I would rather put it that the problem with 'no-brainers' is twofold. Sometimes they encounter an idiot, who *insists* upon using their brain (and they think they know better). Sometimes the 'no-brainer' solution isn't always appropriate, and people assume that it's suitable in a circumstance where it isn't because it has 'worked before'.
He was involved in the first 6 years on the underground and it probably wouldn't exist without him coz he bought the lines and out them under one company
Be careful: you mustn't direct current affairs in a way that would cause alternate current affairs. Jago would not be able to get much traction on that subject, and you can Bank on that!
@Simon Mulcahy No, they're +420v and -210v. Total 630v. The outside rail is the positive, and can be either side of the running rails, but at stations it's furthest away from the platform.
I know more about the subway network of a city Ive spent all of 2 days in than I do about all other public transportation networks around the world combined, thanks to this channel
@@ds1868 Idk, I think most don't care for the subtleties of the tube. It's a shame it's taken for granted, but that's what happens when something is so good.
Ha, how ridicules of you to watch videos about the London underground when you don’t even live in London. He say’s having never visited London or the even UK, well also being obsessed with videos about said London’s Underground Railway…
2:33 _”...don’t ask me why I can barely even wire a plug.”_ Might I explain? Westinghouse’s AC won out over Edison’s DC for electricity networks, because the former allowed there to be a great distance between the mucky generating station and the residential end user with no loss of power; by using transformers to step down massive transmission voltages (as an aside, this is why ole Tommy invented the Electric Chair to try and convince everyone that his AC competitor was much more dangerous - he even attempted to get the term “being westinghoused” into common parlance as a substitute for the portmanteau: electrocution). In a country like Britain, however, before the National Grid - so, when the Underground network was mostly being built - there was *no fixed standard* for the AC being generated either in terms of phase, voltage or amperage oompf. Whatever factory or local generating station, from which the outside user tapped off their power, fancied or needed their AC to be, it was: _this presented a challenge for those powering expensive industrial machinery, like a leccy train, which could be ruined by the variation in AC type being provided across the country; or a growing metropolis like London._ Nevertheless, as power *over great distance* was not a concern, for most _initially_ purchased/manufactured (Victorian) electrical machinery - because the firm or factory would usually be using its own steam powered generator of leccy, on site - DC was the established standard for such plant expenditure; hence why it was for the growing tube network too; also “safer” for the tumbling passenger - debatable. As outside companies providing generated power through grids became more cost effective, however, the *industrial* end user was faced with a tricky problem: either chuck out ALL their very expensive original DC kit, to purchase all new AC machinery - and some of the tube network’s complicated signalling tackle has only been fully replaced relatively recently - or stick to DC and save money, by just changing supplied grid power near the point of use. (the Kempton Steam Museum channel has a good vid on the haunting looking “Mercury Arc Rectifiers” used before the invention of Silicon-based diodes to accomplish this, which they still maintain, that lays out the whole palaver far better than I’ve just done)
« By 1922 there were in Greater London 80 electrical undertakings operating between them 70 generating stations employing 50 different systems of supply at 24 voltages and 10 frequencies. » Standardisation was proposed before 1900 but didn't really get much headway until the creation of the National Greid in the 1930s. Even so by the 1960s non-standard AC and DC supplies were still in use in four areas of London and the last continued right up to the decommissioning of the last press that used it in Fleet Street in 1987. [From _London's Power Supplies_ by M.A.C. Horne, 2012, www.metadyne.co.uk/pdf_files/electricity.pdf ]
@@calmeilles The technology historian Adam Hart-Davies once did a bit where he showed off a box the size of a large toaster, manufactured as a “handy” portable adapter for just *all the different plug sockets,* dozens, historically in use across Britain too! It never occurred to me that newsprint would be a natural context in which many decades-old machinery would continue in original DC use _but that makes complete sense_ - especially as the UK’s industrial “workshop of the world” status waned, towards a service economy instead, the more time that passed, the more expensive such replacement (importation) would likely become. A while back in trawling old abandoned station websites, there was a page on a visit to the detached-from-the-network deep level parallel tunnel, used as a records store, near Goodge Street. As they were no longer supplied by the Underground, they still used the place’s 100+ year old mercury arc rectifier which was shown pictured in use (on the webpage), to turn the National Grid’s AC into the DC which all the tunnels’ lighting, lifts and machinery had been built for - which presumably had also served Ike and chums down there in their planning of D-Day too.
Another point is that in the days before inverter drives DC motors were generally easier to deal with in terms of speed control, which is why the overwhelming majority of electric tramway and urban railway systems from the late 19th/early 20th C used DC. Since most such systems had their own local generating plant the advantages of AC for long distance transmission weren't important.
This is a classic demonstration of "things you never even noticed or thought about, but find fascinating anyway". And for probably the one and only time, I'm seeing this while it has only one view... yet 12 upvotes. The up vote current must be leaking through the CZcams viewing stats.
@@kanedaku actually it's because of the way that CZcams takes in its counters of views and likes. There's so many ppl watching that if there was one thread of updating the counters then it would take too long and some views or likes won't record it. So CZcams uses a multithreaded version, which can have some syncing issues early on.
"The problem with no-brainers is that it can be circumvented by people using their brains." I'll have to remember that phrase. As far as I know, many railways continue to use the rails as a means to operate the signalling system. A break in the rails will automatically set the signal to red. This of course presents the issue that rails are more flexible than they are fragile, which creates its own issues...
In the Netherlands, this is true for our traditional signalling system (NS54) which works with track cirquits. Newer systems (based on axle-counters or train reporting like ERTMS) don't have this built in to the signalling system. However, the detection of track breaks was deemed an "unintended beneficial accident" of how the track cirquit was set up, so it wasn't necessary for the newer systems.
What the quote actually was “ it was a no brainer, but the problem with no brainers is that it can be circumvented by people “refusing” to use their brains….just saying…😂
That is only correct about 50% of the time. A break in the continuous rail has many other parallel paths which may well be low enough resistance to prevent the detection of a broken rail. Also quite often the ends of the broken rail are in compression if they are above the designed temperature of the track. In this case the electrical resistance across the break will probably be too low to allow the break to be detected. Also some breaks involve pieces falling off the gauge corner rather than a break through the whole of the rail. To further complicate matters some parts of the switches in points are not part of the trach circuit as it is impossible to bond wires near the point tips.
The underground runs on 630V DC. The positive rail is set at 420V DC (which at stations is always furthest from the platform) and the negative rail us set at -210V DC, giving the full 630V. The power rails are 1.5 inches above the running rails.
Having watched the video I was disappointed that this sort of info wasn't included, so thanks. I had no idea that the underground was ever DC at all, let alone that it's still like that nowadays. The older I get, the more I learn, the less I seem to know... but I do enjoy this channel.
@@thiscouldbeeasier I think Jago leaves out some of the technical details as not to scare off non-rail fans. Normally those details being missing doesn't get in the way of the story being told.
I think it is different on stretches of track that are shared with the Overground, which runs on a 3 track system. The Overground section of the Bakerloo Line for example has the same 4 track layout as everywhere else, but the Overground trains only use 3 of them.
@@garycook5071 There's pickup shoes on both sides, and the train can use either of them. You will have a short section with rails on both sides, then one of them will stop.
I live in London and have always used, and loved our Underground system. Among my favourite books is 'London's Disused Underground Stations' by J. E. Conner from whom I have learned a lot. But Jago is an absolute mine of information and his videos are entertaining, informative and totally addictive. Thanks for this one Jago.
Yeah, I've got that book, I borrowed it from the library first of all then when I went to London I bought it at Covent Garden Museum, There are plenty of videos/DVDs in the "London's Lost...." series by Online Video and then there's City Lines Remembered - all with commentary by Jim Connor, one with Barbara Butler joining him. Yeah, I'm a train buff, have been for like 60 years. I got into underground trains when I was 9, the year the Victoria Line was finished.
