Devon & Filton banks - could electrification on uphill sections be possible?

[455driver]

There are at least four 400kV circuits going as far west as Luxulyan (which is one of the reasons it was proposed as a site for a PWR during the 80s).

A 400kV circuit could handle a single phase traction load with no problem at all, and its sufficiently close that you could put the substation adjacent to the power line and run 25kV across country if necessary.

Substations are the biggest expense when carrying out electrification schemes and people are proposing putting 2 or 3 of them to supply short sections where you could just electrify the lot and have one substation!
Where is the cost savings coming from?

 

[HSTEd]

Substations are the biggest expense when carrying out electrification schemes and people are proposing putting 2 or 3 of them to supply short sections where you could just electrify the lot and have one substation!
Where is the cost savings coming from?

But you only need one.
As you have access to the supergrid phase imbalances are essentially irrelevant - which means you can supply 25-0-25kV from a single phase.
You might want at least one autotransformer in each individual section but otherwise the single substation could service sections spread over something like a hundred kilometres.

You just need a single medium voltage pole line linking each section together.

 

[The Ham]

I am sure I recall there was a study done about 70 years ago or more that suggested rather than conventional wisdom of starting in London and electrifying to Penzance, actually start in the South West of England and work forwards exactly because of the Devon Banks.

I love the idea but politicians will not I fear.

Given the lack of trains on the B&H compared with around Exeter and Plymouth and the fact that the new trains are bi-modal, such a suggestion would be quite logical to undertake.

For instance; electrify the local services which run to and through Exeter and Plymouth which would result in being able to replace several DMU's (and potentially with longer EMU's which would further increase capacity) whilst providing power to the long distance services where they need it most. In doing so although the costs may be broadly the same as wiring up between Newbury and Plymouth the benefits would likely be much greater.

 

[MarkyT]

Given the lack of trains on the B&H compared with around Exeter and Plymouth and the fact that the new trains are bi-modal, such a suggestion would be quite logical to undertake.

So HSTed's single new supergrid node placed somewhere near Plymouth could feed all the way back to Newton Abbot, then at a later stage have a high speed but fairly steeply graded cut-off to Exeter added, then the east end of Cornwall, and finally a continuation of new high speed alignment from near Newton Abbot to Plymouth. At all stages the strategy would add some benefit for both long distance and local services.

 

[edwin_m]

The Milwaukee Road (CM&StP) electrified its western extension to Seattle in two long sections, over the Rockies and Cascades, in 1916. The rest of the line was steam/diesel worked.
The electrified sections continued in service until 1972, when the equipment became life expired.
The whole route (apart from the odd section worked as a branch from other lines) is closed and gone now, after the Milwaukee Road's bankruptcy in 1980.
https://en.wikipedia.org/wiki/Chicago,_Milwaukee,_St._Paul_and_Pacific_Railroad

There were quite a number of similar electrification schemes in more mountainous areas of the States before WW2. I believe the reasons were some combination of the better performance of electric traction; the reduction of dangerous levels of pollution in tunnels; and the availability of hydroelectric power. Steam locomotives had to be swapped every few hundred miles anyway so the fact that one of these legs was electric didn't increase journey times or operating costs. However these advantages don't seem to have applied so much in flatter areas and there have never been any end-to-end electrifications of main lines in North America, other than in the Northeast where traffic train sizes and speeds are much more similar to Europe.

Where the sections concerned are still open to traffic they have all been de-electrified, having essentially been made redundant by dieselisation. The diesel could run for thousands of miles with helpers added on mountainous sections if needed. It produced far less pollution so could operate safely in most tunnels, sometimes with extra ventilation. And the lower costs of the diesel and the removal of the overhead line outweighed any performance advantage of the electric, especially as time-critical passenger traffic was becoming less important.

The situation has always been different in Europe where speed is more important and there are far more trains per mile of track so a system that reduces operating costs but requires more fixed infrastructure is more attractive.

 

[HSTEd]

There were quite a number of similar electrification schemes in more mountainous areas of the States before WW2. I believe the reasons were some combination of the better performance of electric traction; the reduction of dangerous levels of pollution in tunnels; and the availability of hydroelectric power.

