Exeter to Waterloo Electrification?

[coppercapped]

I knew Basingstoke very well, changing trains there frequently both before and after resignalling. I doubt a new route for the freights around the north side of the station using the old infrastructure would gain any speed as it was rather a tortuous route to clear the station buildings, and pass over the narrow Vyne Road and Chapel Hill bridges, which couldn't be widened easily. Platfom 4 at the west end is also very narrow, only just compliant for a side platform, so there would likely be trouble converting it to an island at that end and there's clearly no room on the bridge structures to accommodate a platform on the other side of the track, limiting potential length. I think such a line would be useful however, but mainly for up freights and Crosscountry trains, the latter also usually being fairly short so possible to accommodate in a platform likely to be shorter than the 12-car capability of the other through platforms.

A down freight can cross to either the down fast or down slow and if it is using the fast to the west to Worting Jn as part of a long 'weave', the current layout allows a down train on the fast to cross to the down slow in parallel with the freight movement (40MPH crossover, perfect for a stopping passenger train - the majority of trains remember). Whilst a down freight is crossing, the layout also allows an unconstrained up arrival in either up platform (3 or 4) with a clear safe overlap swung over to the Reading branch. If expedient, the signalling allows trains from the Reading direction to run through either up platform (3 or 4) in the down direction and cross over to the down side to the west of the station. This can allow a down freight to run through at the same time as a down fast platform (2) arrival.

I think the idea of AC electrification via Laverstock Loop is primarily about maintaining an alternative equally capable freight route from the port to Basingstoke. That route today is the preferred alternative and can be used with the existing diesel haulage either for planned Winchester route engineering closures, even for short-term reactive diversions. If the freight is converted to electric haulage, both routes need to be AC electrified as there would be insufficient spare diesels remaining to substitute on all traffic.

Your idea to move the junction west of the station has many merits in reducing conflict but I think to make it really useful, at least two additional tracks would be required and necessary widening of the west end road underbridges would make it difficult and expensive. Both roads are rising steeply under the railway from south to north and are already height limited for road vehicles. Widening the railway would make the road vehicle clearance even worse unless the new railway spans were built a little higher than the existing track level. The new independent Reading platforms themselves might then have to be a little higher than the rest of the station to remain broadly level, although that could help with constructing passenger access beneath them. A higher platform level through the Reading lines would provide a good launching point for an additional grade separation flyover to the west, which could also be used by the terminating stopping services from Waterloo to avoid fast line conflicts as they shunt and reverse as well as allow the down freights to cross over to the slow (or the fast depending on which line they were taking west of Worting Junction). The up freights would continue to use Battledown flyover.

I was referring to the use of any re-instated GWR line to the north of the station as being for freight use only. It needs neither the conversion of platform 4 to an island, nor is the speed of the train a limitation as the train is no longer occupying the SouthWestern's Up Slow line. Passenger trains can continue to be routed as present. Pathing an hourly train in each direction through a short length of single track should not be a problem, but if it is then a 750m long passing loop can be arranged on the site of the engineers' siding.

Regarding motive power. There were 46 Class 92s built of which about 10 have been exported and some 15 belong to GBRf and Europorte. Some of these could possibly be re-instated for use on the Eastleigh route when the Salisbury route is blocked, but if the main route is via Salisbury to electrified terminals in the Midlands and points North then I suspect a batch of purpose built AC freight locomotives, possibly developments of the Class 88, would be built. By then some of the earlier Class 66s will be getting long in the tooth with low residual value and could be replaced quite economically, but Freightliner use a lot of the Class 70s on the container trains so maybe this calculation will not work unless the 70s are cascaded.

 

[Philip Phlopp]

Anyway, is there potential for the dismantled DC equipment to be reused elsewhere as an infill scheme, or would it be retained for spares to replace older equipment that is not being converted to AC overhead when that need arises?

Yes and no.

If it's newer equipment, then yes. There's lots of DC equipment which is nudging the 'life expired' stage in its life cycle, which is why we're eyeing AC replacement where possible.

