Dublin Airport Metro to have unconnected terminus?
- This topic has 259 replies, 61 voices, and was last updated 17 years, 8 months ago by
.
- Posts
Frank this is a very good point;
when the extension is eventually commenced in say 2018 this will be the point where the spoil from the bore machine must be removed. The thoughts of 100 plus trucks a day and a massive construction compound at this point do not appeal and would attract massive construction disturnbance compensation to adjoining business as well as rendering Luas inefective. It is my belief that the tunnel should be bored beyond the canal on the Terenure/Tallaght line as far as Cathal Brugha barracks to a point that would be both large enough to accomodate a large compound as well as not being subject to a HGV ban as well as already being in government ownership
@Frank Taylor wrote:
It seems a shame to drive a TBM into the city centre and leave it there
It’s a shame to us a tbm at all. Why not make maximum use of wide long street and simply cut and cover ? gardiner street and the north circular road eventually lead to the old broadstone line why not use this allignment?
Does anyone have any ideas as to where a potential southside Metro should serve. My personal preference would be for it to connect from St Stephen’s Green, via Cathal Brugha Barracks, under Harolds Cross Rd and then continuing either :
South to Terenure, Rathfarnham terminating in Ballyboden
or:
Southwest to Kimmage, Templeogue, Firhouse then swinging west and possibly completing a loop with the existing Luas at Tallaght.What would then be ideal would be some form of East/West luas, Metro or even high quality bus route service from Blackrock to say Crumlin/Drimnagh via UCD Clonskeagh and Terenure which would link stops on the Dart, Luas and Metro lines thus providing a proper integrated public transport system for the southside…
I can dream can’t I! :rolleyes:
I’ve just found a Dail transport committee debate where the RPA boss is asked why they are stopping the metro in the city centre. The answer seems to be that they plan to try to turn on the machine again years later when they have approval for a new line going somewhere like Kimmage. I reckon they’ll have to call in a conservationist and a technological archaeologist to get it working again. @joint transport committee wrote:
Frank Allen: It is reasonable to state that the continuation of the tunnel-boring machine for another two kilometres is not a major increment, but it is more than this. Describing this as a metro line to Cherrywood would not be accurate and would not reflect the concept we have of the degree of segregation. The location of the gated stations would require a considerable amount of work south of Beechwood.
We would make a decision in consultation with the contractor on whether to leave the tunnel boring machine in the ground. Often the machines are left underground as this is a cheaper option than extracting them. We see this north-south metro line as part of a longer development including an orbital metro line that would connect at St. Stephen’s Green, as envisaged in A Platform for Change. At that stage, it would be appropriate to use the tunnel-boring machine for a line in the direction of Kimmage.
We have described the proposal put to Government and the rationale of doing it on that scale. We concluded the scale was manageable. I note the suggestion that it be extended but these are the proposals before Government.
Deputy Eamon Ryan: If one leaves a machine in the ground, and it makes sense to continue boring in five or ten years time, is it possible to turn the machine on again?
Mr. Allen: Yes.
http://debates.oireachtas.ie/DDebate.aspx?F=TRJ20051027.xml&Node=H2&Page=4
But as we all know where one turns it on one must extract the bored spoil and the idea of Stephens Green being the location for this is not appealing given that by selecting a different gauge for the rolling stock it would not be possible to back-haul the spoil via rail freight even if the metro is ever extended back to either the Northern or Maynooth lines
Are there not geological issues with boring south of the canal?
From memory, the rock type changes to igneous formations (Wicklow granites etc) – as far as I can remember, that was one of the reasons behind the original Luas/Metro design in the mid/late 1990s – tunnelling under the southside would be much more expensive and slow.
Then again, the Eastlink tunnel that keeps cropping up would have this problem along some of its alignment also. Whatever the case, it looks very much like the RPA (and Govt) have no intention of ever extending the Metro on the southside.
