DART+ (DART Expansion)

donvito99

Last Stop wrote: »

Not a hope of adding platforms to Tara or Pearse without substantial property acquisition so not going to happen.

What properties are you looking at in the case of Pearse?

Last Stop

donvito99 wrote: »

What properties are you looking at in the case of Pearse?

Where are you proposing to put the platforms?

donvito99

Last Stop wrote: »

Where are you proposing to put the platforms?

Essentially in the existing footprint of the station. It should be possible to have two approx 5m island platforms in the confines of the actual shed. You'd have to move platforms further east in order to bring 4 lines into the bridge at Westland Row without modifying the bridge or the existing screening facing Westland Row.

Last Stop

And how exactly would you access the platforms? I’m sure you’re aware that the access currently is from either side i.e. where you are suggesting the new ones are built.
BTW 5m would not be wide enough for an island platform handling this amount of people.

donvito99

Last Stop wrote: »

And how exactly would you access the platforms? I’m sure you’re aware that the access currently is from either side i.e. where you are suggesting the new ones are built.
BTW 5m would not be wide enough for an island platform handling this amount of people.

Accesa would likely be virtually impossible from the pearse st side. From Westland Row, you would have to come up directly onto what would be the end of the platform, rather than coming up to the sides of the platform at present. This would require moving the platform along the line further east slightly.

A single large island and two conventionally sized at the side may allow for wider platforms all round as more space can be taken with a bit of creativity from the north side of the station and there is loads to the southside however that would require lifting the existing rails and installing a curved alignment. Again, complicated and a major bit if work, but as per my original question, if it could deliver a substantial chunk of the extra capacity DU promises for a fraction of the cost, why not?

Last Stop

donvito99 wrote: »

Accesa would likely be virtually impossible from the pearse st side. From Westland Row, you would have to come up directly onto what would be the end of the platform, rather than coming up to the sides of the platform at present. This would require moving the platform along the line further east slightly.

A single large island and two conventionally sized at the side may allow for wider platforms all round as more space can be taken with a bit of creativity from the north side of the station and there is loads to the southside however that would require lifting the existing rails and installing a curved alignment. Again, complicated and a major bit if work, but as per my original question, if it could deliver a substantial chunk of the extra capacity DU promises for a fraction of the cost, why not?

There isn’t a hope of tying back into the mainline unless you move the existing platforms significantly further east. The turnouts can’t start until the end of the platform and then they have to travel at least 5m (the width of the platform) to tie back in. That would require moving the platforms over 20m to the east. That would in turn require pushing your outer tracks further out on approach which would require property acquisition. Plus a large part of the platforms would be uncovered (unless you extend the shed).

Add in the significant works to reconfigure the station involved in doing this and you’re talking hundreds of millions which would be a sizeable chuck of the DART Underground budget for limited extra capacity.

Adding these platforms would be nowhere near as effective as DU which offers a secondary Liffey crossing which (based on the city centre resignalling and to a lesser extent Metrolink) would at least double existing capacity crossing the river.

donvito99

Last Stop wrote: »

There isn’t a hope of tying back into the mainline unless you move the existing platforms significantly further east.

It would be at most 50m based on the configuration of existing turnouts at Pearse, which in the grand scheme of things is insignificant when you consider that passengers are already walking that distance to access the northbound platform from the Pearse St entrance. But I don't think that would be necessary.

On the Western/Tara St end, there is space to bring tracks over a widened bridge into the mainline gently and without the need to move platforms as east as one might have thought, at least not on the outbound platform side.







This would obviously require the removal of the screening (not structurally integral going off the absence of same on the east side) at this end.

That would require moving the platforms over 20m to the east. That would in turn require pushing your outer tracks further out on approach which would require property acquisition.

Again, I can't see what property you are referring to? On the approach from the east, the station is effectively plumbed for 4 platforms already.



When you're actually in the station, you notice just how spacious it is and it's entirely plausible for the northern/southbound side to accommodate an additional platform either in the form of a wider island platform or a platform on the right hand side of the below picture, hugging the brick buttresses essentially.



The southern/northbound side essentially mirrors the other, but is narrower in its current configuration as a result of the ramp to the platforms.

All in all, it seems to me to be quite possible to accommodate 4 platforms of sufficient size within the footprint of the shed, and also bring the outside lines back to the mainline on both sides of the station without the need to move platforms a great deal eastward.

