DART+ (DART Expansion)

Last Stop

Pete_Cavan wrote: »

I wish you would stop stating this as if it was a fact. Tara Street station will have the most scope for interchange capacity: the DART station already has two entrances, the Metrolink station will have two entrances and will be located on a plaza with space available. It is the city centre location with the most scope for interchange facilities.

A full Dart carries 1800 people. A full metro carries 700.
Let’s assume the AM peak and approx half of passengers get off at Tara given it is the only central DU station and the main interchange.
6 DART per hour per direction so a total of 24 DARTs
30 metros per direction so 60 metros

24x900 + 350x60 = 42,600 people passing through the station at peak.

I don’t care how many entrances you have, that is difficult to handle. But the biggest issue with Tara is how do you handle that many people on the existing DART platforms which don’t have space to expand.

So let’s take the worse case scenario and say that a DU train in each direction arrives 8 minutes before existing DARTs are due. Again assuming 500 people on each train want to interchange and it’s an even split. Assume 150 from each metro want to interchange.

That give you 575 people interchanging to each platform. Add in say 200 who get their first train from Tara and you have 775 people waiting on the platform. That’s at least 3 deep. Now here’s where it gets really fun, how do the 900 people get off the arriving dart onto the platform? That means you could have over 1500 people on the platform. That’s almost 8 deep and there is no way Tara can handle that even with 2 entrances.

Last Stop

Pete_Cavan wrote: »

DU is about releasing additional capacity on the existing heavy rail network and providing interchange possibilities with existing and planned light rail services, creating a proper network. Talk about works served at a particular location completely misses the point, particularly when said location is/will very well served by public transport.

A network is only as good as the areas it serves. Sure you could connect Heuston to Connolly direct if that was the case or have no exits on the motorway to Cork. SSG is designed to be a world class interchange between 4 modes and close to the CBD with lots of offices and shops relatively close by as others have pointed out. Putting a station here will attract passengers which will increase the cost benefit ratio of the project which is what it will come down to.
I don’t buy the argument that you could interchange at Tara and get the metro for 1 stop as the interchange penalty proves this is not what humans like to do. Not putting a station there bypasses a huge area of the city.

Pete_Cavan

Last Stop wrote: »

A full Dart carries 1800 people. A full metro carries 700.
Let’s assume the AM peak and approx half of passengers get off at Tara given it is the only central DU station and the main interchange.
6 DART per hour per direction so a total of 24 DARTs
30 metros per direction so 60 metros

24x900 + 350x60 = 42,600 people passing through the station at peak.

I don’t care how many entrances you have, that is difficult to handle. But the biggest issue with Tara is how do you handle that many people on the existing DART platforms which don’t have space to expand.

So let’s take the worse case scenario and say that a DU train in each direction arrives 8 minutes before existing DARTs are due. Again assuming 500 people on each train want to interchange and it’s an even split. Assume 150 from each metro want to interchange.

That give you 575 people interchanging to each platform. Add in say 200 who get their first train from Tara and you have 775 people waiting on the platform. That’s at least 3 deep. Now here’s where it gets really fun, how do the 900 people get off the arriving dart onto the platform? That means you could have over 1500 people on the platform. That’s almost 8 deep and there is no way Tara can handle that even with 2 entrances.

Honesty, those figures are made up nonsense and based on some ridiculous assumptions - every train maxed out with passengers and half of the passengers on every train get off at Tara Street! More than half the people who get off a DART immediately want to get on another DART! Almost half the people getting off Metro immediately want to get on a DART despite a portion of them having already had the opportunity to make that change at Glasnevin!

But my point is that detailed modelling will determine capacity needed and if that can be provided. Just like engineering analysis will determine tunnel design and what alignment is achievable. You can'tjjust keep making statements as if they are verified facts and just insist that you are right.