Apparently a key factor in the case of the Milwaukee Road was that during the winter it would get so cold that it was difficult to get good steam production from the locomotive as they would loose huge amounts of heat to the environment.
Additionally if a locomotive had to dump a fire for whatever reason or it went out overnight it was almost impossible to relight it.
These are not problems experienced with electric locomotives.

Where the sections concerned are still open to traffic they have all been de-electrified, having essentially been made redundant by dieselisation. The diesel could run for thousands of miles with helpers added on mountainous sections if needed. It produced far less pollution so could operate safely in most tunnels, sometimes with extra ventilation. And the lower costs of the diesel and the removal of the overhead line outweighed any performance advantage of the electric, especially as time-critical passenger traffic was becoming less important.

The Milwaukee Road indeed had two sections of overhead line, with a gap between them - the system was life expired however General Electric had offered to underwrite new locomotives and overhead line equipment, even electrification of the central section so there would be one long continuous electric run.
However the railway's board had concluded that their Transcontinental operatino was an anchor that was dragging the railway under and shut the entire thing down, turning themselves back into a regional short line operator.

Tragically it later transpired, when it was too late to do anything, that the expenses of the electric sections, and of the Transcontinental operation more generally, had been double entered. Far from being an anchor it had been the only thing keeping the company afloat.

But by then the scrappies had taken away all the copper - which coincided with a crash in the copper price so they didn't even get the money they had hoped from the decommissioning.

 

[Taunton]

I think the GWR came up with this or similar in the 30s - I suspect because government money was being made available. Can't easily find a reference online, sorry.

The study was in 1938, for the section from Taunton (of course) to Penzance. That's where things start to get a bit hilly. The voltage was to be 3,000v DC (same as nowadays in Belgium, Italy and Russia). Charles Merz, of electrical power consultants Merz & McClellan wrote the report for the GWR. The report is in the National Archives

http://discovery.nationalarchives.gov.uk/details/r/C1927241

Not all trains in steam loco days took an assisting engine from Newton to Plymouth. The Cornish Riviera was nonstop to Plymouth, and up to about 9 coaches a Castle would go for it on its own, in good weather maybe with a couple more.

 

[GRALISTAIR]

I am sure I recall there was a study done about 70 years ago or more that suggested rather than conventional wisdom of starting in London and electrifying to Penzance, actually start in the South West of England and work forwards exactly because of the Devon Banks.

I love the idea but politicians will not I fear.

The study was in 1938, for the section from Taunton (of course) to Penzance. That's where things start to get a bit hilly. The voltage was to be 3,000v DC (same as nowadays in Belgium, Italy and Russia). Charles Merz, of electrical power consultants Merz & McClellan wrote the report for the GWR. The report is in the National Archives

http://discovery.nationalarchives.gov.uk/details/r/C1927241

Not all trains in steam loco days took an assisting engine from Newton to Plymouth. The Cornish Riviera was nonstop to Plymouth, and up to about 9 coaches a Castle would go for it on its own, in good weather maybe with a couple more.

Thanks for that - I knew I had heard or read about somewhere in my past.

 

[Hartington]

The USA wasn't the only place that had electrification in short bursts. In New Zealand the sections were extremely short; the Otira Tunnel and Christchurch/Lyttelton on the South Island neither more than about 15 miles point to point.

 

[Cliveblackpool]

There are at least four 400kV circuits going as far west as Luxulyan (which is one of the reasons it was proposed as a site for a PWR during the 80s).

A 400kV circuit could handle a single phase traction load with no problem at all, and its sufficiently close that you could put the substation adjacent to the power line and run 25kV across country if necessary.

Luxulyan Valley has a small hydro-electric generating station at Ponts Mill. (owned by the clay company) The water crossing the old granite Aquaduct/ viaduct helps to supply it.

A 5 coach train could have one diesel engine/ generator to power it, and electric traction on 4/5 bogies.

 

[Taunton]

My info was that it was because they wanted to negotiate lower prices from the coal factors. I can't remember where I read it .

I think that (which I've heard elsewhere) is a bit of an urban legend, in particular because the GWR would still have needed to buy, and haul down to the South-West, coal for the power station. That is unless they planned a dam and hydro-electric station on the Exe at Cowley Bridge, eliminating the regular flooding there. Two birds with one stone!