To some extent on the western side you would need to move escalators/staircases, although this is not a huge task on the face of it. You would likely have to move the existing subway entrances by a few metres on both sides, and realign the lifts/staircases to the Pearse St entrance at the eastern end of the station. Costly? Yes. Complicated? Not terribly, the underpasses are already there.

Plus a large part of the platforms would be uncovered (unless you extend the shed).

You wouldn't have to extend the shed to provide shelter, an arrangement similar to the through platforms at Connolly is perfectly adequate. But again, it may not be necessary to extend significantly eastward.

Add in the significant works to reconfigure the station involved in doing this and you’re talking hundreds of millions which would be a sizeable chuck of the DART Underground budget for limited extra capacity.

Well that's kind of what I'm saying. I don't think it would be a sizable chunk, however, but suppose it did cost €1bn and did deliver a 10tph to the loopline, you're talking about 50% of the capacity of Dart Underground for one third or one quarter of the cost of Dart Underground - an enormous project that continues to be pushed back largely as a result of that cost, as well as its complexity and disruption.

Adding these platforms would be nowhere near as effective as DU which offers a secondary Liffey crossing which (based on the city centre resignalling and to a lesser extent Metrolink) would at least double existing capacity crossing the river.

I'm not suggesting it would be as effective as DU, but I am suggesting that a project such as this addresses the central issue of capacity in the short to medium term. DU is now a long term solution unfortunately. If a government is unwilling to put up billions for DU, they may look to 'compromise' and put up "hundreds of millions" (as you say) and ease congestion to some extent. We already see evidence of this: hybrid trains instead of electric because they've rolled back electrification; MetroLink interchange at Glasnevin to push out DU even further; etc.

dubhthach

Well the station use to have 5 platforms. Two of which were 'bay platforms' which can be seen in older photo's



Platform 5 I believe is now a carpark for staff. Of course these platforms in their original configuration would only be useful for services terminating at Pearse from southbound sources.

Last Stop

Unfortunately while I admire your enthusiasm, you’re being too simplistic.

I’m open to correction but I’m pretty sure the facade on Westland Row is protected meaning it would be next to impossible to do any works to it. Plus it’s far too tight to install a new bridge there.

This means you’ll have to move your platforms further east. This will push the tracks in your picture of the eastern end outwards as if you zoom out a little you’ll see that they are only starting to diverge at this location. This would thus require property acquisition on Erne Terrace and an alternative maintenance access on the south side.

While inside the shed may feel spacious now, if you’d added 2 more tracks it would feel incredibly cramped with extremely congested platforms.

I really struggle to see how this would add capacity to the loopline. City centre resignalling will bring it up to 20 trains per hour which will allow an additional 8 trains per hour. That’s huge. If all of these were 8 car DARTs your talking about an additional 8,000 passengers per hour.

If they really want to save money on DU then value engineer that project instead of investing money (which would go towards DU) developing short term alternatives. I’m sure the cost of DU could be reduced by:

A shorter tunnel going from Docklands to Heuston rather than Inchicore

A single bore tunnel similar to Metrolink

Top down construction of boxes

Simplified station box design

Shorter platforms

Dropping the station at Christchurch (or building it at a later date)

ncounties

I agree with all your amendments except:

Last Stop wrote: »

Dropping the station at Christchurch (or building it at a later date)

There is a lot of development gaining traction in the Liberties, and I could see this area finally transforming. We should build infrastructure when/before it's needed, and not 20 years after. Furthermore, when, any form of Luas is delivered along the south side of the Liffey, it would interchange with this, and help relieve passenger numbers proceeding onward to the city centre on the Luas service.

On the platform front, what is the planned length for Dart Underground? Is it designed for 8 car, or longer?

SeanW

I'd take issue with the "shorter platforms" that's guaranteed to cause unresolvable congestion problems in the future. The current DART, Maynooth and Northern lines can max out 8 car trains today, failing to future-proof the DU would (in the long term) nearly be as bad as not building it at all!

Everything else on that list makes sense, e.g. if it is possible to bring the tunnel up to a portal around Kilmainham and then 4 track from that point onwards.

budhabob

Single bore v's twin bore - there isnt necessarily a saving to going single bore due to the size of the bore required. A dividing fire wall would still be required.

