[Irish Times - 29 Dec. 2009] Dart line to be split

Hungerford · 30-12-2009 7:08pm

Metrobest wrote: »

Is it not possible to have a tunnel portal to the Bray line somewhere near Pearse and have it run underground to a new hub under Connolly/Tara.

That would isolate Pearse from the rest of the system and would make it impossible to run diesel-powered services to Rosslare. The Dart underground tunnels are going to be for designed electric trains only.

Again, there could also be protests from cultural figures and historians as the Pearse - Dun Laoghaire stretch of the line was the world's first commuter railway, having opened in 1834.

Hungerford · 30-12-2009 7:11pm

Metrobest wrote: »

Fity years from now, the decision to build Dart Underground without rectifying the loop line bridge mistake will be rued by planners, architects and social workers.

Huh?

The loop line has been around for nearly 12 years and I don't recall any banlieues springing up around it.

dowlingm · 30-12-2009 7:16pm

Metrobest

You ask is it not possible to have a portal near Pearse. Whip out Bing Maps Birds Eye View and tell us where your portal would go, accounting for the elevation change and therefore the gradient between +1 over ground to Level -1 (I'll be generous and say the Interconnector will go under yours at -2)

You're proposing this, the onus is on you to show how it would work.

This would be a multi-billion euro replacement for infrastructure that already exists, albeit overground, with massive construction impacts given the dense urban form. The replacement would not permit through diesel haul services between the Sligo and Rosslare outer networks, would impede maintenance movements since there is no depot on the Rosslare line to service the 22Ks and 28Ks and would not permit any notional freight movements with existing rolling stock.

The Dublin rail system is not a network but rather a series of radial lines into termini now linked by jerryrigged solutions and surrounded by buildings built right up against the alignments. It is what it is, and it's distracting the discussion from the reality of the project going forward - which hopefully it will continue to do notwithstanding the disaster that is the public finances.

Blackjack · 30-12-2009 7:30pm

Cookie_Monster wrote: »

I personally find the bridge more impressive than the customs house from an engineering point of view.

Heathen!!;)

Carawaystick · 30-12-2009 11:41pm

Metrobest wrote: »

I agree. Instead of running a tunnel to Inchicore under Viking Dublin (bound to throw up delays), they could build build a vast underground hub somewhere in the vicinity of Tara/Connolly, and an underground termnius at the Green.

How does this get rail passengers who use the line into heuston to the city centre?
How does this get extra passengers into the city from Kildare, west Dublin, and further afield?

Judgement Day · 30-12-2009 11:51pm

Slight off topic but it seems to be the opinion of many posters on Boards.ie that inter-city rail travel is on its last legs so is there a need for the interconnector just to cater for Dublin commuters?

dowlingm · 30-12-2009 11:55pm

Judgement Day, I'm not sure how you got from one to the other there. After all, getting commuter traffic out of Heuston will certainly help platform availability for starters, which has held up many an intercity just short of destination.

Carawaystick · 31-12-2009 12:05am

Judgement Day wrote: »

Slight off topic but it seems to be the opinion of many posters on Boards.ie that inter-city rail travel is on its last legs so is there a need for the interconnector just to cater for Dublin commuters?

If commuters living in Carlow, Kildare, Laois, Offaly & west Dublin could get the train to dublin city centre instead of several km away, I'd imagine then there'd be a better service to market to potential customers, and potentially more of them on the train and less of them clogging up the streets by car. I'd imagine waiting for service times could (I wish I was confident to say would) be reduced gain increasing the attractiveness of rail.

L1011 · 31-12-2009 3:46am

Metrobest wrote: »

Is it not possible to have a tunnel portal to the Bray line somewhere near Pearse and have it run underground to a new hub under Connolly/Tara. Presumably, there is engineering scope here to do something, as CIE has slated an underground station to be built at Pearse. Why this station cannot connect to a Connolly underground hub and remove the loop line eyesore has not been explained.

There isnt the space to drop the line near Pearse, end of. Trains have a very limited maximum gradient and the existing line is *elevated*.

Metrobest wrote: »

Fity years from now, the decision to build Dart Underground without rectifying the loop line bridge mistake will be rued by planners, architects and social workers.

