Diesels under the Wires...

[Hoyerman]

Just a little something I'm interested in...

I've had a look around the forum and I've seen a lot of talk about the inefficiencies running Diesel trains under the wires, but not anything about how the costs of each actually compare (apologies if I've missed it!).

Given the requirement for each of the TOC/FOC to actually make a profit, it would lead me to think that the actual cost differential of running a Diesel vs Electric train may not be all that great - otherwise I feel sure that these companies (driven by money as they all are) would change traction at the appropriate point in the journey - or specify a single mode of traction for the entire journey.

Thinking about it, Diesel trains in many cases are also a kind of electric trains, the electric power for the traction motors in many cases being provided by an on board diesel engine... so is this less efficient than overheads or third rail? Are track access charges different for each? What drives the decision - is it as simple as availability of traction? Does anyone have some figures on a cost per tonne/mile basis?

Just interested, that's all...

Cheers
H

 

[jopsuk]

I don't have the figures, but certainly, if the wires are there, the fuel/energy cost of running a similar sized diesel versus an electric is much higher. small and multiple diesel generators are far less efficient compared to centralised power generation, even with transmission losses accounted for.

EMUs are also a lot lighter than DMUs in general- if you compare an EMU and DEMU, the DEMU may have similar traction motors, but has those on every carriage plus the disel engine plus the fuel tank, whilst the EMU will have only some carriages powered, and may only have one heavy transfomer per set.

 

[YesToHS2]

If it's such a problem why aren't more trains dragged. I've seen Pendolinos dragged through Chester on occasion but that is usually after problems with the Voyagers. It would be much better for passengers if Pendolinos were dragged from Holyhead to Crewe. Voyager interiors don't even compare to Pendolinos.

 

[Geezertronic]

If it's such a problem why aren't more trains dragged. I've seen Pendolinos dragged through Chester on occasion but that is usually after problems with the Voyagers. It would be much better for passengers if Pendolinos were dragged from Holyhead to Crewe. Voyager interiors don't even compare to Pendolinos.

I believe there are scheduled services that use 390s between Euston and Holyhead usually of a weekend.

During the normal working week, there are probably insufficient 390s to be able to operate the diagrams completely plus a couple of services a day are operated by 2 x 221s which join/split at Chester with one service to/from Wrexham and the other to/from Holyhead.

 

[YesToHS2]

I believe there are scheduled services that use 390s between Euston and Holyhead usually of a weekend.

During the normal working week, there are probably insufficient 390s to be able to operate the diagrams completely plus a couple of services a day are operated by 2 x 221s which join/split at Chester with one service to/from Wrexham and the other to/from Holyhead.

Ah, that explains it. I knew part of the problem would be the number of free 390s but didn't know about the splitting service.

 

[Geezertronic]

Ah, that explains it. I knew part of the problem would be the number of free 390s but didn't know about the splitting service.

I believe that in order for VT to perform their weekday VHF service they need 47 available 390s out of the pool of 52. The split/join at Chester and the Wrexham service only happens on a couple of services a day (1810 ex Euston as one example) but saves paths on the WCML South as a result which as you know is at a premium at the best of times

 

[MCR247]

Don't most (if not all) Holyhead trains run double 221s to Chester, where the rear unit detaches and forms the next train back to Euston?

 

[YorkshireBear]

they should of ordered more pednilinos to be honest and the extra 4 should of been an extra 10

 

[ralphchadkirk]

EMUs are also a lot lighter than DMUs in general- if you compare an EMU and DEMU, the DEMU may have similar traction motors, but has those on every carriage plus the disel engine plus the fuel tank, whilst the EMU will have only some carriages powered, and may only have one heavy transfomer per set.

That is a huge generalisation. Not all DEMU's are the same, and some don't have traction motors on every carriage and thus are really the same as EMU's in that respect.

 

[50010 Monarch]

The use of Voyagers on the Birmingham to Glasgow/Edinburgh through services is a farce in my opinion.

