Rail (UK)

South­ern electrics: the cur­rent think­ing

It is 100 years since the first elec­tri­fi­ca­tion of the rail net­work in the South East of Eng­land. PAUL CLIFTON as­sesses its fu­ture

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It is 100 years since what we now call South West Trains and South­ern Rail­way started us­ing an elec­tri­fied third rail.

Elec­tri­fi­ca­tion ac­tu­ally started be­fore that - in the late 19th cen­tury, when Volk’s Elec­tric Rail­way in Brighton opened in 1883. Cur­rently about 40% of the rail net­work is pow­ered by elec­tric­ity, ac­count­ing for 60% of jour­neys. Of the elec­tri­fied routes, roughly two-thirds use over­head 25kV AC cables and a third uses 750V DC third rail.

The elec­tri­fied net­work is now be­ing ex­panded, with large parts of the Great Western Main Line to be fol­lowed by the trans-Pen­nine route and the Mid­land Main Line. The pro­por­tion us­ing third rail power will there­fore re­duce.

The Lon­don Un­der­ground be­gan us­ing a fourth rail sys­tem in 1890, on what is now the North­ern Line. Sub­ur­ban elec­tri­fi­ca­tion in south Lon­don fol­lowed some years later.

In 1921 a govern­ment com­mit­tee chose 1,500V DC over­head cables to be the na­tional stan­dard, but this was widely ig­nored. The South­ern Rail­way opted in­stead for a 660V DC third rail sys­tem, and by 1929 its patchy over­head net­work in south Lon­don had been re­placed. The Brighton Main Line was fin­ished in 1933, Portsmouth was reached in 1937, and Maid­stone in 1939.

Dur­ing this pe­riod the Lon­don and North East­ern Rail­way chose the Wood­head route be­tween Manch­ester and Sh­effield for its first ven­ture into over­head wires, us­ing 1,500V DC. Work be­gan in 1936 but was not com­pleted un­til the 1950s. As it was not adopted na­tion­ally, the route be­came iso­lated, and to­day only the Tyne and Wear Metro uses 1,500V DC over­head lines.

Af­ter na­tion­al­i­sa­tion, Bri­tish Rail­ways ex­panded elec­tri­fi­ca­tion and (from 1956) adopted to­day’s 25kV AC over­head stan­dard for all projects out­side the ex­ist­ing third-rail sys­tems in south­ern Eng­land and two lines on Mersey­side.

Af­ter that, progress slowed. The South Western Main Line to Southamp­ton and Bournemout­h was elec­tri­fied only in 1967, as the steam age came to an end. It reached Wey­mouth in 1988, built on the cheap with a lim­ited power sup­ply - the con­se­quences of which are still felt by the train op­er­a­tor to­day.

Only a hand­ful of lines in the South re­main diesel-op­er­ated. The line from Bas­ingstoke through Sal­is­bury and the route to Uck­field are per­haps the most glar­ing omis­sions.

A key elec­tri­fi­ca­tion de­bate cen­tres on third rail ver­sus over­head.

“If you were just look­ing at the abil­ity to trans­mit elec­tric­ity, over­head is def­i­nitely best,” says Wil­liam Powrie, Pro­fes­sor of Geotech­ni­cal En­gi­neer­ing and Dean of the Fac­ulty of En­gi­neer­ing and the En­vi­ron­ment at the Univer­sity of Southamp­ton.

“Over­head line wins be­cause you can trans­mit elec­tric­ity at 25kV. That is to do with dis­tance from the ground.

“In sim­ple terms, if you have a cer­tain volt­age it will spark across to the ground. The higher the volt­age, the greater the dis­tance it will jump. So if you tried to put 25kV through the third rail, which is about four inches off the ground, it would just arc straight to ground.

“But the great ad­van­tage of 25kV is that you do not lose much power in the trans­mis­sion. Power = volt­age x cur­rent. So 25,000 volts does not need much of a cur­rent. The en­ergy loss is small.”

So why did a large part of the coun­try go with a third rail sys­tem, when the power losses of a low-volt­age sys­tem were well known?

