Purely technical - Dart/Metro

sliabh

There is a lot of heat being generated in the current Interconnector debate and a question occurred to me that I felt was better asked in a quieter thread

From a TECHNICAL point of view only what is the difference between Dublin's Dart system vs what is generally termed metro elsewhere (e.g. U-bahn in Germany)?

Is the rolling stock heavier/lighter, carraige clearences different, speeds/accelerations different?

For the moment we can leave out rail gauge as I know we use our own one, and I don't think service frequency is relevent either as that's largely dependent on your rail network and signaling (but I am open to correction).

BTW: I would like if this didn't become another interconnector vs. airport metro debate

Andrew Duffy

A Metro is a metropolitan transport service, usually made up of segregated railways and supplemented by trams and buses. Since when long distance railways were built they terminated on the edges of cities, most rail track in urban areas could be called Metro as it serves the greater city area as well as long distance travellers.

BrianD

What is a metro? Here's one definition:

An urban, electric, high-frequency mass-transit train system with its own independent right-of-way.

This is not a rule nor is there a metro standard - it is more of a loose descriptive term rather than a set of standards. It's really a matter of opinion. Some German cities use trams that run above and below ground, the Tube in London is a metro that runs above and below ground as does the metro in Prague. The train sets used by the DART are similar to those on other "metro" systems. Every system will have its own unique requirements and this will be reflected in the design of the trains e.g. Tube trains are low roofed and are powered from an electric rail. Some cities will include non-rail transport such as buses under the metro umbrella. Metro service levels are not solely driven by technical constraints such as signalling but also passenger demand.

The DART line for all purposes is a metro line as it meets the above definition. The guage issue is important to the Dublin situation and is a decision making criterion. A line incorporating the existing Green Line tram route would be a different guage to the rest of the rail network meaning that the line would have its own unique set of trains, maintenance facilities etc.

sliabh

Thanks for that info.

As a follow on question, I know the Luas trams are pretty much off the shelf (apart from the gack purple) but is it the same with the Dart units or are they custom built for Ireland? (gauge differences aside)

BrianD

Most trains are custom built for the operator though there may be a generic design that they start from. The guage here does influence train design. Don't know if the DART type train units are used anywhere else.

murphaph

sliabh wrote:

Thanks for that info.

As a follow on question, I know the Luas trams are pretty much off the shelf (apart from the gack purple) but is it the same with the Dart units or are they custom built for Ireland? (gauge differences aside)

Ok, there are 2 types of gauge. There is the well known distance between the rails or track gauge and there is the loading gauge. The loading gauge is all to do with clearances between the rolling stock and things like bridges and other rolling stock as trains round corners etc. The loading gauge for Europe is different than that for Britain, for example, even though they both use 4' 8.5" track gauge, so you see longer, narrower coaches in Europe. The loading gauge for Ireland is pretty unique. The DART units are all custom orders as are most rolling stock orders. Other factors such as the body electrics and in cab signalling systems are unique too.

chewy

the platform11 guy says the dart is a metro

Metrobest

BRIAN D ''Some cities will include non-rail transport such as buses under the metro umbrella.''

Which cities?

jlang

Metrobest wrote:

BRIAN D ''Some cities will include non-rail transport such as buses under the metro umbrella.'' Which cities?

The Silver Line of the T in Boston, for one. Do a search for "Bus Rapid Transit" and quite a few cities come up. Before LUAS was LUAS, I remember hearing consideration of it being a guided busway - a super-QBC if you like.

Capacity is obviously less than a train, so whether that passes the "Metro" definition depends which city you're in and who's promoting it. Valley Metro in Phoenix even has Metro in the title.

sliabh

chewy wrote:

the platform11 guy says the dart is a metro

--sigh-- this one didn't stay "purely technical" for long.

As far as I can see "Metro" is pretty much a brand. It's a label you can stick on any urban transport solution (even buses). There is little point having a theological discussion on it.

In the Dublin context through "Metro" is the label that is applied to the Swords/Airport to Stephen's green rail project.

Dart=Metro as an argument is about as relevent as renaming Motorway to Autobahn. It's just a label and doesn't change anything.

John R

sliabh wrote:

--sigh-- this one didn't stay "purely technical" for long.

As far as I can see "Metro" is pretty much a brand. It's a label you can stick on any urban transport solution (even buses). There is little point having a theological discussion on it.

In the Dublin context through "Metro" is the label that is applied to the Swords/Airport to Stephen's green rail project.

Dart=Metro as an argument is about as relevent as renaming Motorway to Autobahn. It's just a label and doesn't change anything.

How could it stay "purely technical" when it is essentially a thread about marketing terms.

DART, metro, u-bahn, s-bahn, underground, subway, Luas, arrow, etc. They are all tags to identify them to consumers. As far as technical details go they are meaningless.

None of them have any inherent standards or specifications implied.

There are as many different technical specifications as there are railway lines around the world.

The only obvious area where a "standard" could be implied is standard/heavy rail as opposed to light rail/trams. Even in that there is a certain blurring with trams getting larger and more like small trains than a traditional tram.

