Why some electric trains use a third rail, and others don't

[@SeverityOne]

Fun fact about the Eurostar and third rail (before the completion of HS1): Trains coming from England often forgot to pull up the collector shoe for third rail pick-up, and this damaged track equipment on the French side. The French eventually solved this by installing a concrete block that would simply break off the collector shoe if it were still down. There is much to be said for simple solutions to engineering problems.

[@ballyhigh11]

That is a very French solution!

[@MRTransportVideos]

You can always trust the French to think "Blockade!"

[@user-cy7bs8rs9k]

There was a whole bunch of paperwork and visual checks around gauging issues - but no concrete blocks. Also- it wasn’t possible to “forget” to raise the collector shoes - it was either pans up or shoes down. Though in the winter the shoes could become stuck in the lowered position with a build up of ice.

[@JW1_1]

Did they genuinely forget though? 🤔🤷🏾‍♂️😉😆

[@abzzeus]

An electric system having potential? Did jago really sneak that one in? Yes he did

[@Julius_Hardware]

The man has no shame!

[@paulhollis8879]

With very little resistance…

[@lordmuntague]

Jago making a physics pun? Ohm my...

[@TimHall42]

Watt?

[@lordmuntague]

@@TimHall42 We'll have to have Jago inducted into the Hall-effect of fame...

[@josephturner7569]

I started on the North Clyde. Had a quite intensive electrification module on my Guards course. When I transferred to Reading, I pointed out that I knew nothing of 3rd rail. My conversion course consisted of the words 'don't step on it'.

[@tonys1636]

Should have included "and don't pee on it".

[@highdownmartin]

Pretty much all you need to know. When the lovers walk open days were on at Brighton 1990 the juice was off in the entire depot. You could tell staff and punters as staff were still stepping over it where punters were sitting on it eating their sandwiches.

[@hairyairey]

​@@highdownmartinit's a habit you don't want to break!

[@batman51]

When I joined the SR in the 60s I was taken to Stewarts Lane for a look round. At one point it was decided to cross the depot to the other side (we had been told not to step on anything metal) and we set off over the network of lines. At one point (literally) I found myself with nowhere to put my foot but fortunately, after an ungainly hop, managed to extricate myself from serious embarrassment and what would have been a very red face. Nevertheless, I much prefer the tidiness of 3rd rail to all that knitting.

[@blameless_hyperborean8638]

I had a friend at school whose father was a senior engineer on the Glasgow Subway, after having started his career on the Tube. His rule was simple: just don't stand on any rail ever.

[@pjelbro3492]

Also an interesting story on the early Eurostar trains that ran from the tunnel into Waterloo in the early days. When the train exited the tunnel there was a lineside sign to tell the driver to lower the pantograph as he was now in a third rail area. Unfortunately, there were a few instances when the driver forgot and then reported the incident to the control room. The lineside engineers knew which bridge to collect the bits of pantograph from.

[@filanfyretracker]

imagine explaining that to your car insurance that you have the top of a pantograph in your back seat because a train hit the bridge while you were driving over.

[@southcalder]

I can’t resist a good video about electricity. It’s good to keep current with what’s happening.

[@favesongslist]

Never understood the capacity for resistance to electrics potential and now EVs :)

[@SupremeLeaderKimJong-un]

This reminds me of an interesting story about a station called Manhattan Transfer in Harrison, NJ. You may know Manhattan Transfer as a vocal group, but basically the group got the name from a novel, and the novel was in turn named after the station. Until 1910, none of the railroads that crossed NJ to reach New York City crossed the Hudson River. Instead, passengers rode to terminals on the Hudson Waterfront, where they boarded ferries. In 1910, the Penn RR opened a tunnel extension under the Hudson to NY Penn Station. The PRR built the Manhattan Transfer station that year so trains bound for New York Penn paused there so that their steam locomotives could be replaced by electric locomotives that could run through the tunnel under the river, and for people to change trains like another Penn train to Exchange Place or the Hudson & Manhattan Railroad (now PATH) In 1913 the PRR's board voted to electrify its main line in the Philadelphia area using an 11 kV overhead catenary system due to the length of time it took for steam trains in Philly to change directions. Tracks at Manhattan Transfer were originally electrified with 650 V third rail, which was used by PRR electric trains to Penn Station and Exchange Place, and by H&M trains (PATH today is still powered by third rail). In 1928 the PRR and the Newark government agreed to build a new Newark Penn Station to replace three stations around Newark with Newark Penn Station. In June 1937, the H&M moved to Newark Penn Station, and Manhattan Transfer and Park Place closed. The third rail on the NJ side of the Hudson tunnels was finally removed in 1940.