The Baker Street & Waterloo Railway had the polarity reversed, with the live rail in the centre, between the running rails, and the return rail on the outside, closest to the tunnel rings. For some complicated reason involving the shared power supply to the Metropolitan District Railway, when they tried it the other way round, they couldn't achieve the necessary low leakage so the engineers swapped them over. The practical outcome? Bakerloo line trains ran "backwards" until 1917, when the polarity was swapped back.
That last sentence made me laugh out loud. If you hadn't put the word "backwards" in inverted commas, I would've thought you were taking the proverbial, but I know what you mean.
If you swap the polarity of the rails you would need to modify the train power wiring as well as the line breakers only work with the current going through them in the designed direction. If you try to operate them with the current in the wrong direction the arc will be blown into the circuit breaker rather than out through the arc chutes. If the arc is blown inwards the ionised air will not be cleared, the arc will not be broken and the line breaker will be destroyed in a spectacular fashion.
The Underground is one of the few railways electrified on the four-rail system. There are two rails that supply power to the trains, one outside the running rails electrified at +420 V DC, the other in the middle at -210 V, producing an overall traction supply voltage of 630 V.
Interesting. So, when a Network Rail train, goes over the section of track between Wimbledon and East Putney, before curving away to Clapham Junction, it's presumably only getting 420 V DC, as it's not connected to the return rail, in the middle.
Alexandra Clement As my Father (at least I think he was !!)used to say "it's a wise man indeed who knows who his Father is. Happy Fathers day to my Dad who is 101 or he would have been if he hadn't died in the year 2000 !! He loved a joke did my Dad so I didn't disappoint!! You'll get that joke in a bit !!
@@andyhall7032 The tricky one is when they added the second routeway from Monument to the DLR Bank one, its easier to do the walk to the northern line platforms then down one escalator to get to the DLR platforms, going the other way takes ages. Dont try it when busy , and I used to travel about 11pm at night (PS when the 02 empties and the night time economies are back places like Surrey Quays for Jubilee to Overground are more crowded than mid peak daytimes !
I feel yerkes is twisting the end of his tash and nodding “yes it was me” from beyond at the “mere” mention in another video. Or maybe that’s just him trying to “flog us some electricity”.
One side note: most other surface electric railways using the running rails as part of the traction current circuit operate on many thousands of volts alternating current. The earth leakage problem is reduced in its effects by the lower voltage drop over line length and that AC will not cause corrosion to the same extent as DC. The ions in the electrolyte are thrust first in one direction then in the other, never really reaching the electrode to be corroded. Thanks, Jago for your continuing direction. May your volts and amps continue to flow.
Many main-line electric locomotives have DC motors, typically of about 750V rating. The 25kV (sometimes 6.25kV under low height tunnels, as in Birmingham) AC overhead supply is transformed down to less than 1kV and rectified. So the traction motors are similar to those on SR.
@@john1703 Sorry to be pedantic, but all of Britain's AC electrified railways have been at 25kv for years, and Brigadier Langley conducted his experiments regarding clearances long before the lines through Birmingham were electrified, and thus they have always been at the higher voltage Whilst there are still some underground trains with DC motors, the majority now have AC ones, and I think the only remaining DC ones on SR are Southern's class 313s and 455s
@@grumpyoldman47 Thank you. The early AC locos were built for 25/6.25 kV. www.aclocogroup.co.uk/index.php/history-introduction/history-1st-generation-ac-locos
@@john1703 I don't think that the locos were. Multiple unit trains, yes and it caused a lot of trouble in Glasgow in the early days, when the 6.25/25Kv switching didn't operate properly, causing transformers to explode. I think that there was even a fatality.
Interestingly (well, not to most people, but it is to me), the voltages on those two power rails are not symmetrical. The positive rail is at +420V whilst the negative is at -210. I assume there is a good reason for this, possibly the way that the DC power is derived from three phase electricity. One thing that the video leaves unanswered is how the Underground and the (now) Network Rail systems sharing track was resolved as the latter uses only a third rail running at 750V DC. The answer is, apparently, that the -120V line is bonded to the running rails, and the outer rail is run at 660V DC. It seems that underground trains are happy enough running at 660V rather than their normal 630V. Indeed, it seems that there are provisional plans to run the underground network at 750 V which should add a little extra zip to journey times. I suspect that two electrified rails ought, in principle, allow for even higher voltages as the potential to earth from either is lower. If the outer was run at +660V and the inner at -330V is would provide 990V of potential difference allowing for almost 60% more power at the same current (or reduced loss at the same power). Another interesting point to some, is that part of the French Metro system used a fourth rail system is the trains used rubber tyres to reduce noise and they, of course, do not conduct electricity.
It's actually more complicated. Only a few places use the old +420/-210 arrangement. Most of it is +500/-250 and the bits shared with National Rail use +750/0, with the centre bonded to the running rails. The Wikipedia article on LU infrastructure has the full list.
Speaking of rubber tires... Trolleys/trams commonly use the running rails as the return path. But trolleybuses use two wires (supply and return), since they run on rubber tires on the street, rather than steel wheels on rails.
The voltage on the Victoria Line was increased both to increase the power available to the trains and to increase the distance that energy re-generated during braking could be used my other trains. The gains were quite large even for a modest increase in voltage. From memory the voltage on the Victoria Line can now reach around 900V during braking. The increased voltage does not impact the acceleration of the 08TS trains unlike older trains so the signal overlaps are not compromised.
I would would think of Yerkes more of a step-father who moves in, makes a lot of changes, but there is a feeling that there is some thing wrong some where but we just can't see it.
Were it not for his dodgy dealings, he might well be remembered this way but Charles Pearson probably gets that title, especially as he was in there right at the beginning. The UndergrounD was well established by the time Mr Yerkes arrived. The system still owes a lot to him though, so maybe a step-father or uncle.😁
I have to confess to revelling in a bit of smug anticipation of the mention of a certain American businessman in this video, as i already knew of his involvement in the 4th rail system. However, when the name "Charles Tyson Yerkes" was finally uttered, it was no less joyful than had i not been expecting it. Fascinating video - as always - and especially interesting to learn of the tussle between the District and Metropolitan over electricity.
I suppose nowadays in the spiv economy the fourth rail would be essential because someone at the top of the organisation had links to rail manufacture.
The other subway to use a fourth rail system is Milan Metro Line 1. Other lines on the Milan Metro either use the 750v DC third rail system or the 1500v DC overhead system.
@@TheEulerID Paris metros, whether MP (Pneu) or MF (Fer) use 2 rails with the usual 1435 mm gauge for guidance and a third rail for DC power. The MP have 2 additional tracks for the tires. The return current is sent back to the running track via a contact shoe because the steel wheels do not carry much weight unless a tyre is flat.
Great explanation Sir! As a Signal electrician in Australia, I have often wondered why 2 rails were used on the Tube! We are having leakage issues with the new Tram network on the Gold Coast, as the ground is mostly sand and a very high water table! I have been watching the building of "CrossRail" with a lot of interest and I see it will finally be finished next year...Covid permitting:-) CHeers , Gregg.
I have tripped over those conductor rails 100s of times working on the rails 🤣 - you find train shoes all the time in the tunnels that have fallen off the trains
Couldn't agree more about Bank. I've lost count of the number of times I've become lost down there with signage (or lack of) that seems deliberately designed to confuse. Finding the right way to the Waterloo & City is always a challenge.
Most other systems are built so their tunnels have a masonry or concrete lining to prevent current leakage. They also don’t bolt the rails directly to the tunnel structure. For example, here in NYC, the tunnels have always been concrete and the tracks were originally laid on a normal gravel roadbed inside the tunnel box. Today the roadbed is mostly wooden ties (sleepers) embedded in the concrete floor of the tunnel. Most are “half ties”, with a gap in the middle for a drainage channel (which also allows people who fall off the platforms a safe place to move to to avoid being hit by a train, with some going all the way across to provide stability.
The running rails and conductor rails in LU are either fixed to sleepers set in the ballast (Sub-Surface) or concrete floor (Deep Tube); or else are direct-fix into the concrete floor of the tunnel. There’s also a few patches of slab track down there. At no point are the running rails or the conductor rail fixed to the cast iron tunnel rings. however on part of the Western Central Line there is very minimal clearance between the conductor and tunnel ring due to poor construction quality.