 

[snowball]

The idea of isolated electrification of the Devon banks got a boost in the recent Commons Public Accounts Committee hearing on GW electrification.

http://www.railforums.co.uk/showthread.php?t=139069

Either Mark Carne or one of the other witnesses mentioned that the banks might be electrified before the rest of Bristol-Plymouth.

 

[The Ham]

If you electrified the downhill too you could get the benefit of regenerative braking.

However, would doubling the wiring costs be offset by enough to justify the extra expense?

Of course given the nature of the line in question it could effectivity be designed as a single track electrification, it just swaps from one direction to the other, between Exeter and Plymouth.

 

[Trog]

Network Rail do now own a rather fetching tunnel (re)boring machine, in the shape of "Fillie", the Farnworth Tunnel boring machine.

Don't be too surprised if it makes a few notable appearances in the plans for Control Period 6 or 7; there are a number of tunnels on the network which are drifting towards being life expired as it is (Farnworth was one such example) so rebuilding will have to happen in places.

The machine has an 8 metre diameter, so you get electrification clearance even if it's not immediately needed.

Unless there is something expensive on top, would it not be cheaper to just open the tunnel up into a cutting and be done with it?

 

[najaB]

Unless there is something expensive on top, would it not be cheaper to just open the tunnel up into a cutting and be done with it?

That depends on how deep and how long the tunnel is.

 

[jimm]

I think that (which I've heard elsewhere) is a bit of an urban legend, in particular because the GWR would still have needed to buy, and haul down to the South-West, coal for the power station. That is unless they planned a dam and hydro-electric station on the Exe at Cowley Bridge, eliminating the regular flooding there. Two birds with one stone!

Or you just build your power station on the coast and deliver the coal in bulk by ship.... rather like the CEGB did at the old Plymouth power stations.

A power station wouldn't need best (and expensive) South Wales anthracite, which the GWR's steam locos did, which was what prompted them to look at the electrification.

 

[NotATrainspott]

However, would doubling the wiring costs be offset by enough to justify the extra expense?

Of course given the nature of the line in question it could effectivity be designed as a single track electrification, it just swaps from one direction to the other, between Exeter and Plymouth.

The cost of doing one line wouldn't be half the cost of doing both. Without increasing the amount of piling you could use twin-track cantilevers, which may well be necessary anyway when only one side of the twin-track formation is suitable for the mast base and it's on the wrong side for the uphill track. Tunnel and bridge clearances tend to be symmetrical so any works needing done for one track will mean clearing the other as well. The only saving would be the wires and suspension equipment, but that's only a tiny fraction of the total cost of electrification.

 

[HowardGWR]

By lowering the Dainton tunnel track base, the eastern (and western) bank could be made less 'Lickey'-ish, I suppose. Not really then, totally an electrification. Jimm made a good point about coastal shipping for coal transport. Torbay gas works (through Kingswear harbour) was another example. Remember that Brunel only accepted the steep gradients, because his atmospheric engines were going to whizz the trains over the banks, thus saving money on digging it out flatter for steam traction.

 

[class26]

By lowering the Dainton tunnel track base, the eastern (and western) bank could be made less 'Lickey'-ish, I suppose. Not really then, totally an electrification. Jimm made a good point about coastal shipping for coal transport. Torbay gas works (through Kingswear harbour) was another example. Remember that Brunel only accepted the steep gradients, because his atmospheric engines were going to whizz the trains over the banks, thus saving money on digging it out flatter for steam traction.

Aren`t we supposed to be against coal fired power stations due to climate change ? I would have thought the chances of one being built were slim.

 

[edwin_m]

Aren`t we supposed to be against coal fired power stations due to climate change ? I would have thought the chances of one being built were slim.

I think we were talking about the historic GWR idea at that point. Interesting to speculate whether the power station would have used less coal than the steam locos replaced by electric ones, in which case GWR would have had less need to transport it. Either way it would be simpler to transport it all to one power station rather than distribute to a range of locomotive sheds.

 

[najaB]

Aren`t we supposed to be against coal fired power stations due to climate change ? I would have thought the chances of one being built were slim.