Architechts usually rue what people 5 years ago built, indeed what they built five years ago.

Social workers??

Cookie_Monster · 31-12-2009 9:51am

Metrobest wrote: »

Is it not possible to have a tunnel portal to the Bray line somewhere near Pearse and have it run underground to a new hub under Connolly/Tara. Presumably, there is engineering scope here to do something, as CIE has slated an underground station to be built at Pearse. Why this station cannot connect to a Connolly underground hub and remove the loop line eyesore has not been explained.

Overhead and surface railway lines are being removed in cities all over the world.

Melbourne buried its lines at Flinders Street station to build Federation Square.

Barcelona buried a costal line when it built the Olympics.

Paris... buried a railway line and built an elevated park in its place.

Fity years from now, the decision to build Dart Underground without rectifying the loop line bridge mistake will be rued by planners, architects and social workers.

Every one of your posts in this thread have been about getting rid of the line. Its a vital piece of infrastructure and a Dublin landmark and this will never change. It will still be there in 50 years regardless of other transport initiatives. Building a tunnel simply to replace a perfectly sound and capable bridge for no reason other than "it would look nice" is moronic and unjustifiable in every way.

Hungerford wrote: »

Huh?

The loop line has been around for nearly 12 years and I don't recall any banlieues springing up around it.

I may well be wrong but I imagine its a lot more than 12 years that line & bridge has been there :P

Blackjack wrote: »

Heathen!!;)

Engineer

Hungerford · 31-12-2009 2:16pm

Cookie_Monster wrote: »

I may well be wrong but I imagine its a lot more than 12 years that line & bridge has been there :P

Sorry - I forgot about the zero. It should of course be 120 years - the line opened in 1891.

strassenwolf · 01-01-2010 8:00am

Olivia Kelly of the Irish Times wrote:

Presenting the proposed lines to a recent meeting of Dublin city councillors, Dart underground project manager Peter Muldoon said the severing of the current Dart line would not affect journey times.

“If you are going from one side of the city to the other, you will have to change trains; just like every other major city. We hope to have one train every five or six minutes, so the time from leaving your house to arriving at work will not be adversely affected,” he added.

This is not very encouraging. IE now "hope" to have a train every five or six minutes - i.e. ten-twelve trains per hour (presumably in each direction).

This is quite some way off the capacity of the tunnel.

According to previous statements by IE, the tunnel will have a capacity of 20 trains per hour in each direction, but it seems they are now only "hoping" to use the tunnel to around half of the capacity which they think it has.

And, of course, ten to twelve trains per hour is in or around a third of the capacity which the tunnel could have, going on the capacities of similar tunnels in other cities, including the main cross-city tunnel in Munich (which carries a steady 30 trains per hour in each direction).

It would be nice to see any plan from IE as to how they ever propose to use the tunnel to anything like its capacity. Otherwise the 20 trains per hour fantasy will remain an attempt to pull the wool over people's eyes as to what will actually happen with this tunnel.

At the projected cost of 3 billion euro for the tunnel project and related works, there needs to be precision about what is being proposed and what is going to happen in reality.

Barname · 01-01-2010 10:55am

KC61 wrote: »

At the moment every train that operates to Maynooth uses a slot that could be used for a Northern line train from the loop line bridge. Every train from Maynooth blocks both Northern line directions.

At the moment every train that operates to the North uses a slot that could be used for a Maynooth train. Every train from the North blocks Maynooth trains

:P

paulm17781 · 01-01-2010 3:34pm

Barname wrote: »

At the moment every train that operates to the North uses a slot that could be used for a Maynooth train. Every train from the North blocks Maynooth trains

:P

And that's what this plan will fix.

bush Baby · 01-01-2010 3:55pm

Don't forget about the 12% budget cut proposed in the budget?

http://www.insideireland.ie/index.cfm/section/news/ext/publictransport001/category/1111

That project will never happen - sadly

GerardKeating · 01-01-2010 11:24pm

strassenwolf wrote: »

This is not very encouraging. IE now "hope" to have a train every five or six minutes - i.e. ten-twelve trains per hour (presumably in each direction).

This is quite some way off the capacity of the tunnel.

