[article] RPA defends capacity of proposed metro trams
This article from the Irish Times was posted at here a couple of days ago:
Quote:
Quote:
|
The issue here is not length of trams and stations or frequency but rather the actual width of the units which in order to keep costs down and to provide interoperability with the Luas is set at 2.4m. Most metro units are 2.65 or 3m wide.
Something will have to give. |
Figures which I've seen suggest a 22.5-25k capacity
Originally it was 18k Question: Will it be busier inbound or outbound in the Morning Rush? |
What is the actually story regarding tunnel widths, forgetting about the station platforms at the moment, can the tunnels cater for wider trams?
Surely in this day and age it is possible to have platform edges which automatically extend to meet the tram? In New York when the two subway systems were combined, automatic ramps were installed so that trains from the narrower system could use stations from the wider system. Some stations still have them. |
Quote:
|
Quote:
|
It's interesting you should mention the overhead wire. That reminds me how proper metro systems normally use third rail, not overhead - for the very reason that it allows smaller diameter tunnels to be bored, reducing costs. Of course, with a third rail, at-grade intersections are impossible. I wonder if the RPA ever weighed the higher cost of proper segregation against the reduced costs of tunelling at a lower diameter. It might just turn out that a real metro is even cheaper to build.
|
I can just imagine it if they had opted for third rail, another railway system being built in Dublin that is not compatible with those existing. Papers would have had a field day.
|
I remember reading somewhere (I half-recall it was a discussion of the Tyne and Wear Metro in an engineering journal, but I could be mistaken) that there was no tunnel-diameter advantage for third rail if you had to provide an emergency walkway anyway.
|
Quote:
Quote:
Quote:
Quote:
|
Quote:
|
Conductor rail systems are not recommended by the RSC
|
Heavy or light rail makes no difference as long as it runs on time and carries enough people. For anyone who thinks light rail can't do Metro, book a cheap flight over to London and have a look at the Docklands Light Railway. While it's quite different to the system proposed for Dublin, it does show that a light rail system running at high frequency can provide a lot of capacity.
|
Right, is there anyone out there who can give an accurate (say with a 2500 people pd/ph margin for error either side) what the demand for this service should be
i) when it opens in 2013 (hopefully)? will 20,000 people pd/ph use this line the first week it opens? if not? how many will? also, in the longer term. is there authoritative evidence as to what the demand would be ii) circa 2025? iii) circa 2050? In my opinion, International comparisons are pretty useless when it comes to this. The build capacity ought to be dictated by one thing and one thing alone, the current and future demand on this route!!.... If only someone could accuratley pinpoint this! |
Firstly the capacity is closer to 22,500, a good 3 times beyond the Green line Luas
Demand is split three ways City, DCU, Airport So in fact the system will carry well more than 20k an hour since it will be heavily used in both directions Rough guess is year one peak flow would be 12k, they are only quoting 30 million passengers at start RPA are working on 2 minute intervals, they could go to 90 seconds and then be hitting 30k per direction capacity Remember when this started 4k was year one capacity with a limit of 18k on capacity, now at 22.5k with potential to get 30k easily |
Quote:
|
Is the Paris metro not a real subway or metro system? Does it use third rail? Not that I'm aware of anyway!!
|
Absolutely, Paris is a proper heavy rail metro using third rail for its power on all its lines, whether using steel wheels or rubber tires, human drivers or driverless.
|
I'm not sure how Madrid is suddenly comparable to Dublin as a city?!
The Madrid metropolitan area contains 4 858 000 people and Berlin's got >3.7 million! Munich, Frankfurt, Leeds, Lyon, Porto, Copenhagen, Stockholm, Saville, Glasgow and Marseilles are more comparable to Dublin http://en.wikipedia.org/wiki/Largest...European_Union On the capacity issue, installing something grossly below capacity would be completely nuts, but at least it would be in line with normal Irish planning policy which has been used for everything else .. M50... ? Also, whether it's 3rd rail or overhead wires really makes no difference. Plenty of other modern metros use overhead power, including many of the major Spanish cities' systems. There's basically a bus bar at the top of the tunnel, it doesn't take up very much space. When the train's in the tunnel, the pantograph (contactor on top) is folded almost completely down and just scrapes along the ceiling. When it's above ground, the system's more like the DART or Luas. It's safer, and really not a huge issue to implement. 3rd rail's generally only implemented in extensions to old systems and has a lot of safety and maintanance disadvantages. They don't comply with modern (post 1950s) electrical safety legislation but are "grandfathered" in countries that had significant 3rd rail infrastructure since the turn of the 20th century as it was simply too complicated and too costly to replace. I don't really see 3rd rail or overhead power being much of an issue, the issue is the capacity of the trains and the future-proofing of the tunnel(s) |
Looking at these numbers and the claims that it has a capacity 3 times that of the current luas green line, i can easily see that this sevice fulfills "current" needs.
However current needs are meaningless! The true goal of a proper future transport system would be to cater for all commuter corridors with large capacity high frequency services. Not only that but it will have to be GREEN! ITs an electric system, it has to get power from somewhere, where is it going to come from, the national grid? With population growth and a proposed electrification of several Dublin lines, there will be a huge demand on power, wheres it going to come from:confused: The Metro should be built to this plan, as it seems efficiant for the time being, but to respect are children and grand children the tunnels should be wide and the platforms adjustable so that with minor work to a segregatted line we can make the metro a real underground service.:rolleyes: Also, if we all want to stop global warming etc etc, trains, trams and buses and anything else should be the governments only priority. Its not like hydrogen fuel cells or sollar cars are viable in the very near future.:rolleyes: |
Low-capacity design favoured for Metro North
Quote:
|
Quote:
|
This is *MY* tax they're spending. I would like to see a full justification of this decision published a.s.a.p.
