DART underground - options

bk

"Dart+ as a project within Transport 42 doesn't envisage stations at Christchurch and St. Stephen's Green"

But Stephens Green is reachable by Metrolink with a transfer at Cross & Gun from DART+ Sure, of course it will be slower and less convenient, but certainly not a bad connection.

That just leaves Christchurch, which frankly I don't see as a major destination. Sure it is popular with tourists, but I don't see it being a major destination for folks of West Dublin commuting in daily.

Plus if the Lucan Luas is built, there will be a connection from Heuston to Christchurch anyway, again with a transfer, but quiet doable.

Again I'm not seeing the justification for building a 5 to 10 Billion tunnel for basically two stations, which would already have transfer options. I can see why it would fall flat on a CBA.

"Perhaps some real-world examples of cities achieving great transit successes without cross-city rail would help inform the discourse here better."

I mean I'd argue we do have cross city heavy rail in the form of the PPT. I know it doesn't go right through the center of the city, but that is more just a reflection of how small Dublin actually is. I mean at it's closest, it is just 1KM for O'Connell St. Pretty much any big city would call that a cross city rail line!

Again I'm not saying it will never happen, but I'm struggling to see the justification for it any time in our lifetimes.

KrisW1001

https://www.boards.ie/discussion/comment/121003381#Comment_121003381

PPT solves the problem of tying the northern and southwestern lines, but it doesn't enable any more stations - although I sometimes think adding a new DART station here serving Dublin Zoo would be a big ridership generator: the tunnel runs about 200 metres from the Zoo entrance.

The biggest benefit of DU was the addition of two stations to the DART system in the southern core of the city that weren't served by any other mode. The South West quarter of Dublin city is densely populated, but badly served by rail, and the future metro plans don't seem to offer any hope for a change for that. I am aware that tunnelling would be prohibitively expensive, but any brownfield option for a line from Heuston heading south would be worth looking at.

bk

"PPT solves the problem of tying the northern and southwestern lines, but it doesn't enable any more stations"

But again, just two stations, one of which Stephens Green will be accessible by transfer to Metrolink and the other potentially by Lucan Luas connection.

Don't get me wrong, I can see whay people liked the idea of DU. Direct connection from West Dublin to Stephens Green and onto Spencer Dock.

But I can also see why a 5 to 10 billion tunnel would miserably fail a CBA now with the reality of DART+ and Metrolink. It really doesn't make that much sense any more. Or at least I'm failing to see the benefit now.

Sure, some day the capacity of PPT + Connolly/Spencer Dock might be maxed out and we then need a tunnel, but that seems to be in a very distant future.

KrisW1001

As I said, PPT solves the problem of linking the two major stations in Dublin, and I am not in any way saying it shouldn't be done. But it does nothing for a part of Dublin that has no rail access. Most of Dublin's railways run North of the Liffey, and most of the city's economy is South.

For me, Stephen's Green wasn't the big positive in DU - I actually think it would have been a weakness, as the station design they presented wasn't nearly big enough to be a "Dublin Central", but within a year it would de facto become just that, and would quickly become heavily congested. The thing that I felt really added something to the city's transport was the station at Christ Church, as this is a part of the city that's difficult to get to by public transport, despite being very central.

So: PPT yes, but additionally a route serving south and south-west inner city Dublin should be on the plans somewhere, and not one that requires passengers to cross all the way over to the east first... This doesn't even have to be a tunnel, but I suspect it would need to be at some point, and that would probably kill the project.

bk

"As I said, PPT solves the problem of linking the two major stations in Dublin, and I am not in any way saying it shouldn't be done. But it does nothing for a part of Dublin that has no rail access. Most of Dublin's railways run North of the Liffey, and most of the city's economy is South."

Eh, the south side of the city has plenty of rail, two Luas lines and an up coming Metro. Sure it isn't "heavy rail", but most people don't care or understand the difference. As long as it gets them from A to B they are happy.

