DART underground - options

Consonata

https://www.boards.ie/discussion/comment/120950540#Comment_120950540

As advised by Iarnród Éireann, the DART Underground project has not been considered in the development of the design for Spencer Dock Station.

I would argue it would be foolish to consider a project that

a) likely won't be occuring till 2050

b) will likely have to be redesigned, much like ML is a highly redesigned version of Metro North.

brianc89

Zone-B.pdf

https://www.boards.ie/discussion/comment/120950609#Comment_120950609

You're overlooking the thing that has changed. A 30-40metre wide, 400metres long, 3metres thick reinforced concrete slab for the Spencer Dock surface station. This surface station was not planned when DU was planned. It's not about digging it up "temporarily". It's obnoxiously in the way.

The Northern line is at +8m elevation and the bottom of the platform is at -6m elevation. Including the c. 9metres height required for a Metro tunnel and platforms, the Northern line needs to drop at least 23metres in height before reaching the platforms of the surface Dart station.

Assuming intercity trains would need to be accommodated, the gradient is simply too steep. Every wheel in a Metro train is connected to power (allowing steeper gradients), while an intercity train is pulled by a locomotive and requires less steep gradients.

gjim

Brian, intercity trains have always been explicitly EXCLUDED from using the Interconnector, DU or any incarnation of this idea. There was never any idea of locomotives being hauled into the DU.

The formula - used in every S-Bahn type tunnel across Europe built in the last 50 years, which IE copied for DU, is to only run high frequency, metro or S-Bahn services through the tunnels. EMUs can and do handle gradients.

Even in London (with crossrail) and Paris (with the RER system), intercity trains still terminate in the old 19th century stations they always used, while the new tunnels are exclusively for high-frequency - 5 minute or less headway - services. Running intercity trains through such tunnels wasn't even given a second of consideration. You're giving the impression that you don't understand the idea of the DU at all or the problem it solves.

brianc89

https://www.boards.ie/discussion/comment/120950883#Comment_120950883

They're not gonna spend billions on a rail line that can't facilitate intercity Cork to Belfast trains. Spencer Dock Dart plans are forcing a steeper gradient for a tunnel, which will exclude the intercity trains.

It's simply not going to happen, hence the point I'm banging on about. The Dart plans have fundamentally altered DU.

gjim

Brian, there was NEVER a plan to facilitate Cork to Belfast trains? There was a plan, abandoned because of the GFC, to build an exclusively DART underground tunnel which actually got through planning and was granted a Railway Order. This plan had government approval. Although I'll admit I remain skeptical of the FF government's commitment with hard cash even if the countries finances hadn't blown-up in 2008.

But there was never even a question of accommodating inter-city trains. 300 people an hour arrive in Dublin from Belfast on average (how many would travel on to Cork?). DART/DU was to carry 20,000 per hour. Rail tunnels under the centre of cities will only pass CBA if they can be used to to carry tens of thousands of passengers per hour per direction. Even if all 300 of the Belfast passengers actually wanted to go to Cork, accommodating them would have the square root of FA effect on any CBA. And accommodating them by mingling intercity trains and DARTs in a tunnel would be such an operational nightmare, it would scupper the entire project. And that's before considering that you'd have to electrify the entire Cork Dublin Belfast route beforehand - as you can't have diesel trains stopping at underground stations.

brianc89

https://www.boards.ie/discussion/comment/120951007#Comment_120951007

Fine then, let's exclude the intercity trains. You still can't ignore, the proposed surface Dart station is obnoxiously in the way of the tunnel.

Here's a picture since it said to paint a thousand words. Please note the requirement to maintain connection of two shiny new Dart lines to the surface station while also maintaining freight access to Dublin port.

Pete_Cavan

As I pointed out already, DU had the TBM launching from the Docklands which has a totally different space requirement than the extract site. Everything you provide clearly states "DU project" so considers the constraints imposed by that particular (now dead) design. DU is a specific tunnel project and it isn't going to happen. Another tunnel will be designed and obviously the DART+ team can't comment on it because they don't know what it will involve. Launching the TBM from the western end completely changes the space requirements at Spencer Dock and is the only logical solution for multiple reasons.