Another engineering question. Just how practical is it to suggest that the Interconnector can be built /after/ the Metro is operation? It would mean that, for a start, they’d have to bore under the working Stephens Green station, lay track works and build a station, all while Metro was working away. Unless of course the plan is to horizontally separate the two stations, which would mean a bloody great hole in Stephens Green from the period 2009-2015. Thats something to look forward to.
I very much doubt that there are large differences between Stephens Green and the City end of Rathmines/Harlods Cross, given that the line will someday be extended anyway is it not best to give such an extension a viable launch pit as opposed to the Centre of the retail district?
Just checked, there are some granite formations south of the river, but they’re not very substantial until you get as far south as Blackrock. Most of the city sits on a heavy glacial till, which is not particularly difficult to bore through.
There have been fairly extensive studies done on the geology for this purpose;
http://www.irishscientist.ie/2000/contents.asp?contentxml=046as.xml&contentxsl=insight3.xsl
Of course it would make sense to create the possibility of extending the metro in the future, thats how these systems are ‘grown’. Brussels is still developing its metro system ‘at the ends’, many years after the initial two lines were bored out in the 1960s. To do otherwise just creates a stranded asset. This idea of ‘restarting’ the existing TBM years later is clearly a red herring.
Why are the RPA not considering this? Who knows, at a guess its probably the results of an attempt to keep costs down so as to get D/Finance to sign off on it.
As can be seen from Tara – the only way to have any influence on decisions is to get your comments in early.So make sure to write full and complete emails to the rpa.
Indeed, all the discussion on this site and in forums such as Platform 11 and Boards.ie won’t matter a jot unless you engage directly with the RPA by submitting comments during their Consultation Process.
@a boyle wrote:
It’s a shame to us a tbm at all. Why not make maximum use of wide long street and simply cut and cover ? gardiner street and the north circular road eventually lead to the old broadstone line why not use this allignment?
Cut-and-cover is better because you’re closer to the street level but
-there is more disruption during build
-and you have to follow street alignments
-and what happens when you reach the Liffey? How do you cross a river with cut-and-cover? Is there an engineer here who knows this? The circle line in London is partly cut-and-cover but I’m guessing it has to tunnel under the Thames.The circle line doesn’t go under the Thames it is all on the City/West End side of the river but the point you make is very valid this line will need to go under the Liffey
@Frank Taylor wrote:
Cut-and-cover is better because you’re closer to the street level but
-there is more disruption during build
-and you have to follow street alignments
-and what happens when you reach the Liffey? How do you cross a river with cut-and-cover? Is there an engineer here who knows this? The circle line in London is partly cut-and-cover but I’m guessing it has to tunnel under the Thames.Yes you would have to tunnel under the river. Yes it means you have to follow road alignments , and so there are only a few configurations that would work.
I think either method will result in mayhem either way , there is no getting around tearing up the roads to install stops, or huge numbers of air vents.
What is good about cut and cover is this :
It is a lot , a lot quicker . Instead of building a tunnel and all the complexities that go with that, it’s more like building an underground car park. You just dig with a whole load of caterpillars till you can set foundations. the supports only have to hold the road surface up. This makes it a lot simpler. It finally makes it relatively easy to consider three/four tracking. ( new york did this , the result is incredible ease of movement )
Further to my previous remark , if a concensus could be found we could all write to the rpa with a joint point of view. It’s much easier for the rpa to dismiss comments if they are all different!
@a boyle wrote:
Further to my previous remark , if a concensus could be found we could all write to the rpa with a joint point of view. It’s much easier for the rpa to dismiss comments if they are all different!
You are right. Do you want to put together a one page comment on why the metro tunnel should be continued through the centre to the southside? Once we reach agreement on the wording, get as many as people to put there names to it and I’ll print it out and post it in.
Or join platform 11 who possess a very strong multi-disciplinary technical team and are currently looking to build with new blood.