 

[GRALISTAIR]

There's lots of DC equipment which is nudging the 'life expired' stage in its life cycle, which is why we're eyeing AC replacement where possible.

IMHO - All the more reason why we need a "PILOT SCHEME" asap.

 

[Tio Terry]

Regarding the Basingstoke - Southampton AC electrification, I believe that the Bournemouth - Weymouth section was DC electrified with a low specification circa 1988, possibly making this the youngest DC section on BR/NR metals.

Would it be possible to electrify AC all the way to Weymouth, with the DC equipment being dismantled and reused to extend the DC system from Ormskirk to Preston and Kirkby to Wigan Wallgate?

It's very doubtful that the ORR will allow any significant extension of 3rd rail systems in the future. There are a number of current laws that such systems breach. It may be possible to get a few short in-fill jobs done but their policy is no more.

 

[GRALISTAIR]

Would it be possible to electrify AC all the way to Weymouth, with the DC equipment being dismantled and reused to extend the DC system from Ormskirk to Preston and Kirkby to Wigan Wallgate?

One of my favourite sayings - which I claim credit for is: "Anything is possible with enough time and money spent. Not everything is desirable"

25KV AC is the future and both schemes you mention scream out for AC from the gitgo with dual voltage units.

 

[HowardGWR]

Going back to the OP post, we are, I assume, agreed that Worting Junction to Exeter electrification, if approved, has to be AC. I can't see that happening unless, as I wrote earlier, the line is dualled where single, and that surely has to be done before wiring, Combine this with the alternative multi modals needing two Spine routes that should both be wired, this really amounts to the total electrification of the former Southern Railway except the two Devon branches (Exmouth and Barnstaple, perhaps Okehampton later). It would seem odd, as someone else wrote, to leave Southampton to Weymouth as third rail.

That seems one big project to me.

 

[MarkyT]

I was referring to the use of any re-instated GWR line to the north of the station as being for freight use only. It needs neither the conversion of platform 4 to an island, nor is the speed of the train a limitation as the train is no longer occupying the SouthWestern's Up Slow line. Passenger trains can continue to be routed as present. Pathing an hourly train in each direction through a short length of single track should not be a problem, but if it is then a 750m long passing loop can be arranged on the site of the engineers' siding.

As an extra option for routing freights I have no problem with that at all. If two freights turn up at the same time then the down one could still go through the station in parallel as it can now if there's a path in real time through any of the other platforms. It will still have to cross both ups and the down fast at the west end of the station if the trains are still going to be routed via Winchester though, but it gives another option in real time to keep things moving if another route is already set across the east junction.

Regarding motive power. There were 46 Class 92s built of which about 10 have been exported and some 15 belong to GBRf and Europorte. Some of these could possibly be reinstated for use on the Eastleigh route when the Salisbury route is blocked, but if the main route is via Salisbury to electrified terminals in the Midlands and points North then I suspect a batch of purpose built AC freight locomotives, possibly developments of Class 88, would be built.

It strikes me that adding DC capability should not be a great problem for a new freight locomotive, just like the 92s, which are getting fairly old anyway now and are not known for their high reliability. It has been stated that modern solid state traction control systems run natively on DC in the high hundreds of volts. The big AC step-down transformer and a rectifier delivers this power in this form to the control system which could just as easily obtain it from a DC 3rd rail infrastructure or a diesel alternator set.

An electro-diesel like the 88 with the last mile shunting diesel engine could also have 3rd rail shoes, giving it an additional mid power range capability on 3rd rail routes (including channel tunnel routes), which, although not as high as the AC rating, could be significantly better at keeping up with other traffic than the loco might achieve on its comparatively small engine! The 88 has a 700kW diesel and is rated at 4MW on AC. On DC it might manage say 2.5MW just as the cl 92 rating varies according to supply type and capability. Potentially that could be a very flexible locomotive. On the LSWR, Such a freight hauler, combined with a uniform fleet of dual voltage longer distance passenger trains could allow 'easy' rural stretches of fast mainline west of Basigstoke to be converted to AC first whilst leaving the more complex hubs on DC. I've mentioned this before for the Southampton area, where such a strategy could continue to allow DC only Southern trains to work in from the Brighton direction without there being many miles of complex dual electrified territory with it's current return and earthing challenges.
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Would it be possible to electrify AC all the way to Weymouth, with the DC equipment being dismantled and reused to extend the DC system from Ormskirk to Preston and Kirkby to Wigan Wallgate?

