A Solution for freight services running diesels 'under the wires'?

[DW54]

Those batteries are light by comparison with lead acid batteries but nothing compared to lithium ion batteries.
Additionally they are only rated for 0.5C, which means that is a two hour discharge time.... and an 8.4 hour rated recharge time.
It is also rated for only 4500 cycles which mean multiple replacements over the life of the locomotives.

These are far from ideal for a last mile engine.

The cost of deploying these locomotives on a widespread basis is probably more expensive than simply deploying trolley-wire on the "last mile" routes that cause the problem, and possibly using Furrer and Frey movable overhead contact rails for top loading areas that prevent conventional wir being installed.

You've quoted some quite specific numbers for the NaMh battery. Can you provide a link to your source? I have had my doubts about GE's status on these. They've been launched twice now. And I haven't spotted a tech spec on their site. I'm particularly interested in the claim of a 4500 full cycles lifetime, how this compares with the 20-year claim by GE. Put simply, that's 225 cycles per annum, which wouldn't even cut it for a solar PV site.

My point about such things, per the Leeds thread, is that they are emergent technologies. I think what has happened is that GE have recognised that the NaMh characteristics don't suit a lot of applications, but that Li batteries are very expensive. They've probably spent the interregnum developing the power management system to blend different sources with different characteristics.

Anyway, my thesis is that as the technologies mature we will increasingly find a combination of 2, 3, 4, 5 or 6 storage types used to optimise the recovery/storage system to the application. They would be made up of:

- Lead Acid/Gel
- NiMH
- Li
- NaMh
- KERS (flywheel)
- Supercap

Meanwhile, fuel cell technologies are getting a lot of R&D attention. So, as per their bus, a hybrid system will probably become the new paradigm in time.

Coming back to "last 50 miles" capability, while yes there are ways of delivering current in depot situations and the like, let's accept that there are a lot of short holes in the electrified network as well as a huge number of unsparked sidings. When comparing a fleet of perhaps 100 locos with "last 50 mile" capability with wiring up all the sidings, headshunts, minor branches and intermodal transfer areas, I'm not at all convinced about the cost balance.

A stronger argument would be to compare the performance and cost of using a high-speed high-power diesel genset with its fuel needs plus refuelling time and additional maintenance of the diesel genset, against an optimised multi-technology storage "pack" system.

Whereas the storage system could deliver anything up to the full short-term rating of the electric loco, I can't see a 6000hp diesel being used. Maybe a V8 1200hp unit would be more realistic where covering gaps in the sparked network (~Class 73 anyone)?

 

[HSTEd]

You've quoted some quite specific numbers for the NaMh battery. Can you provide a link to your source? I have had my doubts about GE's status on these. They've been launched twice now. And I haven't spotted a tech spec on their site. I'm particularly interested in the claim of a 4500 full cycles lifetime, how this compares with the 20-year claim by GE. Put simply, that's 225 cycles per annum, which wouldn't even cut it for a solar PV site.

Here are the technical specifications for the modules that the larger Durathon arrays are apparently built from.
I think the 20-year claim involves the "shelf-life" of the battery, it also depends on how they measure the end of life condition, since even a 50% loss of capacity might not be considered absolutely crippling in a grid storage application.

My point about such things, per the Leeds thread, is that they are emergent technologies. I think what has happened is that GE have recognised that the NaMh characteristics don't suit a lot of applications, but that Li batteries are very expensive. They've probably spent the interregnum developing the power management system to blend different sources with different characteristics.

There has been some very interesting work on lithium-sulfur batteries and even on graphene super-capacitors that have battery-like energy density, but I am sceptical that either will be arriving in traction suitable applications any time soon without significant production costs sufficient to prevent huge use.

Also there is the question about what mass use of rapid recharging electric vehicles will do to the grid.

Meanwhile, fuel cell technologies are getting a lot of R&D attention. So, as per their bus, a hybrid system will probably become the new paradigm in time.