If the tunnel is running at or near full capacity in the first few years of operation, then they have seriously under spec'ed it. The Loop-Line bridge is 120 years old, i would expect the Inter-Connector to last at least as long and be able to meet the demands of the 22nd century.

It should not be used at or near full capacity for many years if they get it right...

mysterious · 01-01-2010 11:32pm

Instead of writing about what they are planning.

Why they don't get on building what they planned to begin with.

I'm sick of this balony.

strassenwolf · 02-01-2010 2:28am

GerardKeating wrote: »

If the tunnel is running at or near full capacity in the first few years of operation, then they have seriously under spec'ed it. The Loop-Line bridge is 120 years old, i would expect the Inter-Connector to last at least as long and be able to meet the demands of the 22nd century.

It should not be used at or near full capacity for many years if they get it right...

I think you might look at how some other cities of a similar size to Dublin approached it. Munich and, particularly, Frankfurt, would be cities which used their tunnels to capacity from pretty much day one.

In those cities, once the connecting tunnel was built, they were then able to rapidly expand overground services which could use the tunnel, without affecting throughput through the tunnel.

A quick look at the development of the rail transport systems of those cities would show you that it need not be a mistake to use the highest capacity, most expensive sections of the network to their peak capacity from day one.

There just needs to be a clear road map as to how this is to be done effectively.

strassenwolf · 02-01-2010 9:39am

Let me give you an illustration of what I mean.

[Hypothetical situation]

Day one: interconnector opens, with 20 trains per direction per hour (tpdph). 5 of these trains travel between Malahide/Howth and Hazelhatch, 3 travel between Malahide/Howth and Heuston, and the remaining 12 travel just between Heuston and Docklands. (the latter would probably, initially at least, be 2-4 carriage trains, but they would enable people to know that they can go to the station and only have to wait a maximum of three minutes to get onto a train going right across the city, quickly).

8 of them provide something similar to what is currently provided between Malahide/Howth and the city. 5 of them provide hitherto unimaginable services between Hazelhatch and the city.

And all 20 trains enable very rapid travel between the east and the west of the city.

Year 2: the long-awaited line to/from Clondalkin opens: still 20 trains tpdph. 5 of these trains travel between Malahide/Howth and Hazelhatch, 3 travel between Malahide/Howth and Clondalkin, 3 travel between Docklands and Clondalkin and the remaining 9 travel just between Heuston and Docklands.

And all 20 trains enable very rapid travel between the east and the west of the city.

Year 4: the much-desired extension of the Clondalkin branch opens, enabling a 20 minute connection between Tallaght and the city: still 20 trains tpdph through the tunnel. 5 of these trains travel between Malahide/Howth and Hazelhatch, 3 travel between Malahide/Howth and Tallaght, 3 travel between Docklands and Tallaght and the remaining 9 travel just between Heuston and Docklands.

And all 20 trains enable very rapid travel between the east and the west of the city.

Year 6: the eagerly anticipated line to/from Lucan (or along the West Dublin route originally proposed for the crazy metrowest) opens: still 20 trains tpdph. 5 of these trains travel between Malahide/Howth and Hazelhatch, 3 travel between Malahide/Howth and Tallaght, 3 travel between Docklands and Tallaght, 4 travel between Docklands and Lucan (or areas which were to be "served" by the crazy metrowest proposal) and the remaining 5 travel just between Heuston and Docklands.

And all 20 trains enable very rapid travel between the east and the west of the city.

No diminution of service has occurred to any area in the above plan. All of those trains make a serious contribution to linking the east and the west of the city, and an increasing number are gradually able to provide rapid connections into the city, out of the city, and across the city.

[/hypothetical situation]

All of this should be possible except that, while IE have spoken about 20 tpdph, they really don't intend more than about 10 max. And they've got the station layout plans at Docklands to prove it.

Hungerford · 02-01-2010 2:08pm

strassenwolf wrote: »

Let me give you an illustration of what I mean.

Erm... I don't think you fully grasp the value of train paths. Your suggestion only works if IE can increase train lengths to an infinite amount to meet increasing demand. Unless you are suggesting that demand will remain constant over the period involved.

But trains have maximum potential lengths, meaning that at some point, to increase capacity, you need to use more paths.