[@Ishaanbiniwale]

Do they have it in your country would be cool

[@SiVlog1989]

One system that deserves a shout out is the Mersey Railway, today part of Merseyrail. Opened in 1886, it made history in 1903 by being the first railway in the world to be converted to electric traction. The reason for the electrification was due to the tunnel under the river Mersey. Approached on each side by a punishingly steep 1 in 27 gradient, for context, the Licky Incline between Bromsgrove and Barnt Green is 1 in 37 3/4, and the steam and smoke from the initial steam locomotives played their part the ferry (across the Mersey) being more popular at the time. When the route was electrified and stations at (Birkenhead) Hamilton Square and (Liverpool) James Street were cleaned up, passenger numbers unsurprisingly increased dramatically. Today, the system Merseyrail uses (for the most part), is a 750v dc third rail, similar to the more extensive system on the Sputhern Region. Incidentally, in the 1980's, Class 508 units, displaced from their original services on the South Western Suburban services, were shortened* and sent north to work in Merseyside and are now (at the time of comment) seeing out their retirement before final withdrawal. As every Jago, you've been the Ferry to my River Mersey. *: if you know where to look, surpluss trailer cars from Class 508's were incorporated into the incoming Class 455/7 units, which explains the lower roof on these compared to the rest of the 455 fleet

[@kerimbozkurt3301]

Jago, I eat my lunch at my desk at the office and everyday your videos are chosen to accompany my lunch, thank you for posting these great videos,

[@jamesgilbart2672]

Interesting! Converting the 3rd rail network to overhead (catenery) power would also face the problem of low bridges at numerous locations. It's a pity that the former Southern Railway's pre-war plan to electrify their entire network was never fully completed - to this day there are still about 6 routes that remain diesel-operated.

[@adrianbaron4994]

If the recently started experiment with the ex-Vivarail D stock battery train conversion running on the GWR Greenford to Ealing shuttle service works out, some of the shorter Southern diesel services like Ashford to Hastings, which one way is 26 miles, might become battery-operated, The Ds range with a full battery seems to be about 50 or so miles on a single 10-minute full charge, done automatically from a large trickle charged static battery whilst they stand at the terminus waiting for the return trip. The longer diesel lines, like the Uckfield via Oxted to London route, might not be able to use the ex-D trains as the route is long and the D trains can't recharge in motion from the third rail when they eventually reach it from Uckfield as it hasn't enough power capacity for them! Sad irony.

[@stevecox6416]

I used to live near Acton Main Line. When the Heathrow express was started we had months of road disruption while that very thing occurred, all the railway bridges were raised up a foot or so to accept the overhead wires.

[@jamesgilbart2672]

@@adrianbaron4994 Thanks for that. It would be great to see these battery-powered trains operating on those routes and eliminating diesel propulsion. These ex-D trains are clearly a test bed and hopefully will lead to further units more suited to longer distances. Yes, on the Uckfield line, despite the inability to charge in motion, bimodal units i.e. 3rd rail and battery power, may be the solution.

[@BenGillam]

Thanks, so this pretty much confirms Uckfield line will never change. What's the answer then? Are there battery electric trains?

[@jamesgilbart2672]

@@BenGillam Yes, the Uckfield line should have been electrified decades ago (and the link to Lewes restored). Failing that, battery/electric trains exist and could be used on that route if only the will is there to do it.

[@CharlesTysonYerkesOfficial]

Nothing to do with me

[@cjf97]

😂

[@tomleader7054]

Denying everything even after all these years.

[@benmorris9310]

😂😂😂😂

[@JeanLouisBourdon]

sorry, was about to blame you

[@quintuscrinis]

I mean, you somehow weren't named in this video for once. 🎉 However, the Watford DC is mentioned as being third rail because of the need to work with the Bakerloo, which was a UERL (and thus your) line. So you played a part there.

[@simonwinter8839]

As my regular readers will know(you'd think this was my channel) I've been a bus driver for many years.Whilst the Docklands light railway was being built the trains didn't run in the evening and were supplemented with buses numbered in,appropriately enough, the "D" series amd operated by Kentish bus now part of Arriva. I used to pick up this chap who had lived in the East end all his life and since these buses didn't do much business in the evenings we used to chat.So I would ask him about the changes he had seen and I also asked him what he thought of the DLR and he said "well it's alright for running up and down Brighton beach I suppose ", A direct reference to Volkes Electric Railway !!