Really fuel cells have been getting a lot of R&D attention for years, but their precious metal requirements (which are only ameliorated with impractically high operating temperatures for mobile applications) seem to be holding them back, getting an internal reformer that works properly is also proving to be.... problematic. (My degree is in Chemistry and I have been following the field quite closely).

Coming back to "last 50 miles" capability, while yes there are ways of delivering current in depot situations and the like, let's accept that there are a lot of short holes in the electrified network as well as a huge number of unsparked sidings. When comparing a fleet of perhaps 100 locos with "last 50 mile" capability with wiring up all the sidings, headshunts, minor branches and intermodal transfer areas, I'm not at all convinced about the cost balance.

There aren't really that many of such places left, certainly not compared to what there was even 20 years ago, the demise of many industrial sidings has seen to that.
The wiring would in almost all cases be very close to existing electrified lines (or on lines that would have other traffic that would ameliorate the cost) and that would tend to imply that major upgrades would probably not be necessary, especially since I doubt the locomotive would go above Notch 1 or 2 in a siding. Could probably even get away with AWAC contact wires if you were really trying to cut costs.

A stronger argument would be to compare the performance and cost of using a high-speed high-power diesel genset with its fuel needs plus refuelling time and additional maintenance of the diesel genset, against an optimised multi-technology storage "pack" system.

The weight disadvantage of the "pack" would likely be such that you could fit a sufficiently large fuel tank to allow the locomotive to run for weeks of normal operation without refuelling.

Whereas the storage system could deliver anything up to the full short-term rating of the electric loco, I can't see a 6000hp diesel being used. Maybe a V8 1200hp unit would be more realistic where covering gaps in the sparked network (~Class 73 anyone)?

6000hp would consume something like 1.26kWh per second.... which is frankly scary to power with a battery.
And why are freight electrics mostly BoBos? surely it would be better to build 92-esque CoCos? I crunched the numbers that seemed to suggest that a pure 25kV CoCo could have ten thousand continuous horsepower with modern technology, which would allow them to hold very heavy trains at high speed thanks to the torque curve of electric transmissions.

 

[Trog]

The converted class 501 battery locos, if I remember rightly after 30 years.

Could pull about as much as a class 25, from Cricklewood to the City Widened Lines and back at a low speed. It then needed to have its batteries recharged all 100 tons of them.

 

[DW54]

Here are the technical specifications for the modules that the larger Durathon arrays are apparently built from.
I think the 20-year claim involves the "shelf-life" of the battery, it also depends on how they measure the end of life condition, since even a 50% loss of capacity might not be considered absolutely crippling in a grid storage application.{SNIP}

(1) No mention of a 4500 cycle life in those specs.
(2) Why should delivering 6000hp from an ARRAY of batteries managed by traction electronics be any different to the output of a 4.5MW transformer/rectifier?
(3) Lower hp, more tractive mass helps with starting trains and putting power on the rails up ruling gradients. Extreme hp is really only useful for high speed. For freight, even 6000hp in 80-84t probably means wheelslip. 6000hp in 120-126t (Co-Co) is probably a good balance between tractive effort and speed - so batteries are as good a ballast as a diesel genset and fuel. Either way.
(4) My thinking is gaps like the GoBlin, parts of Reading-Redhill, Thames Gateway/Shellhaven - LT&S, Felixstowe branch, etc. If these are to be electrified, NR would only have them electrified to a standard they approve.

I respect your chemistry credentials, but when it comes to railway operations, transport planning and town planning - we're all partially informed amateurs or inexperienced academics.

 

[HSTEd]

(1) No mention of a 4500 cycle life in those specs.

Did you check page 2? It is the first entry.

(2) Why should delivering 6000hp from an ARRAY of batteries managed by traction electronics be any different to the output of a 4.5MW transformer/rectifier?

Because you would need an insanely enormous array of batteries to keep full power on for more than a few seconds.

(3) Lower hp, more tractive mass helps with starting trains and putting power on the rails up ruling gradients. Extreme hp is really only useful for high speed. For freight, even 6000hp in 80-84t probably means wheelslip. 6000hp in 120-126t (Co-Co) is probably a good balance between tractive effort and speed - so batteries are as good a ballast as a diesel genset and fuel. Either way.