With a dual voltage fleet, if it is accepted that trains may switch systems more than once during a journey, there's no reason why the isolated section west of Bournemouth or Pool could not be AC equipped to improve its power capability.

I don't know whether the recovered DC equipment would have any value for reuse elsewhere, but any significant extension of third rail is very much frowned on today for safety reasons as others have said. The only exception might be a very well segregated urban system such as a metro in tunnel or on viaduct and even there if it was completely isolated system partial shielding like on DLR would probabaly be favoured. The sub-station kit might alternatively be useful for a 750VDC OHLE tramway, possibly?
--- old post above --- --- new post below ---

Going back to the OP post, we are, I assume, agreed that Worting Junction to Exeter electrification, if approved, has to be AC. I can't see that happening unless, as I wrote earlier, the line is dualled where single, and that surely has to be done before wiring

I don't think that's a given. AC Electrification of the existing infrastructure west of Salisbury could be a lot easier for OHLE clearance through former double track bridges and tunnels. That could make subsequent further doubling more difficult to an extent, but at least new stanchions in open areas of single track could be placed clear of the likely location of a future second track.

 

[D1009]

I don't think that's a given. AC Electrification of the existing infrastructure west of Salisbury could be a lot easier for OHLE clearance through former double track bridges and tunnels. That could make subsequent further doubling more difficult to an extent, but at least new stanchions in open areas of single track could be placed clear of the likely location of a future second track.

That seems madness to me. Surely the additional capacity that double track would give, if taken up would make a far better case for electrification?

 

[MarkyT]

That seems madness to me. Surely the additional capacity that double track would give, if taken up would make a far better case for electrification?

I don't think electrification beyond Salisbury would stand up at all with current traffic, even if Basingstoke - Salisbury was done as part of a freight diversionary route. The LSWR might make the grade as a diversionary route If Devon and beyond was wired via Bristol or Westbury.

 

[SpacePhoenix]

With a dual voltage fleet, if it is accepted that trains may switch systems more than once during a journey, there's no reason why the isolated section west of Bournemouth or Pool could not be AC equipped to improve its power capability.

If Poole-Weymouth were to be done off a single feed (if that's possible), in theory would it be able to handle every scheduled train being a 10 car 444 and any freight trains (not sure if the one from Wool is the only one) running off AC as well?

If Waterloo-Weymouth and Waterloo-Exeter were converted to AC, could a cord be added to allow Weymouth-Exeter as a direct service without reversing?

 

[edwin_m]

It strikes me that adding DC capability should not be a great problem for a new freight locomotive, just like the 92s, which are getting fairly old anyway now and are not known for their high reliability. It has been stated that modern solid state traction control systems run natively on DC in the high hundreds of volts. The big AC step-down transformer and a rectifier delivers this power in this form to the control system which could just as easily obtain it from a DC 3rd rail infrastructure or a diesel alternator set.

I think the problem here would be the amount of current drawn through the DC system which is close to its limits anyway. As far as I know 92s aren't cleared on the SW main line, and upgrading for heavy freight probably involves a lot of extra and replacement supply equipment. Performance may also be reduced due to current limits.

We're being told that upgrading to 25kV is a similar price to replacing the existing life-expired equipment, in which case if a power upgrade is needed too then it's almost certainly better to go to 25kV anyway.

 

[Philip Phlopp]

That seems madness to me. Surely the additional capacity that double track would give, if taken up would make a far better case for electrification?

Not only but also.

If the route is upgraded to twin track throughout, then consideration must be given to future electrification and W12 gauge clearance with new bridges, properly relocated signalling equipment (much of it presently sits in the abandoned second trackbed) and correctly planned platforms.