I really don't see the attraction of Christchurch, it isn't a major employment location, that is the Docklands and Stephens Green area. Yes lots of tourists and of course as a result some jobs, but of course it isn't exactly a million miles from Heuston and potentially that entire south corridor could be served by more "rail" with Lucan Luas.

I just can't see Christchurch justifying a 5 to 10 Billion tunnel!

Brian CivilEng

I'm trying think through this logically, as I understand the points being put forward here and agree that DART Underground wouldn't make sense if its sole benefit over DART+ is to connect Christchurch. So I'm asking myself is it still necessary if we get everything else?

East West connections through the city are currently Luas or bus based. Post DART+ there will also be the option to go around the city centre to access destinations to the west when coming from the East and vice versa. Post Metrolink there will also be a new spine that travels through the centre of Dublin in a North South direction, closer to popular destinations and connecting with the DART network.

Thinking of some trip pairs.

1. Coming from Belfast, going to Cork.

With DART Underground you'd arrive from the Enterprise in Connolly, walk to Docklands and get a DART to Heuston, and get the Cork train.

With planned projects you'd arrive from the Enterprise in Connolly, get the PPT dart to Heuston West, walk from there to Heuston and get the train to Cork.

Neither is perfect but advantage planned infra in my opinion.

2. Coming from Kildare, going to Landsdowne Rd.

With DART Underground you'd take the commuter train to Heuston, take the Underground to Pearse and switch to a DART for Landsdowne.

With planned infra, you'd still take the commuter train to Heuston and get Luas to Connolly before switching. Alternatively you can switch to a PPT train in Hazelhatch and change to a DART in Connolly.

DART Underground would be better but not significantly.

3. Coming from Blackrock going to Stephen's Green

With DART Underground you'd take the Dart to Pearse then switch to the Underground.

With planned infra you'd take the DART to Tara and switch to Metrolink to backtrack to Stephen's Green.

Much of a muchness there.

OK, not sure what my point is. I'm sure there are plenty of trip pairs that are not served by planned infra but it does seem that a lot of the business case for DART Underground will be removed if all of DART+ and Metrolink go ahead.

TLDR: I believe DART Underground would make travel around the city easier, but not enough to justify the cost if DART+ and Metrolink are built in full

bk

On Belfast to Cork, you could potentially route Cork Trains through the PPT to Connolly area, to meet up with the Belfast train.

Intercity trains have used the PPT in the past for match days etc. So it isn’t anything new.

If you really wanted to you could even do Belfast to Connolly, then have the same train route through PPT to Heuston West and onto Cork. Obviously would require some works, signalling changes etc. I’m sure it would cost, but probably much cheaper then a tunnel. Of course the question would be realistically how much demand there is for such a service.

From Blackrock you’d probably just take the 7 or 7a bus straight to Stephen’s Green. Or take the DART to Pearse, Stephen’s Green is just a 10 minute walk.

For some connections don’t forget about BusConnects and the orbital routes.

bk

Thinking about it a bit ore, once Metrolink and DART+ start actual construction, I think we will need a new GDA plan that looks at what the next steps once Metrolink, DART+ and BusConnects are in place.

What plans still make sense, which new plans should be built on the Metrolink/Luas/DART backbone.

Extending Metrolink North to meet the Northern line is a no brainier IMO. Green line upgrade? Rerouting the Green Luas line? New South West Metro line or branch? Lucan Luas? Extend Finglas Luas to the Airport? Metro West back on the table? BRT or Luas on other lines like Swords road? And how does DU fit in all this?

Consonata

https://www.boards.ie/discussion/comment/121004300#Comment_121004300

I think honestly there will be logic to make Glasnevin a fairly major interchange in this regard, facilitating through trains if required. Building a short spur between Northern and GSWR allowing for bypassing Connolly could do a lot of the job and it allows Belfast trains to link directly with Metrolink to get them to town.