No idea where this 3m reinforced concrete slab is coming from. Rail lines aren't built on concrete slabs and even a bridge wouldn't have a slab anything close to 3m thick. Practically every other metre of rail track in the country has a trackbed of compacted hardcore and suitable ballast. The Spencer Dock station site was previously a rail line which carried steam locomotives, its unlikely to have major bearing capacity issues, particularly more than 3m below ground level where the ground is more compacted.

The transition from passing under the Liffey to joining the Northern line was previously fully designed and deemed workable by IÉ engineering team and the planning authority. There's no reason why that can't still happen.

hans aus dtschl

https://www.boards.ie/discussion/comment/120951007#Comment_120951007

I agree with everything you write. The problem is that the all-island strategic rail review alludes to there being Cork to Belfast (and Dublin Airport) connectivity: this doesn't appear to make sense.

bk

"I agree with everything you write. The problem is that the all-island strategic rail review alludes to there being Cork to Belfast (and Dublin Airport) connectivity: this doesn't appear to make sense."

And it isn't just alluding, it seems to be a major part of the plan and is mentioned multiple times throughout the plan!

As for some here saying it isn't an official plan, well the athurs of the plan say they discussed the options with the experts at Irish Rail and they dropped a couple of ideas (e.g. new separate line for the Northern Line) as IR experts said it would be too expensive/couldn't happen. I find it extremely unlikely that they didn't run this tunnel idea past the IR folks and even that the idea didn't come from them.

I find it extremely unlikely that such a radical new idea didn't come from folks at IR.

I suspect the folks at IR know that DU will never pass a CBA now with DART+ and so instead they want to try and force intercity trains into it to try and improve the CBA. And yes, I think it is all a terrible idea.

brianc89

https://www.boards.ie/discussion/comment/120951912#Comment_120951912

The 3metre thick slab is shown in the RO docs (Zone B doc attached).The space required for a TBM and materials is irrelevant. The new surface Dart station and platforms is "in the way" of the tunnel.

As per my crayon pic, the yellow is the 3m thick slab plus surface lines. The red and purple is a "hypothetical" tunnel route connecting to Northern line. The red section would need to drop under the yellow area by using a gradient close to 5% while doing an 80° turn. This is the only possible route that maintains access to Dublin port and doesn't cut off the new Dart lines from the surface station.

Conclusion: it's impossible.

Zone-B.pdf

brianc89

https://www.boards.ie/discussion/comment/120952679#Comment_120952679

Irish Rail are well aware. They gave a presentation in the UK in May where they refer to Belfast-Dublin-Cork services through a Dart+ tunnel (post 2050).

I think they are also well aware of the impact of the proposed Spencer Dock surface Dart station, which makes a tunnel at Spencer Dock impossible. See my previous post.

https://youtu.be/JCK8teu2ry8

gjim

Brian - the exercise you are proposing is pointless. You want me - who is NOT a rail/civil engineer - to propose "engineering solutions" which you - also who is NOT a rail/civil engineer - will critique.

As others on the thread have said, it's not like in 2045 or whenever, the original 2008 Interconnector plans will dusted off and the lads will start digging. The plans will be nearly 40 years old at that stage.

This highlights the glaring non-sequitur in your argument/position - you've taken the fact that "specific 20 year-old plans for a northern line to SW line tunnel link-up are not compatible with the DART+ Spencer Dock station" and concluded that it will NEVER be possible to link the NL with the SW once DART+ Spenser Dock is built.

There will be a redesign if/whenever Dublin belatedly follows the lead of other European cities who have embraced urban tunnels to support heavy rail metro systems.