Running these trains (each carriage having a 750hp engine) all the way under the wires on such a long journey is surely the definition of inefficiency.

I know that the Pendolino's are at full stretch & can't be spared, but some decent mark 3's & a Class 90/DVT on self contained diagrams would surely have been the answer. Probably too late now though......

 

[TGV]

That is a huge generalisation. Not all DEMU's are the same, and some don't have traction motors on every carriage and thus are really the same as EMU's in that respect.

Agreed - and a Desiro is not exactly light on it's feet as an example. If anything the modern breed of DMU's are pretty much an equivalent weight of an EMU - maybe even lighter.

 

[ainsworth74]

I know that the Pendolino's are at full stretch & can't be spared, but some decent mark 3's & a Class 90/DVT on self contained diagrams would surely have been the answer. Probably too late now though.

They wouldn't be able to keep to current times which would have knock on effect to the other services on the WCML and probably screw up the VHF timetable by causing pathing issues.

Besides most of the remaining 90s+Mk3s sets spend their days tootling along the GEML and there is nothing equivalent to replace them there.

 

[jopsuk]

Agreed - and a Desiro is not exactly light on it's feet as an example. If anything the modern breed of DMU's are pretty much an equivalent weight of an EMU - maybe even lighter.

the class 185 are an average of 58t per car. 444 is 45t per car (with the TSOs being lighter, the driving motors heavier, but I can't find exact figures). 450 is 42.5 per car.
For the 360:
DMC - 47.6 tonnes
PTSO - 48.3tonnes
TSO - 35.1tonnes
DMC - 48.3tonnes

Bombardier seem to be a bit better- a three car 170 is about the same weight as a three car 170 (and both are a bit lighter than Desiros)

 

[YorkshireBear]

the class 185 are an average of 58t per car. 444 is 45t per car (with the TSOs being lighter, the driving motors heavier, but I can't find exact figures). 450 is 42.5 per car.
For the 360:
DMC - 47.6 tonnes
PTSO - 48.3tonnes
TSO - 35.1tonnes
DMC - 48.3tonnes

Bombardier seem to be a bit better- a three car 170 is about the same weight as a three car 170 (and both are a bit lighter than Desiros)

a 3 car 170 is about same wieght as a 3 car 170?

 

[TGV]

the class 185 are an average of 58t per car. 444 is 45t per car (with the TSOs being lighter, the driving motors heavier, but I can't find exact figures). 450 is 42.5 per car.
For the 360:
DMC - 47.6 tonnes
PTSO - 48.3tonnes
TSO - 35.1tonnes
DMC - 48.3tonnes

Bombardier seem to be a bit better- a three car 170 is about the same weight as a three car 170 (and both are a bit lighter than Desiros)

Interesting. And crazy. I was thinking of a class 170 being a typical modern DMU and a desiro AC or DC being a typical modern EMU, in which case the EMU is very much similar or slightly heavier per car. But yes, as an example that 185 seems ridiculously heavy.

58t per car?! That's only 10t lighter than a TGV power car (10t is basically the weight of the main transformer) - and nearly twice the weight of it's carriages which I know haven't any traction kit, but still - that seems insanely overweight for a low/medium speed regional diesel train!
--- old post above --- --- new post below ---

a 3 car 170 is about same wieght as a 3 car 170?

True story.

 

[YorkshireBear]

True story.

i know, incredible

 

[jopsuk]

58t per car?! That's only 10t lighter than a TGV power car (10t is basically the weight of the main transformer) - and nearly twice the weight of it's carriages which I know haven't any traction kit, but still - that seems insanely overweight for a low/medium speed regional diesel train!

As far as I know, they cannot use ANY differential speed limits- definitely not "MU" and "DMU" (which apply I think class 142-171 inclusive? MU also includes EMUs) and not even "HST" (which I'm pretty sure 22x and 180s can use) limits.

 

[YesToHS2]

This is a bit off topic but I'm I thought I saw a prop shaft on a Class 220? Are the motors inside the boogies like most DEMUs?