Connolly is in an awkward part of town and is poorly served transport wise to be honest from North and South Dublin. Making Glasnevin the main interchange station for Sligo-Dublin, and the Belfast/Cork Corridors makes a lot more sense imo.

brianc89

Another observation I think is worth raising, regarding Spencer Dock, is the plans do not include a connection from the Northern Dart into Spencer Dock Dart station.

This would be massively short sighted. Ideally, 30-40% of the Dart North trains could go to Spencer Dock. 50-60% of the Dart West / South West trains could go to Spencer Dock, with the remainder going to Connolly / GCD / Bray.

However, without a Dart North connection to SD, there is severely limited capacity from Connolly to run Cork trains, or commuter services from Dart W + SW onto Connolly / GCD / Bray.

p_haugh

https://www.boards.ie/discussion/comment/121004300#Comment_121004300

Just to point out, the 7/a don't go to the green, they go past Merrion square then go down Westland Row to Pearse Street. Still slightly closer compared to the dart mind you!

p_haugh

https://www.boards.ie/discussion/comment/121004259#Comment_121004259

Another option would potentially be:

Intercity to Connolly, DART through the PPT and stay on the DART until an interchange station further out (i.e. hazelhatch).

Only potential issue with this is that everything would need to be running smoothly as depending on timings there could be a missed connection!

KrisW1001

Mode-changes are pain in the hole for intercity travel. A change across platforms at the same station is about the limit of what you can expect people to do if you are offering an end-to-end serivce, but the ideal to produce good revenue is through-running. The original DU was to be shared with Inter-City through-services. I really don't think the capacity is there on PPT for hourly Heuston-Belfast trains (continuation of Limerick/Cork originated services) plus the increased DART traffic; even it it was, it would be better served by DART services.

An aside: the more I think about a Zoo station, the more it seems to makes sense - Dublin Zoo gets about 1.25 million visitors a year. Making it accessible by DART and (with a single change) from the national rail network would need to have a really big negative not to do it, and it would solve the huge problems of finding parking at the Zoo during busy times.

As for mainline services, I don't think they justify their own tunnel under Dublin unless there’s really a plan to create a Dublin Central station (not a bad idea in itself, but it would be hugely expensive). It really doesn’t matter how you connect Heuston to the Northern and Western lines for inter-city, and this could be done by a single track further away from expensive land, but it should be done.

I wasn't in favour of DU for the mainline link, though, and I do believe that now that PPT is being given a capacity expansion for DART services, there isn't a purpose for it anymore. Any tunnelling in Dublin should really be for local services, as the big advantage of tunnelling is that you can pop up stations along the way in places that would otherwise be hugely expensive to lay track to overground. As I noted above, there’s a big segment of Dublin’s south inner city that has no rail service, either current or planned: MetroLink will fill the big gap that exists on the Northside, but there will be a mass transport desert between Red Line and Green on the south side of the city. (I’ve no skin in this game, incidentally: I don’t live in Dublin, and the friends I do have there all live north of the river)

Pete_Cavan

The idea that the PPT is any kind of replacement for a cross city tunnel is incredibly misguided. For a efficient system, we need trains running through the city and out the other side. Terminating so many trains in the city centre is far from ideal but in the absence of a tunnel, it is what we have to do for now. The LLB can't indefinitely be the only city centre heavy rail Liffey crossing.

Not sure why people are still talking about the DART tunnel going via SSG and Pearse. SSG is almost certainly off the table as the DU plan was based on that station already being pretty much already built for the MN station. The Metrolink station at SSG wont have any provision for a heavy rail station and going to SSG adds a lot to the tunnel length. Part of the area for the intended Pearse DU station has been built on so its gone.

A new route will have to be looked at for the new tunnel. Tara Street is the ideal place for a combined DART/Metrolink interchange and effectively a "Dublin Central" station. I reckon the new tunnel plan will have to be based on shorter station boxes and that opens more possibilities.

Facilitating the tunnel portal at Spencer Dock is likely to be cheaper than tunnelling somewhere else.