The DU idea is/was simply a variation of https://en.wikipedia.org/wiki/Hirschengraben_Tunnel or https://en.wikipedia.org/wiki/Trunk_line_2_(Munich_S-Bahn) or at a bigger scale https://en.wikipedia.org/wiki/Crossrail in turn influenced by https://en.wikipedia.org/wiki/R%C3%A9seau_Express_R%C3%A9gional which as the wikipedia article states "The performance of the RER has made it a model for proposals to improve transit within other cities." - or https://en.wikipedia.org/wiki/Rhine-Main_S-Bahn - these are systems I have used personally. Heavy rail metro using tunnels under city centres has undergone a huge renaissance in the last few decades around Europe.

bk

"As others on the thread have said, it's not like in 2045 or whenever, the original 2008 Interconnector plans will dusted off and the lads will start digging. The plans will be nearly 40 years old at that stage."

Does anyone actually think the original DU Rail order and plan will actually get built now! I thought everyone knew that is dead and gone now and when/if DU gets looked at again, it will likely be a totally new design, taking into account DART+, PPT and Metrolink.

The original DU design was very much integrated with Metro North, given that isn't happening, a new DU will need to be a total redesign taking into account the new realities. Think how Metro North got redesigned into Metrolink.

"Heavy rail metro using tunnels under city centres has undergone a huge renaissance in the last few decades around Europe."

Hmmm.. I wouldn't really say that. Metro's are now all the buzz in mid sized European cities like Dublin. Shorter vehicles, but higher frequency, fully automated, etc. The shorter vehicles mean smaller stations, which keeps costs down, but the higher frequencies gives you capacity similar to longer heavy rail vehicles, but at a lower cost and the high frequency is much more popular with passengers.

The renaissance you speak of is more happening in the much larger, denser cities like London, Paris, etc. which wouldn't be applicable to Dublin.

Having said all that, it wouldn't really make sense to run the East - West tunnel as a Metro, given it could hook up two heavy rail lines.

A compromise might be something like a Metro-ish like DART Tunnel. Build the stations to 90 meters length, to take 4/5 carriage heavy rail DARTs, rather then the original plan for full 180m 8/10 carriage DARTS and run them at a high frequency. Cut and cover stations where ever possible.

The striking thing about Metrolink is how focused it is on a simple Metro system, with a much simpler alignment and much smaller and simpler cut and cover stations, compared to the original massive mined stations of the Metro North plan. I fell the original grandiose DU plan could do with a similar slimming down.

Having said all that, the hints from the recent all island rail review seems to go in a completely different direction, sending intercity trains into the tunnel! That would be a whole different kettle of fish.

Honestly I don't know what they are thinking and planning now, it all seems to be completely up in the air.

brianc89

https://www.boards.ie/discussion/comment/120965486#Comment_120965486

You want me - who is NOT a rail/civil engineer - to propose "engineering solutions" which you - also who is NOT a rail/civil engineer - will critique

This is not what I want. All I want is that people stop referring to DU / Spencer Dock as a plan that will ever happen, and 'start discussing what might be possible'....

Hopefully a tunnel is not 40 years away. I certainly think it's worthwhile to have that discussion now, do you disagree @gjim ?

For example:

• lands at Clontarf Golf Club are likely to be sold and developed soon. Should we keep some of those lands for a tunnel connection to Northern line?

• or the CIE lands east of East Wall - maybe a tunnel could exit there? But where would it go then?

• or a totally new line, such as Heuston / Tara St / Beaumont / Airport / Northern line.

• or Heuston / SCR/canal / Cathal Brugha / GCD / SD / Clontarf / Northern line.

VeryOwl

https://www.boards.ie/discussion/comment/120966028#Comment_120966028

The Rail "strategic" review is a total mess that's done more harm than good. More cooks in the kitchen, more confusion, more awful ideas being reheated.

I agree that a slimmed down DART Underground plugging into the completed DART+ network with the necessary Northern Line upgrades, would be an excellent asset.