In my country train tunnels are built of concrete, & some use "floating slab" track - where the tracks are nailed onto concrete slabs that're are in-turn mounted on dampers situated between them & the base of the tunnel's lining. The dampers help absorb some of the vibration caused by trains passing by & thus reduce the noise & disruption to nearby buildings I think
Mums least favourite station would be Charing Cross because she got lost there in the late 1960s. I was with her, we were trying to get to Goodge St to go to Middlesex hospital.
For whatever reason, it's a good thing that the NR 3rd rail system is -- at least on the looks -- the LU system minus the negative rail. As a non-British person I had been to few LU stations (which did include Bank), but I think I dislike Heathrow T4 for, well, I had to wait for ridiculous amount of time when I was going for a plane from T3 -- and the Picc was being chaotic at that time so there were no trains directly to T23
@@owensmith7530 yes it’s working! It had several faults when I took it on, but I sorted those out. It’s part of a collection of exchanges that I have in my shed (got to have a hobby right?!) and I place several calls though it a week to keep it happy. I don’t appear to have any video of it on my channel - I should fix that! It’s a 50 line exchange that was for internal use only, there is some evidence it was linked into the London Electricity Board (LEB) private network. My research to confirm that stalled last year when visiting the London Transport archives became impossible.
I'd never heard of Charles Tyson Yerkes before Jago came along but boy have I made up for it since subscribing to the channel. What an absolute cad and a bounder to boot. Yerkes, not Jago.
You want to read up why he left America ! However he was outdone by the astronomer who persuaded him to finance the Yerkes Observatory in Chicago in the mistaken belief that any 'new stars' found would be named after him !
I understood from a friend who worked on the underground that the motors used needed 440V dc but the lighting in the trains used domestic bulbs for lighting etc as they were cheaper and also less dangerous as 400V filament bulbs tend to explode when failing, so one rail is at +220V and the other at -220V giving a difference of 440V for the traction motors and 220V for any illumination. Later when bulbs were replace by fluorescent tubes again domestic cheap ones could be used. Also if you fell on the track and touched one of the rails you tended to just die and not explode which made a real mess!
Basically this is rubbish - the lighting used to be a number of bulbs in series powered from 600 V but you need to go back 100 years to the 1920's & standard tube stock to find that. For your information the florescent tubes were not standard - they had a different rating to domestic ones as they ran on 850 Hz from the motor alternator set. As the brightness increases with frequency standard 50Hz tubes would burn out very quickly.
I've worked on the baker loo line years ago &have met railwaymen like your friend. They enjoyed talking shit then laughing at people who believed them. "It takes all sorts"
Many DC transport systems running at 400 V plus use a rotary converter on the train to drove the onboard circuits to 32 v as this was considered the upper safe limit as passengers stick their fingers into broken light bulb bayonet fittings. Railway systems here in the Great South Land copied slavishly what was done in the mother country, so we ended up with a concoction of things copied from Great Britain. We even copied the Irish running gauge to use in some places!! Stavros
@@stevecallachor The London Underground used 50V DC for lighting & control. I believe national rail in the UK used to use a higher voltage around 110V DC. The earlier DC generators were replaced with alternators due to their better performance. I think they were self excited to allow them to start when the battery was flat - I assume this was done by placing permanent magnets in the rotor probably in conjunction with coils to regulate the output current.
Thank you, thank you, THANK YOU for this video!! As a bona-fide train enthusiast and particularly a subway nut (I was born and raised in New York City riding the subway since age 7) and a model railroading enthusiast modelling three scales (gauges) HO, OO and O. I absolutely LOVE literally everything British as in that accent (of course), humour, cathedrals, pipe organs, architecture, automotive interests, of course your superb railway network and the gorgeous trains. For my birthday in 2018 because he knew that I loved the London Underground, my wonderful son bought the Bachmann London Underground S-Stock OO-scale model set for me (NOW I'll put him in my will Lol) and in watching the many videos of the London Underground, I often wondered about the fourth rail as I knew that there of course would be two running rails and a third rail for power, but I never knew what the fourth rail was for and this explains it, so thanks! Terrific footage throughout the video. In the opening footage of the London Underground entering that station, what stock is that and might it be pre S-Stock or post? Speaking of the S-Stock, the footage of it entering the stations at 3:44, 4:10 and 4:38 is gorgeous. I've liked and subscribed! Thanks again!
Yerkes was the subject of a trilogy of novels; very popular in their day, by Theodore Drieser: “The Financier”, “The Titan” and “The Stoic”. They were entertaining enough that I read them all. He was an amazing if unscrupulous entrepeneur. It seemed that bribery and corruption was the only way to get anything done in those days.
Once I had to change trains at Bank from the Northern to Waterloo & City. The normal route was closed for rebuilding. Was sent on a long diversion along dimly lit corridors, up and down spiral stairways. Took about 20 minutes to get to the right platforms.
The pickup rail runs at +420V DC and the return rail runs at −210V DC, total of 630V DC. There's also a plan to increase the voltage to a total of 750V DC, that is, +500V and −250V.
Bank - definitely one to miss if you are travelling and need to interchange there. I found that leaving the gateline and walking on the streets then re-entering the gateline was best if Bank could not be avoided.
I like the stations where you see the trains coming out of and going in the tunnel section, like Stratford, East Finchley, Finchley Road, Queens Park and White City. Not sure about the Piccadilly ones because the ramps are curved at Baron's Court and Arnos Grove so you might not see the train headlights in the tunnel before it bursts out.
Brilliant explanation. When noticed two rails, instantly remembered ground leakage. Nasty thing which can eat out any metal constructions, metal pipes and cables around leakage. We in Riga had plenty of issues with that below street tram rails. Actually have no idea about situation now, but in 20th century ground leakage wrecked piping and constructions around tram lines quite a lot.
Bank is a glorious amalgamation of train lines, ideas, monuments and banks in to vision of the future. Maybe some day all underground stations can be like Bank
Well, damn and blast it, old man... er Jago... or T.G., or... tube nerd. (Pick your favourite) You caused me to spend 3 days binge watching almost every single episode of your channel. Excluding the model painting and beer reviews. Fascinating stuff, old man. I've been a tube nerd myself for many years, with several books. Geoff over at Londonist dramatically reduced his videos in recent years, so I discovered your delightful channel. Splendid job. Keep them coming please.
As next year sees the 120 anniversary of the foundation of what was to become The Underground, UERL as was, it would be nice if London Underground were to mark the occasion by painting mustaches on the front of its trains in celebration of the man himself, Charles Tyson Yerkes!
Have you noticed how much Yerkes looks like the "capitalist" character on the "Monopoly" box? Yes, he really does... makes you wonder if it was just a coincidence..?
I was really shocked to learn that it was mainly due to the electrolysis of the tunnel rings and other potential ring circuits :-) Another electrifying set of underground facts !! Very interesting. Thank you.
I have pondered why the four rail system many times while standing on a platform. Thanks for the historical input on the question! I am much better informed and will now ponder other curiosity's while waiting for a train.
Don’t forget The Central Line, if my memory serves me correctly, the 3rd rail on that line is at a different height to the other lines. ( when LTL took over the Waterloo and City Line from BR they had to install a 4th rail, as like the rest of the Southern it only had a live rail. Return was through the running rails.
The w & c was “Yerkesfied” before transfer, because BR decided to buy the same stock LU ordered for the Central. So a new negative rail was put in, while they lifted out the old trains and put in new
The Third rail is higher and of a different 'inverted angle iron' section with a copper bus bar as the tunnels in the central part of the Central Line are too small to allow the normal positive rail to be fitted.
I live in South West France and Bordeaux, like a lot of cities, has a tram network. The tramway uses 750v DC and is mostly supplied by overhead cable. However, in the city centre, they did not want to spoil the aesthetics with ugly cables so a third rail is at the same level as the running rails. At particular stops, the tram will switch from pantograph to a shoe under the power car. The system is such that the third rail only becomes live when the power car is over it.