The whole Cork - Belfast thing is a weird obsession here. The number of people making such a journey would be tiny, it is an irrelevance. It is so far down the list of considerations that it's not worth mentioning.

brianc89

https://www.boards.ie/discussion/comment/121008977#Comment_121008977

The idea of building a cross city tunnel, at a cost of several billion while:

1) an alternative has been opened in PPT (5minutes from Heuston West to Glasnevin and

2) 10s of billions needs to be spent on more important upgrades

... is incredibly misguided.

What exactly is inefficient about a system lacking multiple cross-city heavy rail links? Interchange is part and parcel of an efficient system. In any case, there are currently 2 rail lines crossing the Liffey (PPT and Dart Coastal) and 2 Luas lines. The Metro will be a 5th line. A Luas spur from James to College Green would be a 6th radial into the city.

brianc89

https://www.boards.ie/discussion/comment/121008977#Comment_121008977

Not sure why people are still talking about the DART tunnel going via SSG and Pearse. SSG is almost certainly off the table as the DU plan was based on that station already being pretty much already built for the MN station. The Metrolink station at SSG wont have any provision for a heavy rail station and going to SSG adds a lot to the tunnel length. Part of the area for the intended Pearse DU station has been built on so its gone.

So, you assume SSG is off the table because MetroLink hasn't planned enabling works. You also assume Pearse is off the table because a single office building on a tiny piece of land, while continuing to ignore the enormous difficulty a 4-Tracked surface Dart station at Spencer Dock will create for a tunnel exit point.

You also say SSG is unnecessary as it would make the tunnel too long. So basically, you want a several billions tunnel for one station at Christchurch, because of the opportunity it creates for cross-city travel?

bk

“The whole Cork - Belfast thing is a weird obsession here. The number of people making such a journey would be tiny, it is an irrelevance. It is so far down the list of considerations that it's not worth mentioning.”

That is the thing, we all agree! The reason it is being discussed is because the latest news on DU comes from the All Island Rail Report and now for some bizarre reason, IR seem to want to jam intercity trains into the DU tunnel!

Non of us understand why they would want to do this, what would the benefit be, etc.?

I would tend to agree that an updated DU plan would be simpler, straighter line, maybe smaller stations for just 4 carriage dart, simple cut and cover stations. Cheaper cost, more Metroish.

But obviously the above isn’t compatible with intercity trains.

Honestly I don’t know what they are taking at IR and at least for me I’m trying to make sense of it.

Citrus_8

PPT route is snail-pace slow. Are there any plans to change that? If not, then people should stop praising it as an equally good substitute to the DU tunnel.

lucernarian

https://www.boards.ie/discussion/comment/121010293#Comment_121010293

Journey times at the expected periods of peak travel from Pearse to Park West seem to be 28 to 30 minutes. I expected a worse journey time tbh. That journey with Dart Underground would be between 15 and 20 minutes, though the RO that I can't find should be able to give a more precise estimate. If it is likely that a station will be provided in Cabra as well as Inchicore, the differential increases a little. And that's assuming electrified routes. Speed increases are possible on the GSWR line after the tunnel but it would result in ~a minute benefit assuming Cabra is built, and 2 minutes assuming Cabra station isn't.

lucernarian

https://www.boards.ie/discussion/comment/121004259#Comment_121004259

I think this is the conclusion I'm reaching, though I'm not convinced by the second scenario. A) because Dart Underground will not be possible with its original alignment so it's not a very useful comparison, b) the Dart+ SW and W plans go beyond what Dart Underground envisaged for the terminal stations in particular and c) ridership figures involving Kildare as a starting destination are not much more relevant than the Enterprise to Cork ridership projections.