Hhhm, perhaps your right, although a 10,000hp locomotive would likely be able to maintain its starting tractive effort to 50-60mph or more, which could be a game-changer for inter-modal freight traffic.

(4) My thinking is gaps like the GoBlin, parts of Reading-Redhill, Thames Gateway/Shellhaven - LT&S, Felixstowe branch, etc. If these are to be electrified, NR would only have them electrified to a standard they approve.

You will likely struggle to transit such long distances on battery power with heavy trains like the ones we are seeing increasingly (the FOCs are constantly lobbying for longer loops to allow longer, heavier trains to be run).

 

[DW54]

Did you check page 2? It is the first entry.

2)Because you would need an insanely enormous array of batteries to keep full power on for more than a few seconds.

3)Hhhm, perhaps your right, although a 10,000hp locomotive would likely be able to maintain its starting tractive effort to 50-60mph or more, which could be a game-changer for inter-modal freight traffic.

4) You will likely struggle to transit such long distances on battery power with heavy trains like the ones we are seeing increasingly (the FOCs are constantly lobbying for longer loops to allow longer, heavier trains to be run).

Page 2 didn't come up on my several attempts about 9-10 hours ago. Now I see it. It is a show-stopper as far as I am concerned. GE had better go away and try again if they want to sell these batteries in 200+ ton 6-axle hybrids for the North Amercian market. Durathon has just slipped off the agenda for electric buses and trains until they get a 100,000 cycle life, and more rapid recharge ability.

Is "insanely large" smaller or more than twenty-thirty tonnes?

I'm assuming 775m trains, with ~15m vehicles (ie ~51 cars + 1 loco) = max tonnage around 3700. This would need a 126t, 3700hp loco to work at normal freight speeds, or 6000hp in 126t to achieve fast freight status.

High acceleration requires good traction, and would indicate a combination of one powerful loco plus perhaps a battery-equipped and MU controlled traction and brake booster unit (which could be built into a recycled former diesel carbody and bogies). At least in booster apps, the duration of discharge time is relatively short, though recharge rates would be quite high as the booster unit would be brought up to full regerative rating first, before the main loco went into dynamic or regen braking.

 

[#1 driver]

For freight, even 6000hp in 80-84t probably means wheelslip.

really ?

with a heavy train a cl66 ( with 3300hp ) slips !

an 80 ton loco is just gonna dig holes in the track !

 

[RichmondCommu]

It's a big problem and likely to increase as the numbers of both freight and passenger trains both grow.

In all fairness, the growth in freight traffic has been nothing like the increase in passenger numbers. In fact as power stations close I would be surprised if freight traffic showed any real growth at all.

Loops are used but not as effective as one might expect, because the freight has to start out of the loop straight onto an adverse gradient and with limited power avaiable from the diesel it struggles to pick up much speed. Some of them are also rather short and have slow entry and exit speeds (though this could of course be fixed given the will and the money).

Not all loops are on or at the foot of adverse gradients. Network Rail have a launched a programme to extend loops around the country to 775 metres.
--- old post above --- --- new post below ---

Wouldn't that be a huge waste of the existing 90s and 92s? Difficult or impossible to retrofit a diesel engine in them though, which is why I think encouraging FOCs to use electric where possible and swap locos when the wires run out would be a good idea.

But it's surely more cost effective to use one loco for the entire journey. I'm very surprised that the Felixstowe branch wasn't electrified at the same time as the GEML.

 

[edwin_m]

In all fairness, the growth in freight traffic has been nothing like the increase in passenger numbers. In fact as power stations close I would be surprised if freight traffic showed any real growth at all.

Network Rail's recent freight market document indeed showed coal traffic virtually disappearing (some offset by biomass). But there was continuing growth forecast in intermodal traffic, and if you believe this forecast it is most likely to appear on a long-haul route like the WCML.

Not all loops are on or at the foot of adverse gradients. Network Rail have a launched a programme to extend loops around the country to 775 metres.

