DART underground - options

loyatemu

it would be a real false economy to not have a connection to the Dart at Pearse.

KrisW1001

https://www.boards.ie/discussion/comment/123166951#Comment_123166951

Regarding Merrion Square, “people” is only me, really - I haven’t seen anyone else propose this… probably with good reason.

My reason for suggesting this arrangement is that it would remove the need for the very deep station at SSG, plus a mined station under Pearse DART just 700 m down track. Keeping the stations well spaced keeps the average speed up.

A station at Merrion Square could be built as cut and cover if it sat diagonally in the park. Cut and cover is something that's impossible at Pearse, and really disruptive at SSG because of the depth needed. The pedestrian tunnels to link this Merrion station to its two neighbours would need to be mined, though.

I think the “Christchurch” station is very important, as it would serve everything west of SSG, as well as the courts and the civic buildings at Wood Quay. Of the others, I feel a better link to Pearse is more important than to Metro: SSG to me seems to be very much a destination, rather than a place where people change direction.

CatInABox

https://www.boards.ie/discussion/comment/123167891#Comment_123167891

Ah, I didn't mean that comment as a dig or anything, I saw people talking about it but didn't want to go back and reread the history of it, so I apologise if it came across as something I didn't intend.

I actually think your Merrion station plan is a good idea as well! I just don't think it'll happen. I really think that the NTA will be laser focused on cost, to the point that most of us will hate aspects of the project. I'd love for them to include all five stations of the original plan, I just think that they're going to cut down to the bone, and then keep cutting.

The aim won't be to solve all of the problems, but rather to solve the issue of terminating trains in the city centre. When you narrow there project down to that and that alone, you can see that stations might be on the chopping block.

blanch152

https://www.boards.ie/discussion/comment/123167989#Comment_123167989

The Merrion Square station might come on the table then, but without the connecting tunnels. Change will happen groundside.

DrivingSouth

There's no such thing as a low cost solution here. If low construction cost is the priority then let's just not build it at all. We can transfer the cost from the construction column to the other columns such as passenger journey time, poor work life balance, unnecessary emissions, etc.

But if the priority is to build an effective transport system that's going to convince the majority of people in the greater Dublin area to leave behind the idea of having a personal car and face life with public transport and access to a car sharing option like go car, then let's go build it and do it right.

Btw I shouldn't have to mention cost effective spending. Most of the changes from metro North to metro link seem sensible and will leave us with just as effective a transport solution (excluding the south of charlemont issue). All spending should be cost effective, from a weekly shop all the way up to a national project such as this.

loco_scolo

Assuming the East-West tunnel is Dart rather than Metro, then I don't believe a Christchurch station is truly needed. A proper Luas network would provide the same connectivity by switching at Heuston. The Dart+ tunnel could focus on stations at Heuston, SSG, Grand Canal Dock and Spencer Dock.

Assuming a Luas spur from James down to College Green, you could run Luas trams from the Point via Heuston and onto College Green, eventually creating a full loop line by continuing down Pearse Street and to Ringsend.

At GCD, the canal basis between the Dart line and Pearse Street is 250m long, so could well support a cut and cover station, while still leaving an 800m gap to a Spencer Dock station.

The exact solution at Spencer Dock is another discussion (rebuild the SD Dart station, connect to Maynooth line instead of the elevated Northern line, continue the tunnel to Clontarf Golf club etc. etc.)

DrivingSouth

https://www.boards.ie/discussion/comment/123169778#Comment_123169778

You are moving one station from north Stephens green to south Stephens green, and the other from pearse to grand canal dock. This is moving it away from the centre which reduces it's usefulness. And you are increasing the meters of tunnelling required. These are costs that need to be factored in to the cba.

murphaph

https://www.boards.ie/discussion/comment/123168221#Comment_123168221

That wouldn't be the end of the world if it helped get the project over the line. Those connecting tunnels could be added later. It would be easy to do the prep work at Merrion Square at almost no cost.

blanch152

https://www.boards.ie/discussion/comment/123170528#Comment_123170528

The connecting tunnels could also be cut and cover surely, coming up from the Metro most of the way to the surface first.

loyatemu

tunnels won't be added later. If people can walk underground, they can walk on the street will be the general narrative. When would these tunnels which add no public transport capacity ever become a spending priority.,

KrisW1001

https://www.boards.ie/discussion/comment/123170726#Comment_123170726

They do add capacity, as they make transfers quicker between services. It’s been done in cities all around the world: an extreme example is London Underground’s Bank/Monument Station which is actually several station boxes linked together via pedestrian tunnels.

Idbatterim

With the population exploding the way it is, hopefully it gets dart under back on track ASAP. All this talk of cost... its an absolute irrelevance as a figure, in the context of Irish government income...

The quick the population rises, the quicker it's going to sort these issues...

