3rd rail vs OHLE

[MML-Ben]

Morning,

Just browsing the Open Railway Map & I noticed that lines which operate on third rail is primarily in the South/South East of England. I don't know the in's & out's of the rail industry hence this question. Can anyone explain why this is? I find it odd that it's just this section of England & the rest of England uses OHLE or is not electrified at all.

 

[Brissle Girl]

History. The Southern Railway electrified a lot of its suburban railways in the early part of the last century because of the relatively intensive nature of the services. Remember the performance advantage was against steam, not diesel, so very considerable. I don't think AC overhead was around that long ago. Once the third rail network was established it made sense to extend it, particularly given the services operated are relatively self contained.

There's a good book "Southern Electric" by GT Moody if you are interested in more detail. I quickly found a second hand copy online.

 

[WAO]

Third rail DC is favoured for short distances and tight clearances but poses a safety hazard on the track and needs topping up from closely spaced substations. Overhead AC can deliver vastly more power efficiently over long distances from each substation. The overhead system at 6.6kV AC, was first in the South East out of Victoria but the LSWR DC system won out. The SR network favoured electrification as it was intensive and relatively short. Third rail DC was also used on Merseyside, Bury and Tyneside, the latter closed by Labour! Overhead DC was really a casualty of WW2 with only Altrincham, Woodhead and Liverpool Street eventually being wired. Finally the French 25kV AC overhead system won out and technical advances since in rectification, insulation and protection have stretched that lead.

Unfortunately the UK government is the last to have the penny drop.

WAO

 

[LNW-GW Joint]

BR did consider wiring the Kent Coast and Bournemouth routes in the 1950s, but that would have meant converting large sections of the 3rd rail network as well.
So the 3rd rail continued to expand until the 1990s, including the then Channel Tunnel routes (before HS1).
The LNWR and L&Y (later LMS) also started with 3rd rail on local lines around London, Liverpool and Manchester.
Another reason for the SR and LMS to adopt 3rd rail around London was to retain compatibility with the London Underground network, which overlaps in places.

 

[59CosG95]

BR did consider wiring the Kent Coast and Bournemouth routes in the 1950s, but that would have meant converting large sections of the 3rd rail network as well.
So the 3rd rail continued to expand until the 1990s, including the then Channel Tunnel routes (before HS1).
The LNWR and L&Y (later LMS) also started with 3rd rail on local lines around London, Liverpool and Manchester.
Another reason for the SR and LMS to adopt 3rd rail around London was to retain compatibility with the London Underground network, which overlaps in places.

Cases in point around London include the Watford DC line (now used by LO), and the East Putney-Wimbledon stretch of the District Line, which sees occasional use by SWR for stock moves to/from Wimbledon Depot.

 

[XAM2175]

The SR network favoured electrification as it was intensive and relatively short. Third rail DC was also used on Merseyside, Bury and Tyneside, the latter closed by Labour! Overhead DC was really a casualty of WW2 with only Altrincham, Woodhead and Liverpool Street eventually being wired.

It's interesting to note that it was a British electrical engineering consultancy (Merz & McLellan) that introduced electrification to Australia - with a proposal of 800 V DC third-rail for the Melbourne suburban system in 1908 that was revised to 1500 V DC overhead in 1912, and then implemented as such from 1919. Planners in Sydney also backed the 1500 V DC overhead system in 1915 and implemented it from 1926 onwards. A fortuitous set of decisions, I'd say!

 

[A0wen]

Third rail DC is favoured for short distances and tight clearances but poses a safety hazard on the track and needs topping up from closely spaced substations. Overhead AC can deliver vastly more power efficiently over long distances from each substation. The overhead system at 6.6kV AC, was first in the South East out of Victoria but the LSWR DC system won out. The SR network favoured electrification as it was intensive and relatively short. Third rail DC was also used on Merseyside, Bury and Tyneside, the latter closed by Labour! Overhead DC was really a casualty of WW2 with only Altrincham, Woodhead and Liverpool Street eventually being wired. Finally the French 25kV AC overhead system won out and technical advances since in rectification, insulation and protection have stretched that lead.

Unfortunately the UK government is the last to have the penny drop.

WAO

I think you're not being entirely fair.

On the LSWR (3rd rail) vs LBSC (OHL) decision by Southern, part of it was driven by the technology of the time, the DC technology was "better" it that it was more established. AC was still at an early stage (bearing in mind this is pre 1925) and when merged to form the Southern railway, the route miles of 3rd rail far outweighed those of the OHL. It's also worth remembering much of the early AC electrical equipment originated in Germany or Switzerland - the former was a bit problematic in the immediate post WW1 period.