Unfortunately the slide from the Irish Rail presentation that @brianc89 linked unfortunately suggests IE are equally unserious as the authors of the report about what this tunnel project is now meant to be for - if it ever does happen. It feels like what's being suggested now is a very expensive way to link Cork and other cities to Dublin Airport.

brianc89

https://www.boards.ie/discussion/comment/120971242#Comment_120971242

Here's a cheaper version to link Cork to Belfast (and the airport via Metro at Glasnevin).

It requires knocking a few houses in North Strand but mostly uses a Fire Station (that might be moved anyway) and a vacant site that's been empty for decades.

They could repurpose the Drumcondra line for Cork-Belfast services (mostly) while directing the majority of Dart SW and Dart W services via the MGWR (Royal Canal line) directly to Spencer Dock with a new Drumcondra station at Whitworth Avenue.

Consonata

https://www.boards.ie/discussion/comment/120971242#Comment_120971242

They're unclear as to what the tunnel should be for because the business case for the tunnel has been unclear since PPT reopened.

bk

brianc89, not a bad idea if the goal is just to get to the airport, however the obvious issue is that it would create a worse experience for the majority of intercity passengers heading to Dublin City.

They wouldn’t be really going to Heuston anymore, nor Connolly. I know Heuston West, but under DART+ it is just a simple commuter station, I suppose you could redevelop it as an intercity station, but it would be a very long walk to the Luas/buses. Perhaps redevelop them too, have a Luas extension to Heuston West!

Cross and Guns would be a nice interchange, change to Dart to Connolly / Spencer Dock or Metrolink to the airport or City. But again I suspect it would need to be massively beefed up to become an intercity station.

Of course with the Metrolink interchange, then you’d have to ask would it even make sense for the Intercity to go to the Airport, seems redundant.

Specially if Metrolink gets extended North and interchanges with the Northern line, really no need for the intercity trains to go to the airport then.

Which would actually solve a problem I see with Northern line trains going to the airport. Going via a spur from the Northern line to the airport would add a significant delay to passengers on the Northern line heading to Dublin City, making journey times worse for most people. I can’t see it being popular with the majority of passengers who are going to Dublin City, not the airport.

Really, how many people would be going to the Airport, versus commuting to Dublin daily?

Ive no idea if there is the space at Connolly for this idea. But a modification of your idea:

Cork - Heuston West - Cross and Guns - Connolly - Belfast

Connolly basically become the main Dublin City intercity station. Folks coming from Cork, etc. heading to the airport transfer to Metrolink at Cross & Gun, folks heading to the airport from the Northern line transfer to Metrolink at a new interchange with an extended Metrolink line.

Northern line passengers continue to be brought into Connolly, with no delay heading to the airport.

Cork, etc. passengers now have a more central city center station at Connolly and can continue onto Belfast if they want (and vice versa). They also have a pretty good link to the airport at Cross & Gun and other locations in the city.

No need for a tunnel or expensive CPOing of houses. Of course it would all hinge on Connolly capacity and intercity trains reversing into and out of it and some complicated movements across the DART track. Perhaps instead use Docklands or Spencer Dock as the new intercity station, though I know slightly less central.

Of course you could still do a version of DU, but focused on DART’s and not intercity trains. Perhaps create an almost circular line, Heuston West, Christchurch, Tara/Stephen’s Green, Docklands.

brianc89

https://www.boards.ie/discussion/comment/120971987#Comment_120971987

Yeah I think the obvious issue is the need, or lack thereof, for direct Cork Belfast services. I think most people here agree this is v.low priority.

You raised a lot of good points. Here's my take:

• Cork-Dublin services should be every hour with every second service using Heuston West, Glasnevin and Connolly. A 10minute stopover before a separate Dublin-Belfast train departs would be fantastic.

• MetroLink extension to Northern line is a no brainer, offering Airport access to the entire Cork-Belfast Corridor (together with Glasnevin).

• Spencer Dock might have been a great intercity terminus, but that ship is about to sail. The proposed Dart station is only 4 platforms. Additional platforms would need to be further away from the Luas. Heuston is well set up with refueling, cleaning, general services needed for intercity.