Possibly a crazy question, but would it be possible to run the tunnel, down the liffey channel ?

murphaph

https://www.boards.ie/discussion/comment/123172163#Comment_123172163

Technically I guess almost anything is possible but for what benefit? I cannot imagine that it would be cheaper than boring the tunnel. You couldn't float tunnel sections up the river to place them (like they are doing with the Fehmarn tunnel, submerging precast sections of tunnel into a trench on the sea bed). Each section would need to be craned in or cast in-situ. The river would also need to keep flowing during construction and the river is tidal of course so it comes from both directions. It's never going to happen I think we can safely say that much.

Idbatterim

Yeah aware it'd tiday, but I thought, simply damn it up, at which ever point, boats don't come further up stream than, say the customs house etc...

Idbatterim

Also another question, could it stick to the north side of liffey to reduce cost ?

loco_scolo

https://www.boards.ie/discussion/comment/123170032#Comment_123170032

As many people have said, the biggest benefit of the tunnel is to remove the bottleneck at Connolly and fully separate IC trains from commuter trains. It's not about getting every single customer into the absolute heart of the city. Regardless, I would consider SSG south and GCD to be prime city centre locations.

The route I suggested is 700m longer in the tunnel, which could cost 300-500m more, but this would likely be saved by enabling cut and cover construction at GCD and moving SSG construction to the south of the park. Remember the original plan was to fully close SSG and drain the lake during construction!!!!...

gjim

https://www.boards.ie/discussion/comment/123173380#Comment_123173380

Have a look at the very first post in this discussion - there's a map of some of the routes that were considered in a relatively recent Jacobs report including a few that start by crossing under the Liffey around James Joyce Bridge. These options did fairly poorly in their appraisal from what I recall.

Idbatterim

They only care about cost here. Whichever one, connects the lines for the least amount of money, is the best bet. If its something that might actually happen V something that definitely will not…

We get much more cross city dart capacity, is one big advantage or it, instead of it being a metro line, I assume?

L1011

https://www.boards.ie/discussion/comment/123174626#Comment_123174626

You really have absolutely no knowledge of how things get approval

A crap cheaper option will not get approved just because its cheaper, because it will have a vastly worse cost-benefit ratio.

riddlinrussell

Lets assume for the sake of argument that it wouldnt get objected into the ground.

Would there be any world where an elegantly designed elevated track running directly along the Liffey from Heuston and then meeting the north side of the loop line bridge could possibly work instead of going underground?

Operationally would that just be a total nightmare?

goingnowhere

That was put forward back in the 1800’s

Wasn’t a runner then, nor is it now

A1ACo

An interesting article below from The Guardian (online) from a few days ago about the brand new, soon to open (end 2025) Melbourne 'Metro Tunnel' with some nice pictures, interesting info and a short video.

Station to station: first look at the Metro Tunnel set to revolutionise Melbourne travel | Melbourne | The Guardian

It is of some comparison to the 'DART Underground' iterations I think, as the Melbourne tunnel will appear to link two heavy rail lines from either side of a city centre, and to be of 9km length. It started construction seven years ago in 2018 with a promised opening time of this year, and stated as a year ahead of schedule.

Interestingly, it is also of comparison to the DART Underground line in that the Melbourne line tunnel would also have the same 1.5kV DC electric line running and the ('Irish') Broad Gauge track width of 1,600mm (5ft 3in), and has a similar small number of stations, with 5 underground stations built.

The Melbourne tunnel also has station depths of around 13m down to 36m underground(!) including the deepest where it has to pass under an existing underground rail line (the Circle Line)… which maybe a future DART tunnel might have to do also?!

Population and density-wise the city centre of Melbourne looks like a far more dense 'megalopolis' than Dublin, with many tall buildings packed into its CBD, and the population of the Greater Melbourne Area at circa 5.35m over twice that of the the Greater Dublin Area (of circa 2.15m). However, the Greater Melbourne area appears at 9,993km2 to be a third larger in area than the circa 6,986km2 of the Greater Dublin area, and also the overall greater urban area density of Melbourne appears to be far less than that of Dublin…

The interior and exterior design and finishes of some of the Melbourne stations appear to be relatively cheerful too and varied, and possibly a bit more so than it appears that some of the Sydney Metro stations look like in some photos at least (with more corporate Black/Silver/ Grey/White and some Brown/Red materials in the Sydney Metro - and I'd venture that the separate Dublin Metrolink is patterned a bit more towards the Sydney Metro colours, signage and interior design and finishes).

KrisW1001

https://www.boards.ie/discussion/comment/123614537#Comment_123614537

It must have been more than seven years, as I visited Melbourne in January 2018, and this project was well under way at that point. I remember there being hoardings all down one of the the main streets in the Central Business District with “Metro Rail Tunnel” all over them. One nice touch was that they put perspex panels in some of the hoarding boards so you could see what was happening.

Good to see it finally open.