DC OHL - the LNER had planned those before WW2 as you said and they were completed in the 1950s. At this time 25kv was still fairly experimental - DB had done some AC OHL before the war, at 20kv rather than 25kv and it was this that the French copied in the early 50s, but in parallel they continued to electrify using 1500v DC and other European countries continued with 1500v or 3000v DC. In some ways rather than the UK govt being the last to have 'the penny drop' they were actually early adopters of 25kv AC for widespread electrification - which has become the 'standard' AC system.

 

[snowball]

I think 1500V DC overhead was agreed as a national standard in the 1930s, but only used for a few lines before the standard was changed to 25kV AC overhead in the 1950s. This decision came in time for 25kV AC overhead to be used for the first really long-distance electrification, from Euston to Birmingham, Manchester and Liverpool in the 1960s, and on to Glasgow in the 1970s. Meanwhile the third rail network south of London continued to receive some expansion - if you're extending an existing electrified network, it makes sense to continue with the same system.

 

[MarkyT]

I think you're not being entirely fair.

On the LSWR (3rd rail) vs LBSC (OHL) decision by Southern, part of it was driven by the technology of the time, the DC technology was "better" it that it was more established. AC was still at an early stage (bearing in mind this is pre 1925) and when merged to form the Southern railway, the route miles of 3rd rail far outweighed those of the OHL.

DC OHL - the LNER had planned those before WW2 as you said and they were completed in the 1950s. At this time 25kv was still fairly experimental - DB had done some AC OHL before the war, at 20kv rather than 25kv and it was this that the French copied in the early 50s, but in parallel they continued to electrify using 1500v DC and other European countries continued with 1500v or 3000v DC. In some ways rather than the UK govt being the last to have 'the penny drop' they were actually early adopters of 25kv AC for widespread electrification - which has become the 'standard' AC system.

Germany and other German-speaking and Scandanavian countries had already established significant AC OHLE networks before WW2, but at a lower frequency of 16 2/3Hz, more recently updated to 16.7Hz, except in Scandinavia. The LBSC AC equipment followed German practice with a lower frequency than standard today of 25Hz and a supply voltage of 6700V. It was supplied by a German company through a British contractor. I do wonder if some anti-German feeling may have had a role in decisions after WW1 to standardise on the DC 3rd Rail for the new Southern and abandon the overhead, although better compatibility with already electrified LU and former LSWR lines is probably the more compelling argument for this.

 

[snowball]

16 2/3Hz, more recently updated to 16.7Hz

I'm surprised to hear that - 16 2/3 seems a more obvious frequency to use, as it's one-third of 50Hz which is the standard mains frequency in Europe.

 

[A0wen]

I think 1500V DC overhead was agreed as a national standard in the 1930s, but only used for a few lines before the standard was changed to 25kV AC overhead in the 1950s. This decision came in time for 25kV AC overhead to be used for the first really long-distance electrification, from Euston to Birmingham, Manchester and Liverpool in the 1960s, and on to Glasgow in the 1970s. Meanwhile the third rail network south of London continued to receive some expansion - if you're extending an existing electrified network, it makes sense to continue with the same system.

The million dollar question is what would have happened had WW2 not intervened.

The LNER had various plans in place from the 1930s - two of which were completed immediately post war, the Woodhead line and Liverpool St - Shenfield. They had also proposed doing the Kings Cross suburban as far as Hitchin. In their eternal battle with the LMS for 'who was fastest to Scotland' I could easily envisage their electrifying the ECML from London to Newcastle at 1500v DC with a fleet of EM2s to run the services.

Not for the first time, BR were far too 'flat footed' in the early 1950s by ordering a huge number of steam locos which they'd retire early.

The decision on moving to 25kv AC was in 1956 - but again, BR could have done what other European countries did and follow different paths. Many others continued with DC OHL electrification on main lines for many years and have only moved to 25kv when building new fast lines.

 

[LNW-GW Joint]

Interestingly the Italian side of the Brenner route (Trento-Brenner) was initially electrified at 3.7kV AC at 16.7Hz by FS in 1929, and converted to the FS standard 3kV DC in 1934.
The Brenner Base tunnel now under construction will use 25kV AC.

 

[alf]

Several thousand trains a day use third rail in England, with journeys up to 130 miles perfectly safely day after day, year after year.

It is an economical, safe,system for passengers trains up to 90 mph. But not practical for heavy freight trains.

25kv wires down are highly disruptive & not rare events.
Displaced conductor rails are very rare & do not cause wholesale network cancellation.