If the route is to be electrified without redoubling, then sensible location of masts and bases will be important, with twin track cantilevers employed in locations where track slews would be needed in future, passive provision for S&Cs and the like. Moving masts and installing new bases is a complicated exercise, moving small part steelwork on a TTC or portal is easy.

I'd also like to see masts being installed if/when redoubling work is done - we know approximate mast spacing - between 50m and 70m (ideally towards the lower figure) so for a lot of the route, installing mast bases at the same time as redoubling could be a massive time and cost saver, even if it requires a little additional expenditure in the short term.

 

[swt_passenger]

If Poole-Weymouth were to be done off a single feed (if that's possible), in theory would it be able to handle every scheduled train being a 10 car 444 and any freight trains (not sure if the one from Wool is the only one) running off AC as well?

Why does Weymouth supposedly need 10 car 444s as a matter of routine? It seems to be regularly suggested here but where's the demand? Where's the spare rolling stock?

The freight to Wool hasn't run in months, and possibly never will again. There is nothing else.

If Waterloo-Weymouth and Waterloo-Exeter were converted to AC, could a cord be added to allow Weymouth-Exeter as a direct service without reversing?

Why would electrification of the two geographically separate lines result in an increased likelihood of the Heart of Wessex line being electrified? Is the latter line even on the electrification radar at all?

ISTM that a new chord is unlikely whether electrified or not, because there is an existing route by reversing at Pen Mill that isn't much of a detour, and gives additional access to Yeovil.

 

[MarkyT]

I think the problem here would be the amount of current drawn through the DC system which is close to its limits anyway. As far as I know 92s aren't cleared on the SW main line, and upgrading for heavy freight probably involves a lot of extra and replacement supply equipment. Performance may also be reduced due to current limits.

We're being told that upgrading to 25kV is a similar price to replacing the existing life-expired equipment, in which case if a power upgrade is needed too then it's almost certainly better to go to 25kV anyway.

I'm just suggesting that an electric loco with 3rd rail capability would be extremely flexible, able to work through different areas during a phased changeover in the south. Some small areas of higher complexity where immediate wiring would be very difficult could be left as DC at least at first whilst out on the higher speed simple sections between major settlements the performance benefits of AC could be exploited. For my Southampton suggestion, DC would be retained south of (say) Southampton Airport Parkway, a station where (I think) all passenger trains stop so potentially ideal for changeover. Freights would changeover on the move in this scenario. For DRS or any other operator, 88s with shoes could be useful for channel tunnel traffic over classic lines to Dollands Moor or anywhere else on the Southern, subject to current limits as necessary on DC. My Southampton idea would incorporate some strengthening as necessary of the remaining Southampton area DC to cover conversion of freight from 100% diesel today to electric clearly, but that would be limited to the area concerned. North of the changeover point all DC equipment would be removed in favour of the new AC OHLE with it's significant substation savings and better capability. That's where it is really needed on fast and hilly sections where all trains are drawing significant power.

 

[Taunton]

Why does Weymouth supposedly need 10 car 444s as a matter of routine?

I've never encountered a 10-car at Weymouth, always 5-car. But also, this 5-car now seems to be run unaltered right through to Waterloo every time I've used it, so there aren't many from Weymouth, but standees by the time you are leaving Basingstoke. The old 4-REP/TC arrangement divided at Bournemouth was so much more sensible, as the formation reflected the loads on each stage.

 

[Philip Phlopp]

I'm just suggesting that an electric loco with 3rd rail capability would be extremely flexible, able to work through different areas during a phased changeover in the south. Some small areas of higher complexity where immediate wiring would be very difficult could be left as DC at least at first whilst out on the higher speed simple sections between major settlements the performance benefits of AC could be experienced. For my Southampton suggestion, DC would be retained south of (say) Southampton Airport Parkway, a station where (I think) all passenger trains stop so potentially ideal for changeover. Freights would changeover on the move in this scenario. For DRS or any other operator, 88s with shoes could be useful for channel tunnel traffic over classic lines to Dollands Moor or anywhere else on the Southern, subject to current limits as necessary on DC. My Southampton idea would incorporate some strengthening as necessary of the remaining Southampton area DC to cover conversion of freight from 100% diesel today to electric clearly, but that would be limited to the area concerned. North of the changeover point all DC equipment would be removed in favour of the new AC OHLE with it's significant substation savings and better capability. That's where it is really needed on fast and hilly sections where all trains are drawing significant power.

