Possible third rail electrifications

[A0]

Wires down at Retford today. Haven't heard of any third rail being displaced recently.

Care to show me which stretch of 3rd rail is passed for 125mph running?

And since you seem to believe 3rd rail is a good idea, would you care to tell where else you think it's acceptable to have an uninsulated high voltage live electricity supply running across the ground? I assume you don't have exposed mains circuit cables running across the floor of your lounge ?
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I was responding to post 108 where it was said it takes 60 mins to ensure the third rail is off. I was not advocating possessions take place with the third rail live. I suggested it could be possible to manage this 1 hour down. Why one hour to turn off the third rail & confirm it's off? Bridging between sections could be eliminated with short circuit bars,or that is how I am told it used to be done.

I'm going to hazard a guess that all of those have been looked at, but are either unsuitable or susceptible to failure which isn't acceptable. I'm sure Bald Rick will be able to confirm.

 

[Philip Phlopp]

Wires down at Retford today. Haven't heard of any third rail being displaced recently.

That's tempting fate, don't go there. It'll be hot for the regulation three days soon and there will be buckled third rail all over the Southern region.

 

[Mutant Lemming]

No one has produced any figures for fatalities involving OHLE and third (and fourth) rail electrocutions but contact with the overhead is far far more likely to result in a fatality than contact with a current rail. Not that I am advocating a switch to third rail as it is unsuitable for many situations but I doubt it is responsible for many fatalities.

 

[Bald Rick]

Wires down at Retford today. Haven't heard of any third rail being displaced recently.

And you never will, as it is never advertised as such. However some 3R has been displaced today. It happens about once a month somewhere on the DC network in the south east.
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No one has produced any figures for fatalities involving OHLE and third (and fourth) rail electrocutions but contact with the overhead is far far more likely to result in a fatality than contact with a current rail. Not that I am advocating a switch to third rail as it is unsuitable for many situations but I doubt it is responsible for many fatalities.

For those of us who have done the training, seen the videos, and spoken to those who have survived such instances, please be assured that coming into contact with high current DC at 750V is just as likely to be fatal as coming into contact with lower current AC at 25kV. And if you do survive, the burns with DC are worse.

And being rather pedantic, the DC system causes a lot of fatalities, albeit in the animal kingdom. Not a week goes by where a badger, dog, fox, stray sheep or similar gets zapped. More often than not this causes a fire and/or trips the current delaying trains. And someone then has the unpleasant job of picking it up.

 

[najaB]

No one has produced any figures for fatalities involving OHLE and third (and fourth) rail electrocutions but contact with the overhead is far far more likely to result in a fatality than contact with a current rail.

That may well be true, however you are much more likely to make contact with third-rail than you are with overhead - if only because third-rail is down here where we walk and overhead is up there where the birds fly.

 

[snowball]

I think the last time they looked at electrifying Bidston-Wrexham with third rail, it was ruled out as too expensive because of steel sleepers.

 

[Philip Phlopp]

No one has produced any figures for fatalities involving OHLE and third (and fourth) rail electrocutions but contact with the overhead is far far more likely to result in a fatality than contact with a current rail. Not that I am advocating a switch to third rail as it is unsuitable for many situations but I doubt it is responsible for many fatalities.

NR have - I've got the figures somewhere. Off the top of my head, fatalities and overall risk is around 400% greater on third rail than OLE.

I'll dig them out over the weekend if I have time.

 

[SpacePhoenix]

I know in 3rd rail areas if there's any trespasser the power gets shut off. In overhead areas if there's a trespasser do all train in the area slow to walking pace (keeping an eye out for the trespasser) or is the power still switched off?

 

[Deepgreen]

And you never will, as it is never advertised as such. However some 3R has been displaced today. It happens about once a month somewhere on the DC network in the south east.
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I recall a few months ago there was a disastrously-delaying juice rail displacement after overnight works near Clapham Junction that was referred to as such in the explanations given.
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Care to show me which stretch of 3rd rail is passed for 125mph running?

And since you seem to believe 3rd rail is a good idea, would you care to tell where else you think it's acceptable to have an uninsulated high voltage live electricity supply running across the ground? I assume you don't have exposed mains circuit cables running across the floor of your lounge ?

But possibly have much higher voltage exposed cables running across the ceiling? I don't think it's reasonable to compare a living room with a tightly-controlled environment such as the railway, no matter what the perceived rights and wrongs are of the third rail regime.