“I think third rail merely came first. It was sim­pler. The over­head cate­nary is quite a dif­fi­cult thing. It is a flex­i­ble struc­ture. It hangs in an arc and you need a pan­to­graph that can ac­com­mo­date that, in ad­di­tion to the sway of the roof of the train - lat­eral move­ment is more of an is­sue than it is closer to the ground. So the en­gi­neer­ing re­quire­ment for an over­head power sup­ply is a lot more so­phis­ti­cated.

“The third rail is a great big piece of metal. It is held pretty rigid, so you can have a sim­ple and cheap col­lec­tor shoe mech­a­nism on the train.” So, should third rail be re­placed? “There is no fu­ture for ad­di­tional in­stal­la­tion of third rail,” says Dave Ward, Net­work Rail’s South East Route Man­ag­ing Di­rec­tor un­til his re­tire­ment last year.

“You might be able to ar­gue a case for do­ing Ash­ford to Hast­ings, but that’s it. Third rail is not com­pli­ant with the Elec­tric­ity at Work Act, and ORR [the Of­fice of Rail and Road] put a pro­hi­bi­tion on fur­ther third rail.”

In 2011, Net­work Rail’s Head of Elec­tri­fi­ca­tion Peter Dear­man sug­gested there was an eco­nomic case to con­vert the en­tire third rail net­work to over­head lines, stat­ing that

I can­not imag­ine go­ing to our pas­sen­gers to ex­plain that we might spend bil­lions of pounds to move the elec­tric power from un­der­neath their trains to on top of them. No sane busi­ness would do that.

Tim Shov­eller, Man­ag­ing Di­rec­tor, South West Trains

third rail “has no long term fu­ture” ( RAIL 673).

Dear­man ar­gued that the net­work was at the limit of its power ca­pa­bil­ity, with trains re­stricted to a top speed of 100mph, but more gen­er­ally achiev­ing only 80mph with a quar­ter of all power lost in the form of heat.

“There have been many at­tempts to make the eco­nomic case,” coun­ters South West Trains Man­ag­ing Di­rec­tor Tim Shov­eller. “There isn’t one. I can­not imag­ine go­ing to our pas­sen­gers to ex­plain that we might spend bil­lions of pounds to move the elec­tric power from un­der­neath their trains to on top of them. No sane busi­ness would do that.

“The busi­ness case for re­plac­ing DC as­sumes that AC would be faster and re­duce jour­ney times, with the time ben­e­fits bring­ing ad­di­tional rev­enue.

“But the scope for speed is lim­ited. Take the Portsmouth route: most of it is 70mph or 85mph. We could in­crease that to 90-100mph in places. Jour­ney time is cer­tainly an is­sue for us, but for that level of im­prove­ment we wouldn’t need over­head cables to achieve it.”

In 2012 the con­cept was in­tro­duced of an ‘Elec­tric Spine’ of over­head cables link­ing Southamp­ton docks to the Mid­lands to im­prove freight ca­pac­ity.

This would en­tail con­vert­ing part of the South West Main Line be­tween Southamp­ton Cen­tral and Bas­ingstoke to 25kV AC, and was seen as a pi­lot scheme to de­velop a busi­ness case for full con­ver­sion of the third rail net­work. The High Level Out­put Spec­i­fi­ca­tion slated a start date be­fore 2019.

But the au­tumn 2015 Wes­sex Route Study states only: “It is in­tended to pro­vide 25kV AC over­head line elec­tri­fi­ca­tion be­tween Bas­ingstoke and the docks at Southamp­ton at some point dur­ing CP6” [the five-year fi­nan­cial Con­trol Pe­riod end­ing in March 2024]. The re­cent Hendy Re­view does not up­date this.

And there are enough warn­ings in the Route Study to sug­gest that it could be kicked into the long grass.

“A sig­nif­i­cant cost is in­volved in con­vert­ing the present day elec­tric pas­sen­ger fleet to dual volt­age ca­pa­bil­ity, it be­ing as­sumed that it will not prove pos­si­ble or prac­ti­ca­ble to keep in place the third rail DC sys­tem,” the re­port states. “There is very lit­tle over­all pas­sen­ger ben­e­fit,” it adds.