What I'm still bothered by is the cost projections - we don't seem to believe that a tunnel can be built cost-effectively for heavy rail even though central Dublin has relatively suitable subsoil/bedrock for a TBM and the marginal cost per km should still be reasonable if densified locations (like Christchurch) are not considered. Case in point, the Bray Head situation that isn't really dealt with in any of the aspirational plans for the GDA's rail system even though a tunnel would be relatively simple, welcomed, and effective in increasing capacity towards the southeast

Citrus_8

https://www.boards.ie/discussion/comment/121010328#Comment_121010328

28-30 min on a train for such a short inner M50 Dublin area distance is very long! PPT is very slow and an uncomfortable route at the moment and from your reply it doesn't seem there will be anything better.

At least having a station at the zoo could justify a slow speed in that section. I'm very much for a station at Inchicore/Kylemore Road. However, not for a cost of a speed... Irish Rail are already painful slow and outdated. We need an improvement in speed, frequency, better price, safety, better access etc... Paid P+R is another nonsense. Are the parking spaces at the train stations on the private land that most are administered by the Apcoa or similar leeches? Is there a special scheme to avail of a free parking having a train ticket or valid Leap card?

Pete_Cavan

https://www.boards.ie/discussion/comment/121009249#Comment_121009249

I don't assume the SSG station is off the table, it is a fact that the Metrolink RO contains a SSG station with no provision for a heavy rail station. Adding an east/west underground heavy rail station at SSG would require utilising a much larger chunk of the Green, look at the issues OPW have been raising about losing a small number of trees for Metrolink. Going to SSG would only make a tunnel longer and make the station box more difficult, it's almost certain a new tunnel plan wouldn't go there.

The original Pearse DU station box plan isn't possible now. A new plan at the same location may be possible but would require excavating the station box directly under said building. It would be far more difficult than later adapting Spencer Dock to a thru station which you insist wont happen. It is almost certain that station locations will be chosen that don't require building station boxes directly under recently built buildings. As I said, shorter stations opens more possibilities.

A new tunnel plan wouldn't just be for one station, no idea where you got that from. And Luas and Metrolink aren't/wont be city centre heavy rail Liffey crossings so no idea why you mention them. My point is that discussing things in the context of the old DU station locations is pointless. You seem to ignore most details in a post and just focus on a few high level points in isolation rather than considering a post in its entirety.

As I said, a tunnel will be needed to allow for future heavy rail capacity increases, PPT is only a stopgap. With the LLB maxed out, every train not using it will has to terminate at Heuston, Connolly or SD (and a small number at GCD). That includes all intercity, outer commuter and DART trains. If we ever want to increase rail services into and around Dublin beyond what's currently envisaged, we need more thru-running DARTs and use the city terminating capacity for longer distance services.

brianc89

https://www.boards.ie/discussion/comment/121010328#Comment_121010328

The journey times in PPT are not as bad as some people assume. The lack of off-peak service is a bigger issue.

Several of the trains are 26mins (Pearse to CO&PW direction). That assumes no upgrades on speed, electrification, signalling etc., however you need to add stops at Cross&Guns, Cabra and Heuston West. On the other side, PW&CO is 7minutes to Heuston. The DU tunnel not take an additional 8-13minutes to get to Pearse...

• The comparison, in my view, is more like 22-25mins via PPT and 12-13minutes via DU...

... however if you make Connolly your starting point, the comparison is more likely 18-20mins via PPT and 18-20mins via DU (change to Dart at Pearse).

brianc89

https://www.boards.ie/discussion/comment/121010388#Comment_121010388

Which cross-city routes are you talking about when you refer to heavy rail? Commuter rail? Like Drogheda to Heuston, or Newbridge to Swords?

Can you give an example of a required heavy rail link across the Liffey, for which Metro would be an inefficient replacement?

KrisW1001

Regarding PPT, the DART+ works include new signalling and track work on this link to reduce headways and increase speed. The current service speeds shouldn’t be thought of as a limit on what can be done.

densification

https://www.boards.ie/discussion/comment/121010293#Comment_121010293

https://www.boards.ie/discussion/comment/121010467#Comment_121010467

The speed limit between Islandbridge Junction and Glasnevin Junction is 20-25mph. This is not due to change with Dart+ SW. However, the four tracking west of Islandbridge Junction will result in a 70mph speed limit from east of Memorial Road.

