Phoenix Park tunnel

LXFlyer

Captain Chaos wrote: »

I don't buy that reason when IE are now hiring more DART drivers to operate a 10 min frequency with all the extra sets lying around doing nothing from next year.

8 car DARTs have been needed more and more over the past year. I don't buy that it cost that much more to run extended sets.

I have watched the same DART set for the past 18 months at Fairview being tagged and re washed every week because the set is lying idle. Some guy has to keep scrubbing that one set over and over because it's not used to generate revenue and it is costing money to keep in a siding doing sweet FA.

Come on - do you really think IE are running shorter sets for the fun of it? Clearly they are doing so to save money.

The NTA have committed to provide additional PSO funding to finance the increase in DART frequency.

LXFlyer

lucernarian wrote: »

As forseen currently, a plan for continuous 10 minute DARTs is a long way off and unfunded and the only recent publicly stated intentions are for a peak time service. I think the remarks were quite accurate.

No the commitment from the NTA is to increase the core DART frequency from every 15 minutes to every 10 minutes from 2016, and to provide the funding for that.

lucernarian

lxflyer wrote: »

No the commitment from the NTA is to increase the core DART frequency from every 15 minutes to every 10 minutes from 2016, and to provide the funding for that.

When there is actual funding in next year's budget from the Dept. of Transport to the NTA for it, then there is funding. Though you're right, it's fair enough to say it's forseen as of right now. It's a liberal use of what we know right now to say "it will happen" however.

trellheim

is there a certain amount of sophistry here. Which is better - 10 minute frequency or longer sets ? If you had to pick one or the other

Sam Russell

trellheim wrote: »

is there a certain amount of sophistry here. Which is better - 10 minute frequency or longer sets ? If you had to pick one or the other

Frequency wins out.

The Dart takes about an hour to get from one end to the other so a 10 min service will have 12 trains or 48 coaches while a fifteen min service will 8 trains or 64 coaches. Outside of peak times, the 8 coach trains appear empty, and few 4 coach trains appear full.

So a 10 min service with 4 coaches costs less than a service of 8 coaches every 15 mins, while giving a more frequent service. It is unlikely that the more frequent service will have full trains, even if they have 4 coaches.

lucernarian

Sam Russell wrote: »

Frequency wins out.

The Dart takes about an hour to get from one end to the other so a 10 min service will have 12 trains or 48 coaches while a fifteen min service will 8 trains or 64 coaches. Outside of peak times, the 8 coach trains appear empty, and few 4 coach trains appear full.

So a 10 min service with 4 coaches costs less than a service of 8 coaches every 15 mins, while giving a more frequent service. It is unlikely that the more frequent service will have full trains, even if they have 4 coaches.

How does it necessarily cost less? I mean, there is the cost of more drivers with a ten minute service?

Sam Russell

lucernarian wrote: »

How does it necessarily cost less? I mean, there is the cost of more drivers with a ten minute service?

Does a driver cost more than a train costs per hour?

If a carriage cost €10 per km, and it is 25km from one end of the line to the other, then a single train consisting of 8 coaches will cost €250 to travel from one end to the other, €250 per hour. A 4 coach will cost half that, saving €125 per hour. Running a 15 min service requires 4 trains to pass a given point per hour, and 10 min service requires 6 trains per hour or 50% more. So running 4 coaches @ 10 min vs 8 coaches @ 15 mins means that 10 min service cost €1,500 per hour versus €2,000 for the 15 min service. (Both ways)

The 10 min service is 25% cheaper, unless the driver earns a lot more than I think he does. A driver would need to be earning more than €125 per hour.

alofek

I can't see how it would be that simple. Surely the cost would decrease as you add more carriages, due to economies of scale. Presumably, there's also a base cost to running a train without carriages - then as you add one carriage and as you continue adding, the cost per carriage reduces.

Sam Russell

A train without carriages is not a train. I am talking about the actual marginal cost of running a train, not the cost of running a railway service.

An empty train without passengers is just an expense.

A train of 4 carriages is not even full at present for much of the day, adding carriages does not add revenue, just cost. (By full, I mean no standing passengers - by overfull, I mean no-one can fit into the carriage and some passengers choose to wait for the next train).

I think there are few instances each day when 4 coach trains are overfull. There are many instances per day when a 4 coach train is too much, and perhaps even a 2 coach is too much.

I also think IR should do more about revenue protection.

alofek

My point was that a train with 8 carriages surely cannot cost exactly eight times that a train with one carriage. There are too many variables at work to start basing calculations on cost and frequency without knowing more about the real figures at issue.

Sam Russell

I am using sort-of numbers that are of the order of costs of running carriages. Diesel trains cost more than Darts. An unused carriage does cost, but not close to that of a moving one. The major cost, I would assume, is energy cost which certainly are of per-carriage nature for a railcar based train. All Dart trains are based on a two car trainset, whether configure as a two car set as the original ones, or a four car set as the later ones are.

There may be other costs that I am not aware of, but energy use must be the largest component.

sdanseo

The cost of running a 4-car diesel set is directly proportional to running an 8-car. The figure is simply doubled. It's not like an aircraft or a bus where a unit with 50 seats almost never weighs exactly half of the one with 100 seats. There's no energy saving because both 2-car or 4-car units weigh identical amounts.

I haven't first hand experience of running costs for EMUs but one would imagine the principle is the same, the laws of physics don't change just because the source of power is electrical rather than diesel.

alofek

There is a logical flaw in this as the engine does not transport itself. So if as you say the fuel bill for each carriage is identical, a longer train becomes progressively cheaper.

Carawaystick

alofek wrote: »

There is a logical flaw in this as the engine does not transport itself. So if as you say the fuel bill for each carriage is identical, a longer train becomes progressively cheaper.