Pete_Cavan

Last Stop wrote: »

A network is only as good as the areas it serves. Sure you could connect Heuston to Connolly direct if that was the case or have no exits on the motorway to Cork. SSG is designed to be a world class interchange between 4 modes and close to the CBD with lots of offices and shops relatively close by as others have pointed out. Putting a station here will attract passengers which will increase the cost benefit ratio of the project which is what it will come down to.
I don’t buy the argument that you could interchange at Tara and get the metro for 1 stop as the interchange penalty proves this is not what humans like to do. Not putting a station there bypasses a huge area of the city.

First of all, SSG isn't "designed to be a world class interchange", there's a Luas stop there and a Metro station is currently planned for the other side of the Green. Any potential DU station wouldbe separate and could well be on another side again. The multi level interchange station there is long dead. Everything else you say could be said about any location in the city. SSG isn't the centre of the city which all city life revolves around, it certainly doesn't need to be the central hub for all transport options to converge on. And I'm not trying to sell you an argument, just pointing out that SSG isn't the be all and end all.

Last Stop

Pete_Cavan wrote: »

Honesty, those figures are made up nonsense and based on some ridiculous assumptions - every train maxed out with passengers and half of the passengers on every train get off at Tara Street! More than half the people who get off a DART immediately want to get on another DART! Almost half the people getting off Metro immediately want to get on a DART despite a portion of them having already had the opportunity to make that change at Glasnevin!

But my point is that detailed modelling will determine capacity needed and if that can be provided. Just like engineering analysis will determine tunnel design and what alignment is achievable. You can'tjjust keep making statements as if they are verified facts and just insist that you are right.

I’ve made what I believe to be reasonable assumptions. Yes I have assumed that every DART will be maxed out durIng that specific service at morning peak. I believe half getting off is a reasonable assumption given the Tara st location relative to the city centre and the proposal to make it an interchange between 8 different lines (both directions plus Luas nearby as has been mentioned) and multiple buses. Ok my assumption that every metro was maxed is a tad unrealistic but completely coincidentally I neglected to multiply my metro interchange figure by 6 so it’s arguably conservative.

My post all along has been that at Tara there is simply not enough capacity on the existing lines or any of the new lines to handle such vast number of interchanges. This does not even include the stairs etc. between each of the stations which would be at unsafe levels during peak times. Therefore I believe that Tara would not be suitable as a DU station.

While I appreciate there needs to be/ will be detailed design on this to prove it doesn’t work, I can tell you now it doesn’t and no one has pointed to any evidence to the contrary. I don’t think there is any example worldwide (besides Grand Central which is on a completely different scale entirely) where so many lines converge on a single station. That is not due to bad planning but simply because it wouldn’t work.

Last Stop

Pete_Cavan wrote: »

First of all, SSG isn't "designed to be a world class interchange", there's a Luas stop there and a Metro station is currently planned for the other side of the Green. Any potential DU station wouldbe separate and could well be on another side again. The multi level interchange station there is long dead. Everything else you say could be said about any location in the city. SSG isn't the centre of the city which all city life revolves around, it certainly doesn't need to be the central hub for all transport options to converge on. And I'm not trying to sell you an argument, just pointing out that SSG isn't the be all and end all.

An interchange doesn’t not have to in the same building. The two Luas lines are now connected and you interchange between them. DU at SSG would create an underground link between Luas and Metro which in my mind is typical of a world class interchange.

I’ve never said it’s the be all and end all, what I’m an trying to point out is that it would be foolish to omit it from the route to save around 5% of the budget. I don’t believe any other location has the same potential as SSG in terms of its proximity to both metro and Luas stops while also affording the opportunity for a station to be construction cut + cover which I believe to be the biggest cost saving which can be achieved on any new design of DU. Add in the main shopping district in Dublin to the north and the large office facilities and nightlife to the south and I believe you have a pretty good location for a station.

Pete_Cavan

Last Stop wrote: »

it would be foolish to omit it from the route to save around 5% of the budget.