The problem you have is that any locomotive using third rail would have a significant power draw; leaving ports in the south, they'll spend a lot of time accelerating a heavy train from a standing start, which is very power intensive, and then having to work in and out of commuter services, they'll spend a lot of time stopping and starting, which is again power intensive.

To actually use an electric locomotive on DC, the train length and weight would be seriously curtailed - in some circumstances, it's possible that an electric (DC) service would have lower capacity than a diesel, certainly lower than a Class 70 if maybe not a Class 66.

 

[swt_passenger]

I've never encountered a 10-car at Weymouth, always 5-car. But also, this 5-car now seems to be run unaltered right through to Waterloo every time I've used it, so there aren't many from Weymouth, but standees by the time you are leaving Basingstoke.

There are still many peak services that are strengthened to ten car somewhere on route, but if you travel mainly off-peak you'll stay as a 5 car throughout. But strengthening more up trains to 10 car from Bournemouth would be the answer to that, not starting them back from Weymouth as 10 car.

 

[The Ham]

I've never encountered a 10-car at Weymouth, always 5-car. But also, this 5-car now seems to be run unaltered right through to Waterloo every time I've used it, so there aren't many from Weymouth, but standees by the time you are leaving Basingstoke. The old 4-REP/TC arrangement divided at Bournemouth was so much more sensible, as the formation reflected the loads on each stage.

There are still many peak services that are strengthened to ten car somewhere on route, but if you travel mainly off-peak you'll stay as a 5 car throughout. But strengthening more up trains to 10 car from Bournemouth would be the answer to that, not starting them back from Weymouth as 10 car.

I would have to agree with swt_passenger on this, as the issue of capacity isn't between Weymouth and Bournemouth rather between Basingstoke and London. As such, why have extra units than you need just so they can run around empty.

Yes, there maybe a case for better electrification, but that has to stand on it's own merits. One possible option could be if there was a need to provide a direct coastal service from west of Bournemouth through to east of Southampton (not that I am saying that there is).

 

[MarkyT]

I've never encountered a 10-car at Weymouth, always 5-car. But also, this 5-car now seems to be run unaltered right through to Waterloo every time I've used it, so there aren't many from Weymouth, but standees by the time you are leaving Basingstoke. The old 4-REP/TC arrangement divided at Bournemouth was so much more sensible, as the formation reflected the loads on each stage.

The ability to run 10 car 444 or up to a 12-car 450 all the way to to Weymouth under AC or a strengthened DC supply would be useful, even if that wasn't the routine during normal off-peak working. With 444s today it is possible to join the Weymouth 5 car unit to another at Bournemouth, mirroring the old REP/TC operations. I'm surprised at your experience of the 5 cars running all the way to Waterloo. I would have expected strengthening at Bournemouth to have been routine, especially in the weekday peaks.

 

[swt_passenger]

The ability to run 10 car 444 or up to a 12-car 450 all the way to to Weymouth under AC or a strengthened DC supply would be useful, even if that wasn't the routine during normal off-peak working.

They already can run occasional lengthened trains, under controlled conditions.

With 444s today it is possible to join the Weymouth 5 car unit to another at Bournemouth, mirroring the old REP/TC operations. I'm surprised at your experience of the 5 cars running all the way to Waterloo. I would have expected strengthening at Bournemouth to have been routine, especially in the weekday peaks.

