General state of electric loco fleet

[Tom Clarke]

Not sure if it's wibble but I've seen December being mentioned. 86s will be 'canned' by then, replaced by 90s displaced from GA.

This could be wibble too but I'd heard that the GA Class 90s are to go to a new operator who plans to run a Paddington to Cardiff high speed service. Not sure if this is correct but also heard that Grand Central plan to get some for use on London to Blackpool trains. Sounds like the future isn't certain for those 90s. Again, could be wibble!?

Not sure if Freightliner will completely withdraw their 86s though as noticed quite a bit of work has gone into them for overhauls etc. I could be wrong of course but that is what I've seen.

 

[hwl]

This could be wibble too but I'd heard that the GA Class 90s are to go to a new operator who plans to run a Paddington to Cardiff high speed service. Not sure if this is correct but also heard that Grand Central plan to get some for use on London to Blackpool trains. Sounds like the future isn't certain for those 90s. Again, could be wibble!?

Not sure if Freightliner will completely withdraw their 86s though as noticed quite a bit of work has gone into them for overhauls etc. I could be wrong of course but that is what I've seen.

Both the open operator proposals assume the use of 91s in their submissions to ORR not 90s.
The current suggestion is that 13 of the Anglia 90 will go to FL.

FL are currently operating a number of services with Diesels that could be electric (especially after scrapping a number of 86s in recent years) hence there might be an element of adding electric capacity rather than just a swap of 13 for 16.

 

[supervc-10]

Both the open operator proposals assume the use of 91s in their submissions to ORR not 90s.

I would assume that at least on the GWML the 91's extra speed would be greatly appreciated over the 90, causing fewer issues getting in the way of 125mph IETs. The WCML of course has lower speeds, as there's nothing capable of making use of the higher speeds for tilting.

Edit: Nothing available which can make use of the higher speeds I should say!

 

[edwin_m]

I would assume that at least on the GWML the 91's extra speed would be greatly appreciated over the 90, causing fewer issues getting in the way of 125mph IETs. The WCML of course has lower speeds, as there's nothing capable of making use of the higher speeds for tilting.

There are probably some straight bits of the WCML that could be cleared for over 110mph without tilt, if anyone was prepared to spend some time and money on it.

 

[GrimShady]

Yep, they could even be semi-permanently coupled — with the electric gear in one segment, diesel in the other, and batteries next to whichever is smaller. Mix and match halves to cover maintenance (maybe have a few extra diesel halves to allow for their extra maintenance).

Why hasn't it caught on seen as we suffer the most from restrictive loading gauges/axle weights?

 

[43096]

Why hasn't it caught on seen as we suffer the most from restrictive loading gauges/axle weights?

Because it is prohibitively expensive?

 

[GrimShady]

Because it is prohibitively expensive?

Is it though?

What are the costs vs an electric plus diesel fleet?

It certainly solves a number of problems.

 

[edwin_m]

A permanently coupled diesel-electric hybrid would cost as much as two locomotives, but only give the benefit of one. In fact it would be less benefit because the dead weight of the half not providing any power would knock 100+ tonnes off the trailing load for the same timings.

Having said that in a few years time it's probably going to be impossible for daytime diesel-hauled freight to run on the double-track sections of the ECML and WCML if the various aspirations for better passenger frequency come to pass. There are loops, but by the time a diesel has re-started and got somewhere near line speed the next passenger train will be right behind it.

 

[ac6000cw]

Having said that in a few years time it's probably going to be impossible for daytime diesel-hauled freight to run on the double-track sections of the ECML and WCML if the various aspirations for better passenger frequency come to pass. There are loops, but by the time a diesel has re-started and got somewhere near line speed the next passenger train will be right behind it.

Yes, that capacity problem is already driving some freight off electrified routes onto secondary lines e.g. the GN-GE Joint line as an alternative to the ECML between Peterborough and Doncaster, and shifting transit freight away from the London area. Ironically this might make electric traction (or expensive bi-mode locos) even less attractive to the FOC's unless there are serious incentives to move that way e.g. maybe very cheap traction electricity.

 

[apk55]

A permanently coupled diesel-electric hybrid would cost as much as two locomotives, but only give the benefit of one. In fact it would be less benefit because the dead weight of the half not providing any power would knock 100+ tonnes off the trailing load for the same timings.

Having said that in a few years time it's probably going to be impossible for daytime diesel-hauled freight to run on the double-track sections of the ECML and WCML if the various aspirations for better passenger frequency come to pass. There are loops, but by the time a diesel has re-started and got somewhere near line speed the next passenger train will be right behind it.

If we went for a for a permanently coupled diesel and electric locomotive I would expect a power cross feed between the two halves so all axles are powered all of the time. For a BoBo + BoBo arrangement this means that you would be looking at a starting tractive effort of at least 600kn which either means you can haul a very heavy train or accelerate a lighter train much quicker particularly from a standing start. Think standing start 1km (ie from a signal clearing to vacating that signal section) and you you could be looking at a 30 to 40% reduction in time in comparison with a simple BoBo.
Do not forget that an electric locomotive like a class 88 can only deliver its rated power at speeds greater than 40 to 50MPH as tractive effort limits power. (Remember power = speed X tractive effort.) And the same applies to a lesser extent to a class 68.
If paths are to be obtained in congested urban areas then quick starting might be more important than top speed.

 

[edwin_m]

If we went for a for a permanently coupled diesel and electric locomotive I would expect a power cross feed between the two halves so all axles are powered all of the time. For a BoBo + BoBo arrangement this means that you would be looking at a starting tractive effort of at least 600kn which either means you can haul a very heavy train or accelerate a lighter train much quicker particularly from a standing start. Think standing start 1km (ie from a signal clearing to vacating that signal section) and you you could be looking at a 30 to 40% reduction in time in comparison with a simple BoBo.
Do not forget that an electric locomotive like a class 88 can only deliver its rated power at speeds greater than 40 to 50MPH as tractive effort limits power. (Remember power = speed X tractive effort.) And the same applies to a lesser extent to a class 68.
If paths are to be obtained in congested urban areas then quick starting might be more important than top speed.

It probably depends on the relative importance of diesel and electric sections of the route.

In electric mode your proposal would be similar to a pair of class 86 - we can assume that modern traction could deliver the power of two 1960s designs from the electric half of the combination. Creep control systems would give a bit more tractive effort (do 90s have these anyway?).

In diesel mode the available power would be similar to a class 68 (2800kW). I don't have a TE curve for a 68 but the one for the 66 starts dropping at around 10mph so I'm not sure the extra low-speed TE would make much difference to journey times. There's still that loss of payload compared to a striaght diesel, albeit now only 80 tonnes or so, and it looks like a pair of 80-tonne units wouldn't have much weight or space for batteries.

 

[ac6000cw]

Creep control systems would give a bit more tractive effort (do 90s have these anyway?).

According to book I have which is a history of GEC Traction, the 90's have sep-ex motor control, so they probably have wheel creep control to some degree. It's not clear if they have doppler radar as well (it says the 91's have it, which are a contemporary GEC Traction design). Whatever, it should be somewhat better than the common-to-all axles tap-changer control of an 86.

 

[edwin_m]

According to book I have which is a history of GEC Traction, the 90's have sep-ex motor control, so they probably have wheel creep control to some degree. It's not clear if they have doppler radar as well (it says the 91's have it, which are a contemporary GEC Traction design). Whatever, it should be somewhat better than the common-to-all axles tap-changer control of an 86.

According to Wikipedia the TE of a Class 90 is actually slightly less than that of an 86, despite it being a bit heavier.