[@frglee]

One of the oddities of the third rail system in the South is that it wasn't really suitable for large goods yards or goods lines, where staff had to couple and uncouple wagons manually. Steam locomotives or diesel shunters were used, but later on overhead wires were added (after 1940), such as at Hither Green and at Ashford(Chart Leacon) in Kent, where interestingly, they used a unique tram-style 750v DC overhead wire that could be used by the class 70 and later class 71 electric locomotives, designed for 650/750v third rail use but with an added pantograph.

[@MervynPartin]

The Southern Railway "Booster" locomotives (later class 70) were constructed in the 1940s and were fitted with pantographs for use at Ashford and Hither Green when built. They predated the class 71s which used the same booster technology. There were only 3 of them but they worked well. I have the EFE (Bachmann) model on my model railway.

[@frglee]

@@MervynPartin Thanks for that, I do remember seeing the wiring at Ashford in the late 60s, but I didn't know the tram-style wires dated back to WW2 or about the class 70s, but I've corrected my mistakes above. Wiki says they were installed to prevent trackside staff accidents with third rail during the blackout.

[@nicholaskelly1958]

750v DC overhead was also used at Snowdown Colliery in Kent

[@neilcrawford8303]

Some of the earliest electrification was in the North West. The Liverpool Overhead Railway opened in 1893 with electric operation. The Lancashire and Yorkshire Railway's Liverpool to Southport line used electric trains from 1904 on a 4th rail system. Now part of todays Merseyrail Electrics network, it operates using 3rd rail just like the SR. Manchester to Bury, also L&Y, was electrified to 1200 volts dc in 1916 using a side contact 3rd rail system. It is now part of the Manchester Metro tram system.

[@MRTransportVideos]

Another element to consider when looking at the two systems is train speed - because the contact between shoe and rail is more difficult to maintain compared to between pantograph and catenary, maximum speeds on 3rd rail systems are much lower (the world record for 3rd rail is only about 175kph, set by a Class 442 Wessex Electric unit), therefore are well suited for slower-speed commuter systems, where their cost advantages come into play.

[@thesteelrodent1796]

3rd rail also has much higher friction than the catenary. Where the catenary excells is that is has a very tiny contact area, which means there's virtually no resistance from the contact, and thus it works better for high speed rail

[@MRTransportVideos]

Correct, very good point, although the down side is that, due to the small contact area, the friction has the potential to cause more damage to the pantograph than the rail does to the shoe, which is why catenary has to 'snake' laterally along the track. However, that's been known since the beginning of OHL operation, so isn't a major factor in construction.

[@olasola1013]

Isn’t the strict limitation for third-rail voltage also a cause for being limited to low speeds?

[@MRTransportVideos]

@@olasola1013 The delivery system is not neccessarily an issue, as tram systems use DC overhead at similar voltages to 3rd rail systems (750v DC), it's more down to the improved efficiency of AC power over DC power at higher speeds - in the Netherlands, for example, their EMUs operate up to 160kph under 1500v DC (the same speed as BR 3rd rail) , but up to 200kph under 25kv AC.

[@AverytheCubanAmerican]

Just like Thameslink, two lines in the US that switches from third rail to overhead wires are the Metro-North's New Haven Line and the MBTA's Blue Line. The MBTA Blue Line in Boston is more unique in its operations because it's a subway line that does this! The Blue Line's predecessor was first a streetcar line before it was converted to a subway line in the 1920s. The Blue Line switches from third rail to catenary or vice versa at Airport station. When it was extended in the 1950s using the former Boston, Revere Beach and Lynn Railroad right of way, the northern section of the Blue Line became catenary to reduce the risk of winter ice buildup due to proximity to the ocean. The Blue Line also stands out in that its East Boston Tunnel was the first underwater rail tunnel in North America when the tunnel opened in 1904. For the New Haven Line: As part of the construction of the iconic Grand Central Terminal in the early 1900s, all of New York Central's lines that ran into the terminal were electrified as NYC banned steam locomotives. Third rail was installed on the Hudson and Harlem Divisions, while the New Haven Division received overhead wires on the segments that were not shared with the Harlem and Hudson Division. So what are now the MNR's Hudson and Harlem Lines are electrified (mostly; the northern portions are not electrified) using third rail. The LIRR is mostly electrified with third rail, and that's thanks to the Penn RR, who also added catenary to the portion of the Northeast Corridor between NYC and DC. LIRR was once owned by the Penn RR and they used third rail for the tunnels to Penn Station, but later opted to use catenary for the NEC.