 

[XDM]

NR have - I've got the figures somewhere. Off the top of my head, fatalities and overall risk is around 400% greater on third rail than OLE.

I'll dig them out over the weekend if I have time.

Very helpful. Can you show the source & any qualification? Then the issue is do we divide total AC DC deaths by route miles,track miles or number of stations( to try & reflect relative pop density)

Re the Southern rail displacement. Some southern drivers who asked, were told NR or their contractor had put back a third rail after work with no drop down for the shoe. Hence it decapitated all the shoes that went past. Not a fault of third rail,& minor damage on trains & infrastructure compared with wires down. Train running restored much faster & cheaper than wires down.
The more I consider third rail the more I think southern infill in is a no brainer; subject importantly to the weekend stats being kindly posted for us.

The unsourced claim dc uses 20% more power for the same work,doesn't reflect lighter trains due to not dragging transformers about & no regime for checking power isn't leaking to earth due to ballast etc piled up on third rail. I accept DC properly maintained will use about 10% more power at southern speeds because of the high current, but that is balanced by the far lower cost of the third rail versus the staggering cost of ever more sophisticated & unsightly AC knitting.

The trouble is no vested interest is batting for third rail,as minor infill.

 

[najaB]

The unsourced claim dc uses 20% more power for the same work,doesn't reflect lighter trains due to not dragging transformers about & no regime for checking power isn't leaking to earth due to ballast etc piled up on third rail.

"Don't bother me with facts, my mind is already made up."

As Bald Rick has pointed out, most DC units carry a lump of concrete (or similar) where the transformer would be in order to have common characteristics with their AC brethren, and the ballast piled up against the third rail is much less of a problem than you've made it out to be.

I accept DC properly maintained will use about 10% more power...

Another unsourced claim...

...but that is balanced by the far lower cost of the third rail versus the staggering cost of ever more sophisticated .

And again you ignore the fact that the whole life cost of third-rail is significantly more than that for OHLE due to the requirement for much more wiring and many more sub-stations, as well as the fact that DC isn't able to support as many trains, and those trains it can support can't travel as fast and that it is much easier to put power back into the grid with AC OHLE than it is with third-rail DC units.

...unsightly AC knitting

I think this is the crux of the matter - you just don't like how OHLE looks.

 

[AM9]

But possibly have much higher voltage exposed cables running across the ceiling? I don't think it's reasonable to compare a living room with a tightly-controlled environment such as the railway, no matter what the perceived rights and wrongs are of the third rail regime.

I doubt whether the HV cables would be live for more than a few cycles of ac after they first shorted. Just touching any part of the train below would trip the circuit protection. This is simple to do when the difference between the maximum current draw of trains is well below the current of a short circuit, even at the remote end of a long section. The maximum load on a single track circuit is ISTR in the hundreds of amps. range whereas the short circuit current surge would be a few thousand amps. As a slight but relevant aside, some national grid circuit protection systems are sensitive enough to sense the rapid and non-characteristic current change on a pylon route and determine a likely cable brakage. It would also be likely that the falling cable would have the power removed before it touched anything below, the only danger being its weight!
Conversely, the maximum demand possible on a 750VDC 3rd rail section of track is about 8000 - 10000 amps.. That would allow as few as six modern 4-car EMUs to run concurrenly, probably with their performance artificially limited by their software. A short circuit at a location remote from the feed point could result in a current of not much more than that meaning that to prevent frequent random disconnections, safety switchgear would need to discriminate between a random event like 2 or three trains accelerating at the same time, and a major safety hazard like the conductor rail lifting and touching train superstructure, bridges or anything that creates a risk to human safety. Indeed, there are probably situations in dry weather where the rail could be laying on dry sleepers or ballast and not cause a safe shutdown until something actually made a short circuit, be it mechanical or animal (including humans).

 

[Mutant Lemming]

For those of us who have done the training, seen the videos, and spoken to those who have survived such instances, please be assured that coming into contact with high current DC at 750V is just as likely to be fatal as coming into contact with lower current AC at 25kV. And if you do survive, the burns with DC are worse.

And being rather pedantic, the DC system causes a lot of fatalities, albeit in the animal kingdom. Not a week goes by where a badger, dog, fox, stray sheep or similar gets zapped. More often than not this causes a fire and/or trips the current delaying trains. And someone then has the unpleasant job of picking it up.