It is very much routine in the peaks. In the morning some 10 car 444s start at Poole, some are strengthened at Bournemouth, and some 5 cars combine into 10 car at Southampton, and at least one 10 car starts from Parkway. By Winchester there are also 12 car 450s that have joined the route from Portsmouth via Eastleigh, for significant capacity at Basingstoke.

In the pm peak, there are 9 x 10 car departures in a row on the Weymouth route, half hourly from 1535 until 1935. (they were much easier to find in the CWNs.)

 

[HowardGWR]

The ability to run 10 car 444 or up to a 12-car 450 all the way to to Weymouth under AC or a strengthened DC supply would be useful, even if that wasn't the routine during normal off-peak working. With 444s today it is possible to join the Weymouth 5 car unit to another at Bournemouth, mirroring the old REP/TC operations. I'm surprised at your experience of the 5 cars running all the way to Waterloo. I would have expected strengthening at Bournemouth to have been routine, especially in the weekday peaks.

My wife is travelling from Dorchester to Poole at the moment and there is very light loading between them, even in the peak. Might be different in summer. 5 car class 444 is plenty. I assume they can do what the 159s do at Salisbury. Only takes 3 mins max, - I've timed them.

On the Weymouth to Exeter without reversing, the chord to Yeovil Junction is already there (built in the dark ages) but no track ever laid on it. Now, the enthusiasts have straddled it with their playground, so they would have to be given the push. Dorset County Council has had it specified for connecting in its Transport Plan for over a decade.

 

[The Ham]

That seems madness to me. Surely the additional capacity that double track would give, if taken up would make a far better case for electrification?

Although I can see the benefit of more double track even 4tph (two to Waterloo, one for diversions and one local service) could be maintained on the line without having to fully redouble the line. Yes redoubling would mean that there could be extra services and/or provide provision for a train that was a few minutes late so it wouldn't miss it's slot on the line, but a few more and/or longer passing loops could provide much of the same advantage at a lower cost.

The thing that would make a better case for electrification would be more services (likely only possible after Crossrail 2 is built - i.e. post 2030), as there is no point having a line capable of, say, 10 trains an hour in each direction yet at most normally only have two or maybe even three an hour because of constraints elsewhere (mostly towards London).

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One thought on Electrification west of Basingstoke, is there any advantage of extending the Basingstoke stoppers to Salisbury and remove some of the more minor stops on the current Salisbury services?

In doing so it would only increase capacity between Basingstoke and Salisbury but could speed up journey times on the fast services. Yes the stations which were removed from the existing Salisbury services could see an increase in journey times for many of their direct services to London by about 25 minutes, although this would be offset (for some at least) by a more frequent service (i.e. at least half hourly service rather than hourly service) and the ability to change to a faster train at Basingstoke which would reduce the increase in journey time.

It would also mean that travel between places such as Andover and Farnborough would be a lot easier and quicker which may attract more passengers.

 

[MarkyT]

The problem you have is that any locomotive using third rail would have a significant power draw; leaving ports in the south, they'll spend a lot of time accelerating a heavy train from a standing start, which is very power intensive, and then having to work in and out of commuter services, they'll spend a lot of time stopping and starting, which is again power intensive.

To actually use an electric locomotive on DC, the train length and weight would be seriously curtailed - in some circumstances, it's possible that an electric (DC) service would have lower capacity than a diesel, certainly lower than a Class 70 if maybe not a Class 66.

The 92 manages 4MW on DC apparently vs 5MW on AC (source: Wikipedia), but can only exert a maximum of up to 400kN of tractive effort in short-term boost mode. The cl 70 has an engine power of only 2750kW yet can exert extraordinary 534kN tractive effort, despite being only 9t heavier on the same number of axles. I haven't any other sources but Wikipedia doesn't, as for these two classes, always include separate figures for starting vs running tractive effort so perhaps the cl. 92 starting figure is actually rather better and the cl. 70 is quoted for starting. I really don't know.

