of the Beechwood station, with the last 4 being a full Beechwood-Sandyford closure for trialing the upgrade. However I think this has more to do with the layout of the plan, with the ML station taking the location of the current Beechwood luas station, and the Beechwood luas being relocated north of Dunville ave. It might be possible to reduce the time Beechwood would be closed, but I think it would add onto the overall time.

That said, I don't think your logic that bad. If the rebuilt section is kept inbetween two stations like it is with the Ranelagh in-line option, that could make the closure time have much less of an impact. To be generous to the Beechwood option, if we assume 12 months just for construction of the Ranelagh portal, and then 4 months of trialling. During that full 12 months Ranelagh might not need to close for most if any of it, so it would limit it to just walking between Ranelagh and Charlemont. Also I think the Beechwood time table assumes full Beechwood-Sandyford closure, so up to an extra 4 weeks to upgrade both platforms and OHLE. I did consider this because I don't know how long those works will take or how long the trials would be delayed because of them.

Also its important to add, there will be a lot of logistics to keep the GL running. Mainly if they plan to keep using the Sandyford depot for the GL, the units operating north of the closure would be loosing access and need to be maintained in either Red Cow or Broombridge. I don't think that is a problem for either of these options as they would not maintain a link to Sandyford so they would require a new depot anyways. However for example the Ranelagh off-line option has the option for a link between the GL and Sandyford, so for at least the 3 months of the estimated closure they might need to maintain the units somewhere else.

Oh guaranteed they are going to need a new depot sooner than later, and ideally they would build the new depot before the metro upgrade, but they might not build it before they have to. We might not see the new GL depot until the next major expansion connecting to the green line. That could be UCD or Tyrrelstown, Knocklyon if it doesn't use units from Red Cow, or Bray if it isn't built as a metro. That of course assumes they start building the metro upgrade before they build the next luas line, and at the current rate ML is going that might not be the case. Especially if they fast track more future Luas projects like they are trying with Finglas, and hopefully they will.

The TBM won’t be continuing anywhere. The time line to get another route approved and then the delay it would cause to the planned line would be unacceptable. Any future route would have to be tunnelled toward charlemont for extension

Of course there would be a delay if the TBM kept going. It couldn’t open until the extension would be finished