DART+ (DART Expansion)

Sam Russell

cgcsb wrote: »

I think routing DU to Tara St, if technically feasible, would be a mistake in passenger loadings. It's a tight enough site and you'd be centralising a LOT of interchanges there. MetroLink, 2 DART lines, both luas lines a short walk away and countless bus routes. We already have problems because of an over concentration of bus routes into O'Connell Bridge and College Green, it'd be replicating the same thing only worse because bus routes can be changed easily, rail routes not so much.

If you think of the various routing possibilities with DU and Metrolink (with GL extension - you would have:

Bray to the airport - change at Tara St.
Bray to Heuston - change at Pearse.
Heuston to Airport - change at SSG.
Maynooth to Airport - change at Crossguns.
Maynooth to Bray - no change.
Maynooth to Sandyford - change at Tara St.

and so on. That is without considering Luas lines.

CatInABox

bk wrote: »

It is definitely a very attractive idea, but I wonder if the curve from Docklands to Tara St area would be too tight.

I'd also think that the desire to avoid complexity would mean that adding a second underground level there would be a big factor in in any decision there.

There's just far more room to do the construction of a second underground level at SSG, even if College Green and Tara St might be preferable from a usage point of view. A triangle of stations, Tara, Pearse, and SSG, is just as good at interconnection as one station.

To be honest, I'm also unconvinced that a station at college green is as necessary/desirable as it used to be, when the design of the new metro station at Tara St opens up the path towards College Green, along with the plans in the area to increase permeability, like the Hawkins House, and the new entrance into Trinity.

As an aside, I think that they might reduce complexity by only making the stations long enough for four carriages, and just doubling the frequency. That'd make construction a hell of a lot easier.

Pete_Cavan

I don't think capacity would be an issue at Tara Street if DU had a stop there, you just design facilities to cater for that number of people. A single city centre interchange is better than having multiple permutations depending on where you want to go.

Tara Street will be much more than the current entrance onto the quays post Metrolink. There is considerable space on the Townsend Street side to develop an adequate station. The current Metrolink image for it is not sufficient anyway, they indicate people with wheelchairs/buggies having to make their way between quays and Townsend Street to move between DART and Metro which is not acceptable for a new build station. Lifts serving ground level and both platforms are required.

A DU station at Tara Street would most likely be located directly under Townsend Street to allow for easier interchange and it would also reduce the tunnel curve.

CatInABox

Pete_Cavan wrote: »

A DU station at Tara Street would most likely be located directly under Townsend Street to allow for easier interchange and it would also reduce the tunnel curve.

Directly under Townsend St is a gigantic sewer, and if they aren't moving the sewer to save the apartments for Metrolink, then they're not going to be able to move it for DU.

Pete_Cavan

CatInABox wrote: »

Directly under Townsend St is a gigantic sewer, and if they aren't moving the sewer to save the apartments for Metrolink, then they're not going to be able to move it for DU.

Does it run the length of Townsend Street or across it?

CatInABox

Pete_Cavan wrote: »

Does it run the length of Townsend Street or across it?

I have to admit, I can't remember. All I can remember is that it's what stopped them moving the station further south, onto/across Townsend St, which would have saved the apartments.

A quick Google tells me that GMC repaired/upgraded 100m of sewer on Townsend St, so most likely along it.

EDIT: A slightly more in-depth search has revealed that there are two sewers traveling West to East along Townsend Street, a 1.2 metre tunnel, and a 2.4 metre sewer trunk. I'd hazard a guess that it's the second one that is the problem, it seems to be the main pipe for most of the city, bringing everything to Ringsend.

bk

CatInABox wrote: »

As an aside, I think that they might reduce complexity by only making the stations long enough for four carriages, and just doubling the frequency. That'd make construction a hell of a lot easier.

I've been thinking exactly the same. It will make building station boxes much easier and cheaper.

8 carriage DART's is a bit of an anomaly due to it being the only way to increase capacity with the constraints of the line. Had the option been available, I've no doubt they would have preferred to stick with 4 carriages, but higher frequency.

BTW as to the question of where to put a station near Tara, well the obvious answer is either in the river or on the quays. Sounds a little crazy, but there are examples of Metro stations being built in rivers. Though given the width of the quays, that might be doable to for a station box.

The downside being that it would make for a very tight curve with Docklands.

Really in the end I'd say Tara versus Stephens Green will come down to if the curve is too tight or not. I can also see the advantage of SG being a relatively cheap and easy station box in comparison.

donvito99

bk wrote: »

I've been thinking exactly the same. It will make building station boxes much easier and cheaper.