You'll see the same in Reims. We have the same trams in Dublin, but were too cheap to use the third rail solution in places where it was warranted (e.g., O'Connell Street & College Green).
The trams in Lincoln (way back in the day) had pickup and return "pads", spaced so the tram was always over two of them. The trams had magnets to lift the supply up to touch the plate when they passed over. It was supposed to drop back down afterwards, so the plate wouldn't stay live. Was supposed to!
Thanks Jago. I've always wondered why the Underground and Tube used a separate return rail rather than using the running rails but this l makes sense now
Great video. Bank is a banker of station. Often needed to change there to get on the DLR and with the escalators shut at the time it was so many stairs. Once had to help a woman with her luggage down both sets of stairs fun times. Have similar feeling toward Green Park.
Thanks again Jago. Currently am still glad of your vids.. When things get back to normal I will get back down to London and being better informed will enjoy my trip better thanks to you. But that is far a day away. (best pun I could make of that )
Thanks for the video very well explaind. I get asked the question all the time from Sweds living in Stockholm when they visit London. Their tube uses Southen Region 3 rail configuration. I will send them to this video.
Hello Jago! This gets a like, but may I please be the 97,000th person to point out that the fourth rail is actually conducting at minus 210VDC, with the third at plus 420VDC, giving 630VDC total. To add a further layer of pedantic physics, current (made up of electrons) actually travels away from a negative potential and towards a positive one, so if anything the third rail is where the current returns. Other commentators, please feel free to rip me to shreds on this, I probably deserve it. I'd get out more but my Merseytravel Trio ticket isn't valid on LU...
Electrons flow from negative to positive. Electricity is positive to negative. Remember hole flow in a transistor? I went to an electronic school and still will say negative to positive. i relearned that when i went to work for the transit agency in Philadelphia. The third rail is positive in relation to ground while the return rail the running rail is at zero in reference to ground. But not at ground. This as stated in the video is to prevent or reduce electrolysis. Also the running rails are used in the signaling circuit to show where the trains is located and to trip the next signal or to stop the train should it go into the next block when it shouldn't
I seemed to recall that the Central Line (Central London Railway) initially used a different configuration of power rails. Possibly one either side of the running rails, but cannot clearly remember.
I was the Supervisor for Pirelli construction who had the contract to install the new aluminium conductor rail on the Jubilee Line Extension. Tunnelling works first, then Tarmac who installed the running rails and then us behind installing the conductor rails and cables. From Stratford to Green Park. We undertook Installation and testing from Finchley Road, Swiss Cottage, St Johns Wood. Fact: the conductor rail was all Aluminium except the top part where the train shoe would touch which was steel, but since good steel is not very conductive to electricity it had to be of a poor quality steel which had a better conductivity. The reason for the steel on top was to stop the rail wearing away too quickly when the shoes from the train would be rubbing continuously on the rail. That's why the newly installed conductor rail on top all ways looked rusty.
Sounds a bit like the electrical excuses used by the Cincinnati Street Railway for the streetcars using double overhead poles. Came in handy though when they switched over to trolleybuses.
A lot of people used to wonder why Sydney's underground lines as well as the North Shore Line as far as St Leonards appeared to have a third rail. The "third rail" was laid in the middle of the running rails and always very rusty. In fact, it looked like old track re-purposed. What was going on was that the rails on these lines were made of wear-resistant steel which also didn't give a good current return on the overhead DC 1500V system. Hence older discarded track with better current return was used as a "third rail", and bonded to the running rails. The reason for the wear resistant track in the first place was to reduce the need for track maintenance and replacement in the tunnels. The old "third rails" have now gone.
Bank is a good shout, also Euston, mainly I hate how the northern line isn't signposted correctly, so you never know which platform to go to for the edgeware train and always end up on the high Barnet platform
As LT train crew in a previous life that's as good a technical description for the four rail system as I've seen anywhere. Re the Met/District discussions on the proposed systems for electrification, I seem to recall reading of a trial of the Met's preferred overhead system.
Bless you for giving Yerkes another well deserved mention in this story. Whatever his personal failings he at least had the good taste to die before the full extent of his financial chicanery could be revealed. I think he merits a statue somewhere on the network. Cheers
I had a friend decades ago who once went for a job interview as a London tube driver. One of the interview questions was what are the 4 rails used for which he couldn't answer. Needless to say, he didn't get the job.
3:42 "The trouble with no-brainers is that they can be circumvented by people refusing to use their brains." How true is that?
Vintage Jago!! 👏🏻👏🏻
I would rather put it that the problem with 'no-brainers' is twofold.
Sometimes they encounter an idiot, who *insists* upon using their brain (and they think they know better).
Sometimes the 'no-brainer' solution isn't always appropriate, and people assume that it's suitable in a circumstance where it isn't because it has 'worked before'.
Y'all are correct. We in the G.A.R. 335th confirm these operations as facts and common problems.
But, surely, the point of a "no-brainer" is precisely that you don't have to use your brain. That's what it means!
@@IMelkor42 Nah, you're overthinking it.
It's amazing that the Underground has been going for 160 years and Yerkies was only involved for six of them, yet his name crops up everywhere.
He was involved in the first 6 years on the underground and it probably wouldn't exist without him coz he bought the lines and out them under one company
I do love hearing about current affairs.
That's clever. :)
Nice one
*golf clap*
Be careful: you mustn't direct current affairs in a way that would cause alternate current affairs. Jago would not be able to get much traction on that subject, and you can Bank on that!
*rim shot*
You are my +420v to my -210v
I would place your bromance at 9 on the, mostly arbitrary, Plainly Difficult bromance scale.
Liking this comment cameo ! 👌🏻
Yes I was taught that one rail was 420v and the other was 210v but I don't know why
Now kiss
@Simon Mulcahy No, they're +420v and -210v. Total 630v. The outside rail is the positive, and can be either side of the running rails, but at stations it's furthest away from the platform.
I know more about the subway network of a city Ive spent all of 2 days in than I do about all other public transportation networks around the world combined, thanks to this channel
The Brits are nuts about their transport systems. Perhaps understandable since they invented them.
@@ds1868 Idk, I think most don't care for the subtleties of the tube. It's a shame it's taken for granted, but that's what happens when something is so good.
safe to say ive never been near the UK yet I can tell how to get from one point of the city to the other
Ha, how ridicules of you to watch videos about the London underground when you don’t even live in London.
He say’s having never visited London or the even UK, well also being obsessed with videos about said London’s Underground Railway…
2:33 _”...don’t ask me why I can barely even wire a plug.”_ Might I explain?
Westinghouse’s AC won out over Edison’s DC for electricity networks, because the former allowed there to be a great distance between the mucky generating station and the residential end user with no loss of power; by using transformers to step down massive transmission voltages (as an aside, this is why ole Tommy invented the Electric Chair to try and convince everyone that his AC competitor was much more dangerous - he even attempted to get the term “being westinghoused” into common parlance as a substitute for the portmanteau: electrocution).
In a country like Britain, however, before the National Grid - so, when the Underground network was mostly being built - there was *no fixed standard* for the AC being generated either in terms of phase, voltage or amperage oompf. Whatever factory or local generating station, from which the outside user tapped off their power, fancied or needed their AC to be, it was: _this presented a challenge for those powering expensive industrial machinery, like a leccy train, which could be ruined by the variation in AC type being provided across the country; or a growing metropolis like London._
Nevertheless, as power *over great distance* was not a concern, for most _initially_ purchased/manufactured (Victorian) electrical machinery - because the firm or factory would usually be using its own steam powered generator of leccy, on site - DC was the established standard for such plant expenditure; hence why it was for the growing tube network too; also “safer” for the tumbling passenger - debatable.