It seems completely short sighted. Are they just fixated on Luas trams or is there some logic to this?! |
Its partly costs and partly the ability of the metro concept to be interoperable with the Luas.
In my opinion I believe the Red line and Lucan line and possible Rathfarnham - Liffey Junction lines (ie on street) should be 2.4 and tramlike while all other lines should be at least 2.65 if not 2.8m in width. Length or frequency are not the issues here - its width. |
I actually think there are no Technical reason whatsoever for the RPA's blind push for Trams.
The RPA will never recommend Heavy Rail, as this skirts far too close the IE's "expertise". Bottom line on what should be done: - Sort out the union issues within IE (Probably an imposable task at this stage) - Combine the RPA and IE into a single body. - Start making proper engineering based decisions (ie Heavy Rail on Major Corridors and Luas Trams as short interconnectors) Unfortunately it's far too late for all of this. The easy decision was made years ago when the RPA was formed. |
The RPA will never recommend heavy rail on their corridors simply cos its too expensive and not needed.
I think the RPA felt they could not have developed another transport mode that would not integrate with either the DART or the Luas. Unfortunately it'll be to our detriment when they realise that 2.4m is just too narrow for a metro. Originally they were going to get around this issue by curving the rolling stock body outwards but no supplier was interested in this concept. Siemens seems to be the biggest name argueing that 2.4m is too small. For comparison Porto is 2.65 and Madrid is 2.8. |
End of the day the simplest solution here is to allow the 4 tendering consortia to simply put their best proposal on the table
So consortia 1 might charge y but offer wider carriages with more capacity, other consortia might stay narrow and charge z, x and v respectively What if y was the lowest cost overall? What if they will charge 10% more but promise a 6 month quicker job? This isn't lowest cost tendering this the most economically beneficial or something similar. Sadly the passenger impact isn't considered, obviously its easy make money when the trains are stuffed to the roof, having a significant % of spare capacity doesn't go down well with bean counters, but goes down well with us since you will always fill it And no the answer isn't 42 Can we take the tech spec stuff to the technical forum folks |
The best was to do alternatives in tendering is to get everyone to tender for both options, with one being a preferred option.
|
Said it before, saying it again. Leave Green Line as is except expanded to 50m trams, keep the TBM heading south from SSG into Terenure/Templeogue and down to Tallaght. No worries about compatibility, no shutdown of the Green Line to connect it to Metro North, no waste of money on Line BX.
Dig out the tunnel and rough in the stations and then add stations progressively south as funds permit. Yes, it will cost squillions but it adds a quantum increase in capacity in an area of the city choked by buses, and gives an alternative to Green Line in terms of catchment management in the inner City. It is a reverse of the usual method of Irish transit planning - accept a minority level of transit usage and build capacity behind what little demand there is. |
Ya agree the tendering groups should put their best proposal forward for the metro and then choose the best option.
They should continue tunnelling onwards towards rathmines/rathgar or terenure, should'nt just stop in st stephens green. |
Meant to post this yesterday but am up to my eyes in work...
From the Irish Times (article was actually about Luas... but anyway) Quote:
|
Im still of the opinion that they are leaving themselves open to capacity issues by using the narrow 2.4 width. Far too narrow.
A lot can happen in 5 years. The same was said about the Luas capacity - that it was more than enough. Its the governments plan to bring in congestion charging like London. Have they taken that into account? |
Have the specifications been made public?
"While he acknowledged the tunnel could not be expanded when built, he reminded the members of the committee that Metro west was also being developed and passengers could divert to that, along with all the new Luas lines." - not much use for DCU-Trinity. |
Quote:
There's always the option to run parallel surface routes beside the Metro North to help with demand, especially since it is likely to take a lengthy commissioning period before maximum peak capacity can be safely operated. Many people may dislike going underground whether through phobias, security issues or mobility issues such as out of service escalators/elevators. Others might like to continue to use transit but retain cellphone service. Both the Yonge and Sheppard subway lines in Toronto have a parallel bus which also serves people who live in the midpoints between stations. That's the kind of coordination integrated transit authorities can bring. |
Quote:
But do you really want to hear "I'm on THE METRO!!" |
You're right Victor, and there has been talk about doing that here in Toronto too. I'd be happy with mobile transmitters on platforms to replace the public phones and to allow Blackberrys to check in for mail but not in the tunnels. Sometimes it can be annoying with some eejit on the streetcar telling the world and his/her mother the details of their life.
|
I think mobile coverage in the tunnels is unavoidable. It's about to be allowed on planes even and people will demand it be available *everywhere*.
Whether that's a good thing or not is a separate question entirely, but I expect people will be noisy about it until it happens. |
Quote:
|
Quote:
I've always thought that a great idea for a sitcom would be to just put a camera on the Luas or DART and just listen to snippets of people's telephone conversations. Can be comedy gold! |
:( IT looks like we just have to wait for the rpa to go for the company dumb enough not to argue that we need bigger trains and bigger tunnels and will do it half arsed and cheaply.
Or we could get some genious's in with a mix of german and japanese know-how with endless coffers like the middle east and make a perfect system, if only:rolleyes: |
All times are GMT. The time now is 00:53. |
Powered by vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.