“The eco­nomic case for the Elec­tric Spine is shot through,” is Ward’s view. “The spine is in spasm. It was a well-in­tended idea.”

Shov­eller agrees: “The case is cer­tainly

dead in the short term. I ut­terly re­ject the no­tion of leav­ing a diesel route to Sal­is­bury while elec­tri­fy­ing an al­ready-elec­tric line to Southamp­ton. It would be a non­sense. Only an en­gi­neer­ing com­pany would think of do­ing that… you get the in­fer­ence!

“I would ab­so­lutely elec­trify to Sal­is­bury. That would be AC over­head from Wort­ing Junc­tion, be­cause that is the na­tional stan­dard and we are not likely to see new DC third rail. It’s no prob­lem to have a dual-volt­age train for that.

“If an Elec­tric Spine is go­ing to hap­pen, great. But I would like to see that money spent via An­dover and Sal­is­bury to pro­vide two elec­tric routes to Southamp­ton. That would be much bet­ter value for money.”

The el­e­ment of putting power back must also be con­sid­ered.

“The im­pact of re­gen­er­a­tive brak­ing is now also a sig­nif­i­cant fac­tor,” says Powrie. “If you have regen brak­ing on high volt­age AC, you can put power back into the wire fairly eas­ily. And from there it can go to the na­tional grid.

“Power put back into the DC third rail at a low volt­age can­not go back into the na­tional grid. If you put en­ergy back into the third rail through regen brak­ing, it can only be used by an­other train in the same sec­tion of track. Oth­er­wise it is just lost.

“The sur­prise to me was when the rail­way started to claim the over­head line was more re­silient to bad weather, be­cause I have al­ways as­so­ci­ated it with the risk of high winds and the ef­fects of ice.

“But three years ago, when we had a bad win­ter, SWT put on a diesel ser­vice on my lo­cal line be­tween Southamp­ton and Portsmouth. The mod­ern trains have such a light­weight col­lec­tor shoe that it tends to lose con­tact, shut­ting the trains down.

“I would have thought the risk was pretty even. Third rail is more sus­cep­ti­ble to the in­crease in flood­ing which hap­pens with cli­mate change; cate­nary is more sus­cep­ti­ble to high winds. They’re about equally sus­cep­ti­ble to ice.

“One rea­son we can have chaos now is un­fore­cast heavy ice overnight. If ice is pre­dicted, they put out the de-ic­ing trains to make sure ev­ery­thing is OK by morn­ing. They don’t go out as a mat­ter of rou­tine, be­cause of the cost. In terms of cli­mate change re­silience, it’s a close thing.”

The elec­tri­fi­ca­tion pro­gramme is “too

I find it very dif­fi­cult to be­lieve that you could make an eco­nomic case for con­vert­ing to third rail now. The price would be pro­hib­i­tive. Wil­liam Powrie,

Pro­fes­sor of Geotech­ni­cal En­gi­neer­ing and Dean of the Fac­ulty of En­gi­neer­ing and the En­vi­ron­ment at the Univer­sity of Southamp­ton

ex­pen­sive”, he says, shift­ing the bal­ance.

Powrie thinks that al­though over­head wires are in­her­ently bet­ter, the eco­nomic case for re­plac­ing third rail is di­min­ish­ing as a re­sult of the lat­est pro­gramme of elec­tri­fi­ca­tion.

He points out that when Net­work Rail’s Dear­man ar­gued there was a case for re­place­ment in 2011, the cost of the Great Western elec­tri­fi­ca­tion was put at about a sixth of the lat­est es­ti­mates.

“I find it very dif­fi­cult to be­lieve that you could make an eco­nomic case for con­vert­ing to third rail now. The price would be pro­hib­i­tive,” he says.

“Net­work Rail is ar­gu­ing that one jus­ti­fi­ca­tion for the cost in­crease is that the equip­ment is much bet­ter. Ac­tu­ally, it isn’t. It is all quite agri­cul­tural. It is struc­turally in­ef­fi­cient, and that makes it more ex­pen­sive.