Another completely baseless figure made up entirely to suit yourself. It is laughable.

Last Stop

Pete_Cavan wrote: »

Another completely baseless figure made up entirely to suit yourself. It is laughable.

€4bn budget and I think each station will cost around €200m so 5% therefore there is logic behind my point.

I’m not trying to be argumentative, I’m just trying to have a debate as to why there won’t a station at Tara for the following reasons
1. The sewer
2. Capacity of Tara
3. Value engineering of a cut + cover solution
4. Alignment from SSG.

And also why there will be one at SSG
1. Option of cut + cover.
2. Serves shopping + offices
3. Interchange with Luas and metro
4. It’s a strategic location in Dublin

As hard as you have tried to discredit my points (by borderline trolling in my opinion) you have yet to prove I am incorrect in what I am saying.

You haven’t demonstrated that it is possible to move it sewer
You haven’t proven that Tara has the space to expand to provide sufficient capacity
You haven’t proven that cut + cover isn’t a one of the biggest cost savings possible
You haven’t proven that SSG won’t significantly improve the cost benefit ratio.

ohographite

D.L.R. wrote: »

If you sent Sligo trains to Heuston instead, or even through the PPT, they could avoid this section and take advantage of the quad track out of Heuston.

Would the Sligo trains rejoin the Sligo line by going from Hazelhatch to Maynooth on a new line that would have to be built? I'd agree with running them from Connolly through the PPT and onto the multitrack, as Connolly is in a more central location than Heuston.

Pete_Cavan

Last Stop wrote: »

€4bn budget and I think each station will cost around €200m so 5% therefore there is logic behind my point.

I’m not trying to be argumentative, I’m just trying to have a debate as to why there won’t a station at Tara for the following reasons
1. The sewer
2. Capacity of Tara
3. Value engineering of a cut + cover solution
4. Alignment from SSG.

And also why there will be one at SSG
1. Option of cut + cover.
2. Serves shopping + offices
3. Interchange with Luas and metro
4. It’s a strategic location in Dublin

As hard as you have tried to discredit my points (by borderline trolling in my opinion) you have yet to prove I am incorrect in what I am saying.

You haven’t demonstrated that it is possible to move it sewer
You haven’t proven that Tara has the space to expand to provide sufficient capacity
You haven’t proven that cut + cover isn’t a one of the biggest cost savings possible
You haven’t proven that SSG won’t significantly improve the cost benefit ratio.

This is beyond laughable at this stage. You bang on about a sewer on Townsend Street yet Metrolink documents show a 1800mm sewer on SSG east and there is likely to be similar sewers or other infrastructure right round the green. Nothing is as simple as you make out and detailed analysis will determine what options are viable from engineering and economic povs. At this stage we can't say that a station at Tara Street is less viable than one at SSG.

I don't need to prove anything, I fully accept that routing via Tara Street may not be possible but the potential to reduce the tunnel by 1km certainly warrants in depth examination (and such a reduction would be a significant cost saving which you haven't acknowledged in your 5% saving). I don't need to discredit your points, you have done that yourself with your ridiculous made up figures.

And you suggest that I am trolling!

CatInABox

Pete_Cavan wrote: »

This is beyond laughable at this stage. You bang on about a sewer on Townsend Street yet Metrolink documents show a 1800mm sewer on SSG east and there is likely to be similar sewers or other infrastructure right round the green. Nothing is as simple as you make out and detailed analysis will determine what options are viable from engineering and economic povs. At this stage we can't say that a station at Tara Street is less viable than one at SSG.

In fairness, they specifically moved the SSG station west to avoid impacting that sewer.

TII wrote:

Disruption in St Stephen’s Green area will also be reduced under the new plans. This station will be located as previously proposed at St Stephen’s Green East, but we are now moving it slightly south so that Hume Street can remain open during construction, and slightly west so as to avoid closing the road during construction. This also means we can avoid a major sewer that would otherwise require diversion. St Stephen’s Green park itself will be impacted to a small extent as a result.

