DART underground - options

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.

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?