[article] RPA defends capacity of proposed metro trams

[undo]

This article from the Irish Times was posted at here a couple of days ago:

Specifications for Dublin's Metro North to be released later this month are to concentrate on 90-metre trams as opposed to the higher capacity heavy rail carriages, the Railway Procurement Agency has confirmed. Tim O'Brien reports.

The confirmation comes amid mounting concern over capacity problems on the existing Luas lines as well as fears that Metro North could suffer similar peak-hour capacity problems within a decade of opening.

The Irish Times has learned the RPA was advised by some of the bidders for the Metro North contract that even if it opts for the narrower 2.4 metre tram system, it should build the tunnel wide enough to later convert to 2.8 metre carriages.

The RPA has also been told that comparable capital cities to Dublin, including Prague, Hamburg, Vienna, Berlin, Lisbon, Munich and Madrid all utilise the higher capacity, wider-bodied carriages in their undergrounds.

Munich, which was the subject of a Department of Transport visit in 2005, uses a "low capacity metro" at 2.8 metres wide, and is capable of carrying in excess of 30,000 people per hour in each direction , some 50 per cent more than the 20,000 capacity of the proposed Dublin underground. Dublin's Dart which can be up to 170 metres long has capacity for 36,000 people per hour per direction. The capacity issue comes as RPA planners face criticism over passengers being left on the platform during the morning rush because trams are full. A Dublin City Business Association spokesman, Tom Coffey, said "to be credible the underground has to have a capacity of about 35,000 people per hour in each direction.

"We can't have a metro which is going to reach capacity six years after it opens. There is no going back to widen a tunnel after it is built and this infrastructure should be designed to last 100 years, as it did in London and elsewhere," he maintained.

The issue also comes as a two-day conference on infrastructure heard details of a Dublin Institute of Technology Futures Academy report which predicted population on the island would rise to seven million people by 2020, with about 1.5 million extra people moving into the Dublin Belfast corridor.

A number of commentators including the head of the National Roads Authority Fred Barry said the population increase - similar in size to the existing population of Dublin - would require another large-scale increase in public transport. Mr Barry said the increase would result in demand for much more rail transport as part of "a successor to Transport 21, a Transport 22, if you like".

However, speaking at the conference the chief executive of the RPA, Frank Allen, said he was "absolutely confident" that the capacity of 20,000 people per hour in each direction was sufficient for Metro North.

He remarked that just "isolated parts" of the London and Paris metros were operating above that capacity and it would be very hard to find other examples in cities in Europe. He said he was "very, very confident" of the capacity of the 90-metre carriages operating at a two minute frequency during peak times.

Mr Allen said the population forecast in the Fingal County Development plan was more pertinent than the all-island forecast. Metro North was, he said, "fully integrated with population projections" and "Fingal is absolutely confident that the capacity is more than is required".

The Irish Times

The Independent also isn't too sure about metro light's capacity (link):

Metro 'too small' to cope with demand, says expert

Wednesday February 06 2008

A boss of world metro maker Siemens says the planned Metro from Dublin city centre to the capital's airport will be far too small to cope with projected demand.

Dr Werner Kruckow, chief executive of Siemens Ireland, said yesterday that the proposed Dublin Metro will only be able to handle 20,000 passengers an hour in each direction which is far "too small".

The transport chief said the development of a sustainable city like Dublin requires the fast implementation of a high capacity transportation network, similar to that in other European cities.

Munich in Germany had a metro with a capacity for 36,000 passengers per hour in each direction, yet the maximum it has ever carried was 30,000.

"Dublin is planning for a peak of 20,000 per hour in each direction. This is much too low," the Siemens chief said in Dublin yesterday.

The Metro plan also failed to take account of projected population increases, which is due to reach two million.

[Mark]

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.

[Mark Gleeson]

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?

[Brian Condron]

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.

[undo]

Originally Posted by Brian Condron

Surely in this day and age it is possible to have platform edges which automatically extend to meet the tram?

But that would require the RPA admitting that underground Luas won't cut it. And that they are currently not prepared to do.

[Mark]

Originally Posted by Brian Condron

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.

Given the height of the trams plus OH is 3.8 m plus and the tunnels are singel bore then the width of the trams wont be an issue. Its platforms and at grade and elevated structures which are the issue.

[undo]

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.

[Brian Condron]

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.

[Prof_Vanderjuice]

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.

[Colm Moore]

Originally Posted by Mark Gleeson

Question: Will it be busier inbound or outbound in the Morning Rush?

Given that the city centre and the Nass Road areas are the two prime destinations, why would it be busier outbound?

Originally Posted by Brian Condron

What is the actually story regarding tunnel widths, forgetting about the station platforms at the moment, can the tunnels cater for wider trams?

I imagine the difference in cost beteen the two tunnel sizes is relatively modest in terms of overall cost. If larger vehicles are used later, the smaller vehicles can be cascaded onto other lines

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.

I imagine it is better to operate with a single fleet. Designing the platform edges such that they can be changed over say a weekend closure in a "Big Bang" changeover would be desireable, although the familiarisation training of drivers on the new vehicles for the characteristics of that section of track might be an issue. Basic training of the drivers on the vehicles could be done somehwere else.

Originally Posted by undo

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.

Aren't new third rail systems banned on safety grounds?

[undo]

Originally Posted by Victor

Aren't new third rail systems banned on safety grounds?

By whom? The Irish government? Or on an EU level?

[Mark Gleeson]

Conductor rail systems are not recommended by the RSC

[James Shields]

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.

[ofjames]

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!

[Mark Gleeson]

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

[undo]

Originally Posted by Mark Gleeson

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

If the initial plans were so far off the real demand, how can we be sure the current estimates are anywhere near accurate? Wouldn't it be better to build the system so it can be expanded to >> 30k peak if the demand arises say 50 years from now?

[luasifer]

Is the Paris metro not a real subway or metro system? Does it use third rail? Not that I'm aware of anyway!!

[undo]

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.

[MrX]

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)

[Aphfaneire]

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

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.


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.