“If they try to get them­selves out of jail us­ing that ar­gu­ment, then any fu­ture elec­tri­fi­ca­tion scheme sim­ply be­comes un­af­ford­able, how­ever you try to jus­tify it.

“That re­ally is a worry for peo­ple who sup­port the rail­way. It is not help­ful when Net­work Rail en­gi­neers de­fend the cost of the cur­rent scheme. We have to get costs down be­fore the next pro­ject.”

Powrie sug­gests that NR has been let down badly by the sup­ply chain. Its new high out­put “fac­tory” train, spe­cially built to speed up wiring the Great Western, was de­signed to drive tubu­lar steel piles to a depth of 5.5 me­tres.

On pre­vi­ous elec­tri­fi­ca­tion jobs, a depth of three to five me­tres was seen as ad­e­quate. But the in­dus­try has since come up with a re­vised over­head gantry sys­tem that re­quires much greater pile depths. So rather than 5.5 me­tres be­ing a max­i­mum depth, it turns out to be a min­i­mum.

Says Powrie: “Part of the prob­lem is that the Fur­rer + Frey over­head line equip­ment they are us­ing on the Great Western is a lot heav­ier and chunkier than be­fore. That means the wind loads are greater. The ice loads are also greater, and you have to de­sign for them. It pushes up the en­gi­neer­ing re­quire­ments out of all pro­por­tion.

“With the new method they have piled a fac­tor of safety on top of a fac­tor of safety, cau­tion on top of cau­tion.

“Net­work Rail I think now un­der­stands it has to re­design the masts. Fur­rer + Frey Se­ries One equip­ment uses a lot of steel - it could come down by 40%. That would re­duce the weight, and re­duce the wind, snow and ice load.”

Powrie ex­plains that a col­umn bolts on top of the steel pile. The boom that stretches across the rail­way tracks can slide up and down that col­umn. It is then clamped into place, which al­lows for a mar­gin of er­ror in erect­ing it at

The in­dus­try can­not even be­gin to con­sider the re­place­ment of third rail for an­other ten to 15 years. What we’ve seen on the Great Western in ef­fect will ex­tend the longevity of third rail. Dave Ward, for­mer South East Route Man­ag­ing Di­rec­tor, Net­work Rail

not quite the right height. “That ad­justa­bil­ity is like hav­ing a fold­ing bike,” he says. “If you have a bike which folds in places it doesn’t need to, it is go­ing to be heav­ier than a bike which does not fold. The ad­justa­bil­ity comes from slid­ing and bolted joints in­stead of sim­ple welded joints. It is struc­turally less ef­fi­cient and there­fore needs more steel to achieve the same re­sult. It is there­fore heav­ier and more ex­pen­sive.

“Foun­da­tions have to be­come big­ger to take the ex­tra weight. They take longer. The high out­put train hasn’t been able to de­liver what is now wanted. The whole thing has be­come a bit of a disas­ter, re­ally. But they are too far ad­vanced now - they have to push on.”

Ward, for­merly in charge of Net­work Rail’s South East routes, takes a sim­i­lar view: “The in­dus­try can­not even be­gin to con­sider the re­place­ment of third rail for an­other ten to 15 years. What we’ve seen on the Great Western in ef­fect will ex­tend the longevity of third rail. It’s not eco­nom­i­cally vi­able or phys­i­cally de­liv­er­able un­til a mod­u­lar over­head sys­tem be­comes avail­able, one that can be in­stalled quickly and with­out dis­rup­tion.

“It would be very dif­fi­cult to in­stall even then. Stand at the end of the plat­form at ei­ther Water­loo or Lon­don Bridge and look at the tracks. Now imag­ine how dif­fi­cult it would be to in­stall a sys­tem of wires above all that. Al­most im­pos­si­ble.

“I’d say on a list of pri­or­i­ties for the South­ern Re­gion it comes about 15th. There are far more im­por­tant things to do. South of the river the rail­way is all about ca­pac­ity, not speed. And third rail can de­liver ca­pac­ity.

“One day some­one will have to grasp the net­tle. But the change would take years and cost bil­lions of pounds. For what gain? It won’t pro­duce more than a marginal change in ca­pac­ity, and there are many other changes which would pro­duce much greater ca­pac­ity.”