Network Rail have admitted that their stats, which led them to claiming a few years ago that third rail was eight times more dangerous than overhead ac, are unreliable.

And that eight times figure was a subjective weighted index which gave undue weight to injuries, even minor ones like a sprained foot from tripping on a third rail. All contact with AC leads to death. Contact with DC is often survivable. So unfair to assessment of third rail.
The network rail stats are not reliable enough to judge. They have been told to reassess the issue.

If the Uckfield line/Rye lines were third railed then it would be prudent to replace foot crossings with bridges.
But that would probably be done with 25kv electrification too, or if quiet battery power units were introduced.

The end of third rails could be terminated in yellow insulation.

Versus 25 Kv, for non 110 mph lines & heavy freight, tried & tested third rail is far cheaper to build, cheap to run & probably as safe. And it is fast to build. We need more electrification now.

 

[hwl]

I think you're not being entirely fair.

On the LSWR (3rd rail) vs LBSC (OHL) decision by Southern, part of it was driven by the technology of the time, the DC technology was "better" it that it was more established. AC was still at an early stage (bearing in mind this is pre 1925) and when merged to form the Southern railway, the route miles of 3rd rail far outweighed those of the OHL. It's also worth remembering much of the early AC electrical equipment originated in Germany or Switzerland - the former was a bit problematic in the immediate post WW1 period.

DC OHL - the LNER had planned those before WW2 as you said and they were completed in the 1950s. At this time 25kv was still fairly experimental - DB had done some AC OHL before the war, at 20kv rather than 25kv and it was this that the French copied in the early 50s, but in parallel they continued to electrify using 1500v DC and other European countries continued with 1500v or 3000v DC. In some ways rather than the UK govt being the last to have 'the penny drop' they were actually early adopters of 25kv AC for widespread electrification - which has become the 'standard' AC system.

The LBSCR AC OHLE system was mostly installed Pre WW1 (~1909) and the availability of parts from AEG in Berlin (later Adtranz/ Bombardier Berlin / Europe HQ in more recent times) became difficult from 1914 onwards hence opting for British DC technology for further extensions.

 

[A0wen]

Several thousand trains a day use third rail in England, with journeys up to 130 miles perfectly safely day after day, year after year.

It is an economical, safe,system for passengers trains up to 90 mph. But not practical for heavy freight trains.

25kv wires down are highly disruptive & not rare events.
Displaced conductor rails are very rare & do not cause wholesale network cancellation.

Network Rail have admitted that their stats, which led them to claiming a few years ago that third rail was eight times more dangerous than overhead ac, are unreliable.

And that eight times figure was a subjective weighted index which gave undue weight to injuries, even minor ones like a sprained foot from tripping on a third rail. All contact with AC leads to death. Contact with DC is often survivable. So unfair to assessment of third rail.
The network rail stats are not reliable enough to judge. They have been told to reassess the issue.

If the Uckfield line/Rye lines were third railed then it would be prudent to replace foot crossings with bridges.
But that would probably be done with 25kv electrification too, or if quiet battery power units were introduced.

The end of third rails could be terminated in yellow insulation.

Versus 25 Kv, for non 110 mph lines & heavy freight, tried & tested third rail is far cheaper to build, cheap to run & probably as safe. And it is fast to build. We need more electrification now.

I think those that actually work on the railways probably disagree with your first point about it being a 'safe' system. And I'm not sure that failures of the infrastructure are any the less rare on 3rd rail than they are on OHLE - the big difference is that when it happens on OHLE it takes out either the WCML, ECML or Thameslink, which tends to be "front page" news. Whereas a 3rd rail failure which brings the Hastings line or Brighton Mainline to a stand isn't as high profile.

The biggest challenge with the speed of building of any electrification as @Bald Rick keeps pointing out is that it needs a connection to the National Grid - and that's not quick or easy to achieve. And 3rd rail installations need more of them, by virtue of the system not transmitting power as far as AC OHLE does. So whilst chucking down a few miles of 3rd rail on its own *may* be quicker than an OHL installation, if the connection to the National Grid isn't there it's completely academic.

 

[Robertj21a]

I think those that actually work on the railways probably disagree with your first point about it being a 'safe' system. And I'm not sure that failures of the infrastructure are any the less rare on 3rd rail than they are on OHLE - the big difference is that when it happens on OHLE it takes out either the WCML, ECML or Thameslink, which tends to be "front page" news. Whereas a 3rd rail failure which brings the Hastings line or Brighton Mainline to a stand isn't as high profile.