Again I agree, but Grayrigg and Beattock (not Beattock Summit) loops were specifically mentioned and both are near the foot of severe gradients. As I pointed out previously, longer trains need longer loops but they also need more power and tractive effort unless they are to be even slower and have to be looped even more.

 

[RichmondCommu]

Network Rail's recent freight market document indeed showed coal traffic virtually disappearing (some offset by biomass). But there was continuing growth forecast in intermodal traffic, and if you believe this forecast it is most likely to appear on a long-haul route like the WCML.

Well from what I can any growth in intermodal is likely to be between the ports of Felixstowe and Southampton and the Midlands and the North West. With Scotland's limited population it's difficult to see any scope for further increases in intermodal traffic.

Again I agree, but Grayrigg and Beattock (not Beattock Summit) loops were specifically mentioned and both are near the foot of severe gradients. As I pointed out previously, longer trains need longer loops but they also need more power and tractive effort unless they are to be even slower and have to be looped even more.

I'd be interested to know how much of an issue Shap and Beattock are to diesel hauled intermodal trains? One would imagine that once a train is on the move its highly unlikely to stall or else we would have bankers at Tebay.

 

[DW54]

really ?

with a heavy train a cl66 ( with 3300hp ) slips !

an 80 ton loco is just gonna dig holes in the track !

I was comparing the hyper-power being used in Europe (as cited by HSTEd) with what was realistic. I've read of instances of Class 87 (6000hp) suffering wheelslip on Shap at 100mph.

My point was, just as you state, that what freight locos need is as much adhesion as outright power. So putting batteries in a mid-powered electric loco to achieve maximum adhesive weight (along with AC drive, wheelslip protection, etc) would be more beneficial than having more outright power.

A Class 66 at 3000hp net for traction (3150 gross flywheel bhp EMD 12-710E3 engine) has DC drive and is more vulnerable to wheelslip than an AC drive diesel (I think the GE class 70 has AC drive). So the latter, at a nominal 3700hp would probably be a better comparison.

 

[edwin_m]

I'd be interested to know how much of an issue Shap and Beattock are to diesel hauled intermodal trains? One would imagine that once a train is on the move its highly unlikely to stall or else we would have bankers at Tebay.

The loco's maximum tractive effort must be more than what is needed to haul the load on the steepest gradient so the loco can physically move the train. This basically depends on the weight of the loco and how well it uses available adhesion.

However once the train is moving the speed and acceleration also depend on the power available, so the heavier the train the slower it will go particularly on a severe uphill gradient. This is more of a problem with diesels because the total power is usually less than an electric of the same size.

 

[HSTEd]

A 10,000hp CoCo super-electric would be able to generate the same ~534kN of a Class 70, but would be able to produce that effort at a far higher speed. In this case ~30mph instead of ~10mph.

Since the speeds that freight is likely to climb something like Shap are almost certainly in the power limited domain, it is highly likely that the electric would be able to haul a heavier train faster up the slope.

 

[RichmondCommu]

Since the speeds that freight is likely to climb something like Shap are almost certainly in the power limited domain, it is highly likely that the electric would be able to haul a heavier train faster up the slope.

Oh I dare say it would but I've not read anything that suggests diesel locos are currently unable to cope with hauling intermodal freight up Shap. In fact, Stobart now use DRS Class 66's to haul their trains for the entirety of the route where as before DBS used Class 92's over Shap.

 

[HSTEd]

Oh I dare say it would but I've not read anything that suggests diesel locos are currently unable to cope with hauling intermodal freight up Shap. In fact, Stobart now use DRS Class 66's to haul their trains for the entirety of the route where as before DBS used Class 92's over Shap.

Yes, but with a higher power electric the train could be made longer or just run over Shap faster.
I assume the Class 66 hauled freights don't reach the summit still moving at 75mph?

 

[RichmondCommu]

Yes, but with a higher power electric the train could be made longer or just run over Shap faster.
I assume the Class 66 hauled freights don't reach the summit still moving at 75mph?