There's a ~1.6km section in Cabra, just north of the PPT, where the track is perfectly straight. But it will continue to be 20-25mph. The curve from Cabra to Glasnevin is also not that severe.

A reasonable speed limit could save about 2 minutes on every journey.

Citrus_8

https://www.boards.ie/discussion/comment/121013066#Comment_121013066

Ah, I'm more about the comfort and attraction as a mode of transport, not the minutes to be spefic. It's just slow. Very boring. PPT isn't a pleasant route to me when I use it. I appreciate your pragmatic reply and some details, though. I'm just surprised PPT route wasn't made more straight so that it could reach a reasonable speed, not a nearly Dart snail pace as we have between some stops.

lucernarian

https://www.boards.ie/discussion/comment/121010412#Comment_121010412

I'm avoiding off-peak comparisons as they are not reflective of potential or expected bottlenecks to maximum capacity. By doing that, I'm assuming that the end goal of a given project is commuter/capacity oriented, but I think that's a reasonable assumption.

The MGWR track (i.e. the Dart+ West) proposals looked into permanent way restrictions more than any of the other studies did. And intriguingly, no works were recommended - The bulk of expenditure beyond electrification and fleet purchase will be for level crossing closures. The PPT line (Heuston to Glasnevin Junction) has a ~2 km straight section with currently a 30mph speed limit, and a station that will be built roughly halfway along this. I also think it's very unlikely that Cabra would be built without a station in the vicinity of Inchicore, however that is equally the case with the approved railway order for Dart Underground.

So, if that is a valid basis for the journey time hypothesis, I could not see a way where addressing line speed could shave more than 2 minutes off the CO&PW to Pearse journey on the existing infrastructure. The Connolly - Glasnevin Junction stretch was explicitly studied in the Dart+ reports for potential speed increases but I'm not an expert in how or why the report's conclusions were made. Heuston to PW&CO takes 7 minutes in both directions without a stop, but Heuston to Pearse with DU would involve 2 other stops and a rather tight curve. The two stops in question would be expected to have a relatively high patronage, as would the proposed Glasnevin station on the PPT route.

And then there's the issue of signalling. The PPT route involves 2 at-grade junctions (I'm ignoring Heuston itself) with other DART lines on its journey to Pearse, while DU itself involves none. Signalling optimisations for heavy mainline trains can only achieve so much. Beyond that, the differences are less to do with engineering/permanent way choices and more to do with with operational factors.

As for the starting point, Pearse is the busiest train station in the country and seems like a more worthwhile commuter traffic comparison than Connolly does, along with the fact detailed investigations were made for the Heuston-Pearse route and also those details were used literally when the Dart+ investigations were subsequently carried out.

lucernarian

https://www.boards.ie/discussion/comment/121013066#Comment_121013066

Yes, this matches my calculations (and I thought the speed restriction was 30 mph). Glasnevin Junction will have amendments made to facilitate movements but they're at grade so speed increases through here are unrealistic IMO.

brianc89

I had to dig really deep to find this but I eventually found the "tiny" section on speed. Anyone know what the "Down Loop" is?

Also, what exactly reduces speed along PPT route?

@lucernarian Lots of other popular station parings will give varying results (Tara-HH, GCD-HH, SD-HH, Airport-HH etc.). Pearse-HH comparison unfairly "hypes up" the benefit of DU. Per your numbers, DU would provide a saving of 8-15mins along this route, but we shouldn't conclude the same time saving will apply for every trip.

In any case, on Pearse-HH let's be kind and assume 28mins for PPT route and 15mins for DU route. Are we really suggesting that passengers on "an existing rail line" deserve a shiny new tunnel at a cost of several billion, just to shave 13minutes from their commute time?