What benefits would a shorter tunnel deliver between docklands and inchicore? the DU offers capacity improvements on all lines into and out of Dublin when it connects to the Heuston mainline. without that you deliver very little. you could just not deliver any stations but still improve capacity.

ncounties

Is there any reason to believe that this is be prioritised sooner than is currently the case? Or are we still going to have to wait to 2040?

CatInABox

ncounties wrote: »

Is there any reason to believe that this is be prioritised sooner than is currently the case? Or are we still going to have to wait to 2040?

Dart Expansion is scheduled to be finished by the end of 2027/28, and is roughly on track. Tenders have gone out for design work on the some of the lines (the work will be phased, so it's no surprise that it's only some so far), along with a tender for up to 600 new carriages.

Dart Underground is totally up in the air, to be honest. Will a future government prioritise DU once the expansion is complete? At that stage, all going to plan, Dublin will have had Metrolink, BusConnects and Dart Expansion all completed. I'd say it'd be a tough sell for parties with a countywide base, at least until the capacity becomes a problem again.

Last Stop

ncounties wrote: »

I agree with all your amendments except:


There is a lot of development gaining traction in the Liberties, and I could see this area finally transforming. We should build infrastructure when/before it's needed, and not 20 years after. Furthermore, when, any form of Luas is delivered along the south side of the Liffey, it would interchange with this, and help relieve passenger numbers proceeding onward to the city centre on the Luas service.

On the platform front, what is the planned length for Dart Underground? Is it designed for 8 car, or longer?

I absolutely agree with you but if it’s a choice between not building the station or not building DU at all, I know which one I’d choose.

Last Stop

SeanW wrote: »

I'd take issue with the "shorter platforms" that's guaranteed to cause unresolvable congestion problems in the future. The current DART, Maynooth and Northern lines can max out 8 car trains today, failing to future-proof the DU would (in the long term) nearly be as bad as not building it at all!

Everything else on that list makes sense, e.g. if it is possible to bring the tunnel up to a portal around Kilmainham and then 4 track from that point onwards.

Well that’s all relative. Do you design to current DART rolling stock or do you allow for a newer rolling stock which could be more efficient at handling higher numbers? Could a newer shorter train handle the same amount of people?

The ability to increase frequency is also massive. Running DARTs every 5 minutes should have sufficient capacity on all those lines especially when combined with the odd longer distance service.

Last Stop

budhabob wrote: »

Single bore v's twin bore - there isnt necessarily a saving to going single bore due to the size of the bore required. A dividing fire wall would still be required.

What benefits would a shorter tunnel deliver between docklands and inchicore? the DU offers capacity improvements on all lines into and out of Dublin when it connects to the Heuston mainline. without that you deliver very little. you could just not deliver any stations but still improve capacity.

There’s no dividing wall in Metrolink’s tunnel based on the info I’ve seen so far.

Single bore has many advantages over twin bore including:
reduced amount of spoil
reduced station box width
reduced number of TBMs required
reduced cost as there is no need for the mined cross passages

The shorter tunnel would connect with the Heuston mainline at Heuston rather than Inchicore. This shaves roughly 2.5km of the tunnel which would save hundreds of millions.

SeanW

Last Stop wrote: »

Well that’s all relative. Do you design to current DART rolling stock or do you allow for a newer rolling stock which could be more efficient at handling higher numbers? Could a newer shorter train handle the same amount of people?

The ability to increase frequency is also massive. Running DARTs every 5 minutes should have sufficient capacity on all those lines especially when combined with the odd longer distance service.

The laws of physics dictate that you can only get a certain number of people into a certain space. Design or no design.

The Maynooth Line has trains running in some cases every 10 minutes or so, like in the morning peak. They can totally max out an 8 car train every 10-15 minutes and that's with a line that serves mostly houses.

If Dart U. is built then it may become a development magnet for the Hazelhatch/Kildare line. If developers start building apartment blocks all along it, then you shouldn't be surprised to find that whatever capacity you thought would be fine with say 4 car DARTs is anything but. So do you design for what might be adequate today, or for the future when passenger numbers will likely be much higher?