[@alistairbell3935]

I was about to post about this! I’m sitting on a Hudson Line train right now. It’s actually even worse - Metro-North uses bottom-contact third rail (like the DLR) and the LIRR uses top-contact. The New Haven line switches between third rail and overhead on the fly, and I _believe_ the M8 units they use have shoes that can pick up electricity from top or bottom. Oh, and we have a ridiculous number of different overhead voltages and frequencies in the NE USA… but then again so does continental Europe.

[@SheeplessNW6]

I used to commute into Euston daily on the Watford DC line, which uses third-rail electrification. The trains also had a pantograph (aka "pan") for use on lines with overhead electrification. One day, the driver of my evening train, which I guess had come in via the WCML, forgot to lower the pan before leaving Euston. Shortly afterwards, there was an almighty bang as it struck a bridge. I wouldn't want to be in his shoes after he wrote the report!

[@haweater1555]

In Chicago, one line (the "Skokie Swift" ) of metro trains extends out to the suburbs with level grade crossings. For this part, dual power trains which switched from third rail to overhead pantograph collection were used. Around 2003, it was decided to dismantle the catenary and convert to all third rail, despite the danger to it being accessible to people on the ground. So a rare type of conversion.

[@bkark0935]

Incorrect, the Skokie Swift is part of the CTA Elevated heavy rail (the Yellow Line.) Yes, it has street running but it was never a part of Metra’s Electric line. It did have overhead pantograph for the parts west of the Skokie Shops, the main repair yard for the entire CTA L and Subway. They have had for year safe street running without the need of catenary at the end of both the Brown and the Pink Lines, thus they decided to make all of the Yellow work on third rail.

[@BibTheBoulderTheOriginalOne]

They should electrify the motorways with overhead catenary, then make cars have pantographs to draw their power. Add on couplings so lots of cars can run in multiple and I reckon the motorway would be really useful. Better still, if we had a dedicated vehicle at the front with one highly trained driver the rest of the drivers could relax. To do that we could have one car with a buffet in it. We shall call it "the buffet car". I reckon this system would catch on.

[@charanso143]

Thats called a train sir

[@jadeboswell-rz2ly]

Thank you Jago.. when Watford was connected to Clapham and beyond it was a joy. The South Coast with Central London. Sham it took overhead to third rail to do this. Thank you again.

[@jamesnicholls9969]

i think you should do a series on the electrification of the long distance rail lines and the cock ups that have occurred, especially from Paddington to the west. what was going to cost £750 million ended up costing over £5 billion and they did not even get to where they were supposed to and ended it short

[@tomarse99]

Don’t forget the old Bury line with its unique 1200v DC side contact third rail!

[@Thommygun-qv7um]

Another well explained video Jago. I keep learning from you and the way it is presented just speaks to me! Also, I might add, something similar happened here in germany in the 1920s and 1930s, but on a way smaller scale. The U-Bahn-systems in Berlin and Hamburg, starting before WW1, had used (and still do) a third rail. So, when they started to built S-Bahn-systems in both cities, they used the third rail, despite the fact that the mainlines were about to adopt the overhead wire (which they did). Otherwise, Germany today is in a strong relationship with the overhead wires. Even newer U-Bahn-systems like in Munich or Frankfurt are using overhead wires and modern S-Bahn-systems are basicly regular mainline trains with special rolling stock and dedicated sections in the core (like the Liz line in London, but starting the 1970s). Making these third rail systems kind of an oddity.

[@r.markclayton4821]

The reason for the fourth rail on the tube is that the supply is DC and the return current would pass through the cast iron / steel lining resulting in electrolytic corrosion. So another rail is provided and the voltage split except on the Lioness line where the centre rail is 0V.

[@Sterlingjob]

So how does the district line work? The middle rail is bonded to the running rails, does that mean the middle rail can be touched as it’s earthed?

[@misterthegeoff9767]

Another electrifying episode. I'm amped for the next one Yet again the Underground was an impedance to the adoption of a single standard it seems.

[@nicktecky55]

Tough crowd today. Go on have a tick for sheer nerve!

[@thomascox5808]

Would have liked to hear about Liverpool's overhead railway and mersey railway, electrified in 1893 and 1903, respectively - 6 years prior to London's first suburban rail electrification.

[@normanstevens4924]

Also overhead wires, at a higher voltage, suffer less power loss; so are more efficient with the electricity.

[@stefanhaustein]

And in tunnels, they can be just mounted to the ceiling most of the time...

[@aoilpe]

In tunnels it can be an Overhead Rail too…(for more safety and less maintenance…!)

[@brianfretwell3886]

@@aoilpeThe ovehead at St Panras Thameslink is a bit like that lass chance of a dodgy pantograph tearing it all down too.