Each carriage has 1 or 2 engines, to power that carriage.
Or a motor, if its a dart.

Captain Chaos

DARTs are a bit different in that they have regenerative braking to an extent so under some braking conditions they are giving back electrical power to the grid. Longer trains are also more efficient at braking than shorter trains up to a certain extent. Drivers prefer driving longer trains during leaf fall season for this reason.

On a DART half the train is powered and half unpowered. All the 81xx cars are powered, 83xx are trailers. In the new DARTs the 85xx number cars are powered while 86xx number cars are the trailers.

lucernarian

sdanseo wrote: »

The cost of running a 4-car diesel set is directly proportional to running an 8-car. The figure is simply doubled.

This has already been shown to be incorrect, as the cost of the driver's wages is the same for driving a 4-car and 8-car train.

loyatemu

lucernarian wrote: »

This has already been shown to be incorrect, as the cost of the driver's wages is the same for driving a 4-car and 8-car train.

In fairness, the unions did try to make the drivers wages proportional to the length of the train as well. :pac:

Sam Russell

Captain Chaos wrote: »

DARTs are a bit different in that they have regenerative braking to an extent so under some braking conditions they are giving back electrical power to the grid. Longer trains are also more efficient at braking than shorter trains up to a certain extent. Drivers prefer driving longer trains during leaf fall season for this reason.

On a DART half the train is powered and half unpowered. All the 81xx cars are powered, 83xx are trailers. In the new DARTs the 85xx number cars are powered while 86xx number cars are the trailers.

I think you mean the first carriage provides the motive power while the second carriage provides the compressor and other ancillaries. The result is Dart trains are made up of two car sets, whether joined permanently as two car or four car sets. They can only be used in multiple of two, or in multiples of four for the later trains. The only saving to be derived from running one eight car train over two four car trains is the drivers wages for the second train.

The reason longer trains are better in slippery conditions is that they have more driving wheels are so can sustain more loss of friction on particular wheels.

Sam Russell

loyatemu wrote: »

In fairness, the unions did try to make the drivers wages proportional to the length of the train as well. :pac:

... until that was shown to be ridiculous and could be used to reduce the wages for running shorter trains.

sdanseo

Captain Chaos wrote: »

DARTs are a bit different in that they have regenerative braking to an extent so under some braking conditions they are giving back electrical power to the grid. Longer trains are also more efficient at braking than shorter trains up to a certain extent. Drivers prefer driving longer trains during leaf fall season for this reason.

On a DART half the train is powered and half unpowered. All the 81xx cars are powered, 83xx are trailers. In the new DARTs the 85xx number cars are powered while 86xx number cars are the trailers.

Correct, but the principle of running costs would be that which I mentioned above would still apply, at least for basic calculation (and the same for railcars) because there is no combination of sets which does not have the same number of unpowered cars as powered cars. Even the 22k series which run in three or six car sets aren't exempt from this principle.

You're correct in saying a longer train generates more power when braking but not disproportionately to that of a shorter train. It takes more power to accelerate the longer train. Any benefits are negligible except perhaps when it comes for ease of operation as mentioned above.

Sorry, I was referencing simple fuel costs, not inclusive of wages.

Captain Chaos

Sam Russell wrote: »

The reason longer trains are better in slippery conditions is that they have more driving wheels are so can sustain more loss of friction on particular wheels.

Longer trains do have better brake force too to help. An example is the 071 locos, they are limited to 75mph when hauling nothing, light engine because of their braking ability. Put a rake of coaches, 5 or more and it's operational permitted speed limit is now 90mph because of the reduced stopping distance from the extra brake force added by the coaches behind it.

Anyway going a bit off topic now.

sdanseo

Captain Chaos wrote: »

Longer trains do have better brake force too to help. An example is the 071 locos, they are limited to 75mph when hauling nothing, light engine because of their braking ability. Put a rake of coaches, 5 or more and it's operational permitted speed limit is now 90mph because of the reduced stopping distance from the extra brake force added by the coaches behind it.

Anyway going a bit off topic now.

But not in the case of railcars. The weight and dynamics of a loco - as you've illustrated - are entirely different to a car behind it

Sam Russell

When is the new signalling system operational?

Markcheese

I was about to ask about signaling
If you've got a limited number of train movements per hour available the you could argue that this is a cost as well -if you only have say 10 movements per hour available , then to carry more passengers you hAve to use longer trains or incur higher capital costs to increase train frequency -

Sam Russell

Sam Russell wrote: »

When is the new signalling system operational?

Someone already stated (up thread) that the signalling has already been upgraded, or do you mean some other signals?

Sam Russell

Deleted User wrote: »

Someone already stated (up thread) that the signalling has already been upgraded, or do you mean some other signals?

I am particularly interested in the Connolly to GCD section but also the PPT to Connolly.

LXFlyer

Sam Russell wrote: »

I am particularly interested in the Connolly to GCD section but also the PPT to Connolly.

The next phase of the city centre re-signalling project is due to complete in early 2016.

Sam Russell

lxflyer wrote: »

The next phase of the city centre re-signalling project is due to complete in early 2016.

What will be achieved after that phase goes live? How many trains per hour will be able to travel North through that section?

How many more phases are there?

LXFlyer

The current phase covers from Connolly to Sandymount.

The final phase covers Connolly Station yard.

It will provide up to 8 extra paths through the loop line each hour.

That is a total of 20 per hour.

Carawaystick

lxflyer wrote: »

The current phase covers from Connolly to Sandymount.

The final phase covers Connolly Station yard.

It will provide up to 8 extra paths through the loop line each hour.

That is a total of 20 per hour.

20 Each way or in total?