Carbon capture (if it works) changes the viability of coal-fired power stations. Depending on the sub-sea strata it may be possible to store the carbon offshore.

 

[DarloRich]

As I understand it the proposal to acquire more Hitachi trains to replace HSTs to Devon and Cornwall is actually for "IEP alikes". In particular, they will have the same diesel engines but there will be no power in reserve as (apparently) there is on "real" IEPs.

Would it be fesible to electrify Newton Abbot to Plymouth so that they had sufficient power "plus a bit in reserve"?

I can't see any problems that haven't been solved elsewhere.

Yes, there's a cost and I can't see it being given the go-ahead (yet) but are there any real killer technical resons why it wouldn't work?

why should there be an issue - they aren't the Himalayas!

 

[najaB]

Interesting to speculate whether the power station would have used less coal than the steam locos replaced by electric ones, in which case GWR would have had less need to transport it.

Pretty sure that it would have been more efficient on the generation side, would have lost of some of that benefit on the distribution side, and gained again by dint of the locomotives being lighter and not having to haul coal tenders around.

 

[edwin_m]

Remember that Brunel only accepted the steep gradients, because his atmospheric engines were going to whizz the trains over the banks, thus saving money on digging it out flatter for steam traction.

I've never really understood why people say this. The atmospheric system worked (when it worked at all) by pumping the air out of the pipe ahead of the train, so its tractive effort was theoretically limited to one atmosphere multiplied by the cross-section of the pipe. In practice it would have been considerably less due to imperfect vacuum and friction.

I believe a larger pipe was envisaged for the Devon Banks than for Exeter to Newton Abbot, but assuming for simplicity a square pipe two feet across, the theoretical tractive effort is 8000lbf. I don't know the TE of a contemporary broad gauge steam loco but that is about one quarter of what was needed to qualify for class 1 under the LMS/BR classification. So I would have thought the best locomotives of the time would have been more than a match for atmospheric propulsion, or even if they weren't it was just a question of double heading and developing locomotive technology would make the atmospheric technology obsolete within a few years.

Alternatively Brunel could have compressed the air behind the train instead, to give a theoretically unlimited pressure difference. However a seal to withstand several atmospheres may have been beyond the technology of the time - but it would have been amusing to see any rats attempting to eat it being blown sky-high!

Or am I missing something?

 

[coppercapped]

May I emphasise HowardGWR's post #7? With today's traction the major factor limiting speed on the Devon banks is not gradient, but curvature.

Easing the curves would have a greater effect than electrification.

 

[ac6000cw]

I'm guessing that the original question was posed on the basis that electrification would somehow improve the performance of trains over the Devon banks.

My impression has always been that due to the steep gradients and relatively sharp curvature, the main issue is maximising the use of available adhesion i.e. it's a tractive effort, not power problem. I assume the curvature is the main limitation on maximum speeds, so what you need is the best possible AC traction drives (and sanders!) - it doesn't matter what the power source is.

Both Voyagers and the bi-mode IEP-derivatives are AC-drive DEMUs, so they are essentially EMUs which carry around their own diesel gensets. Provided there is sufficient power available - and at around 15hp/tonne for a Voyager they should have - the performance of an (D)EMU at lower speeds should be identical when running from OHLE or diesel power - the potentially higher power available (particularly short-term) from OHLE is only a real advantage at high speeds where you are on the 'power-limited' part of the tractive effort vs speed graph.

The importance of usable tractive effort (not outright power) is a large part of the reason why the 'mountain only' electrification schemes in the US all got dismantled eventually once diesels arrived - maintaining and renewing the OHLE and a specialised small fleet of locos wasn't worth it when 'run through' diesels could handle the traffic just as well. In fact one railroad (the Norfolk & Western) went from steam to electric in 1915 then back to steam power in 1950 on part of its main line - it decided it was more economic in the long term to re-engineer the line with reduced gradients and a larger twin-track, ventilated, summit tunnel than renew the electrification equipment.

 

[edwin_m]

I'm guessing that the original question was posed on the basis that electrification would somehow improve the performance of trains over the Devon banks.