Have tripped over the damn thing on an odd occasion, seen countless p/way staff walk all over them and followed a dog for about 4 miles and numerous belts from the juice rail - all survived to tell the tale. Doubt any would from overhead.

 

[A0]

Have tripped over the damn thing on an odd occasion, seen countless p/way staff walk all over them and followed a dog for about 4 miles and numerous belts from the juice rail - all survived to tell the tale. Doubt any would from overhead.

But the difference is the 25kv wire is about 20' above you - the only way you could come into contact with it is if it has fallen down and is still live or you're doing something so monumentally stupid you're a budding Darwin Award candidate. That's the point - both are dangerous if you come into contact with it, but the ease with which or likelihood of coming into contact with one is far greater than the other.

 

[XDM]

Thousands of factories & houses back straight onto rail 25kv ac. Scaffolders working at first & second floor level run around with metal scaffold poles carried horizontally. A work colleague had to shout they were within inches of 25 kv. There were no warning signs & the scaffolder did not realise it was a power line. Ok anecdotal, but there are plenty of unconsidered risks with 25 kv 18 foot up. The peril of a ground juice rail is obvious.

 

[Bald Rick]

I recall a few months ago there was a disastrously-delaying juice rail displacement after overnight works near Clapham Junction that was referred to as such in the explanations given.

April 30th last year. It was extraordinarily disruptive! (Hence the more detailed explanation, rather than 'power supply problems')
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Have tripped over the damn thing on an odd occasion, seen countless p/way staff walk all over them and followed a dog for about 4 miles and numerous belts from the juice rail - all survived to tell the tale. Doubt any would from overhead.

Oh absolutely. But then I know of several people who have survived a belt from the OLE. Including several cable thieves.

The difference being that AC tends to 'throw' the person off the conductor, as the alternations cause the shocked muscles to react in that way. With DC the muscles 'grip' and the person can not let go / move even if they are aware and want to.

And as several well respected electrical engineers have told me, it is current that kills. (Otherwise we'd all keel over every time we get a static shock).

 

[NotATrainspott]

Thousands of factories & houses back straight onto rail 25kv ac. Scaffolders working at first & second floor level run around with metal scaffold poles carried horizontally. A work colleague had to shout they were within inches of 25 kv. There were no warning signs & the scaffolder did not realise it was a power line. Ok anecdotal, but there are plenty of unconsidered risks with 25 kv 18 foot up. The peril of a ground juice rail is obvious.

Anyone who carries around metal poles for a living should be aware of the dangers of any elevated cables, whether on the railway or not. That they hadn't been paying enough attention to notice that they're next to an electrified railway is entirely their fault. Even then, how many people have been killed in those circumstances due to 25kV AC OHLE rather than any sort of overhead power cables, the likes of which run across the length and breadth of the country without the safety precautions of the railway?

 

[Bald Rick]

Thousands of factories & houses back straight onto rail 25kv ac. Scaffolders working at first & second floor level run around with metal scaffold poles carried horizontally. A work colleague had to shout they were within inches of 25 kv. There were no warning signs & the scaffolder did not realise it was a power line. Ok anecdotal, but there are plenty of unconsidered risks with 25 kv 18 foot up. The peril of a ground juice rail is obvious.

Very anecdotal; if a scaffolder was within inches of the 25kV, he (or she; we're fully inclusive now) was almost certainly foul to loading gauge and and got their scaffolding well over a metre through the boundary. Much more likely there were within inches of the return conductor, which is only at 25kV under fault conditions. Besides, if they literally were inches away, it is likely they would have picked up some induced current - I know of several cases where colleagues have received shocks from this phenomenon.

And the peril of the ground rail is not obvious to a great many people. As a school friend of mine found out to his cost (although he did survive).


Anyway, let's be clear. I have it on very good authority that some small scale 3rd rail / 4th rail electrification will be possible. Any tube extensions for example (I can't imagine the new Bakerloo line stock will be equipped with pantographs for the extension to Lewisham). Also potential add ons that fill in small gaps (Kew curve) or to help with future battery hybrids.

But, in the absence of DC>AC conversion (which I personally think is unlikely), the remaining 'big' gaps in the DC network will be dealt with by battery hybrids, (Ashford - Hastings, Uckfield, North Downs).