8 carriage DART's is a bit of an anomaly due to it being the only way to increase capacity with the constraints of the line. Had the option been available, I've no doubt they would have preferred to stick with 4 carriages, but higher frequency.

BTW as to the question of where to put a station near Tara, well the obvious answer is either in the river or on the quays. Sounds a little crazy, but there are examples of Metro stations being built in rivers. Though given the width of the quays, that might be doable to for a station box.

The downside being that it would make for a very tight curve with Docklands.

Really in the end I'd say Tara versus Stephens Green will come down to if the curve is too tight or not. I can also see the advantage of SG being a relatively cheap and easy station box in comparison.

What are the limitations at Connolly preventing a station box? This would provide an interchange between both Dart lines and all the Connolly terminating services. The tunnel could then continue via O'CS (red and green lines, station box could be at the derelict block at the back of Irish life) and towards Heuston on a less meandering route whilst still making the key interchanges. The OPW site at Smithfield could also be used, which would tie in with the red line again as well as trunk bus routes from Finglas/Ballymun spines towards Christchurch and the South city.

cgcsb

donvito99 wrote: »

What are the limitations at Connolly preventing a station box? This would provide an interchange between both Dart lines and all the Connolly terminating services. The tunnel could then continue via O'CS (red and green lines, station box could be at the derelict block at the back of Irish life) and towards Heuston on a less meandering route whilst still making the key interchanges. The OPW site at Smithfield could also be used, which would tie in with the red line again as well as trunk bus routes from Finglas/Ballymun spines towards Christchurch and the South city.

The 'Savings' from DU by making it a shorter route could be accomplished if it went: Heuston-Smithfield(OPW site with a high rise resi scheme on top)-The Site of Cleary's Car park(metro and luas interchange and then the site of the Petrol station on Amien St.
I'd expect the droolers of the Indo comments section to parrot about how 'the luas already goes that way Joe'. This route would be about 2km shorter and it also demolishes a petrol station and a multi storey car park, 2 big wins for sustainability.

Zebra3

Funny that you should mention that petrol station on Amiens St......

I got off the Maynooth train in Connolly on Sunday and my connecting northbound DART was delayed so went out and got the bus instead.

The street is a shambles and badly needs to be redeveloped.

Apart from the petrol station, on the same side there is a mix of just two to four storey buildings. And a vacant site.

While standing waiting for the bus I could see the train that I had got off was nearly as far back as the bridge (Newcommen?) that's beside the Five Lamps. An entrance to Connolly at that end (which would be standard in forward thinking countries) would open up a much wider catchment area to the station.

A cheap win, surely?

Pete_Cavan

In all this talk of a shorter tunnel going underground at Connolly, where is there space to build the tunnel portal? It would have to be at Fairview, both for the space and to avoid the conflicts with the Maynooth line which cause most of the congestion. In reality the tunnel is not shorter at all. The key goal is to utilise Docklands Station to ease pressure on Connolly - GCD and it serves a rapidly growing part of the city.

L1011

Amiens Street petrol station is closing for a hotel development imminently.

cgcsb

Pete_Cavan wrote: »

In all this talk of a shorter tunnel going underground at Connolly, where is there space to build the tunnel portal? It would have to be at Fairview, both for the space and to avoid the conflicts with the Maynooth line which cause most of the congestion. In reality the tunnel is not shorter at all. The key goal is to utilise Docklands Station to ease pressure on Connolly - GCD and it serves a rapidly growing part of the city.

The station could be at the petrol station and the tunnel portal at the bakers yard

donvito99

Pete_Cavan wrote: »

In all this talk of a shorter tunnel going underground at Connolly, where is there space to build the tunnel portal? It would have to be at Fairview, both for the space and to avoid the conflicts with the Maynooth line which cause most of the congestion. In reality the tunnel is not shorter at all. The key goal is to utilise Docklands Station to ease pressure on Connolly - GCD and it serves a rapidly growing part of the city.

But the tunnel is what relieves Connolly. There is a great deal of room at the East of the station and the line north towards North Wall to allow two tracks for the loop line/platforms and two tracks to descend gradually into a portal/underground station at approximately the site/yards east of Connolly's shed.

Pete_Cavan

cgcsb wrote: »

The station could be at the petrol station and the tunnel portal at the bakers yard

Is that empty site beside Ossory Road? If so, there is not enough space for a tunnel portal there. The track is elevated and has to get sufficiently deep to pass under the rail line at the other end, nowhere near enough length to do that at an acceptable gradient. Even if it did work, the tunnel would not be any shorter than a tunnel from Docklands via Tara Street.

donvito99 wrote: »

But the tunnel is what relieves Connolly. There is a great deal of room at the East of the station and the line north towards North Wall to allow two tracks for the loop line/platforms and two tracks to descend gradually into a portal/underground station at approximately the site/yards east of Connolly's shed.