As outside companies providing generated power through grids became more cost effective, however, the *industrial* end user was faced with a tricky problem: either chuck out ALL their very expensive original DC kit, to purchase all new AC machinery - and some of the tube network’s complicated signalling tackle has only been fully replaced relatively recently - or stick to DC and save money, by just changing supplied grid power near the point of use. (the Kempton Steam Museum channel has a good vid on the haunting looking “Mercury Arc Rectifiers” used before the invention of Silicon-based diodes to accomplish this, which they still maintain, that lays out the whole palaver far better than I’ve just done)
« By 1922 there were in Greater London 80 electrical undertakings operating between them 70 generating stations employing 50 different systems of supply at 24 voltages and 10 frequencies. »
Standardisation was proposed before 1900 but didn't really get much headway until the creation of the National Greid in the 1930s. Even so by the 1960s non-standard AC and DC supplies were still in use in four areas of London and the last continued right up to the decommissioning of the last press that used it in Fleet Street in 1987.
[From _London's Power Supplies_ by M.A.C. Horne, 2012, www.metadyne.co.uk/pdf_files/electricity.pdf ]
@@calmeilles The technology historian Adam Hart-Davies once did a bit where he showed off a box the size of a large toaster, manufactured as a “handy” portable adapter for just *all the different plug sockets,* dozens, historically in use across Britain too! It never occurred to me that newsprint would be a natural context in which many decades-old machinery would continue in original DC use _but that makes complete sense_ - especially as the UK’s industrial “workshop of the world” status waned, towards a service economy instead, the more time that passed, the more expensive such replacement (importation) would likely become.
A while back in trawling old abandoned station websites, there was a page on a visit to the detached-from-the-network deep level parallel tunnel, used as a records store, near Goodge Street. As they were no longer supplied by the Underground, they still used the place’s 100+ year old mercury arc rectifier which was shown pictured in use (on the webpage), to turn the National Grid’s AC into the DC which all the tunnels’ lighting, lifts and machinery had been built for - which presumably had also served Ike and chums down there in their planning of D-Day too.
The national grid and standardization is also very British : czcams.com/video/Mm5khEUIBx0/video.html
You laid that out very nicely, thank you!
Another point is that in the days before inverter drives DC motors were generally easier to deal with in terms of speed control, which is why the overwhelming majority of electric tramway and urban railway systems from the late 19th/early 20th C used DC.
Since most such systems had their own local generating plant the advantages of AC for long distance transmission weren't important.
Yerkes, Electricity, and a steam-powered underground line? Yeah, this is another classic Jago video!
Free coal smoke inhalations for everyone :P
This is a classic demonstration of "things you never even noticed or thought about, but find fascinating anyway". And for probably the one and only time, I'm seeing this while it has only one view... yet 12 upvotes. The up vote current must be leaking through the CZcams viewing stats.
Did you just call them upvotes? I think you might have been spending a bit too much time on StackOverflow or Reddit.
I did wonder why there were two electrified rails rather than one. Now I know.
I think its when people get early (private) viewings (Patreon people?), their views dont count but their likes do.
@@kanedaku actually it's because of the way that CZcams takes in its counters of views and likes. There's so many ppl watching that if there was one thread of updating the counters then it would take too long and some views or likes won't record it. So CZcams uses a multithreaded version, which can have some syncing issues early on.
As soon as Jago asked rhetorically if anyone was responsible for all this my immediate thought was "Oh god here comes Yerkes again!"
"The problem with no-brainers is that it can be circumvented by people using their brains." I'll have to remember that phrase.
As far as I know, many railways continue to use the rails as a means to operate the signalling system. A break in the rails will automatically set the signal to red. This of course presents the issue that rails are more flexible than they are fragile, which creates its own issues...
In the Netherlands, this is true for our traditional signalling system (NS54) which works with track cirquits. Newer systems (based on axle-counters or train reporting like ERTMS) don't have this built in to the signalling system. However, the detection of track breaks was deemed an "unintended beneficial accident" of how the track cirquit was set up, so it wasn't necessary for the newer systems.
What the quote actually was “ it was a no brainer, but the problem with no brainers is that it can be circumvented by people “refusing” to use their brains….just saying…😂
@@IIVQ Yep , a similar system works in Britain
That is only correct about 50% of the time. A break in the continuous rail has many other parallel paths which may well be low enough resistance to prevent the detection of a broken rail. Also quite often the ends of the broken rail are in compression if they are above the designed temperature of the track. In this case the electrical resistance across the break will probably be too low to allow the break to be detected. Also some breaks involve pieces falling off the gauge corner rather than a break through the whole of the rail. To further complicate matters some parts of the switches in points are not part of the trach circuit as it is impossible to bond wires near the point tips.
The track circuit primarily detects occupancy for the wayside signalling -- a sub-circuit controls roadway level crossing signals and gates.
Jago, you are our DC track Circuits to our AC traction Current. Cheers.
Lol, this is good 😂
I’m sure for royalties reasons, a quick blast of an AC-DC song had to be omitted. Learnt a lot from this fine film :) 👍
The underground runs on 630V DC. The positive rail is set at 420V DC (which at stations is always furthest from the platform) and the negative rail us set at -210V DC, giving the full 630V. The power rails are 1.5 inches above the running rails.
Having watched the video I was disappointed that this sort of info wasn't included, so thanks. I had no idea that the underground was ever DC at all, let alone that it's still like that nowadays. The older I get, the more I learn, the less I seem to know... but I do enjoy this channel.
@@thiscouldbeeasier I think Jago leaves out some of the technical details as not to scare off non-rail fans. Normally those details being missing doesn't get in the way of the story being told.
I think it is different on stretches of track that are shared with the Overground, which runs on a 3 track system. The Overground section of the Bakerloo Line for example has the same 4 track layout as everywhere else, but the Overground trains only use 3 of them.
Does the positive rail move? How can it be always furthest from the platform when on some stations the side you get on/off differs
@@garycook5071 There's pickup shoes on both sides, and the train can use either of them. You will have a short section with rails on both sides, then one of them will stop.
I live in London and have always used, and loved our Underground system. Among my favourite books is 'London's Disused Underground Stations' by J. E. Conner from whom I have learned a lot. But Jago is an absolute mine of information and his videos are entertaining, informative and totally addictive. Thanks for this one Jago.
Ive got it too!
Best three websites: Underground History, Abandoned Stations, Subterrania Brittanica.
Ooh, forgot a really good one, should have been top 4 - urban75.org
Yeah, I've got that book, I borrowed it from the library first of all then when I went to London I bought it at Covent Garden Museum, There are plenty of videos/DVDs in the "London's Lost...." series by Online Video and then there's City Lines Remembered - all with commentary by Jim Connor, one with Barbara Butler joining him. Yeah, I'm a train buff, have been for like 60 years. I got into underground trains when I was 9, the year the Victoria Line was finished.
I love the word "bounder" and it's peculiarly appropriate to practically everything you've told us about Yerkes.
The Baker Street & Waterloo Railway had the polarity reversed, with the live rail in the centre, between the running rails, and the return rail on the outside, closest to the tunnel rings. For some complicated reason involving the shared power supply to the Metropolitan District Railway, when they tried it the other way round, they couldn't achieve the necessary low leakage so the engineers swapped them over. The practical outcome? Bakerloo line trains ran "backwards" until 1917, when the polarity was swapped back.
That last sentence made me laugh out loud. If you hadn't put the word "backwards" in inverted commas, I would've thought you were taking the proverbial, but I know what you mean.
If you swap the polarity of the rails you would need to modify the train power wiring as well as the line breakers only work with the current going through them in the designed direction. If you try to operate them with the current in the wrong direction the arc will be blown into the circuit breaker rather than out through the arc chutes. If the arc is blown inwards the ionised air will not be cleared, the arc will not be broken and the line breaker will be destroyed in a spectacular fashion.
The fact you said bank is the worst station is a big no-no, its got the best announcement on the entire tube and it has some of the best connections.
The Underground is one of the few railways electrified on the four-rail system. There are two rails that supply power to the trains, one outside the running rails electrified at +420 V DC, the other in the middle at -210 V, producing an overall traction supply voltage of 630 V.
Interesting.
So, when a Network Rail train, goes over the section of track between Wimbledon and East Putney, before curving away to Clapham Junction, it's presumably only getting 420 V DC, as it's not connected to the return rail, in the middle.
