European Railroad Discussion > Why Are Their Three Electrical Systems in English Railroads?

Recently I became enamored when looking at several videos of various English trains on the You-Tube web site. The first few videos I watched I became focused on the track system and as a large amount of rail lines in your country are powered using electricity I began noticing after viewing several videos that their appears to be three systems for distribution of the electrical power to the control cab of the trains. At first I thought their was one of those systems that was more common than either of the other two. Further viewing of many of the videos showed me that their appears to be not just one system but all three seem to be used throughout England. Let me explain what I noticed.

As the voltage used in England appears to be the same as in the US at 600 volts DC and that power is delivered to the train using overhead power lines (using a pantograph for pickup) or third rail (or using a pickup shoe attached to the carriage)I discovered a third method not used in the US (at least not to my knowledge)that appears to have wide usage in England and this is a second independent rail running in the center of the track. I do understand the practicality of distributing electrical power in this application for railroad locomotives using high voltage DC current. One cable supplies the current and then returns it back to it's source and your three systems accomplish this feat. Now for my question.

Why are their three methods used on British Railroads which appear to complicate and proliferate a system for operation? Would not simply one system suffice to accomplish the same result. Hope I explained my question and I look forward to someone explaining why are their apparently three methods for distributing electrical current to your locomotives.

Thank you.

Jim
Hatboro, PA

The UK mainline system is primarily two systems - 25kVAC overhead wire and 750VDC top-running third rail around London and the southeastern part of the country. While I'm not an expert on British rail history, my understanding is that the DC third rail system started as a way to electrify all the London-region suburban trains. Third rail low voltage DC, however, is hard to scale to anything requiring real power (such as heavy freight or high speed), so when electrification really took off, British Rail chose the "modern" standard of 25kV. Third rail persists because it works and it has a large install base that would have to be phased out over decades. Plus, the loading gauge is significantly tighter on these older lines, so it may not be possible to retrofit overhead wire onto the third rail system without extensive tunnel and bridge modifications.

The Tube uses 4 rail electrification - 2 running rails, one at +420 VDC, and one at -210 VDC. The intention there was to provide an isolated return path for the current rather than use the running rails, so that stray currents wouldn't corrode the metal tube liners. On the few parts of the system shared with Network Rail trains, they bond the center rail to the running rails (effectively grounding it) and energize the outer power rail at +630VDC so that both Tube equipment and mainline 750VDC equipment can operate.

In addition to those main three, there's a host of oddballs on insular systems, such as DLR.

Had the same questions when I first went over there. Everybody else is looking at the scenery, and I'm staring at the electrification...

Thank you for your response. I now have a better understanding of the British system and why things are the way they are. You sound like me, I am one who looks at "what makes thing go" not "the color of the scenery". Again, thank you for your explanation.

Jim
Hatboro, PA

NDHolmes Wrote:
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> The UK mainline system is primarily two systems -
> 25kVAC overhead wire and 750VDC top-running third
> rail around London and the southeastern part of
> the country. While I'm not an expert on British
> rail history, my understanding is that the DC
> third rail system started as a way to electrify
> all the London-region suburban trains.

Not just London. During the first decade of the last century railways that had traditionally shifted large numbers of commuters were facing something of a crisis, trams (streetcars) had eaten into much of their short haul traffic. A number of companies, generally the more profitable, adopted electrification as a way of fighting back to regain the lost traffic and so by the outbreak of WW1 there were a number of different, mutually incompatible systems across the country. In the London area the London & North Western adopted a four rail 630v DC system, its trains interchanged with the Underground Group (what today is London Transport) and so adopted their system whilst the London & South Western Railway used an over running third rail at 600v. Both these initial electrifications were about ready when war was declared. But the most technologically advanced system, which had been in operation since 1909 was that of the London, Brighton & South Coast Railway which adopted the precursor to day's 25kV standard, an overhead system at 6.6kV 25Hz single phase using Siemens technology. By the outbreak of war they had electrified the South London Line, Victoria to London Bridge and lines from London Bridge and Victoria to Crystal Palace. Plans were in place to extend electrification to Sutton and Coulsdon North (the end of the suburban network) and ultimately the mainline to Brighton (51 miles from London).

Elsewhere around England the solutions adopted differed (as you might expect).

On Merseyside the Mersey Railway electrified its lines serving Liverpool in 1903 using a four rail 600v system, it desperately needed to win back passengers who had abandoned their steam trains for electric trams and the new high capacity ferries across the Mersey.