Nope, if northern line DARTs still mix with Maynooth line trains, congestion remains. Sending trains to Docklands and avoiding the conflicts north of Connolly solves a lot of problems, the problem with that is there is nowhere to go after Docklands, the tunnel then solves that and makes Docklands infinitely more useful.

donvito99

Pete_Cavan wrote: »

Nope, if northern line DARTs still mix with Maynooth line trains, congestion remains. Sending trains to Docklands and avoiding the conflicts north of Connolly solves a lot of problems, the problem with that is there is nowhere to go after Docklands, the tunnel then solves that and makes Docklands infinitely more useful

There is plenty of space already to allow Maynooth and Malahide trains to be segregated on the approach to Connolly. The only issue is through running, as solved by a tunnel. Docklands can be infinitely useful for sure, but it is still isolated in the Docklands.

Additionally, whilst the maximum gradient is presently 1 in 60 on the I.E network, I believe something in the region of 1 in 20 is in place on the Sydney metro (what Dart could be) making a dive beneath Connolly from Ossory Road much more feasibly.

ncounties

Would the plan via Docklands still see a station on the North Wall Quay, in the building facing Cill Airne Bar?

If not, I would think a station there with an alignment slightly east of that to the Docklands station (and closing the Docklands station) to be a more useful piece of infrastructure.

If it was developed along with a bridge across the Liffey, it would provide additional capacity into the Spencer Dock/Grand Canal Dock Area, provide better interconnection with the Luas, and free up the land currently occupied by Docklands station for development.

Pete_Cavan

donvito99 wrote: »

There is plenty of space already to allow Maynooth and Malahide trains to be segregated on the approach to Connolly. The only issue is through running, as solved by a tunnel. Docklands can be infinitely useful for sure, but it is still isolated in the Docklands.

Additionally, whilst the maximum gradient is presently 1 in 60 on the I.E network, I believe something in the region of 1 in 20 is in place on the Sydney metro (what Dart could be) making a dive beneath Connolly from Ossory Road much more feasibly.

Even at a gradient of 1:20 (which is in no way relevant to DART but anyway) there still isn't enough space. The line is already a couple of metres above ground, you need to get sufficiently deep to pass under the rail line at the other end, a change in level of almost 10m. Look how far it takes the Docklands branch beside this to get to ground level after it passes over Ossory Road, a tunnel track level needs to be several metres deeper. Even if the tunnel starts there, the tunnel length is the same as from new Docklands station via Tara Street.

D.L.R.

cgcsb wrote: »

The 'Savings' from DU by making it a shorter route could be accomplished if it went: Heuston-Smithfield(OPW site with a high rise resi scheme on top)-The Site of Cleary's Car park(metro and luas interchange and then the site of the Petrol station on Amien St.

Well done, you've just missed all the main employment areas of the city centre. But why stop there, let's make it single track with no stations. Even cheaper-er.

:rolleyes:

cgcsb

D.L.R. wrote: »

Well done, you've just missed all the main employment areas of the city centre. But why stop there, let's make it single track with no stations. Even cheaper-er.

:rolleyes:

I would prefer the original DART underground, but this would be a penny pinched version.

The main objectives are to relive the connolly/loopline bottle neck and provide through running and good interconnection with other lines

D.L.R.

cgcsb wrote: »

I would prefer the original DART underground, but this would be a penny pinched version.

The main objectives are to relive the connolly/loopline bottle neck and provide through running and good interconnection with other lines

You don't relieve the Connolly/Loopline bottleneck if you fail to provide a second route across the river into the south city.

Last Stop

Would an alignment via Grand Canal work better than Pearse?
I think the city is migrating towards that area anyway and given it already has the third platform it seems a better choice.
The decision to go ahead with this is ultimately going to be driven by cost, the potential to build the station cut and cover by draining a section of the canal is also a key benefit.
Looking at the map, and I know it already had planning but the turn from SSG to Pearse looks tight especially considering it is likely to be single bore following metros example.

Pete_Cavan

Whenever we hear of a new DU proposal, I don't think there will be a SSG station. Routing the tunnel via Tara Street reduces the length of tunnel and lessens the number of underground stations by one. That is big cost savings for no lost of connectivity (arguably better connectivity by having one main interchange station).

Despite the sewer, under Townsend Street may still be an option for a station box, particularly if it is an old combined sewer which would need separating at some point. Alternatively there are empty buildings between the fire station and Shaw Street and going under Shaw Street to the buildings on the other side gives at least 110m which should be sufficient for a 4 car DART station.

