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