• Heuston West (HW) should become the terminus for N2, S2 & H-spine buses. This would provide a constant flow of buses between HW and Heuston Main (HM).

• Another option for HW is a Luas extension from HM (though I think buses will do the job). An additional extension from James Hospital down Thomas/Dame Street to College Green could take half the Tallaght/Saggart trams, freeing up capacity for HW to Connolly/The point.

• In general, all West / SW / South intercity trains should stop at a dedicated Dart station, such as Clondalkin, allowing passengers to transfer to the Dart Network including Glasnevin Metro and Spencer Dock/Connolly. Alternating Cork services should still serve Connolly direct.

I've always liked the idea of a circular line, but I think it should follow the canals. A Metro from Heuston West south to SCR/Harold's Cross, Cathal de Brugha/Rathmines, Charlemont, Mespil/Baggot Street, GCD, then either Spencer Dock, GlassBottleSite or both.

lucernarian

After reading the posts from someone who's done a decent job of pointing out how Dart+ will comprehensively impact the only railway order approved for an underground heavy rail corridor in this country, I'm surprised at the selective nitpicking that forms some of the replies. The conclusion I'm drawing is that DU is dying or dead and yet we need something that functions like what countless other cities have built. Projects that inspired DU in the first place.

So what's left on the table? I'm not really sure what's possible if DU isn't going to happen. So many sites and areas are off the table that it makes building heavy rail in useful/dense areas a challenge of almost biblical proportions. Is there a feasible way to have a tunnel extend from the vicinity of Spencer Dock to the Clontarf golf course while also maintaining northern commuter functionality? While avoiding rampant CPOs like quad-tracking of the northern line would conventionally involve. IMO it remains the best alternative if DU is no longer feasible, but it might inevitably become the even bigger victim of megaproject-itis, as high-speed transport northwards, a heavy rail link to the airport and extra capacity towards Louth all become relevant.

brianc89

https://www.boards.ie/discussion/comment/121002536#Comment_121002536

A few thoughts from me:

• I don't believe a heavy rail link to the airport will ever happen, nor do I think it necessary. Metro / Dart extensions should be adequate.

• 4-tracking Northern Dart and Kildare line will allow for massive increase in Commuter / Intercity frequency, while maintaining high frequency on city network.

• The only likely new underground, IMHO, is Metro SW - Charlemont/ Rathmines/Harold's Cross / Tallaght. The SW of the city has nothing on the rail map.

• Here's my master crayon "plan". Nothing ground-breaking in there:

• Luas extensions - Finglas / Lucan / 'James to College Green' / Ringsend / Bray

• Metro West (mostly over green fields)

• Metro North extension, Metro SW, Dart Airport spur

CatInABox

I'd still put money on the Green Line Metrolink extension happening. Once construction is under way, they'll look again at it, with the main aim to reduce the amount of time that the system is out of order. Get it down below a year and it becomes a no brainer again, albeit a slightly painful one.

Southwest Metro is definitely on the cards as well, but if the Metrolink Green Line extension is done, then it's got to have a new line heading out the other side. The Malahide road is a very strong candidate then, surface around Donnycarney, the road northward is plenty wide enough for surface running. That entire route is prime for redevelopment, with fairly low density, deprived areas along the route.

On whether a tunnel could use Clontarf Golf Club, I'm not sure. Any tunnel would need to be deep enough to pass under the Dublin Port Tunnel, and then immediately rise to the surface. Not sure if that angle is viable, but I haven't worked it out.

KrisW1001

Green-line to Metro won't happen without a new plan or branch for Green Line south of Stephen's Green first - ideally a branch. The big reason Metro on that route was canned was because it would have killed ridership on Green Line between Stephen's Green and Charlemont, without really adding much to the city's public transport availability, and that impacted the cost/benefit significantly.

It was, and is, a better idea to have Metro cover a different part of the city - the only reason Charlemont is still present is that the planning for the underground structures had been prepared, and a new alignment would have meant a further delay. But if there were two Luas lines diverging from Stephen's Green, then an upgrade of part of one to a Metro wouldn't have the same problems.