Again I've no doubt that this is true but the question is how much added value does this give to the customer or to the FOC? Is it worth DRS buying brand new electric loco's to get trains over Shap a bit quicker? Sooner or later the train would still have to be looped and 775 metre trains appear to be the constraint here.

 

[HSTEd]

Again I've no doubt that this is true but the question is how much added value does this give to the customer or to the FOC? Is it worth DRS buying brand new electric loco's to get trains over Shap a bit quicker? Sooner or later the train would still have to be looped and 775 metre trains appear to be the constraint here.

Well we are seeing continuous loop lengthening programmes so 775m will probably not be the constraint forever, and then there are the fuel cost savings from going electric and the improved performance will allow additional trains to be pathed. (Since it will lose less time between loops compared to passenger trains thanks to far faster acceleration in the power-limited regime)

 

[RichmondCommu]

Well we are seeing continuous loop lengthening programmes so 775m will probably not be the constraint forever, and then there are the fuel cost savings from going electric and the improved performance will allow additional trains to be pathed. (Since it will lose less time between loops compared to passenger trains thanks to far faster acceleration in the power-limited regime)

Well you have to ask yourself why loop lengths have been set at 775 metres and it maybe phyically impossible to extend beyond that limit, at least without spending a lot of money. I guess only time will tell.

In terms of additional paths that doesn't appear to be FOC's problem, especially given that freight can be run over night. I think its highly unlikely that DRS are going to buy a fleet of electric loco's to help out NR.

I concur that electric loco's are cheaper to run than diesels but the cost of using two locos for one journey will surely wipe out that saving?

 

[edwin_m]

As an example of the difference, the working timetable for Shap can be found in the CZ03 link from the link below (warning large files):

http://www.networkrail.co.uk/browse...g timetable (WTT)\May 2013 - December 2013\CZ

Picking an example at random, page 4 and 5 columns 19 and 21 show 4Z67 FSX and 4S49 Su0. The timing loads are explained in the CZ index file on the above link, and indicate that 4Z67 is timed for 1600 tonnes behind a class 92, and 4S49 for 1200 tonnes behind a class 66. Both trains are maximum speed 75mph and observe any special restrictions related to container trains. Each train passes Oxenholme and Penrith, with no intervening stops and one minute of timing margin. Afficionados of Real Time Trains can no doubt find these ones there more easily (they pass Oxenholme northbound soon after midnight).

Looking at the passing times for these two stations, including the climb to Shap, the Class 66 needs 43.5min and the class 92 9min less despite having one third more trailing load. So the electric is 20% quicker on this section, and since this includes a descent where both will roll at similar speeds, the difference on the ascent will be proportionately that much greater.

No doubt a similar time difference would appear if the two trains were compared over Beattock, and probably some more for lesser gradients elsewhere on the route. If they were running in the daytime it is very likely that the diesel would have to be looped at least once more than the electric, losing at least another 10min in the process.

Thus the diesel is hauling only 75% of the load of the electric, taking probably 30min or more longer on a journey between the Midlands and Scotland, but costing broadly the same amount in operating and maintenance. I would like to think that over time these crude figures would swing the balance in favour of electrics. 4S49 runs to Grangemouth which is a bit far from the wires for a last mile diesel engine, but I believe EGIP still includes an electric connection there from Mossend.

 

[HSTEd]

Also container transports in the US are sometimes run faster than 75mph, you could potentially make 90mph container freights a reality using electric traction to reduce the cost of the extra fuel.

Would certainly reduce the pathing problems.

 

[RichmondCommu]

As an example of the difference, the working timetable for Shap can be found in the CZ03 link from the link below (warning large files):

http://www.networkrail.co.uk/browse...g timetable (WTT)\May 2013 - December 2013\CZ

Picking an example at random, page 4 and 5 columns 19 and 21 show 4Z67 FSX and 4S49 Su0. The timing loads are explained in the CZ index file on the above link, and indicate that 4Z67 is timed for 1600 tonnes behind a class 92, and 4S49 for 1200 tonnes behind a class 66. Both trains are maximum speed 75mph and observe any special restrictions related to container trains. Each train passes Oxenholme and Penrith, with no intervening stops and one minute of timing margin. Afficionados of Real Time Trains can no doubt find these ones there more easily (they pass Oxenholme northbound soon after midnight).