Yes, the DART Tunnel will have to pass under Metro at some place, as it will run east-west while Metro runs north-south. The last known proposal had that crossover happening somewhere around Merrion Row between the DART St Stephen’s Green and Pearse underground stations.

Thunder87

https://www.boards.ie/discussion/comment/123614537#Comment_123614537

Not sure what figures you're using there but Melbourne is a much bigger city than Dublin in every way. 'Greater Dublin' includes the entire counties of Meath, Kildare and Wicklow whereas Greater Melbourne is an actual continuous urban area so not at all comparable.

I lived there in the mid 2010's and remember when the project kicked off, good to see it's all gone to plan. They've also got a Dart+ equivalent project underway over the same time period (albeit on a much grander scale) where they're modernising their suburban rail network including over a hundred level crossing closures and rebuilding dozens of stations

https://en.m.wikipedia.org/wiki/Level_Crossing_Removal_Project

KrisW1001

You’re correct - Melbourne is 5 million all in one place (quite a lot of it endless suburbia), while Dublin is 2.5 million spread across about thirty “places”. In fairness, though, a “Greater Melbourne” wouldn’t add much to the city’s population anyway - you don’t have to go very far at all out of any Australian city before you’re in the middle of nowhere. Australia is a highly urbanised country, with 70%+ of its people living in the eight largest cities, and a population density in those cities that can support rail.

To make it even more like DART Underground, heavy rail in Melbourne uses the same 1600 mm track gauge as we do. Irish and British rail engineers set out the railways in the Australian colonies without much thought about the fact that they were working with two different track gauges. Melbourne took the lead in railway building in Australia, and investors had built an extensive rail network on Irish gauge before most other cities had started their projects, but those other projects used the international Standard Gauge. As a result, Australia has two different rail gauges, with 1600 mm concentrated in Victoria. It might sound like a problem, but it’s not.There’s so much 1600 mm track in place now that it would be stupidly expensive to replace it, and pointless too in a country that’s so highly urbanised that long rail journeys are extremely uncommon.

(Yes, they’re still talking about a Melbourne-Canberra-Sydney HSR line, but conflicting State and Federal politics makes it just talk)

bennyineire

I was in Melbourne at Christmas visiting my sister, lots of hoarding in the city center, didn't realise it was going to be ready this soon. I also lived there for a few years 20 years ago. The current city loop was always a bit of a mess and added extra travel times for suburban rail. This will have a huge impact and will make it much easier for the tourists to navigate the sometimes confusing map for new comers. It is worth nothing still no train to their airport and indeed no real appetite for it either anytime soon due to projected costs and of course the big car culture for locals. My brother in law (an Aussie who works on government infrastructure) says a rail link to the airport is not really a consideration for people in the vast southern suburbs (airport is in the north) , area and population wise Melbourne is a metropolis compared to Dublin

A1ACo

Yup, I was a little off on the '7' years/2018, whereas the article does say the tunnel boring machines and construction crews have been working away for almost a decade, and that early works began in 2015 (I probably confused 2018 with the references to 2008 and 2028 in the article).

Also I said 'Circle Line' ..but its the 'City Loop' ! (I was probably thinking of the London Tube).

As for the density, populations and city vs. suburbs and 'Greater Areas' it was hard to make direct comparisons without maybe trawling through source documents… so went for what wiki provided! I have heard that Melbourne is definitely a 'Big City' in all regards compared to Dublin!

On another note, its interesting that the article also says that the scheme was first proposed in 2008 as a 17km rail link, and I'm sure some valuable comparisons and lessons could be made from the Melbourne Metro Tunnel project - least not a very modern example of such a project for public and professionals alike.

Pixel Eater

I find it interesting that Melbourne and Sydney, both far larger cities (by any metric) than Dublin have only started to do these big rail infrastructure projects in the last few years. So they were pretty underserved by rail services relative to their size, at least in comparison to some European and Asian cities. Dublin get a hard time for its dilatory approach to rail but it still seems faster off the block than the Aussies.

bennyineire

Both cities have an excellent road network, even most suburban roads are 2 lanes each way, they also have a very strong car culture, their cities are much closer to US cities in layout

citizen6

I expect that if Metrolink is built successfully, the government will be reluctant to do another tunnel that isn't driverless metro. So through-running of Darts may never happen.

I was curious to see if there is a non-tunnel option that would allow through running of Darts from Southwest to North (ignoring the benefit of any new stations).

I know this is bonkers, but for approx 1km of new elevated track you could connect the PPT line east of Croke Park to the Northern line at Fairview Depot.

The CPO would be hideous - that whole block between the existing train line and the canal around Annesley Place, for starters. I'm not saying it's a good idea.

You'd have no interchange with the other (west-south) Dart line, which is a big problem. You'd have Metrolink interchange at Glasnevin and maybe Metrolink2 interchange at a new station in the demolished block near Annesley bridge.

Obviously DU would be far preferable, just curious about any alternatives if it never happens.