The North Eastern adopted 600v DC for its Tyneside (Newcastle) network and 1500v DC overhead for its Shildon to Newport (Middlesborough) scheme, which was all about moving coal for export, although they had plans to extend the 1500v DC system to the Newcastle to York mainline.

The Midland Railway experimented with electrification, they electrified a short line in NW England from Lancaster to Heysham in 1906 using, like the LB&SCR, the 6.6kV overhead system. Both companies were thinking about mainline as opposed to purely suburban electrification when they adopted the more expensive overhead systems

The Lancashire & Yorkshire Railway at one time had THREE systems in operation; they started out with a conventional four rail 625v DC solution for their Liverpool Exchange to Southport & Ormskirk suburban lines. In 1912 using Dick, Kerr & Company equipment they electrified a 3 mile line from Bury to Holcombe Brook (Bury is north of Manchester and the HQ of the East Lancashire heritage operation) at 3.5kV DC overhead. It was really just for test purposes. Their next foray was the line connecting Manchester to Bury, for which they adopted a 1200v DC side contact rail system, unique in Britain (and the world?), and which survived until 1991 when the line became part of Manchester's Metrolink LRT. The Holcombe Brook line was converted to the 1200v DC system in 1918 and closed in the early 1950s.

Today the railways in South East England still use the L&SWR's third rail system (voltage upped to 750v DC), the Brighton Railway's overhead system was junked in 1929 and replaced by the third rail. Railways on Merseyside - the former Mersey and Lancashire & Yorkshire also operate a standardised third rail system, everywhere else on National Rail the 25kV reigns supreme except on a stretch of line between Newcastle and Sunderland where the Tyne & Wear Metro's 1500v DC catenary is strung as Metro trains share trackage with mainline services.

You did ask.

PS: not gone down the blind alley of interwar 1500v DC schemes :-)



Edited 2 time(s). Last edit at 11/09/17 10:07 by 86235.

thanks Nick for the history lesson. I am fascinated by the four rail system. The photos I have seen of the track work blows me away.... the more complicated track work, the more I like the photo. I too would be looking at the electrical while the wife would be looking at th scenery.

Posted from iPhone

Very interesting to a Yank.The "White Heat of Technology"even in the formative years.

Posted from Android

Oooh, we have to mention the 1500V DC overhead Woodhead Route through the Pennine Hills from Sheffield to Manchester; the UK's equivalent to the Milwaukee Road! British Rail's Class 76 'Tommy' = 'Little Joe' EF-4...!



Edited 1 time(s). Last edit at 11/09/17 11:59 by exhaustED.

In the US, historically there were at least a half-dozen different power variations for the electrified railroads in the New York City area alone.

Ray

exhaustED Wrote:
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> Oooh, we have to mention the 1500V DC overhead
> Woodhead Route through the Pennine Hills from
> Sheffield to Manchester; the UK's equivalent to
> the Milwaukee Road! British Rail's Class 76
> 'Tommy' = 'Little Joe' EF-4...!

That was one of the dead-ends I couldn't quite be bothered going in to.

It's interesting that some of the US discussion sounds like it might regard electrification as a rather bizarre slightly obsolete technology, while from our perspective in Western Europe it is so completely mainstream.

The UK is striking in the small extent of electric traction, especially freight, but diesel-powered passenger trains are quite a rarity on many parts of the continent.

We have fewer than a hundred straight electric locos in Britain (all 25kV 50Hz overhead), it seems the future lies wholly in the emu.



Edited 1 time(s). Last edit at 11/10/17 03:01 by spflow.

spflow Wrote:
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> It's interesting that some of the US discussion
> sounds like it might regard electrification as a
> rather bizarre slightly obsolete technology, while
> from our perspective in Western Europe it is so
> completely mainstream.
>
> The UK is striking in the small extent of electric
> traction, especially freight, but diesel-powered
> passenger trains are quite a rarity on many parts
> of the continent.
>
> We have fewer than a hundred straight electric
> locos in Britain (all 25kV 50Hz overhead), it
> seems the future lies wholly in the emu.

I think that in the medium term the 'hybrid' idea will gain some momentum in the UK, mainly because we currently (pun intended...) have insufficient network coverage with electrification. We obviously have some hybrid EMUs starting operation as we speak and one of the freight companies has recently bought a small fleet of electric locomotives which incorporate a 'small' 900hp diesel engine for non-wired areas.

By the way, just for future reference, in the UK we call it a railway, not a railroad....the US seems to have a few small railways also, the Trona railway for example....just a point of interest...



Edited 1 time(s). Last edit at 11/10/17 08:43 by exhaustED.