Looking at the passing times for these two stations, including the climb to Shap, the Class 66 needs 43.5min and the class 92 9min less despite having one third more trailing load. So the electric is 20% quicker on this section, and since this includes a descent where both will roll at similar speeds, the difference on the ascent will be proportionately that much greater.

No doubt a similar time difference would appear if the two trains were compared over Beattock, and probably some more for lesser gradients elsewhere on the route. If they were running in the daytime it is very likely that the diesel would have to be looped at least once more than the electric, losing at least another 10min in the process.

Thus the diesel is hauling only 75% of the load of the electric, taking probably 30min or more longer on a journey between the Midlands and Scotland, but costing broadly the same amount in operating and maintenance. I would like to think that over time these crude figures would swing the balance in favour of electrics. 4S49 runs to Grangemouth which is a bit far from the wires for a last mile diesel engine, but I believe EGIP still includes an electric connection there from Mossend.

I concur that there is a clear difference in performance between the Class 92 and the Class 66. I'd be interested to know whether the Class 92 hauled the train throughout its journey and which FOC runs the 4S49. Clearly if a train operates for its entirety under the wires it makes sense to use an electric loco. However, where OHLE doesn't exist over the entire route its clearly more economical to use one loco throughout.

 

[Rhydgaled]

4Z67 is timed for 1600 tonnes behind a class 92, and 4S49 for 1200 tonnes behind a class 66. Both trains are maximum speed 75mph and observe any special restrictions related to container trains.

Perhaps like HSTEd, (although I didn't know the bit about US container transports) I have wondered whether an electric freight could run in a fast path, whereas a diesel one couldn't (only being able to manage the timings of an all-stations stopping passenger service).

According to wikipedia, 86s can do 100mph, 87s and 90s 110mph and 92s 87mph. Are they ever allowed to get up to these top speeds on frieght, if at all (except 90s, none of the others have passenger work to stretch their legs on anymore)?

Clearly if a train operates for its entirety under the wires it makes sense to use an electric loco. However, where OHLE doesn't exist over the entire route its clearly more economical to use one loco throughout.

Why is it more economical to use a single (diesel) loco throughout than swap locos? The only way I can see it increasing costs is staffing, but I don't see there being much of an increase in that. The one extra job that may be needed is somebody to do the physical coupling of the locos, I don't see them needing more drivers.

On a different note, departing Cornbrook on Metrolink on Thursday evening I saw a container train hauled by a Freightliner class 86 (or was it an 87? I forget). After reading on here that lots of 90s and 92s are in store I'm supprised any of the older electric locos are used at all. Do Freightliner actually use all their 90s then, so that they need to use older electrics too?

 

[RichmondCommu]

Why is it more economical to use a single (diesel) loco throughout than swap locos? The only way I can see it increasing costs is staffing, but I don't see there being much of an increase in that. The one extra job that may be needed is somebody to do the physical coupling of the locos, I don't see them needing more drivers.

You've answered your question. It's the labour cost of a light engine movement to meet the train and along with track access charges and fuel, labour is a large cost to the business. Using too many loco's for one journey has done the once mighty SNCF Fret a lot of damage. Light engine movements cost money!

On a different note, departing Cornbrook on Metrolink on Thursday evening I saw a container train hauled by a Freightliner class 86 (or was it an 87? I forget). After reading on here that lots of 90s and 92s are in store I'm supprised any of the older electric locos are used at all. Do Freightliner actually use all their 90s then, so that they need to use older electrics too?

It can only have been a Class 86.

 

[rebmcr]

With long freight routes, would they not have multiple drivers for the different segments anyway?

 

[RichmondCommu]

With long freight routes, would they not have multiple drivers for the different segments anyway?