BrianD

Metrobest wrote:

BRIAN D ''Some cities will include non-rail transport such as buses under the metro umbrella.''

Which cities?

Washington, DC for example.

As some one else pointed out, Boston brands all modes of mass transit other the 'T' brand. New York is similar.

FX Meister

Some of the Metro lines in Budapest are run by buses with there own corridors no other traffic can enter. I think it's just temporary though

Metrobest wrote:

BRIAN D ''Some cities will include non-rail transport such as buses under the metro umbrella.''

Which cities?

gerire

sliabh wrote:

In the Dublin context through "Metro" is the label that is applied to the Swords/Airport to Stephen's green rail project.

I hope you are referring to a different Stephens Green that the one that has been ruined by the LUAS. I hate even trying to get onto the green its impossible

Andrew Duffy

I hope you are referring to a different Stephens Green that the one that has been ruined by the LUAS. I hate even trying to get onto the green its impossible

Yes, the same Stephen's Green. Here's a tip - don't drive a car in the city centre. Find another route if you intend passing through or get the bus or tram if you want to stop in the city.
People should worry about the complete lack of information on where the RPA intends to site the construction pit for their fancy tram. If they intend digging up Stephen's Green for it I'm camping in a tree with Swampy.

sliabh

Andrew Duffy wrote:

Yes, the same Stephen's Green. Here's a tip - don't drive a car in the city centre. Find another route if you intend passing through or get the bus or tram if you want to stop in the city.
People should worry about the complete lack of information on where the RPA intends to site the construction pit for their fancy tram. If they intend digging up Stephen's Green for it I'm camping in a tree with Swampy.

I think this is one of the reasons why it is also suggested that the metro line starts underground from Ranelagh. There you have Ranelagh gardens to dig up. But it is possible to remove everything (trees included) and put it back afterwards.

Does anyone know if there is a suitable site up by Broadstone for a large tunnelling hole to be dug at the north end of the proposed underground line?

FX Meister

Forget going with Swampy, he's sailing around the worls in his Daddy's yacht for the next year or so. Saw it on the late night news a few weeks ago.

Andrew Duffy wrote:

Yes, the same Stephen's Green. Here's a tip - don't drive a car in the city centre. Find another route if you intend passing through or get the bus or tram if you want to stop in the city.
People should worry about the complete lack of information on where the RPA intends to site the construction pit for their fancy tram. If they intend digging up Stephen's Green for it I'm camping in a tree with Swampy.

Metrobest

Just to get back to what is and isn't metro, I don't imagine people in Boston using the 'Silver Line' bus service say to their friends: ''I'm gonna take the METRO home today!''

In Amsterdam the GVB runs all public transport under the same umbrella: ferries, buses, trams and metos. But important distinctions are made so passengers are not midlead. Example: on a section of line that is shared between trams and metros, the metro service there is branded as 'Sneltram' (express tram).

Metro is a very distinct form of transport: and whatever way you want to 'brand' it, most people do not see the DART as a metro, and frankly, who'd blame them? The DART has no underground sections, it shares track with diseal, level crossings litter the line and the frequency leaves a lot to be desired.

sliabh

Metrobest wrote:

and whatever way you want to 'brand' it, most people do not see the DART as a metro, and frankly, who'd blame them? The DART has no underground sections, it shares track with diseal, level crossings litter the line and the frequency leaves a lot to be desired.

While I don't agree with the P11 idea of calling the Dart a Metro, in purely technical terms I thinks it meets the description.

Being overground isn't a problem (just think of the likes of Chicago's L which is largely elevated. The view overground is better anyway). Frequency and sharing with diesels is a function of the infrastructure in Dublin. I don't think people would argue there is a defined frequency level that an electrified system must meet before it can be referred to as metro. As for the level crossings that's a moot point as the Dart has full priority at all of them. Unlike the Luas which has to stop for motor traffic, even on the Ranelagh to Sandyford sections where there is otherwise full seperation.

Victor

sliabh wrote:

I think this is one of the reasons why it is also suggested that the metro line starts underground from Ranelagh. There you have Ranelagh gardens to dig up. But it is possible to remove everything (trees included) and put it back afterwards.

There is also the old Carrolls factory site, although you need to get under the canal.

Does anyone know if there is a suitable site up by Broadstone for a large tunnelling hole to be dug at the north end of the proposed underground line?

Only a few hundred acres.

murphaph

Sorry metrobest,
The mans name was Rudolph Diesel, no 'a' in his name. It's starting to annoy me so if you wouldn't mind.

Victor

murphaph wrote:

Sorry metrobest, The mans name was Rudolph Diesel, no 'a' in his name. It's starting to annoy me so if you wouldn't mind.

I can't see the relevence ....

Metrobest

murphaph wrote:

Sorry metrobest,
The mans name was Rudolph Diesel, no 'a' in his name. It's starting to annoy me so if you wouldn't mind.

Oh, you mean the man's name. Right. I see now.