DART+ (DART Expansion)

Former Former Former

https://www.boards.ie/discussion/comment/120659333#Comment_120659333

IE have already created a rod for their own backs here. Their public position is "assessment of and potential removal of level crossings" but it's now in the public domain that their plan is and always was to close them.

Of course, everyone knows they had no intention of doing anything but close them, but they now have a public paper trail that proves it.

NIMBY residents are one thing but IE really do themselves no favours.

LXFlyer

https://www.boards.ie/discussion/comment/120669936#Comment_120669936

You have to remember that Spencer Dock will be a four platform basic suburban station with minimal facilities.

Intercity routes need a proper station, with passenger facilities and, importantly, train servicing facilities which Connolly provides.

The planned track layouts does not facilitate regular working of trains between the Northern Line and Spencer Dock Station in any case.

ArcadiaJunction

Is the Spencer Dock station underground deep enough for it to be part of the DART Underground or would an underground station have to be deeper still?

ArcadiaJunction

https://www.boards.ie/discussion/comment/120669936#Comment_120669936

that makes a lot of sense the more you think about it.

cgcsb

https://www.boards.ie/discussion/comment/120671371#Comment_120671371

for a tunnel to get under the river and the quay wall it would have to be wayyy deeper. A future DART+ Tunnel project may not stop at Spender Dock, if it does it'll mean serious reworking of the proposed station and lengthy closures with a temporary terminus at the current docklands station.

brianc89

https://www.boards.ie/discussion/comment/120671371#Comment_120671371

It's not deep enough. The Dart+ West plans acknowledge this by stating the proposed new station would need to be "temporarily relocated" to facilitate Dart Underground.

In short.... DU simply won't happen as currently envisioned. Two shiny new Dart lines (West and SouthWest) will terminate at the new Spencer Dock. Some of the trains will go through Connolly, but capacity will be limited due to Dart+ Coastal and Enterprise.

Additionally, some SW Dart will terminate at Heuston, but either way New Spencer Dock is unlikely to be "temporarily relocated" once it's up and running, as it will be a critical station next to the Red Luas line.

ArcadiaJunction

https://www.boards.ie/discussion/comment/120671531#Comment_120671531

Thanks. Basically implies DART Underground is not going to happen ever. I was wondering why Spencer Dock is designed as such a substantial station and this explains why.

brianc89

https://www.boards.ie/discussion/comment/120672349#Comment_120672349

If we come back to that Irish Rail slide, which another poster posted earlier, the Dart+ Tunnel only gets one mention in the 2050 bracket as part of Cork-Dublin-Belfast services.

As far as I can see, it's effectively been abandoned for now but they just don't want to admit it.

gjim

https://www.boards.ie/discussion/comment/120671371#Comment_120671371

It's not intended to be deep - the opposite in fact. DU is planned to be carried under the Spencer Dock surface/DART+ station via TBM and an underground station will be excavated south of the surface station between Mayor St and the river with the two concourses linked by escalators under Mayor St. These revised (in light of the DART+ plans) DU plans are described in the Jacob's report.

There's no getting away from disruption to access to Spensor Dock given the layout of the tracks just north if/whenever DU were to be constructed. On the other hand, there's no getting around the constraints of the problem - currently increased frequency of DARTs from the west means removing slots from the northern line going into Connolly. Completing DART W (and south west) without adding any passenger carrying capacity into the centre would be ridiculous. Re-configuring Connolly was looked at but dismissed - costing over 1B and involving years of SEVERE disruption.

Pete_Cavan

I don't understand the insistence here that DART+ Tunnel will never happen because it will require temporarily relocating SD station to the nearby existing Docklands station while additional tracks between Clontarf Road and Raheny is going to happen despite it being a far bigger engineering challenge, being far more disruptive to services and requiring massive numbers of CPOs.

cuttingtimber22

When will building start in Spencer Dock?

brianc89

https://www.boards.ie/discussion/comment/120672897#Comment_120672897

It's not fair to link the two points and rubbish one as a conclusion. I have never made that suggestion about 4tracking.