From the Kildare line electrification tender, it is almost certain that DU tunnel will come above ground at Heuston. This significantly shortened tunnel, one less underground station, shorter stations for 4 cars and all the ancillary electrifications done and rolling stock on order, DU will have to be persued as the benefits will far, far outweigh the cost.

D.L.R.

4 tracking being planned into Heuston a sure sign they want to put the DU portal there, and not Inchicore. Easy win imo, no need for a tunnel to Inchicore if you just modify the Heuston throat. May require some bridge demolition and traffic disruption, but worth it.

Combine that with a new mainline station at Spencer Dock and you're well on the way to making DU inevitable. Spencer Dock should be designed as a major interchange station from the start imo, with the ability to handle high volumes and heavy transfer flows. The original DU plan completely ignored the interchange potential here. The better Spencer Dock is handled, the more it can take the strain off Connolly.

I would personally have the station on elevated tracks, allowing for long platforms across Mayor St, with a large concourse at ground level incorporating the original station building, and DU of course below. Or you could do the whole thing underground. Pedestrian bridge across the river the cherry on top.

BonnieSituation

The whole point of Inchicore as the portal was because it avoided disruption.

Where is the portal going at Heuston?

D.L.R.

BonnieSituation wrote: »

The whole point of Inchicore as the portal was because it avoided disruption.

Where is the portal going at Heuston?

Don't think that's been decided yet. But looking at the site the north side seems the most likely choice.

Re disruption, we're going to have to get over that as a country. Large infrastructure requires disruption. These things can be managed.

If nothing else its an opportunity to improve Chapelizod bypass/South circular junction, which is a travesty.

cgcsb

BonnieSituation wrote: »

The whole point of Inchicore as the portal was because it avoided disruption.

Where is the portal going at Heuston?

https://www.google.ie/maps/@53.3467079,-6.2994937,200m/data=!3m1!1e3

There is a gigantic car park there. Engineeringwise the the SSR junction is the most challenging part. There'll be long term disruption here for the 4 tracking project.

D.L.R.

cgcsb wrote: »

https://www.google.ie/maps/@53.3467079,-6.2994937,200m/data=!3m1!1e3

There is a gigantic car park there. Engineeringwise the the SSR junction is the most challenging part. There'll be long term disruption here for the 4 tracking project.

The pinch point is really just the railway tunnel underneath SCR itself, which is only about 30m long. This needn't take long with the necessary resources. The other bridge on the east side of the junction is already wide enough for 6 tracks.

Last Stop

Pete_Cavan wrote: »

Whenever we hear of a new DU proposal, I don't think there will be a SSG station. Routing the tunnel via Tara Street reduces the length of tunnel and lessens the number of underground stations by one. That is big cost savings for no lost of connectivity (arguably better connectivity by having one main interchange station).

Despite the sewer, under Townsend Street may still be an option for a station box, particularly if it is an old combined sewer which would need separating at some point. Alternatively there are empty buildings between the fire station and Shaw Street and going under Shaw Street to the buildings on the other side gives at least 110m which should be sufficient for a 4 car DART station.

From the Kildare line electrification tender, it is almost certain that DU tunnel will come above ground at Heuston. This significantly shortened tunnel, one less underground station, shorter stations for 4 cars and all the ancillary electrifications done and rolling stock on order, DU will have to be persued as the benefits will far, far outweigh the cost.

Tara st is unlikely to have the capacity to handle such a major interchange. It’s quite confined with no room for expansion.
The point of St Stephens Green was to link up with both Luas and metro which increasing the cost benefit ratio so i doubt it will be dropped even if it increases the costs. Plus the fact it’s a stones throw from the Dail.
Cutting the length of stations to 4 cars would also be extremely short sighted. Remember that the long term plan is to run intercity services through the tunnel to the airport or Cork-Belfast so I reckon they’ll stick to 8 car.
I can see a lot of lessons being learned from Metrolink and in all likelihood it will be a single bore from Docklands to Heuston. This would mean only 1 TBM is required and 1 launch site at Docklands so it can go practically anywhere within Heuston. I’d can also see them eyeing up all stations being cut and cover (Heuston, SSG and Docklands being the easy ones) with a relocated one along Cook St in Christchurch a viable option. This leaves the one at Pearse and I just can’t see it happening there which is why I think it will move to GCD with the canal being drained during construction.

donvito99

Last Stop wrote: »

Remember that the long term plan is to run intercity services through the tunnel to the airport or Cork-Belfast so I reckon they’ll stick to 8 car.

This is not the plan at all