8 cars should be the absolute balls-to-the-wall minimum and even that may not be enough over the long term. But anything less than that and you'd be almost better off not building the stupid thing at all. Especially given that modifying the tunnels after the fact would be more or less impossible.

Last Stop

SeanW wrote: »

The laws of physics dictate that you can only get a certain number of people into a certain space. Design or no design.

The Maynooth Line has trains running in some cases every 10 minutes or so, like in the morning peak. They can totally max out an 8 car train every 10-15 minutes and that's with a line that serves mostly houses.

If Dart U. is built then it may become a development magnet for the Hazelhatch/Kildare line. If developers start building apartment blocks all along it, then you shouldn't be surprised to find that whatever capacity you thought would be fine with say 4 car DARTs is anything but. So do you design for what might be adequate today, or for the future when passenger numbers will likely be much higher?

8 cars should be the absolute balls-to-the-wall minimum and even that may not be enough over the long term. But anything less than that and you'd be almost better off not building the stupid thing at all. Especially given that modifying the tunnels after the fact would be more or less impossible.

You’re right that the Maynooth line has a train every 10 minutes. However these are mainly commuter trains which have less capacity than DART (1280 vs 1400). Even simply switching to DART trains would add 10% capacity during peak hours. And that’s not saying DART trains are the most efficient.

Arguably DARTs could be made even more efficient by having seats along the side like they do in other metro type systems (yes I know this isn’t a metro)
Plus the fact that DART trains are made up of effectively 8 carriages means there is a lot of dead space in between. If they were more like Luas trams where you could stand in between sections, you’d increase the capacity.

This coupled with DART running every 5 minutes, potentially even every 3 minutes like city centre resignalling will accommodate on the loop line, and you’re talking about a capacity of nearly 30,000 passengers per direction during peak hours. Given the current capacity on the Maynooth line is roughly 8,000 I think we’d be pretty safe with slightly shorter trains.

And remember that would be just the tunnel section. You’d still have potentially even more services travelling to Heuston and Connolly/Docklands (assuming quad tracking between Connolly and at least Howth Junction).

I’m not saying it’s the perfect solution and personally I would prefer if they went with the current 8 car DARTs as the platform length but if they were trying to cut the costs to make the project viable, this is the sort of options that would be considered.

highdef

SeanW wrote: »

The laws of physics dictate that you can only get a certain number of people into a certain space. Design or no design.



8 cars should be the absolute balls-to-the-wall minimum and even that may not be enough over the long term. But anything less than that and you'd be almost better off not building the stupid thing at all. Especially given that modifying the tunnels after the fact would be more or less impossible.

We really should be making best use of our loading gauge. We've had rolling stock in the past that has been 10' 2" in width. I believe that at least one model of DART (possibly the original 1980s stock) is 9' 6". New rolling stock 8" wider than the current widest rolling stock in the country would fit a fair few extra standing punters when spread over 8 carriages.

Anyone know what the max permitted width is for 20m length stock?

Idbatterim

FFG looking like they are going to do business, they need the greens. Greens support should be conditional on DM starting in 2021 or they pull the plug. next term if they are in same position, tell them DU is up or the same...

SeanW

Last Stop wrote: »

You’re right that the Maynooth line has a train every 10 minutes. However these are mainly commuter trains which have less capacity than DART (1280 vs 1400). Even simply switching to DART trains would add 10% capacity during peak hours. And that’s not saying DART trains are the most efficient.

Arguably DARTs could be made even more efficient by having seats along the side like they do in other metro type systems (yes I know this isn’t a metro)
Plus the fact that DART trains are made up of effectively 8 carriages means there is a lot of dead space in between. If they were more like Luas trams where you could stand in between sections, you’d increase the capacity.

This coupled with DART running every 5 minutes, potentially even every 3 minutes like city centre resignalling will accommodate on the loop line, and you’re talking about a capacity of nearly 30,000 passengers per direction during peak hours. Given the current capacity on the Maynooth line is roughly 8,000 I think we’d be pretty safe with slightly shorter trains.

And remember that would be just the tunnel section. You’d still have potentially even more services travelling to Heuston and Connolly/Docklands (assuming quad tracking between Connolly and at least Howth Junction).

I’m not saying it’s the perfect solution and personally I would prefer if they went with the current 8 car DARTs as the platform length but if they were trying to cut the costs to make the project viable, this is the sort of options that would be considered.