It doesn't change how ludicrous an idea it is, to dig up a shiny new Dart Station to build a tunnel that wasn't properly considered for at the start.

gjim

https://www.boards.ie/discussion/comment/120673329#Comment_120673329

“Service disruption” does not equal “dig up a shiny new DART station”. This has been studied and the findings are in the Jacobs report where they detail how the underground platforms will connect with the DART+ surface station - they will be located on opposite sides of Mayor st with a link via escalators from the Surface station to the DU platforms to the south. It acknowledges that the station will be cut off during DU construction because of work on the tracks north of sheriff street but there is no question of “digging up” the DART+ station.

brianc89

https://www.boards.ie/discussion/comment/120673377#Comment_120673377

The Jacobs report is pre Dart+ and Dart+ has no mention of DU except one tiny paragraph.

We've had this discussion before in detail. By the end we both agreed it was not clear if works could be completed without digging up the new station as the gradient from the Northern line is quite high and DU line would struggle to get under the new station without digging it up.

lucernarian

https://www.boards.ie/discussion/comment/120672897#Comment_120672897

What sort of engineering challenges are you on about? Half of that distance backs onto a publicly owned golf course, and much of the rest of it is in a very broad cutting. CPOing of buildings only required where the line crosses over the Howth road.

ArcadiaJunction

https://www.boards.ie/discussion/comment/120672349#Comment_120672349

https://www.boards.ie/discussion/comment/120672897#Comment_120672897

Well I guess it is a cultural thing too. Irish governments are pathologically terrified of big public transport projects. Generally, when it comes to rail we get poor compromises. Seems to me Spencer Dock station is another one. I hope I am wrong.

brianc89

https://www.boards.ie/discussion/comment/120673991#Comment_120673991

It will be interesting to see ABPs view on the matter.

With the Metro planning decision recently delayed by 7months from May to Dec 2023, what timeline expectation is there for Dart+ West decision??...

AngryLips

https://www.boards.ie/discussion/comment/120670456#Comment_120670456

Spencer Dock will have four platforms - same number as Connolly's terminating platforms, even if you just terminate Enterprise services there, it only requires one platform and one train movement per hour.

LXFlyer

https://www.boards.ie/discussion/comment/120674282#Comment_120674282

You're ignoring the lack of proper passenger facilities, and the lack of any train servicing facilities - you need that for Intercity services.

Intercity trains are regularly fuelled, watered, and have their toilets discharged at Connolly, and use the wash road there between trips.

Spencer Dock Station will be a basic station with minimal passenger facilities. That's not what you need for Intercity services.

The four terminal platforms at Connolly will still exist so why would you move the Enterprise out of there, even allowing for the fact that the track layout won't allow for services to operate to Spencer Dock from the Northern Line.

What you are suggesting makes no sense.

brianc89

https://www.boards.ie/discussion/comment/120674416#Comment_120674416

You're kind of asking for a pissy response there. Spencer Dock hasn't been built yet so it doesn't have anything for sure. Doesn't make the idea nonsense.

Personally I like the idea that all Belfast, Sligo trains and some Cork, Galway Limerick trains depart Spencer Dock. In practice it has limitations and isn't going to happen, but it's not nonsense.

CatInABox

https://www.boards.ie/discussion/comment/120674032#Comment_120674032

Just FYI on the Metrolink decision, that was not actually a delay, just a date that was auto populated. It was always due to take over a year

Pete_Cavan

https://www.boards.ie/discussion/comment/120673434#Comment_120673434

From south of Killester to south of Raheny is not a broad cutting. Outside of the space for the trains and the OHLE supports, etc. is a steep slope. To turn that slope into level trackbed, you have to install a new retaining structure, excavate the slope and then create the trackbed including drainage, OHLE, etc. There is no working space apart from the slope itself, there is no access to bring in materials or remove spoil and works have to happen right beside live electrical cables and trains wizzing by every couple of minutes. The level of work required there can't happen without additional working space which would have to come from adjacent properties.