Oh absolutely. The issue was light engine movements and trains left in yards for goodness knows how long. Cerbere to Calais regularly used three different electric locos. And people wonder why trainload freight through the tunnel has shown almost zero growth.

 

[HSTEd]

Oh absolutely. The issue was light engine movements and trains left in yards for goodness knows how long. Cerbere to Calais regularly used three different electric locos. And people wonder why trainload freight through the tunnel has shown almost zero growth.

Being as SNCF has access to 1500V/25kV dual voltage locomotives (hell TGV power cars are all bi-current...) why would they change electric locomotives at all?

Unless you mean they swap back and forth between diesel and electric over and over? If so, then through wiring using trolleywire might be a way to get rid of the diesel components entirely.

1500V equipment is even cheaper for low performance than 25kV equipment.

 

[edwin_m]

1500V equipment is even cheaper for low performance than 25kV equipment.

Might need slightly smaller insulators, but the conductors themselves might have to be heavier to carry the higher current. I would have thought there is very little in it, unless you have some evidence to say otherwise. Certainly not enough to justify the extra complication of a different voltage in a country like the UK which doesn't have to provide for it already.

 

[Rhydgaled]

You've answered your question. It's the labour cost of a light engine movement to meet the train and along with track access charges and fuel, labour is a large cost to the business. Using too many loco's for one journey has done the once mighty SNCF Fret a lot of damage. Light engine movements cost money!

How many of the movements need to be light-engine? Could they time trains to pass at the loco-swap point, so the diesel loco hauls one train out of the off-wire section and picks up an inbound one with the electric from that taking the first train forward? Or if they can't time things helpfully, park the loco where the swap is needed for a later working (although I suppose that only avoids the track-access since the driver is unlikely to be able to clock-off in the middle of nowhere).

It can only have been a Class 86.

So why not a 90? Do Frieghtlinger actually use all of theirs?

Being as SNCF has access to 1500V/25kV dual voltage locomotives (hell TGV power cars are all bi-current...) why would they change electric locomotives at all?

I didn't think TGV power cars were all capable of using any electrified route in France, don't the long-distance Eurostars (which are a TGV of sorts) have to be formed of special sets with an extra voltage mode?

 

[RichmondCommu]

Being as SNCF has access to 1500V/25kV dual voltage locomotives (hell TGV power cars are all bi-current...) why would they change electric locomotives at all?

That question needs to be aimed at SNCF Fret!

Unless you mean they swap back and forth between diesel and electric over and over? If so, then through wiring using trolleywire might be a way to get rid of the diesel components entirely.

1500V equipment is even cheaper for low performance than 25kV equipment.

The entire route between Cerbere and Calais is electrified throughout so there is no need for diesel traction.

 

[HSTEd]

Might need slightly smaller insulators, but the conductors themselves might have to be heavier to carry the higher current. I would have thought there is very little in it, unless you have some evidence to say otherwise. Certainly not enough to justify the extra complication of a different voltage in a country like the UK which doesn't have to provide for it already.

1500V requires what amounts to overgrown tramway equipment, and such products are widely available on the market already and could thus be more easily deployed. (See Furrer and Frey's 'LIRACOS' product range)
25kV equipment for low performance applications is rather harder to come by and is mostly just used in stabling roads at the present time.

And I was primarily referring to the case of SNCF, which has significant 1500V territory already.
--- old post above --- --- new post below ---

I didn't think TGV power cars were all capable of using any electrified route in France, don't the long-distance Eurostars (which are a TGV of sorts) have to be formed of special sets with an extra voltage mode?

As far as I know all TGV (apparently apart from Eurostars) sets are atleast bi-current because there is significant 1500V territory in the south of France and they would therefore be effectively restricted to purely LGV operations south of Paris as they would be unable to access any classic lines.

Since most Eurostars operate purely north of Paris they were mostly built without 1500V compatibility, but there are apparently a set of Eurostars used for Avignon trains that originally had all four systems (750V, 1500V, 3000V and 25kV) although they are obviously now only tri-current because they have lost the 750V capability.

(I don't normally count Eurostars as proper TGVs myself)