1280 to 1400 is not exactly a game changer. It will help to be sure, but DARTs can carry more people mainly because they have fewer seats and no toilets. The Maynooth line could easily max out those 1400 per train today if the DART went there, and remember that's 1400 every 10 minutes. Today. Apartments are being built along the line, there are some serious high density developments being built around Clonsilla and Hansfield.

Now assume that DU is built with 4 car platforms and is the catalyst for very serious high density development along the Northern and Kildare lines. A 4 car train every 5 minutes would provide the same capacity as an 8 car train every 10 minutes which is already too little on some existing lines today. You can surely see a serious problem coming down the tracks (pun intended)

You're right about many of the economies that could be made to get DU "over the line" in the Dail. But I think shorter platforms would be a disaster and something to avoided if at all possible.

Last Stop

SeanW wrote: »

1280 to 1400 is not exactly a game changer. It will help to be sure, but DARTs can carry more people mainly because they have fewer seats and no toilets. The Maynooth line could easily max out those 1400 per train today if the DART went there, and remember that's 1400 every 10 minutes. Today. Apartments are being built along the line, there are some serious high density developments being built around Clonsilla and Hansfield.

Now assume that DU is built with 4 car platforms and is the catalyst for very serious high density development along the Northern and Kildare lines. A 4 car train every 5 minutes would provide the same capacity as an 8 car train every 10 minutes which is already too little on some existing lines today. You can surely see a serious problem coming down the tracks (pun intended)

You're right about many of the economies that could be made to get DU "over the line" in the Dail. But I think shorter platforms would be a disaster and something to avoided if at all possible.

A 10% increase in capacity is significant!

I understand that the new DART rolling stock will have toilets on board.

Given the journey times, less seats isn’t unreasonable. Maynooth to Connolly is roughly 40 minutes, that similar to Tallaght to Abbey St on the Luas and consider the amount of people that stand from say Red Cow during the morning peak...

Why are you talking about having 4 car platforms? That’s not what I mean when I say shorter platforms. I mean cutting even 10m off the platforms by a more efficient rolling stock design could save hundreds of millions. I don’t think any sane person could justify 4 car platforms

Last Stop

Idbatterim wrote: »

FFG looking like they are going to do business, they need the greens. Greens support should be conditional on DM starting in 2021 or they pull the plug. next term if they are in same position, tell them DU is up or the same...

Given the Green Party lead the fight against the green line upgrade, I wouldn’t hold out much hope of them driving the campaign. I’d say if Eamon Eyan had his way, DU would interchange with metro at Rathfarnham or something

Zebra3

Why is there a discussion about DU platforms and the Maynooth line?

Isn’t the Maynooth DART to run to Bray?

donvito99

Last Stop wrote: »

reduced amount of spoil

Doesn't single bore increase volume of spoil as overall tunnel diameter is larger?

Sam Russell

Last Stop wrote: »

Given the Green Party lead the fight against the green line upgrade, I wouldn’t hold out much hope of them driving the campaign. I’d say if Eamon Eyan had his way, DU would interchange with metro at Rathfarnham or something

It wasn't Green Party policy to prevent the GL upgrade, it was Eamonn Ryan playing the NIMBY card to garner votes. He got his crayons out and designed a whole new Dublin South-side public transport by tram scheme. All was drawn out to gain the Dunville Ave vote.

Sam Russell

donvito99 wrote: »

Doesn't single bore increase volume of spoil as overall tunnel diameter is larger?

Yes, but a lot is left at the bottom of the bore.

Last Stop

donvito99 wrote: »

Doesn't single bore increase volume of spoil as overall tunnel diameter is larger?

The volume of spoil of 2 slightly smaller twin bore tunnels is greater than 1 single bore tunnel.

In the single bore tunnel, the diameter is being driven by the height rather than width so a single bore tunnel isn’t that much bigger.

Last Stop

Sam Russell wrote: »

It wasn't Green Party policy to prevent the GL upgrade, it was Eamonn Ryan playing the NIMBY card to garner votes. He got his crayons out and designed a whole new Dublin South-side public transport by tram scheme. All was drawn out to gain the Dunville Ave vote.

Not just Eamon Ryan, a newsletter was issued by Catherine Martin advocating for Eamons proposals.