 

[edwin_m]

A work colleague had to shout they were within inches of 25 kv. There were no warning signs & the scaffolder did not realise it was a power line. Ok anecdotal, but there are plenty of unconsidered risks with 25 kv 18 foot up.

They'd have been just as dead if they'd touched the third rail with their pole.

Ok anecdotal, but there are plenty of unconsidered risks with 25 kv 18 foot up. The peril of a ground juice rail is obvious.

You'd expect anyone with basic awareness to see wires supported on structures above the track, complete with insulators, and deduce that they could be something to do with electricity. At first and even second glance a third rail looks very much like the normal running rail until you notice it's a bit higher and sitting on pots.

 

[najaB]

It's becoming abundantly clear that certain posters are convinced of the truthiness[1] of their statements, regardless of the facts that are presented and will refudiate[2] anything that doesn't agree with their world view.

1. It is a word.
2. It's not a word.

 

[SodTheDrummer]

There were no warning signs & the scaffolder did not realise it was a power line.

A Darwin award for that gentleman please. What on God's earth did he think the wires were..?

 

[Trog]

I have done surveying under OHLE where the induced current was enough to make the metal fittings on the survey staff feel like they were covered in cellotape. However it is the electric shock to your eyeball each time you look through the survey instrument that is the most disconcerting.

 

[Philip Phlopp]

I have done surveying under OHLE where the induced current was enough to make the metal fittings on the survey staff feel like they were covered in cellotape. However it is the electric shock to your eyeball each time you look through the survey instrument that is the most disconcerting.

Heras fencing appearing on platforms is always good for a laugh. I think half the contractors doing WCRM work on stations got shocked by Heras fencing and the other half got shouted at for trying to bring Heras fencing onto platforms.

 

[miami]

A Darwin award for that gentleman please. What on God's earth did he think the wires were..?

Phone wires I'd assume

 

[najaB]

A Darwin award for that gentleman please. What on God's earth did he think the wires were..?

I'm fairly sure that had you asked, his answer would have been "What wires?"

 

[jopsuk]

(I can't imagine the new Bakerloo line stock will be equipped with pantographs for the extension to Lewisham).

Pfft, surely the Bakerloo will be entirely shut down and rebored to the same diameter as Crossrail with all platforms straigtened and lengthened so that the quietest tube line can get 200m full sized AC trains?

 

[The Ham]

Pfft, surely the Bakerloo will be entirely shut down and rebored to the same diameter as Crossrail with all platforms straigtened and lengthened so that the quietest tube line can get 200m full sized AC trains?

(I know it was said in jest but I'm going to ask anyway)

Could that be possible? (I would guess that the answer is probably not, or at least not without great cost). The thinking behind asking is that if the line is relatively lightly used; could it be a contender to be done so as to form another cross London route, potentially acting as a metro service further out in the way that Crossrail 2 will.

Would having Crossrail type trains allow faster acceleration and/or top speed to make journey times a little faster (so as to bridge some of the 3 minute difference in journey time between Waterloo and Baker Street vs the Jubilee line)?

 

[edwin_m]

Anything's possible given enough time and money. But doing this would be far more costly than boring a new tunnel somewhere else, and involve a long shutdown. The result would be something slightly better than the Bakerloo, whereas if money had been spent on a new tunnel then you'd still have the Bakerloo but a new Crossrail route as well!

 

[furnessvale]

Phone wires I'd assume

Quite possible, but he still in line for a Darwin award.

Anyone who carries steel tubes around for a living,and whose first assumption on seeing overhead wires is that they are telephone wires without any proof, is not long for this world.

 

[The Ham]

Anything's possible given enough time and money. But doing this would be far more costly than boring a new tunnel somewhere else, and involve a long shutdown. The result would be something slightly better than the Bakerloo, whereas if money had been spent on a new tunnel then you'd still have the Bakerloo but a new Crossrail route as well!

I get that, the possible justification for doing it could be because there has to be a limit on how many more central London tunnels that there would be space for (without being crazily deep). IF it was something that was going to be done, you would want to do it at a time when there was capacity on other lines which run parallel to it (so probably sooner rather than later).

Although it also depends on how much better than the Bakerloo it would be. An extra 50 people per train, then probably not worth it, however extra 50% plus per train along with some other benefits (maybe speed) then it could be worth thinking about.