The biggest challenge with the speed of building of any electrification as @Bald Rick keeps pointing out is that it needs a connection to the National Grid - and that's not quick or easy to achieve. And 3rd rail installations need more of them, by virtue of the system not transmitting power as far as AC OHLE does. So whilst chucking down a few miles of 3rd rail on its own *may* be quicker than an OHL installation, if the connection to the National Grid isn't there it's completely academic.

Are there many third rail failures on the Brighton Main Line. It certainly doesn't seem to make the news - but is that because it rarely happens?

 

[A0wen]

Are there many third rail failures on the Brighton Main Line. It certainly doesn't seem to make the news - but is that because it rarely happens?

I was being somewhat 'tongue in cheek' - but the reality is when there is a problem with the ECML or WCML OHLE it invariably knocks out services between either London - Leeds / York / Newcastle / Edinburgh and potentially the suburban services to Peterboro and Cambridge or London - Birmingham / Manchester / Liverpool / Glasgow and possible the commuter services to any number of those. Which is why it is so much more noticeable. Whereas if there is a 3rd rail problem the profile of the places affected is much lower.

 

[zwk500]

I was being somewhat 'tongue in cheek' - but the reality is when there is a problem with the ECML or WCML OHLE it invariably knocks out services between either London - Leeds / York / Newcastle / Edinburgh and potentially the suburban services to Peterboro and Cambridge or London - Birmingham / Manchester / Liverpool / Glasgow and possible the commuter services to any number of those. Which is why it is so much more noticeable. Whereas if there is a 3rd rail problem the profile of the places affected is much lower.

The profile is also limited because 1. Service problems not related to the 3rd rail on the BML aren't exactly unknown ('train delayed on Brighton Line' is hardly a headline that anybody will pay particular attention to) and 2. Problems with the 3rd rail tend to be more difficult to get a good photo of, whereas a picture of OLE hanging down tangled up in a train's pantograph is fairly clear to accompany the article.

 

[JonasB]

2. Problems with the 3rd rail tend to be more difficult to get a good photo of, whereas a picture of OLE hanging down tangled up in a train's pantograph is fairly clear to accompany the article.

But Network Rail Wessex managed to get a couple of photos: https://twitter.com/NetworkRailWssx/status/1409426945608200197

 

[Robertj21a]

I was being somewhat 'tongue in cheek' - but the reality is when there is a problem with the ECML or WCML OHLE it invariably knocks out services between either London - Leeds / York / Newcastle / Edinburgh and potentially the suburban services to Peterboro and Cambridge or London - Birmingham / Manchester / Liverpool / Glasgow and possible the commuter services to any number of those. Which is why it is so much more noticeable. Whereas if there is a 3rd rail problem the profile of the places affected is much lower.

Thanks. I understand the point you are making but I still don't know if the Brighton Main Line has 'regular' third rail problems. I'm guessing it's far more resilient than many ohl operations.....

 

[alf]

I think those that actually work on the railways probably disagree with your first point about it being a 'safe' system.

So important national decisions on third rail or 25kv should be left to guards & platform staff only?

 

[WesternBiker]

3rd rail famously has problems of course when it gets icy or snows.

The "what might have been" of UK electrification is a fascinating story. The North Eastern Railway had plans in the early 1920s to electrify from York to Newcastle at 1,500V overhead and even built a locomotive - see https://www.lner.info/locos/Electric/ee1.php. The plans were shelved by the LNER after grouping in 1923.

And the Great Western also toyed with electrification west of Taunton in 1938 (presumably also at 1,500 DC overhead) to eliminate steam working - both to avoid the cost of coal transport, and because of the operating challenges of the Wellington and South Devon banks.

 

[A0wen]

So important national decisions on third rail or 25kv should be left to guards & platform staff only?

Not what I said. But the reality is unless you work with it or in close proximity to it on a daily basis, I'm not sure you are best placed to make statements like:

"It is an economical, safe,system"

Care to present your credentials for making such a statement?

 

[ChiefPlanner]

The million dollar question is what would have happened had WW2 not intervened.

The LNER had various plans in place from the 1930s - two of which were completed immediately post war, the Woodhead line and Liverpool St - Shenfield. They had also proposed doing the Kings Cross suburban as far as Hitchin. In their eternal battle with the LMS for 'who was fastest to Scotland' I could easily envisage their electrifying the ECML from London to Newcastle at 1500v DC with a fleet of EM2s to run the services.

Not for the first time, BR were far too 'flat footed' in the early 1950s by ordering a huge number of steam locos which they'd retire early.

The decision on moving to 25kv AC was in 1956 - but again, BR could have done what other European countries did and follow different paths. Many others continued with DC OHL electrification on main lines for many years and have only moved to 25kv when building new fast lines.