Pete_Cavan

https://www.boards.ie/discussion/comment/120673329#Comment_120673329

The new SD station will be a big hole in the ground which gets fitted out with tracks, platforms, etc and a roof installed over it. The tunnel will require a deeper hole but once you remove the station elements, you start from a point which is well on the way to creating what is needed for the tunnel. Most of the heavy work which goes in to creating the DART+ SD station is required anyway for the future DART+ Tunnel. It really isn't as ludicrous as you suggest.

prunudo

How deep is deep? I know we're not great at forward planning in this country. But is there merit in piling the SD box walls much further down into the ground than currently needed.

From looking at the plans, it appears the SD tracks are only one level below street level. So maybe it would it require going much further down to allow for DU tunnel.

brianc89

https://www.boards.ie/discussion/comment/120675642#Comment_120675642

The DU line needs to cross directly under the Dart line north and south of Mayor street. The tunnel would need to go at least 11m deeper than the Dart line (5m tunnel, 3m trackbed, 3m clearance between Dart line).

The proposed retaining walls at Spencer Dock are not deep enough for this. The foundations of Spencer Dock are 3m thick of reinforced concrete anchored to the retaining walls.

brianc89

https://www.boards.ie/discussion/comment/120675702#Comment_120675702

Somewhere between the 2 red sections, the DU tunnel needs to be deep enough to pass under the Dart tracks and platforms.

The Northern line is +8.5m elevation.

The Dart+ line is -5.0m elevation.

The DU tunnel would need to be 11m deeper than this.

The DU line would need a gradient steeper than 1 in 20 to achieve this. It's not possible.

gjim

This makes little sense to me - why would the DU tunnel have to be 11m UNDER the GSWR line somewhere between your identified red sections? The DU tunnel has to be under the DART+ station box which is south of Sherrif St.

And your numbers don't make sense:

The Northern line is +8.5m elevation.

The Dart+ line is -5.0m elevation. 

The DU tunnel would need to be 11m deeper than this.

There is no way that the northern line is 13.5m (8.5m + 5m) above the DART+ (MGWR or GSWR) lines - it's less than 4m. You can see this, if you'd ever been in the area, there's barely 3m clearances on Ossuary road for example.

There's over 800m of track between where the spur leaves the northern line and Sheriff St where the DART+ station will be; even at 3% this provides a 25m drop which would be more than enough. Heck, for passenger heavy rail, 4% isn't unheard of, which would provide a 40m drop. There isn't a gradient isn't the issue here.

brianc89

https://www.boards.ie/discussion/comment/120676103#Comment_120676103

The DU tunnel itself needs to be 11m under the station box, otherwise the top of the tunnel will be hitting the Dart tracks??? Pages 13 and 20 of the attached file showed the elevations of:

• Spencer Dock station (-2.6m at the platform to -6.0m at bottom of station box)

• Northern line (+8.5m).

The 3m thick concrete reinforced slab for Spencer Dock station starts from 250m north of Sheriff street, therefore there is a gradient issue.

Zone-B.pdf

brianc89

@gjim see below. The slab for Spencer Dock station starts way further north than you are assuming. I don't see where a DU tunnel has space to drop down below the tracks and platform.

gjim

Yeah but the DU tunnel isn't going to be under the approach track bed - it's to the East of it. And even if it was, the slab doesn't start at 11m under the ground - it's inclined. The basic calculation remains - 2 of the 4 tracks of the northern line going over East Wall Rd bridge have over 800m of gradient to make the depth under Sheriff St. which gives more than 30m - which provides more than enough of a drop to be 10m under the track bed of the surface station.