Happy belated Father's day to our favourite father of the underground, Charles Yerkies.
Please do an episode on Bank, even though you hate it.
Better make it about the whole Manument-Bonk complex, then. I’m hoping for convoluted (and failed) schemes and yet more Yerkies.
@@thomasfrederiksendk everyone remembers the first time they see those stations linked on the map ... and then the actual walk between them ...
@@andyhall7032 you don’t say. That’s half an hour of tunnel walking I’m never getting back.
Alexandra Clement
As my Father (at least I think he was !!)used to say "it's a wise man indeed who knows who his Father is.
Happy Fathers day to my Dad who is 101 or he would have been if he hadn't died in the year 2000 !!
He loved a joke did my Dad so I didn't disappoint!!
You'll get that joke in a bit !!
@@andyhall7032 The tricky one is when they added the second routeway from Monument to the DLR Bank one, its easier to do the walk to the northern line platforms then down one escalator to get to the DLR platforms, going the other way takes ages. Dont try it when busy , and I used to travel about 11pm at night (PS when the 02 empties and the night time economies are back places like Surrey Quays for Jubilee to Overground are more crowded than mid peak daytimes !
I feel yerkes is twisting the end of his tash and nodding “yes it was me” from beyond at the “mere” mention in another video. Or maybe that’s just him trying to “flog us some electricity”.
Like Snidely Whiplash dwiddling his mustash as he ties a damsel to the railway tracks and laughing “nyahhh!, nyahhh!”. (tophat and cloak)
One side note: most other surface electric railways using the running rails as part of the traction current circuit operate on many thousands of volts alternating current. The earth leakage problem is reduced in its effects by the lower voltage drop over line length and that AC will not cause corrosion to the same extent as DC. The ions in the electrolyte are thrust first in one direction then in the other, never really reaching the electrode to be corroded.
Thanks, Jago for your continuing direction. May your volts and amps continue to flow.
Many main-line electric locomotives have DC motors, typically of about 750V rating. The 25kV (sometimes 6.25kV under low height tunnels, as in Birmingham) AC overhead supply is transformed down to less than 1kV and rectified. So the traction motors are similar to those on SR.
@@john1703 Sorry to be pedantic, but all of Britain's AC electrified railways have been at 25kv for years, and Brigadier Langley conducted his experiments regarding clearances long before the lines through Birmingham were electrified, and thus they have always been at the higher voltage
Whilst there are still some underground trains with DC motors, the majority now have AC ones, and I think the only remaining DC ones on SR are Southern's class 313s and 455s
@@grumpyoldman47 Thank you. The early AC locos were built for 25/6.25 kV. www.aclocogroup.co.uk/index.php/history-introduction/history-1st-generation-ac-locos
Except for the whole of Southern Region in the UK with 750V DC traction with a single positive supply rail.
@@john1703 I don't think that the locos were. Multiple unit trains, yes and it caused a lot of trouble in Glasgow in the early days, when the 6.25/25Kv switching didn't operate properly, causing transformers to explode. I think that there was even a fatality.
Interestingly (well, not to most people, but it is to me), the voltages on those two power rails are not symmetrical. The positive rail is at +420V whilst the negative is at -210. I assume there is a good reason for this, possibly the way that the DC power is derived from three phase electricity.
One thing that the video leaves unanswered is how the Underground and the (now) Network Rail systems sharing track was resolved as the latter uses only a third rail running at 750V DC. The answer is, apparently, that the -120V line is bonded to the running rails, and the outer rail is run at 660V DC. It seems that underground trains are happy enough running at 660V rather than their normal 630V. Indeed, it seems that there are provisional plans to run the underground network at 750 V which should add a little extra zip to journey times. I suspect that two electrified rails ought, in principle, allow for even higher voltages as the potential to earth from either is lower. If the outer was run at +660V and the inner at -330V is would provide 990V of potential difference allowing for almost 60% more power at the same current (or reduced loss at the same power).
Another interesting point to some, is that part of the French Metro system used a fourth rail system is the trains used rubber tyres to reduce noise and they, of course, do not conduct electricity.
It's actually more complicated. Only a few places use the old +420/-210 arrangement. Most of it is +500/-250 and the bits shared with National Rail use +750/0, with the centre bonded to the running rails. The Wikipedia article on LU infrastructure has the full list.
Speaking of rubber tires... Trolleys/trams commonly use the running rails as the return path. But trolleybuses use two wires (supply and return), since they run on rubber tires on the street, rather than steel wheels on rails.
The voltage on the Victoria Line was increased both to increase the power available to the trains and to increase the distance that energy re-generated during braking could be used my other trains. The gains were quite large even for a modest increase in voltage. From memory the voltage on the Victoria Line can now reach around 900V during braking. The increased voltage does not impact the acceleration of the 08TS trains unlike older trains so the signal overlaps are not compromised.
Can we say Yerkes is the Father of London Underground on this Father's Day?
I would would think of Yerkes more of a step-father who moves in, makes a lot of changes, but there is a feeling that there is some thing wrong some where but we just can't see it.
Were it not for his dodgy dealings, he might well be remembered this way but Charles Pearson probably gets that title, especially as he was in there right at the beginning. The UndergrounD was well established by the time Mr Yerkes arrived. The system still owes a lot to him though, so maybe a step-father or uncle.😁
@@2H80vids second cousin once removed. The Americans are cousins nothing more.
I have to confess to revelling in a bit of smug anticipation of the mention of a certain American businessman in this video, as i already knew of his involvement in the 4th rail system. However, when the name "Charles Tyson Yerkes" was finally uttered, it was no less joyful than had i not been expecting it. Fascinating video - as always - and especially interesting to learn of the tussle between the District and Metropolitan over electricity.
I suppose nowadays in the spiv economy the fourth rail would be essential because someone at the top of the organisation had links to rail manufacture.
The other subway to use a fourth rail system is Milan Metro Line 1. Other lines on the Milan Metro either use the 750v DC third rail system or the 1500v DC overhead system.
Also part of the Paris Metro that used rubber tyred wheels to cut down noise. The reason for using four rails would be fairly evident.
@@TheEulerID Paris metros, whether MP (Pneu) or MF (Fer) use 2 rails with the usual 1435 mm gauge for guidance and a third rail for DC power. The MP have 2 additional tracks for the tires. The return current is sent back to the running track via a contact shoe because the steel wheels do not carry much weight unless a tyre is flat.
Great explanation Sir! As a Signal electrician in Australia, I have often wondered why 2 rails were used on the Tube! We are having leakage issues with the new Tram network on the Gold Coast, as the ground is mostly sand and a very high water table! I have been watching the building of "CrossRail" with a lot of interest and I see it will finally be finished next year...Covid permitting:-)
CHeers , Gregg.
I have tripped over those conductor rails 100s of times working on the rails 🤣 - you find train shoes all the time in the tunnels that have fallen off the trains
Came here for a railway lesson got an AC/DC video instead 😀
where? I didn't see any rock band in this video
@@illyasvielemiya9059 not talking about the band, but electoral currents.
@@illyasvielemiya9059 I know it's shocking 😂
@@alexandraclement1456 are these electoral currents always negative on the left? Just asking for a thick friend.
@@kevinmothers904 in this, I'm just as thick as your friend.
Couldn't agree more about Bank. I've lost count of the number of times I've become lost down there with signage (or lack of) that seems deliberately designed to confuse. Finding the right way to the Waterloo & City is always a challenge.
I feel the same way about Canary Wharf. Always a struggle to find the right way out.
Most other systems are built so their tunnels have a masonry or concrete lining to prevent current leakage. They also don’t bolt the rails directly to the tunnel structure.
For example, here in NYC, the tunnels have always been concrete and the tracks were originally laid on a normal gravel roadbed inside the tunnel box.
Today the roadbed is mostly wooden ties (sleepers) embedded in the concrete floor of the tunnel. Most are “half ties”, with a gap in the middle for a drainage channel (which also allows people who fall off the platforms a safe place to move to to avoid being hit by a train, with some going all the way across to provide stability.