Vosloh cl. 68s are quoted as follows:
Power output at 1,740 rpm: 2,800 kW (engine presumably)
Tractive effort: 317 kN

Vosloh cl. 88s by contrast are:
Power output: 4MW electrical, 0.7 MW diesel
Tractive effort: more than 475 kN (starting), 317 kN (running)

(suggesting the starting figure for a 68 should be higher since they're both based on the same UK tailored Eurolight design, known as Euro Dual for the electro-diesel variant).

Another approach for gaps in AC, whether covered by DC or having no electrification whatsoever would be to have a much more powerful electro-diesel locomotive (more so than the than the 88 anyway). In addition to the UK locos, Vosloh are also supplying some Euro Duals to South Africa with a 2.8MW diesel like our 68s. Alternatively I wonder if GE could also add AC capability to their UK heavy freight CoCo diesel design. For a UK BoBo I can understand a bigger diesel, as well as main electrical transformer, might be pushing the boundaries as far as axle load and bodyshell space is concerned, but for a CoCo that ought be less of a problem. There should really be no argument about 'dragging heavy diesel lumps around dead under the wires'. Without a heavy diesel many electric locos for freight have to be ballasted anyway, as the modern electrical equipment simply isn't heavy enough. High axle weight (up to the desired route availability limit) continues to be important to achieve the tractive effort necessary for starting and accelerating heavy trains. An interesting extension to this idea is a class 68 and 88 lash-up. If designed to be so capable with compatible control and power transfer cables, such a mighty beast could be capable of an AC power output of 8MW over eight axles, all supplied through the pantograph on the 88. Away from the wires, the small engine of the 88 combined with the large one on the 68 could together output 3.5MW which could also be put down evenly through all eight axles. Such superpower might allow longer trains up to (say) 1000m to run on the electric spine and connected routes whilst also improving performance over today's diesels.

 

[paul1609]

The 92 manages 4MW on DC apparently vs 5MW on AC (source: Wikipedia), but can only exert a maximum of up to 400kN of tractive effort in short-term boost mode. The cl 70 has an engine power of only 2750kW yet can exert extraordinary 534kN tractive effort, despite being only 9t heavier on the same number of axles. I haven't any other sources but Wikipedia doesn't, as for these two classes, always include separate figures for starting vs running tractive effort so perhaps the cl. 92 starting figure is actually rather better and the cl. 70 is quoted for starting. I really don't know.

Vosloh cl. 68s are quoted as follows:
Power output at 1,740 rpm: 2,800 kW (engine presumably)
Tractive effort: 317 kN

Vosloh cl. 88s by contrast are:
Power output: 4MW electrical, 0.7 MW diesel
Tractive effort: more than 475 kN (starting), 317 kN (running)

(suggesting the starting figure for a 68 should be higher since they're both based on the same UK tailored Eurolight design, known as Euro Dual for the electro-diesel variant).

Another approach for gaps in AC, whether covered by DC or having no electrification whatsoever would be to have a much more powerful electro-diesel locomotive (more so than the than the 88 anyway). In addition to the UK locos, Vosloh are also supplying some Euro Duals to South Africa with a 2.8MW diesel like our 68s. Alternatively I wonder if GE could also add AC capability to their UK heavy freight CoCo diesel design. For a UK BoBo I can understand a bigger diesel, as well as main electrical transformer, might be pushing the boundaries as far as axle load and bodyshell space is concerned, but for a CoCo that ought be less of a problem. There should really be no argument about 'dragging heavy diesel lumps around dead under the wires'. Without a heavy diesel many electric locos for freight have to be ballasted anyway, as the modern electrical equipment simply isn't heavy enough. High axle weight (up to the desired route availability limit) continues to be important to achieve the tractive effort necessary for starting and accelerating heavy trains. An interesting extension to this idea is a class 68 and 88 lash-up. If designed to be so capable with compatible control and power transfer cables, such a mighty beast could be capable of an AC power output of 8MW over eight axles, all supplied through the pantograph on the 88. Away from the wires, the small engine of the 88 combined with the large one on the 68 could together output 3.5MW which could also be put down evenly through all eight axles. Such superpower might allow longer trains up to (say) 1000m to run on the electric spine and connected routes whilst also improving performance over today's diesels.

