After BXD: The next big public transport project for Dublin?3

VonZan

Surely the obvious long term solution is to build an underground station at Stephens Green which would initially serve the MN line out to the airport but could be expanded upon to join up the Dart, Commuter Rail and potentially new sites to alleviate traffic flow into the city eg the m50

Stephen15

VonZan wrote: »

Surely the obvious long term solution is to build an underground station at Stephens Green which would initially serve the MN line out to the airport but could be expanded upon to join up the Dart, Commuter Rail and potentially new sites to alleviate traffic flow into the city eg the m50

What do you mean? Are you talking about DART Underground?

orangerhyme

I've an idea instead of the DART Underground. A 360 degree Metro under the canals.

Temporarily drain the Grand Canal and build an underground metro from Heuston to the South Docks using a much cheaper cut and cover engineering. Once completed the canal could be reinstated.
On the northside you could either do similar with the Royal Canal or use the existing railway line there which goes through the Phoenix Park tunnel.
Then tunnel/bridge under/over the liffey from Spencer dock to Grand canal dock.

You would have a 360 degree underground Metro connecting Heuston, Connolly, DART, LUAS and bus services.

The stations would be (going anti-clockwise) : Heuston, Rialto/St James ( connecting with Luas), Harolds Cross, Barge/Portobello (Luas green line connection), Baggott street bridge, Grand Canal Docks, Spencer Dock, Drumcondra/Croke Park, Phibsborough, Cabra/Navan rd - then back to Heuston. So 10 stations.

This could be completely separate from DART and Rail or it could be the same gauge and allow these services to use it.
If using the existing rail along the Royal Canal it wouldnt be difficult to integrate Rail and DART since its above ground.

It would be high frequency and speed due to being underground and not passing any junctions with roads.
Id have Dublin Bike stations at every Metro stop and a top class two way cycle lane on the surface which doesnt cross roads. Also the Metro stations are interconnecting with the main bus routes into the city.

If you look at the main employment and educational spots on its route, it would surely be profitable service : North and South docks, Mater hosp, St James hosp, Trinity, DIT, Griffith College, Trinity College, Camden st/harcourt st going out areas.
Also Croke Park and AVIVA, The point depot.

Then Id produce a simplified map of DART, Luas, rail, Metro and high frequency bus routes similar to this




I believe it would be much cheaper than DART underground since it requires very little tunneling. A top class two way cycle lane could be built on top too.
The Metro north could then just connect at Drumcondra or Phibsborough since the Luas green line is there, therefore making it much cheaper and quicker to build.

I think the major drawback ( other than the idea being a bit "out there") is maybe the Grand Canal is a protected/conserved etc and it simply cant be touched.
But I think it could be drained, dug under and then reinstated without much damage. The ecology would obviously suffer though.

Stephen15

orangerhyme wrote: »

I think the major drawback ( other than the idea being a bit "out there") is maybe the Grand Canal is a protected/conserved etc and it simply cant be touched.
But I think it could be drained, dug under and then reinstated without much damage. The ecology would obviously suffer though.

The big issue I would see is the potential for the Metro system getting flooded if there is going to be a canal above.

orangerhyme

Stephen15 wrote: »

The big issue I would see is the potential for the Metro system getting flooded if there is going to be a canal above.

I dont think its that hard to make it protected and well drained. Its common enough for Metros to go under rivers, lakes, the sea etc.

I think this could be done relatively quickly and cheaply, If the existing infrastructure on northern ring is used.

Tunneling is the most expensive part of building a metro.
The cost ratio of underground to surface rail is 6:1

MJohnston

I have nothing but intuition to back this up, but I suspect the costs of draining an entire canal then doing a cut and cover on the whole thing, would be substantially higher than simply doing some real tunnelling with a boring machine.

Colonel Claptrap

The benefit of tuneling underground is that you are not impeded by physical infrastructure. Your route can potentially go anywhere you want (within reason).

It seems counterintuitive to restrict yourself to a rigid route designed in the Victorian era to carry barges.

orangerhyme

MJohnston wrote: »

I have nothing but intuition to back this up, but I suspect the costs of draining an entire canal then doing a cut and cover on the whole thing, would be substantially higher than simply doing some real tunnelling with a boring machine.

It wouldnt be that difficult, just replace it with a big pipe from Rialto to Grand Canal Dock.
The pipe can run along the canal while the digging is being done.

Cut and cover is considered way cheaper than tunneling.

orangerhyme

Colonel Claptrap wrote: »

The benefit of tuneling underground is that you are not impeded by physical infrastructure. Your route can potentially go anywhere you want (within reason).

It seems counterintuitive to restrict yourself to a rigid route designed in the Victorian era to carry barges.

The main benefit is it could be done quick and cheaply and be very beneficial.
Tunneling is very expensive.

I agree about sticking to the canals is rigid but it seems to fit Dublins needs and particularly the big developments in the docks.

MJohnston

orangerhyme wrote: »

It wouldnt be that difficult, just replace it with a big pipe from Rialto to Grand Canal Dock.
The pipe can run along the canal while the digging is being done.

Cut and cover is considered way cheaper than tunneling.

Is it though? It's certainly cheaper for short sections, but the initial costs of proper tunneling become much less proportionally over a longer distance. In other words, once you have a tunneling machine in the ground, extra km of tunnel have a much lower extra cost, whereas with cut and cover the cost will be linear, and, I think much higher over a longer distance.

This is before we think about stations, and the actual mechanism of draining a long stretch of canal.

I also don't believe the canals are wide enough in all cases for this to be an easy job.

There's also the disruption cost - cut and cover is going to affect huge parts of the city, and hours of work might be restricted. Tunneling is much more invisible and doesn't really disrupt.

Proper tunneling would likely be way faster too, even disregarding any restrictions on construction hours.

MJohnston

My other objection to that idea would be that a radial route at the canals is too close to the city, it should be at the M50 if anywhere imo

VonZan

Stephen15 wrote: »

What do you mean? Are you talking about DART Underground?

Essentially the current metro North but build it with the goal of connecting all rail lines in Dublin eventually. All major and minor rail solutions to the transport problem in Dublin will have to be underground in the city centre so why not build the station at Stephens Green with the idea of being able to upgrade it to meet the population demands of the next decade.

Stephen15

VonZan wrote: »

Essentially the current metro North but build it with the goal of connecting all rail lines in Dublin eventually. All major and minor rail solutions to the transport problem in Dublin will have to be underground in the city centre so why not build the station at Stephens Green with the idea of being able to upgrade it to meet the population demands of the next decade.

Do you mean run DART and commuter trains into the Metro tunnels? That would not be possible as you would have to build them to Irish Gauge meaning more expensive rolling stock as it would have to be custom built.

You're better off with a separate Metro system built at standard gauge as this would mean passengers could change to the system from other modes of transport and it could tie in with the green line which is standard gauge. Also it's a more efficient use of the system as you'd just have one fixed line rather loads of Darts and Commuter going here there and everywhere.

bk

VonZan wrote: »

Essentially the current metro North but build it with the goal of connecting all rail lines in Dublin eventually. All major and minor rail solutions to the transport problem in Dublin will have to be underground in the city centre so why not build the station at Stephens Green with the idea of being able to upgrade it to meet the population demands of the next decade.

In addition to what Stephen15 says, it would also be much more costly, at least double the price. Undergound stations would need to be much larger and longer to be able to take much longer trains. They would also need to be twin bore tunnels for safety. All adds greatly to the cost.

Heavy rail like this is well suited to the biggest cities like New York or London. But Metros like in Barcelona are more suited to a city the size of Dublin.