The only way you can do this is to have surplus paths that you can use and I would sincerely hope that IE would have lots of spare paths through the interconnector to meet future traffic growth.

All the problems with capacity on the Loop Line at the moment stem from a lack of available paths at peak times.

strassenwolf · 02-01-2010 4:27pm

Hungerford, I'm erm...having some difficulty understanding your post.

Would you care to point out specifically where I am incorrect.

strassenwolf · 02-01-2010 4:45pm

Actually, Hungerford, there's no need to reply.

I get it now. Cities like Frankfurt and Munich screwed up, right, running 24 trains and 30 trains per hour (in each direction) through their tunnels, serving considerably over 100 destinations in each case.

IE though, with their proposed 10/20 trains per direction per hour, whichever figure one is supposed to believe, have got it right.

Right?

noelfirl · 02-01-2010 5:30pm

There's no capacity for 20 tph from Hazelhatch to Howth/Malahide/Drogheda (short of tri/quadding the Northern Line, or taking all non-DARTs off it). All well and good that there would be capacity for 20tph from Hazelhatch/Heuston to Docklands and vice versa, but there's probably not going to be anywhere near enough demand for that sort of service for a decade at least.
Personally IMO, starting out with 10-12tph (a vast improvement over current 4-6tph) will be sufficient, and usage of the capacity can be bumped up over time if demand needs it, and other infrastructure is improved to allow it.

dowlingm · 03-01-2010 5:40pm

As a daily user of a system which tries to push >24tpdph (< 2m30s headway) on a fully segregated line (Toronto subway), I can tell you it's trickier than it looks. Dwell times and passenger flows at interchange stations such as Heuston, SSG and Pearse are going to have to be seriously examined right up to safety maximum passenger loads. The problems that humans introduce seem to trump most improvements in signalling and so on.

The design of the Toronto Bloor-Yonge interchange station is now being found seriously deficient for modern loads and because of the structures above it cannot be changed. For instance, all of the passengers coming from the lower line emerge at one end of the platform and are not distributed evenly along the 6-car train when it arrives. This leads to delays because of crushloading - people lean against the doors and the safety mechanisms prevent the train from moving off. This is exacerbated by delays on one line or the other which causes a surge load as soon as this delay is cleared. There are also issues with stair and escalator capacity.

They are now trying to deal with this by putting 10+ personnel (started with 30) on the platform during morning rush to direct people and to stop more people trying to get on once the carriage is full.

The critical issue is to find out what the number of passengers is that will make the tunnel pay its way not just financially but operationally. However, there will come a point where you're becoming over-reliant on that line - that's when investment in smart cards pays off because DTA (should) look at boardings data and design "interconnector relief lines" and other point-to-point services which DON'T go through An Lar, and do so based on demand and not crayons on maps which make sense for marginal seats on councils and in the Dail.

SeanW · 04-01-2010 8:27am

Ok, the weak link in the Malahide/Howth-Hazelhatch line will not be the Interconnector, but the Northern DART line, which will still be only twin-track despite hosting Enterprise, Northern Commuter and whatever DARTs come through the Interconnector. The Interconnector itself AFAIK, doesn't have an inherent upper limit of trains (it could always be resignalled with shorter blocks, if needed) that it can carry, but other trackage on the route would cause any bottleneck.

Oh and I doubt that (for example) Munich's 2.5 minute headways are by original design: the Stammstrecke (sp?) main underground tunnel that is the rough equivalent of our Interconnector was built in the 1970s to transport 250,000 passengers per day, it's now carrying 750,000, or so I read.

murphaph · 04-01-2010 10:34am

SeanW wrote: »

Oh and I doubt that (for example) Munich's 2.5 minute headways are by original design.

That is correct Sean. The Stammstrecke was extensively resignalled about 4 years ago, causing large scale disruption (full weekend closures and many evening closures) to the S Bahn in and around Munich. I reckon if the Interconnector is signalled for 20 tphpd from the off it will suffice forever as Dublin will likely never have as many lines feeding into it as Munich has feeding into their's, simply owing to the fact that Dublin is a coastal city and Munich isn't.

[Irish Times - 29 Dec. 2009] Dart line to be split

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