The LMS had plans also for St Pancras to Harpenden on overhead - with a new station twixt SAC and the latter ! (no Green Belt to worry about then) - why they did not consider a few more miles to Luton ? - but then that was a fairly self contained trade town then.

 

[alf]

The cost of the third rail electricity bill is often inflated because Network Rail let ballast like against the third rail.

In wet weather you can often see the third rail turning water to steam on wet ballast. At a big cost to the electricity bill.

A classic case is visible when coming in at 15 mph into the up fast Clapham Junction loop.
Ballast is piled almost as high as the top of the third rail & steams in wet weather. This has not been rectified for at least two years.

Today’s rare third rail failure at Micheldever was at a break in the third rail where the third rail dips to ensure train shoes go on & off easily.

What’s the betting ballast was piled up on it & in torrential rain which had affected the area 4,000 ampsflowed through the sodden ballast to the runnning rail?

Not an Inherent fault of third rail but inept NR non maintenance.
I hope to be proved wrong but I think I am right.

 

[Taunton]

And the Great Western also toyed with electrification west of Taunton in 1938 (presumably also at 1,500 DC overhead) to eliminate steam working - both to avoid the cost of coal transport, and because of the operating challenges of the Wellington and South Devon banks.

Just for reference, it was 3,000 DC. The outline project was designed by Merz & McLellan, electrical engineering consultants. It is of course interesting to contemplate what the track layout and arrangements at Taunton would have been (nothing shown in the report).

 

[A0wen]

The cost of the third rail electricity bill is often inflated because Network Rail let ballast like against the third rail.

In wet weather you can often see the third rail turning water to steam on wet ballast. At a big cost to the electricity bill.

A classic case is visible when coming in at 15 mph into the up fast Clapham Junction loop.
Ballast is piled almost as high as the top of the third rail & steams in wet weather. This has not been rectified for at least two years.

Today’s rare third rail failure at Micheldever was at a break in the third rail where the third rail dips to ensure train shoes go on & off easily.

What’s the betting ballast was piled up on it & in torrential rain which had affected the area 4,000 ampsflowed through the sodden ballast to the runnning rail?

Not an Inherent fault of third rail but inept NR non maintenance.
I hope to be proved wrong but I think I am right.

Once again, your qualification and credentials for such statements are.....?

The LMS had plans also for St Pancras to Harpenden on overhead - with a new station twixt SAC and the latter ! (no Green Belt to worry about then) - why they did not consider a few more miles to Luton ? - but then that was a fairly self contained trade town then.

Yes, that does seem a little bizarre. Harpenden's not that big even now. Unless it was driven by proposed journey time and minimised turnaround times?

The LNER's suggestion of Hitchin was more understandable as it is where the lines split and Hitchin was probably the outer limit of commuting back then.

Just for reference, it was 3,000 DC. The outline project was designed by Merz & McLellan, electrical engineering consultants. It is of course interesting to contemplate what the track layout and arrangements at Taunton would have been (nothing shown in the report).

Wasn't it also tied up with their suggested Dawlish avoiding line as well?

 

[WatcherZero]

I'm surprised to hear that - 16 2/3 seems a more obvious frequency to use, as it's one-third of 50Hz which is the standard mains frequency in Europe.

Remember in those days though the Railway companies would have had their own power stations so could tailor performance to their particular requirements.

 

[steamybrian]

The South Eastern Railway and London, Brighton & South Coast Railway were built to very tight clearances and installation of overhead electrification would mean massive rebuilding of tunnels and bridges.
The Tonbridge- Hastings Line only permitted special narrow bodied stock until 1986 when the track through several of the tunnels were singled but even today clearances are very tight through the tunnels at Tunbridge Wells.
Restrictions that only permit certain classes of stock still apply through Oxted Tunnel and Shakespeare Tunnel at Dover.

Possibly another reason why that the LB&SCR only installed overhead electification in the suburban area from 1909 until the 1920s before changing to 3rd rail.

 

[Taunton]

Wasn't it also tied up with their suggested Dawlish avoiding line as well?

No, that was 30 years before. Grierson, the GWR Chief Civil Engineer, on a roll after all the GWR new lines built 1900-1910, came up with a scheme for this, not only the Dawlish Inland, but also between Newton Abbot and Plymouth, overcoming the four substantial gradients there. Churchward told the directors it was wasted investment as he could build locomotives at a fraction of the investment, and the directors went with his approach, for 4-cylinder express locos, the Stars etc. Grierson was insulted, and he and Chrrchward scarcely spoke to one another again.