That's on South eastern dc not Southwestern dc! If you don't believe there's a difference take a trip on a 375 to Dover via Tonbridge and compare the performance to a 444 on the Bournemouth line!

 

[Philip Phlopp]

The 92 manages 4MW on DC apparently.

If 4MW at 750V DC is available - that's not always the case, which is the point I'm trying desperately to make.

You could have the most advanced DC capable locomotive, but if the electrical section only has 750kW of power available before tripping, your multi million pound locomotive will either be sitting down with computer errors, or sitting down because it can't start its train.

It's not a problem unique to third rail - we have 25kV OLE with capacity issues, but we can fix that by installing an ATF supply system and adding an extra cable on existing OLE structures - a relatively easy and inexpensive job, we can also plan for an ATF installation on DC to AC conversion, giving a huge amount of headroom for future expansion, including lots of very fast, powerful freight locomotives.

To do the same on DC will be either prohibitively expensive - probably well over a billion pounds, or technically impossible, in that we can't get enough power to some trains without overheating and beginning to melt the third rail.

 

[MarkyT]

If 4MW at 750V DC is available - that's not always the case, which is the point I'm trying desperately to make.

. . . To do the same on DC will be either prohibitively expensive - probably well over a billion pounds, or technically impossible, in that we can't get enough power to some trains without overheating and beginning to melt the third rail.

Fully accept all that, and I was certainly never implying that the complete DC network could or should be upgraded to suite freight operations, merely that in some relatively small areas (such as my suggested Southampton area) DC could be retained and upgraded whilst the vast majority of the route north to Basingstoke and beyond could be converted to AC.

More powerful electro-diesels for freight seems then to be the most appropriate solution in the light of your comments. Whilst the dual voltage passenger trains could switch back from AC to DC through that area, freight in that case would turn on their engines instead, avoiding any additional load on the DC. Just to be clear in my last post I was suggesting AC/Diesel bi-mode operation in that case rather than those locos also having DC shoes! If you had a big enough diesel on board then a DC capability would not be required clearly.

That could also allow diversions via Laverstock without wiring which would put the mockers on going any further along that line.

 

[The Ham]

Trains needing to be at stations to raise their pans will be good news for places like Newbury as after the introduction of the AT300's every train from Cornwall will be stopping there. As I would suggest that a run from Cornwall to Newbury is a lot longer with a much greater risk of having tree debris stuck in it than a run from London to Basingstoke.

 

[Kentish Paul]

Trains needing to be at stations to raise their pans will be good news for places like Newbury as after the introduction of the AT300's every train from Cornwall will be stopping there. As I would suggest that a run from Cornwall to Newbury is a lot longer with a much greater risk of having tree debris stuck in it than a run from London to Basingstoke.

I understood that the changeover could be done on the move.

 

[Philip Phlopp]

I understood that the changeover could be done on the move.

It can, but there are good reasons why you wouldn't necessarily want to do so.

I would probably want a CCTV camera in the pantograph well, allowing the driver to confirm it's safe to raise the pantograph whilst moving, before being happy with an on-the-move transition, but that won't be difficult to achieve, given IEP has CCTV monitors in the driver's cab and there will be pantograph/OLE monitoring equipment installed on some sets anyway.

 

[Kentish Paul]

It can, but there are good reasons why you wouldn't necessarily want to do so.

I would probably want a CCTV camera in the pantograph well, allowing the driver to confirm it's safe to raise the pantograph whilst moving, before being happy with an on-the-move transition, but that won't be difficult to achieve, given IEP has CCTV monitors in the driver's cab and there will be pantograph/OLE monitoring equipment installed on some sets anyway.

Thanks for that. Even so Eurostar did it for years without CCTV at both Sandling and Fawkham Junction when changing from 3rd rail to OHLE. Only hiccup I remember was the train that lost its pantograph on the signal gantry at Sandling after it failed to lower.

More interesting to me is the driver of a train approaching Newbury from London getting all the diesels started up on the move before the wire runs out. I assume this would be automatic to some extent.