The running rails and conductor rails in LU are either fixed to sleepers set in the ballast (Sub-Surface) or concrete floor (Deep Tube); or else are direct-fix into the concrete floor of the tunnel. There’s also a few patches of slab track down there.
At no point are the running rails or the conductor rail fixed to the cast iron tunnel rings. however on part of the Western Central Line there is very minimal clearance between the conductor and tunnel ring due to poor construction quality.
Yes, but most other systems were built a long time after these.
In my country train tunnels are built of concrete, & some use "floating slab" track - where the tracks are nailed onto concrete slabs that're are in-turn mounted on dampers situated between them & the base of the tunnel's lining. The dampers help absorb some of the vibration caused by trains passing by & thus reduce the noise & disruption to nearby buildings I think
Mums least favourite station would be Charing Cross because she got lost there in the late 1960s. I was with her, we were trying to get to Goodge St to go to Middlesex hospital.
This is always an excellent " pub quiz " question ... Have used it many times , over the years ! ....
For whatever reason, it's a good thing that the NR 3rd rail system is -- at least on the looks -- the LU system minus the negative rail.
As a non-British person I had been to few LU stations (which did include Bank), but I think I dislike Heathrow T4 for, well, I had to wait for ridiculous amount of time when I was going for a plane from T3 -- and the Picc was being chaotic at that time so there were no trains directly to T23
Nice to see Lots Rd Generating Station get a mention. I’m the current owner of some telephone exchange equipment that was installed there in 1965.
Is the telephone exchange still in working order? Are you actually using it for anything?
@@owensmith7530 yes it’s working! It had several faults when I took it on, but I sorted those out. It’s part of a collection of exchanges that I have in my shed (got to have a hobby right?!) and I place several calls though it a week to keep it happy.
I don’t appear to have any video of it on my channel - I should fix that!
It’s a 50 line exchange that was for internal use only, there is some evidence it was linked into the London Electricity Board (LEB) private network. My research to confirm that stalled last year when visiting the London Transport archives became impossible.
I'd never heard of Charles Tyson Yerkes before Jago came along but boy have I made up for it since subscribing to the channel. What an absolute cad and a bounder to boot. Yerkes, not Jago.
You want to read up why he left America ! However he was outdone by the astronomer who persuaded him to finance the Yerkes Observatory in Chicago in the mistaken belief that any 'new stars' found would be named after him !
@@johnmurrell3175 at least he got the observatory named after him!
This was electrifying, Jago, electrifying ! Thank you for keeping me current .
I understood from a friend who worked on the underground that the motors used needed 440V dc but the lighting in the trains used domestic bulbs for lighting etc as they were cheaper and also less dangerous as 400V filament bulbs tend to explode when failing, so one rail is at +220V and the other at -220V giving a difference of 440V for the traction motors and 220V for any illumination. Later when bulbs were replace by fluorescent tubes again domestic cheap ones could be used. Also if you fell on the track and touched one of the rails you tended to just die and not explode which made a real mess!
Basically this is rubbish - the lighting used to be a number of bulbs in series powered from 600 V but you need to go back 100 years to the 1920's & standard tube stock to find that. For your information the florescent tubes were not standard - they had a different rating to domestic ones as they ran on 850 Hz from the motor alternator set. As the brightness increases with frequency standard 50Hz tubes would burn out very quickly.
I've worked on the baker loo line years ago &have met railwaymen like your friend. They enjoyed talking shit then laughing at people who believed them.
"It takes all sorts"
Many DC transport systems running at 400 V plus use a rotary converter on the train to drove the onboard circuits to 32 v as this was considered the upper safe limit as passengers stick their fingers into broken light bulb bayonet fittings.
Railway systems here in the Great South Land copied slavishly what was done in the mother country, so we ended up with a concoction of things copied from Great Britain. We even copied the Irish running gauge to use in some places!!
Stavros
@@stevecallachor The London Underground used 50V DC for lighting & control. I believe national rail in the UK used to use a higher voltage around 110V DC. The earlier DC generators were replaced with alternators due to their better performance. I think they were self excited to allow them to start when the battery was flat - I assume this was done by placing permanent magnets in the rotor probably in conjunction with coils to regulate the output current.
Nice tale from the tube Jago , thanks
Decent pressie for Father’s Day!
Keep up the good work fella and stay safe. 🚂🚂🚂
"Two rails bad, four rails good!"
George Orwell, in 'Train Farm'
Good to see CTY back in the frame, it's been a while!
Thank you, thank you, THANK YOU for this video!! As a bona-fide train enthusiast and particularly a subway nut (I was born and raised in New York City riding the subway since age 7) and a model railroading enthusiast modelling three scales (gauges) HO, OO and O. I absolutely LOVE literally everything British as in that accent (of course), humour, cathedrals, pipe organs, architecture, automotive interests, of course your superb railway network and the gorgeous trains.
For my birthday in 2018 because he knew that I loved the London Underground, my wonderful son bought the Bachmann London Underground S-Stock OO-scale model set for me (NOW I'll put him in my will Lol) and in watching the many videos of the London Underground, I often wondered about the fourth rail as I knew that there of course would be two running rails and a third rail for power, but I never knew what the fourth rail was for and this explains it, so thanks!
Terrific footage throughout the video. In the opening footage of the London Underground entering that station, what stock is that and might it be pre S-Stock or post? Speaking of the S-Stock, the footage of it entering the stations at 3:44, 4:10 and 4:38 is gorgeous. I've liked and subscribed! Thanks again!
I know I'm bit late 😅 thats a 1996 stock but I'm not sure about that (it could be 1992 stock) used on deep level lines
Yerkes was the subject of a trilogy of novels; very popular in their day, by Theodore Drieser: “The Financier”, “The Titan” and “The Stoic”. They were entertaining enough that I read them all. He was an amazing if unscrupulous entrepeneur. It seemed that bribery and corruption was the only way to get anything done in those days.
Once I had to change trains at Bank from the Northern to Waterloo & City. The normal route was closed for rebuilding. Was sent on a long diversion along dimly lit corridors, up and down spiral stairways. Took about 20 minutes to get to the right platforms.
The pickup rail runs at +420V DC and the return rail runs at −210V DC, total of 630V DC. There's also a plan to increase the voltage to a total of 750V DC, that is, +500V and −250V.
Anode a thing or two about cathodic protection in utility applications, but didn't node about its use on the underground. Now anode! Thank you Sir!
Bank - definitely one to miss
if you are travelling and need to interchange there.
I found that leaving the gateline and walking on the streets
then re-entering the gateline was best
if Bank could not be avoided.
I like the stations where you see the trains coming out of and going in the tunnel section, like Stratford, East Finchley, Finchley Road, Queens Park and White City. Not sure about the Piccadilly ones because the ramps are curved at Baron's Court and Arnos Grove so you might not see the train headlights in the tunnel before it bursts out.
Brilliant explanation. When noticed two rails, instantly remembered ground leakage. Nasty thing which can eat out any metal constructions, metal pipes and cables around leakage. We in Riga had plenty of issues with that below street tram rails. Actually have no idea about situation now, but in 20th century ground leakage wrecked piping and constructions around tram lines quite a lot.
Bank is a glorious amalgamation of train lines, ideas, monuments and banks in to vision of the future. Maybe some day all underground stations can be like Bank
Well, damn and blast it, old man... er Jago... or T.G., or... tube nerd. (Pick your favourite)
You caused me to spend 3 days binge watching almost every single episode of your channel. Excluding the model painting and beer reviews.
Fascinating stuff, old man. I've been a tube nerd myself for many years, with several books. Geoff over at Londonist dramatically reduced his videos in recent years, so I discovered your delightful channel.
Splendid job. Keep them coming please.
Loved your script on this one. The part about the no-brainers was gold!
Very electrifying content indeed ! :)
Short and to the point. Perfect video! Thanks !
A very positive start to my Sunday thanks 👍
I asked both you and Geoff for a video on this topic - I guess, you won the race! Well done ... and Thanks!
Well done! A very lucid explanation of 'Why does the Underground run on four rails?", and on Yerkes.