Last Stop

Pete_Cavan wrote: »

This is beyond laughable at this stage. You bang on about a sewer on Townsend Street yet Metrolink documents show a 1800mm sewer on SSG east and there is likely to be similar sewers or other infrastructure right round the green. Nothing is as simple as you make out and detailed analysis will determine what options are viable from engineering and economic povs. At this stage we can't say that a station at Tara Street is less viable than one at SSG.

I don't need to prove anything, I fully accept that routing via Tara Street may not be possible but the potential to reduce the tunnel by 1km certainly warrants in depth examination (and such a reduction would be a significant cost saving which you haven't acknowledged in your 5% saving). I don't need to discredit your points, you have done that yourself with your ridiculous made up figures.

And you suggest that I am trolling!

Do you not get that they are choosing to CPO 70 properties instead on diverting the sewer on Townsend st. That shows how big a deal it is.
As someone has correctly pointed out, SSG has moved west to avoid the need to divert the sewer there which is smaller than the one on Townsend st to start with.

You keep hiding behind the need for detailed analysis when I have shown that there are several obvious reasons why a station at Tara doesn’t work and one at SSG does.

Pete_Cavan

CatInABox wrote: »

In fairness, they specifically moved the SSG station west to avoid impacting that sewer.

That’s the Metrolink station. Putting a DU station there as well is almost certainly going to impact on such infrastructure and/or the park given its east/west alignment. My point is that there may not be an alignment via SSG which avoids such conflicts so it is far from cut and dry that building a station there is easier and cheaper.

Last Stop

Pete_Cavan wrote: »

That’s the Metrolink station. Putting a DU station there as well is almost certainly going to impact on such infrastructure and/or the park given its east/west alignment. My point is that there may not be an alignment via SSG which avoids such conflicts so it is far from cut and dry that building a station there is easier and cheaper.

A DU station in SSG will almost certainly go in the Park given the proximity of LCC. This means that while unfortunately the Park will be dug up for 2 years, there is likely to be an impact on public utilities. I would be 99% certain that a station in the park would be on an alignment which would avoid such conflicts and as I have said several times, would be cut + cover making it easier and cheaper.

Pete_Cavan

Last Stop wrote: »

A DU station in SSG will almost certainly go in the Park given the proximity of LCC. This means that while unfortunately the Park will be dug up for 2 years, there is likely to be an impact on public utilities. I would be 99% certain that a station in the park would be on an alignment which would avoid such conflicts and as I have said several times, would be cut + cover making it easier and cheaper.

The park closes at dusk so a station would have to extend outside it to provide an entrance at a minimum so interfering with utilities is certainly a possibility. Cut + cover is a tunnel building method, as Metrolink will ulitise along the Swords bypass, stations require full excavation (unless the tunnel method allows for platforms within the tunnel which is extremely likely with DU). It is almost certain that all DU stations will be the same construction method a SSG station.

Regardless of how cheap a SSG station is, it will still cost €X00m so it being cheap it a relative term. If a Tara Street station is possible, the cost could equate to that of SSG + new Pearse station (an expensive location as there is no clear footprint in which to dig out a station box and passing under roads) and it would still have the significant saving of reducing the tunnel length by 20%.

Last Stop

Pete_Cavan wrote: »

The park closes at dusk so a station would have to extend outside it to provide an entrance at a minimum so interfering with utilities is certainly a possibility. Cut + cover is a tunnel building method, as Metrolink will ulitise along the Swords bypass, stations require full excavation (unless the tunnel method allows for platforms within the tunnel which is extremely likely with DU). It is almost certain that all DU stations will be the same construction method a SSG station.