My impression has always been that due to the steep gradients and relatively sharp curvature, the main issue is maximising the use of available adhesion i.e. it's a tractive effort, not power problem. I assume the curvature is the main limitation on maximum speeds, so what you need is the best possible AC traction drives (and sanders!) - it doesn't matter what the power source is.

Both Voyagers and the bi-mode IEP-derivatives are AC-drive DEMUs, so they are essentially EMUs which carry around their own diesel gensets. Provided there is sufficient power available - and at around 15hp/tonne for a Voyager they should have - the performance of an (D)EMU at lower speeds should be identical when running from OHLE or diesel power - the potentially higher power available (particularly short-term) from OHLE is only a real advantage at high speeds where you are on the 'power-limited' part of the tractive effort vs speed graph.

The importance of usable tractive effort (not outright power) is a large part of the reason why the 'mountain only' electrification schemes in the US all got dismantled eventually once diesels arrived - maintaining and renewing the OHLE and a specialised small fleet of locos wasn't worth it when 'run through' diesels could handle the traffic just as well. In fact one railroad (the Norfolk & Western) went from steam to electric in 1915 then back to steam power in 1950 on part of its main line - it decided it was more economic in the long term to re-engineer the line with reduced gradients and a larger twin-track, ventilated, summit tunnel than renew the electrification equipment.

I don't know enough about this section to comment in any detail on whether the limitation is curvature or adhesion, except to note that the climb out of Plymouth eastbound is steep but fairly straight but that out of Totnes westbound is (I think) a bit less steep but tightly curved. Perhaps a regular Voyager passenger on the route could comment on whether either of these sections sounds as if the engines are going flat out, which would suggest that power rather than curvature is the limiting factor?

At risk of going off topic, another reason for the USA abandoning electrification was probably the loss of passenger traffic. Once there are no time-critical passenger trains it doesn't matter if the freight thrashes up the grade at 10mph as all the other freights will be doing the same.

 

[Taunton]

the climb out of Plymouth eastbound is steep but fairly straight but that out of Totnes westbound is (I think) a bit less steep but tightly curved.

I can tell you from the last days of steam that the descent down to Totnes from both sides is significantly curved, but a Castle westbound that had come over the top of Dainton at 30mph would be driven all-out down the other side, passing through Totnes at well over 60mph to get a storm at the other side.

If I am not mistaken City of Truro's run in 1904, quite apart from its 100mph later, set something of a record for Plymouth to Newton Abbot, I seem to recall someone some years ago showed it had beaten a contemporary HST booking between those points

 

[coppercapped]

In the Down direction the line limits from Teignmouth are 60/80/90 then 60mph through Newton Abbot. Shortly past Newton Abbot it drops to 55mph and stays at that value to Totnes. Through Totnes the limit is 60mph which stays until Hemerdon where it increases to 80 as far as Tavistock Junction at which point it drops to 60mph. There is a short burst to 70mph past Laira and then a crawl into North Road.

The Up road is similar.

The issue is curvature - spending some money on raising the line limit to a constant 80mph between Newton Abbot and Plymouth would make a considerable difference. Electrification with the existing curves would make no difference to the Exeter - Plymouth times at all.

 

[Sir Felix Pole]

I guess the British example of the US Milwaukee Road's partial electrification for difficult sections was the Woodhead line, easing working of the Worsborough Incline and eliminating the foul original tunnels. There was also the NER's Shildon scheme for coal traffic, de-electrified in the Depression, although this was more of a complete route.

The South Devon Railway was always an impoverished affair, struggling to raise the initial capital and then nearly bankrupted by the 'Atmospheric Caper'. Brunel had to built the line cheaply - hence the coastal route to Newton Abbot and the incessant curvature and gradients to Plymouth. I have always thought, however, that the Dainton section, particularly the descent to Totnes, is unecessarily curved given the topography and there is plenty of scope for it to be straightened out. One wonders whether there were problems with greedy landowners when it was built. The Spanish have done a lot of good work with their classic main lines, constructing 'variente' to eliminate the worst curved sections - the 'Euromed' line from Barcelona to Valencia being the best example. I think this should be the approach with the Devon Main Line - any hopes of new high-speed line are a pipe-dream unfortunately.