@Frank Taylor wrote:
You are right. Do you want to put together a one page comment on why the metro tunnel should be continued through the centre to the southside? Once we reach agreement on the wording, get as many as people to put there names to it and I’ll print it out and post it in.
I would love to try!
Let me set out my views. Please don’t give a snap reply , i have put so thought into this.
First off Dublin is 3 times bigger than Brussels or Amsterdam ( which have the same population ).
Frank McDonald has categorically pointed out that no route anywhere in the country has the number of people using it to justify a metro. ( This means adding up walkers,cyclists,drivers,bussers,Dart users and intercity/suburban rail)
The only way to generate enough people to pay for a metro is to get people coming from lots of directions together and then flush them through!
These are CSO figures: 200k live in fingal. 500k live in the city. Allowing for a 50/50 split between north and south (in reality more people live on the south side of the city – the north side contains the second biggest park in the world ! )So anyway that gives max 450k living on the northside. a minimum of 700k live south of the liffey in dublin county.A metro can take anywhere from 50k per hour to 100k per hour. Thus we would need 5 luas lines to meet with the metro ( each luas does around 10k / hour ).
I CAN TELL THIS IS GOING WELL SO FAR !!!contrary to what i have just written might suggest , I do believe that a metro can be routed in such a way so that it can serve enough people.
The airport serves 20 million per year. ( that’s the same as the two luas lines — Oooh its not looking good for the metro! )
anyway enough with the joking!
Given that the metro can ONLY work in conjunction with everything else , i think it has to be considered WITH everything else.
Two points now arise.
Each addition to public transport should make sense by itself.
It hugely important to minize the numbers of changes required between modes of transport. Otherwise you don’t get the maximum amount of cross over between different routes.I feel that the following have most chance of success:
Continue the green line round the back of trinity so their is a connection with the dart. (this route is only marginally slower than using college green because of the number of pedestrian crossings the tram would have to go at walking pace)
reopen broadstone and reroute all trains coming from the direction of sligo into that station.
Continue the green luas line to broadstone.Instead of a north south metro build the interconnector between heuston and the new docklands station via pearse.
build a spur off the rail line to the airport.
This is a good plan because it does what almost all the different plans that have ever been suggested in one go!
1 A metro link to the city and a rail link to the entire rail network!
2 Moving the sligo line traffic to broadstone removes a lot of the time slot problems ( and immediately clears the way for the navan line to run at whatever frequency it likes. This is important : an iarnrod earrean report states the problems with the navan line being economically feasible is the the rail congestion in the city centre means it cannot run enough trains through. )4. The two dart lines can be reorganised as irish rail wants to.( i’m not trying to spell the irish version again ! ) Firstly the southside dart route can along the royal canal on the northside to connect with the sligo line.In fact it could in future be turned around to terminate at broadstone or head on to navan.
the northern dart route can pass through the interconnector and head out towards kildare.
7. the green line has a terminus that makes sense. ( a decision would have to be looked at whether to end the luas at broadstone or at the liffey junction ( it does not make a huge difference ). The basic idea is right!
What really pulls this whole thing together is that it puts in place a huge amount of flexibility.The “metro” link can now connect with ALL (YES ALL) Trains/trams ( and most buses) with a single change. furthermore anyone can change between the dart ( both routes ) and the green and red lines again with one change.
To try to explain my idea i will take the time to make a map and attempt to put it up .
It’s interesting that none of the proposed routes go under Westmoreland Street, College Green and Grafton Street but instead go along D’Olier or Tara Street and then under TCD. I wonder is this due to a problem with tunnelling directly under O’Connell Bridge?
@Seamus O’G wrote:
It’s interesting that none of the proposed routes go under Westmoreland Street, College Green and Grafton Street but instead go along D’Olier or Tara Street and then under TCD. I wonder is this due to a problem with tunnelling directly under O’Connell Bridge?
No when you are tunnelling ,you are well below anything that get in the way !
- You must be logged in to reply to this topic.