Regardless of how cheap a SSG station is, it will still cost €X00m so it being cheap it a relative term. If a Tara Street station is possible, the cost could equate to that of SSG + new Pearse station (an expensive location as there is no clear footprint in which to dig out a station box and passing under roads) and it would still have the significant saving of reducing the tunnel length by 20%.

I don’t foresee an entrance being outside the park but instead tying into the existing fence line like the old scheme (video on YouTube). When I say cut + cover for stations (and I’m sure you are aware of this) I am referring to top down construction where they pile the perimeter wall, dig out the inside, build the station and cover the top with a slab.
I think it is extremely unlikely that the DU will have sufficient space for platforms inside the tunnel itself. That would require a 20m wide tunnel and given the tunnel is circular in shape, 20m tall (only approx. 6m is required). This would also push your stations deeper which would increase cost so I can’t see that being an option. I can foresee all stations being cut + cover or top down construction.

I never said SSG was going to be cheap, in fact I acknowledged it is going to increase the overall scheme cost vs not having it, however I believe the benefits outweight the costs. I do not see a single location in the vicinity of Tara where top down construction is possible therefore I can’t see it as a runner. This argument is further enhanced by the numerous reasons I have mentioned several times which make Tara a poor option.
If the decision was to go with all top down construction then I think that would make Pearse difficult as well (not impossible but difficult). This raises the option of top down in canal at GCD which as I have already suggested would be a good option.
While this would lead to a longer tunnel, I believe that the cost and reduced risk of going with top down construction at all stations far outweighs the savings from a reduced tunnel with even 1 mined station. Going with single bore also has the potential to reduce costs (granted in both cases).

bk

Given the issues we have seen with Metrolink and how they have been dealt with, I'm now certain that the DU station will NOT be built in SSG park.

Doing so will simply raise too many objections and protest that could cripple the whole project. They will likely take the same approach as we have seen with Metrolink of minimising objections.

So no, it won't go in the park. It will either have to be shorter and go on SSG North, which as pointed out, will impact the Greenline turnback, though personally I don't see that being a big issue * Or it will need to go on SSG south, which makes it even more remote from the central locations you want to access.

* They could put an extra turn back facilities on SSG West. Plenty of space there, sure their is on the street parking on that street!

SSG is definitely not the easy option that it might have been in the past. Just bulldozing your way through a city center park isn't going to fly anymore.

cgcsb

The road at Stephen's Green north + a small bit of the park can be done though. As is being done with the ML station on East Stephen's Green.

bk

cgcsb wrote: »

The road at Stephen's Green north + a small bit of the park can be done though. As is being done with the ML station on East Stephen's Green.

Yep, just measured it, 228 meters is available from Dawson St on SSG North or even 250 meters if you don't mind closing access to/from SSG East.

Sounds like plenty of space to me, even for an 8 carriage DART.

Yes, the turnback would probably need to be temporarily moved, either SSG East or even SSG South.

EDIT: Molesworth St would be another potential location for a turnback, so plenty of options there.

cgcsb

The site for the proposed Cabra DART station will now instead become the site for 420 apartments.

https://www.irishtimes.com/business/commercial-property/tristan-capital-buys-two-development-sites-for-rental-market-for-54-5m-1.3963790?mode=sample&auth-failed=1&pw-origin=https%3A%2F%2Fwww.irishtimes.com%2Fbusiness%2Fcommercial-property%2Ftristan-capital-buys-two-development-sites-for-rental-market-for-54-5m-1.3963790

LXFlyer

cgcsb wrote: »

The site for the proposed Cabra DART station will now instead become the site for 420 apartments.

https://www.irishtimes.com/business/commercial-property/tristan-capital-buys-two-development-sites-for-rental-market-for-54-5m-1.3963790?mode=sample&auth-failed=1&pw-origin=https%3A%2F%2Fwww.irishtimes.com%2Fbusiness%2Fcommercial-property%2Ftristan-capital-buys-two-development-sites-for-rental-market-for-54-5m-1.3963790

That site was always up for development. There’s still room for platforms within the permanent way - I don’t see the issue.