As next year sees the 120 anniversary of the foundation of what was to become The Underground, UERL as was, it would be nice if London Underground were to mark the occasion by painting mustaches on the front of its trains in celebration of the man himself, Charles Tyson Yerkes!
@@highpath4776 Not a good enough reason not to put a mustache on the front of an Underground train though!! 😊
Have you noticed how much Yerkes looks like the "capitalist" character on the "Monopoly" box? Yes, he really does... makes you wonder if it was just a coincidence..?
Do not pass go, do not collect $200
You're referring to Mr. MoneyBags? Many guys in that timeframe had muttonchops on the sides of their faces along with walrus mustaches.
Thanks Jago - I learned why there are 4 rails, and was also reminded that I never really understood electrical AC and DC currents.
I was really shocked to learn that it was mainly due to the electrolysis of the tunnel rings and other potential ring circuits :-) Another electrifying set of underground facts !! Very interesting. Thank you.
I have pondered why the four rail system many times while standing on a platform. Thanks for the historical input on the question!
I am much better informed and will now ponder other curiosity's while waiting for a train.
Until you reach Ponders End.
Thanks again. That was first power station I seen for the underground. 👍🇳🇿
There was another at Neasden and a thrird that we will not talk about here.
I already knew this, but it's always great to get someone elses interpretation. Another great video Jago, keep em coming :)
Don’t forget The Central Line, if my memory serves me correctly, the 3rd rail on that line is at a different height to the other lines. ( when LTL took over the Waterloo and City Line from BR they had to install a 4th rail, as like the rest of the Southern it only had a live rail. Return was through the running rails.
The w & c was “Yerkesfied” before transfer, because BR decided to buy the same stock LU ordered for the Central. So a new negative rail was put in, while they lifted out the old trains and put in new
The Third rail is higher and of a different 'inverted angle iron' section with a copper bus bar as the tunnels in the central part of the Central Line are too small to allow the normal positive rail to be fitted.
I live in South West France and Bordeaux, like a lot of cities, has a tram network. The tramway uses 750v DC and is mostly supplied by overhead cable. However, in the city centre, they did not want to spoil the aesthetics with ugly cables so a third rail is at the same level as the running rails. At particular stops, the tram will switch from pantograph to a shoe under the power car. The system is such that the third rail only becomes live when the power car is over it.
You'll see the same in Reims.
We have the same trams in Dublin, but were too cheap to use the third rail solution in places where it was warranted (e.g., O'Connell Street & College Green).
The trams in Lincoln (way back in the day) had pickup and return "pads", spaced so the tram was always over two of them. The trams had magnets to lift the supply up to touch the plate when they passed over. It was supposed to drop back down afterwards, so the plate wouldn't stay live. Was supposed to!
@@worldcomicsreview354 Yikes!
Thanks Jago. I've always wondered why the Underground and Tube used a separate return rail rather than using the running rails but this l makes sense now
Great video. Bank is a banker of station. Often needed to change there to get on the DLR and with the escalators shut at the time it was so many stairs. Once had to help a woman with her luggage down both sets of stairs fun times. Have similar feeling toward Green Park.
Thanks again Jago. Currently am still glad of your vids.. When things get back to normal I will get back down to London and being better informed will enjoy my trip better thanks to you. But that is far a day away. (best pun I could make of that )
Very informative... Thank you!
Fascinating! Thanks for posting!
I don't remember seeing Yerkes in Transport Tycoon ... although some of the avatars are quite big-bushy-beardy so I guess could be based on him 😉
The chap in the monopoly game?
Thanks for the video very well explaind. I get asked the question all the time from Sweds living in Stockholm when they visit London. Their tube uses Southen Region 3 rail configuration. I will send them to this video.
Hello Jago! This gets a like, but may I please be the 97,000th person to point out that the fourth rail is actually conducting at minus 210VDC, with the third at plus 420VDC, giving 630VDC total. To add a further layer of pedantic physics, current (made up of electrons) actually travels away from a negative potential and towards a positive one, so if anything the third rail is where the current returns. Other commentators, please feel free to rip me to shreds on this, I probably deserve it.
I'd get out more but my Merseytravel Trio ticket isn't valid on LU...
Electrons flow from negative to positive. Electricity is positive to negative. Remember hole flow in a transistor? I went to an electronic school and still will say negative to positive. i relearned that when i went to work for the transit agency in Philadelphia. The third rail is positive in relation to ground while the return rail the running rail is at zero in reference to ground. But not at ground. This as stated in the video is to prevent or reduce electrolysis. Also the running rails are used in the signaling circuit to show where the trains is located and to trip the next signal or to stop the train should it go into the next block when it shouldn't
@@MrRonfelder Actually "Elecron flow" is from negative to positive, just to confuse you more
Amazing video thanks for sharing
I seemed to recall that the Central Line (Central London Railway) initially used a different configuration of power rails. Possibly one either side of the running rails, but cannot clearly remember.
Very informational, great video
I've seen enough of your videos on the Underground as soon as I saw Yerkes pic I said, " Yerkes!".
Interesting video. Thank you. As for my least favourite station-Stepney Green, or as it’s known locally, Stabney Green!
Another brilliant video sir!
I did not know that I did not know this and now that I know I am indebted to you Jago, for enhancing my knowledge.
Very educational & interesting
I was the Supervisor for Pirelli construction who had the contract to install the new aluminium conductor rail on the Jubilee Line Extension.
Tunnelling works first, then Tarmac who installed the running rails and then us behind installing the conductor rails and cables.
From Stratford to Green Park. We undertook Installation and testing from Finchley Road, Swiss Cottage, St Johns Wood.
Fact: the conductor rail was all Aluminium except the top part where the train shoe would touch which was steel, but since good steel is not very conductive to electricity it had to be of a poor quality steel which had a better conductivity. The reason for the steel on top was to stop the rail wearing away too quickly when the shoes from the train would be rubbing continuously on the rail. That's why the newly installed conductor rail on top all ways looked rusty.
Sounds a bit like the electrical excuses used by the Cincinnati Street Railway for the streetcars using double overhead poles. Came in handy though when they switched over to trolleybuses.
Great answer from the comment section question. Very much agree.
Glad not just me that avoid bank when at all possible
I love the way Yerkes raises his head above the parapet every so often.
That was very insightful.
A lot of people used to wonder why Sydney's underground lines as well as the North Shore Line as far as St Leonards appeared to have a third rail. The "third rail" was laid in the middle of the running rails and always very rusty. In fact, it looked like old track re-purposed. What was going on was that the rails on these lines were made of wear-resistant steel which also didn't give a good current return on the overhead DC 1500V system. Hence older discarded track with better current return was used as a "third rail", and bonded to the running rails. The reason for the wear resistant track in the first place was to reduce the need for track maintenance and replacement in the tunnels.
The old "third rails" have now gone.
Thank you
Thank you for that. I always wondered "why four rails?"
Bank is a good shout, also Euston, mainly I hate how the northern line isn't signposted correctly, so you never know which platform to go to for the edgeware train and always end up on the high Barnet platform
Yes yes we need a video on all the problems with bank!
Agreed Bank/Monument is a pain to be avoided
Always curious about that infamous third rail
Thank you 😊
Was immediately thinking bank too haha
As LT train crew in a previous life that's as good a technical description for the four rail system as I've seen anywhere.
Re the Met/District discussions on the proposed systems for electrification, I seem to recall reading of a trial of the Met's preferred overhead system.
This video is very electrifying, I was quite shocked about the 4 rail.
Interresting. I really love your videos. Now I finally know why.
Bless you for giving Yerkes another well deserved mention in this story. Whatever his personal failings he at least had the good taste to die before the full extent of his financial chicanery could be revealed. I think he merits a statue somewhere on the network. Cheers
Yes, agreed ...... but let's make it out of Spelter!
Thank you once again 👏👏
I wonder if Yerkes father never bought him a railway set when he was little, and that was why he was so fixated with the London Railway System.
I had a friend decades ago who once went for a job interview as a London tube driver. One of the interview questions was what are the 4 rails used for which he couldn't answer. Needless to say, he didn't get the job.