Nowhere in the world is pur­su­ing third rail as an al­ter­na­tive for main line ser­vices. Ev­ery­one start­ing from scratch would choose 25kV over­head wires. But third rail power is likely to be with us for a long time yet.

 ?? TOM MCA­TEE. ?? The 1630 Lon­don Water­loo to Portsmouth Har­bour stands at Wok­ing on Novem­ber 30 2014. NR’s bids to in­crease ca­pac­ity in the South­ern Re­gion have pushed the elec­tri­fi­ca­tion de­bate down the agenda.
TOM MCA­TEE. The 1630 Lon­don Water­loo to Portsmouth Har­bour stands at Wok­ing on Novem­ber 30 2014. NR’s bids to in­crease ca­pac­ity in the South­ern Re­gion have pushed the elec­tri­fi­ca­tion de­bate down the agenda.
 ?? BRIAN MOR­RI­SON. ?? With Class 423 4-VEP 7753 lead­ing and Class 405/2 4-SUB 4356 also at the helm, the 1050 Water­looGuild­ford and the 1046 Water­loo-Wim­ble­don-Rich­mond ser­vices re­spec­tively pass through Clapham Cut­ting on May 28 1982. Third rail was cho­sen for the South­ern...
BRIAN MOR­RI­SON. With Class 423 4-VEP 7753 lead­ing and Class 405/2 4-SUB 4356 also at the helm, the 1050 Water­looGuild­ford and the 1046 Water­loo-Wim­ble­don-Rich­mond ser­vices re­spec­tively pass through Clapham Cut­ting on May 28 1982. Third rail was cho­sen for the South­ern...
 ?? BRIAN MOR­RI­SON. ?? A Maid­stone East to Lon­don Vic­to­ria train passes Bick­ley Junc­tion on July 27 1955, formed of 2-HAL stock with 2657 lead­ing. The third rail reached Maid­stone in 1939.
BRIAN MOR­RI­SON. A Maid­stone East to Lon­don Vic­to­ria train passes Bick­ley Junc­tion on July 27 1955, formed of 2-HAL stock with 2657 lead­ing. The third rail reached Maid­stone in 1939.
 ?? JACK
BOSKETT/ RAIL. ?? Cost over­runs on wiring the Great Western Main Line have di­min­ished the eco­nomic case for re­plac­ing third rail. South West Trains 450543 ap­proaches Water­loo on March 27 2012.
JACK BOSKETT/ RAIL. Cost over­runs on wiring the Great Western Main Line have di­min­ished the eco­nomic case for re­plac­ing third rail. South West Trains 450543 ap­proaches Water­loo on March 27 2012.
 ??  ??
 ?? BRIAN MOR­RI­SON. ?? The UK’s first elec­tri­fied route opened in Brighton in 1883. Elec­tric mul­ti­ple units 2-BIL 2090 and 4-SUB 4732 work the shut­tle ser­vice to and from Seaford dur­ing the Brighton Open Day on Septem­ber 21 1991.
BRIAN MOR­RI­SON. The UK’s first elec­tri­fied route opened in Brighton in 1883. Elec­tric mul­ti­ple units 2-BIL 2090 and 4-SUB 4732 work the shut­tle ser­vice to and from Seaford dur­ing the Brighton Open Day on Septem­ber 21 1991.
 ?? BRIAN MOR­RI­SON. ?? Class 414/3 2-HAP 6055 leads a Hor­sham-Lon­don Vic­to­ria ser­vice through a win­try Clapham Cut­ting on Jan­uary 10 1982. The pro­por­tion of the elec­tri­fied net­work us­ing third rail will re­duce once over­head wires are in­stalled on the Great Western and...
BRIAN MOR­RI­SON. Class 414/3 2-HAP 6055 leads a Hor­sham-Lon­don Vic­to­ria ser­vice through a win­try Clapham Cut­ting on Jan­uary 10 1982. The pro­por­tion of the elec­tri­fied net­work us­ing third rail will re­duce once over­head wires are in­stalled on the Great Western and...

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