One particularly local issue with Dart Underground and Metro is that they use incompatible tracks: there's nothing much we can do about this at this stage, but we are stuck with a rail system with an oddball track gauge, despite our light-rail/metro using international gauge. Some Metro systems (notably Tokyo's) allow mainline/commuter trains to serve metro stations on the same platforms, but that option would be much more technically challenging here.

Murph85

Varadkar cancelling DU for what now looks like spare change behind the back of a couch , was real genius...

Let's just spend billions on welfare increases every year and nothing on rail... I hope tge eu fine us billions for breaching emission limits , that's probably the only hope of them doing anything about rail development here...

KrisW1001

It was cancelled long before Varadkar arrived on the scene - he only confirmed it, and it was hardly spare change.

bk

brianc, I'd just suggest Metrolink should go straight north, north of Swords, parallel to the M1 and then turn right for Rush & Lusk. That would open up a massive area north of Swords for development of new dense commuter towns along the route. The goal shouldn't be to just get to the Northern Line, it should be also be focused on opening up development land.

"The conclusion I'm drawing is that DU is dying or dead and yet we need something that functions like what countless other cities have built. Projects that inspired DU in the first place."

But do we need it?

It seems like Dart+ and the PPT gives us like 90% of what DU promised. That seemingly DU would only give us a relatively small number of extra passengers over Dart+ and thus the CBA now would look so poor for DU!

Just because other cities have an underground (heavy rail), doesn't mean we automatically mean we need one. Arguably we already have one with PPT. I mean it isn't like cities like Berlin don't have massive amounts of above ground running. Sure they drop underground where needed, but if it wasn't needed, they wouldn't. Building a tunnel is an extremely expensive task, you only do it if there is heavy demand for said tunnel. If the demand isn't there, then it doesn't really make sense.

Don't get me wrong, I'm not trying to be argumentive, I'm more just talking out loud, trying to understand myself what a future DU might look like. If it is really needed? might some other alternative appear? etc.

KrisW1001

A high-capacity link between the Heuston and Connolly rail networks is definitely needed. It doesn't have to follow the path of DU, but it would facilitate a viable commuter-rail line serving the south-west of Dublin city. The idea of through-running services from Cork-Belfast is just a little bonus - the real benefit would be seen within Dublin's hinterland.

bk

https://www.boards.ie/discussion/comment/121003343#Comment_121003343

But Dart+ South West with the PPT already achieves that. Why would you need to build DU to do more of the same?

And mixing DART and intercity trains in the same tunnel is a terrible idea that just repeats the mistakes of the overcapacity Northern and South East line. Mixing services like this is definitely not international best practice.

Brian CivilEng

My own opinion is that the benefit of DART Underground were the stops in Christchurch and St. Stephen's Green rather than the Hueston to the existing DART connection, and I would have expected it to attract way more passengers for that reason only. DART+ is a by-pass of the city centre, useful but not as attractive.

lucernarian

https://www.boards.ie/discussion/comment/121003310#Comment_121003310

In what is reminiscent of the AECOM North Dublin Transport Study and its fanciful if not fictional modelling and comparisons, I am really struggling to see how the 90% equivalency is reached - Dart+ as a project within Transport 42 doesn't envisage stations at Christchurch and St. Stephen's Green, and the effects of far faster journey times that come from having a tunnel to two potent trip generators (plus the interchange potential at other stations). It seems strange that the consultations released to this point seem to portray remodelling at Connolly and Docklands, or the Heuston West station/GSWR electrification as an "either-or" to the original DU concept.

I try to imagine the rail patronage in a city like Leipzig before its Citytunnel was built, and I just can't imagine alternatives that would achieve anything close to 90% of the peak capacity and trips that tunnel facilitates.

Perhaps some real-world examples of cities achieving great transit successes without cross-city rail would help inform the discourse here better. I can think of cities like Manchester in the UK and I wouldn't hold it up as a beacon of success or a place where significant modal shift occurred.