MJohnston

Yes, this site has been approved for a while now. If anything it being built will improve the business case for another station here.

Pete_Cavan

bk wrote: »

cgcsb wrote: »

The road at Stephen's Green north + a small bit of the park can be done though. As is being done with the ML station on East Stephen's Green.

Yep, just measured it, 228 meters is available from Dawson St on SSG North or even 250 meters if you don't mind closing access to/from SSG East.

Sounds like plenty of space to me, even for an 8 carriage DART.

The further east it moves on SSG, the tighter you make the curve of the tunnel, which may not be achievable. The straight line distance between the southern end of the Pearse station and that corner is only 600m and the alignment would have to change from a south westerly direction to north westerly between the station boxes.

bk

Pete_Cavan wrote: »

The further east it moves on SSG, the tighter you make the curve of the tunnel, which may not be achievable. The straight line distance between the southern end of the Pearse station and that corner is only 600m and the alignment would have to change from a south westerly direction to north westerly between the station boxes.

Could be, but there looks to be VERY little difference between the original DU SSG plan and this. The original plan had the station right at the northern end of the park. So you are talking only about 10 meters further north and 20 meters further east.

And of course that is assuming an 8 carriage station box. With a 4 carriage station box, there would be no effective difference in the easterly direction. Just a shorter station.

The original station box looks to be 250meters long. A 150 meters station box will fit between Dawson Street and Kildare Street, with no change in the easterly direction.

L1011

cgcsb wrote: »

The site for the proposed Cabra DART station will now instead become the site for 420 apartments.

https://www.irishtimes.com/business/commercial-property/tristan-capital-buys-two-development-sites-for-rental-market-for-54-5m-1.3963790?mode=sample&auth-failed=1&pw-origin=https%3A%2F%2Fwww.irishtimes.com%2Fbusiness%2Fcommercial-property%2Ftristan-capital-buys-two-development-sites-for-rental-market-for-54-5m-1.3963790

Plan specifically leaves provision for the station and mentions it as a future transport link.

Pete_Cavan

bk wrote: »

Could be, but there looks to be VERY little difference between the original DU SSG plan and this. The original plan had the station right at the northern end of the park. So you are talking only about 10 meters further north and 20 meters further east.

And of course that is assuming an 8 carriage station box. With a 4 carriage station box, there would be no effective difference in the easterly direction. Just a shorter station.

The original station box looks to be 250meters long. A 150 meters station box will fit between Dawson Street and Kildare Street, with no change in the easterly direction.

The original 8 carriage station box would have to be shifted 100m back past Dawson Street to avoid the Luas, bringing it pretty much down to that corner. A 4 carriage station box should fit without extending that original footprint and end before Kildare Street, as you say.

Last Stop

There is no way they will go with 4 car platforms on this. It will be 8 car for sure. This tunnel will be designed to last 100 years so why completely limit the capacity from the outset to save a few quid. If you don’t have the money to do it right, don’t do it.
Based on population growth, the GDA could be well over 2 million by the end of this century so future demand will be far greater than presently.

Qrt

Last Stop wrote: »

This tunnel will be designed to last 100 years so why completely limit the capacity from the outset to save a few quid.

You're new here, aren't you?:pac:

DoctorPan

Qrt wrote: »

You're new here, aren't you?:pac:

Would explain why Irish Rail is ordering fixed 8 piece Dart sets.

Thrashssacre

DoctorPan wrote: »

Would explain why Irish Rail is ordering fixed 8 piece Dart sets.

I think they're four piece sets they're ordering, fixed eight piece sets would be wasteful. Prevents having shorter sets at weekends and late at night and would completely rule out expansion whereas extending to 12 car trains at some point isn’t completely unreasonable 16 though I could never see in the next 50 years.