[@ethmister]

Tunnes often need track bed lower to fit overhead. Very expensive and why it takes so long on GWR for anywhere to get electricity

[@neuralwarp]

... and then the catenary falls down and all the trains stop for 2 days. No thanks.

[@ExpoAviation]

An excellent video and a very good explanation as to why the Southern ended up with 3rd rail, looking in that cab shot at 01:49 and that tap changer on the right hand side looks very impressive though I hope they shielded that in service ;) A special shout out to it being Mather & Platt which was located not too far away from me (though sadly long-gone by the time I was around). The expansion of 3rd rail is still an issue today, there have been numerous plans for the Merseyrail network to adopt the line from Kirkby to Wigan Wallgate but these have constantly fallen through as it would require electrifying several miles of track with 3rd rail which is now no longer allowed (generally speaking). Their solution was a new station "Headbolt Lane" which offers absolutely nothing new for anyone as they still have to change trains like they did at Kirkby, the only difference is that Merseyrail need to use new battery units to run from Kirkby to the new station a mile down the line - literally a new battery EMU which only uses its battery about 4 times a day for a mile at a time...

[@pjelbro3492]

Thank you for the interesting background on the Waterloo & City line. When I worked for Railtrack Southern (1995-2001) the W&C line was always considered part of the mainline railway and my residential (commuting) and work passes covered this line as well whereas a separate LUL/TFL pass was needed for the rest of the underground.

[@highpath4776]

your pass would also cover most of the tram network around croydon

[@highdownmartin]

Waterloo drivers had weeks on The Drain it was a BR job.

[@ad-mc]

0:45 Electricity had potential. Excellent pun, intentional or otherwise 🙂

[@FlaviadaRocha-c5m]

The whole idea had legs.

[@wilsjane]

Technically, it should be "potential difference".

[@ElTelT4ELO]

So there's me sitting on platform A at St Pancras watching the Thameslink trains coming and going with their pantographs raised, but not touching anything overhead, and wondering exactly the question why they had both systems. Then that very evening you've posted an article which explains it all fully. Thanks Jago, perfect timing.

[@adrianbromfild8624]

Another fascinating and informative video from Jago!

[@Martock1017]

Very good explanation of the reasons for different electrification methods. I believe the underground lines used the 3rd and 4th rail system to avoid possible electrolytic corrosion of the tunnel metalwork by earth return currents. I remember reading that an increase in earth currents could be detected a long way from the Southern's third-rail network when the Eurostars were using third-rail pick-up, due to their higher power demands, although their power was much reduced compared with that available when using 25kV overhead pick-up.

[@wilsjane]

You are correct about the 4th rail, but do you know all the reasons. It is something that is not included in driver training, so I have spent many hours fully explaining the full reasons to drivers over the years, along with problems caused by it's absence on the overground network. Many drivers call me the professor and needless to say, some add "nutty" for good measure.

[@MervynPartin]

@@wilsjane It still seems strange that every other metro system (that I know of) in the World manages to use the running rails for the return circuit without any reported problems of leakage, whether they be 3rd rail powered or from an overhead line. Also, two other tube lines in London have or had 3rd. Rail- The Northern City branch which was converted from 4th. rail when taken over by BR, and the Waterloo and City line which was originally 3rd. rail but converted to 4th. rail when the stock was replaced by 1992 stock from the Underground production. There was also the Post Office railway which used 3rd. rail.

[@SteveW139]

@@MervynPartinThe fourth rail system was chosen because, as the first electrified railway of its kind the degree to which electrolytic corrosion of tube lining rings and nearby gas and water pipes wasn’t known and a ‘better safe than sorry’ approach was taken.

[@MervynPartin]

@@SteveW139 There were also concerns about interference with telegraph networks, however, is there any need to continue with a 4th. rail after all these years, after all the Northern City line had similar, but larger cast iron tube segments, and that was changed to 3rd. rail OK. It might save the Underground a lot of money if they used less steel rails, less insulators and also less de-icing.

[@birdbrain4445]

Yeah it's always been interesting to me, as someone that lives in south London and regularly heads southeast, to see that third rail is a relatively regional thing and most electric lines use the overhead system. I never quite understood why there wasn't uniformity across the National Rail network but, the historical factors definitely explain that. Great video!

[@jonathanbutson1385]

One thing often overlooked is the amount of time taken to make the 3rd rail safe when the railway is given up in a possession so engineering works can be done. Each electrical section of 3rd rail (They are about 2 miles long) first has to be turned off by the electrical control room, then if the electrical section spills out the end or side of the possession hook switches have to be opened to isolate these little bits. Then short circuit straps have to be applied to ensure if the electrical section is accidentally re-energised the circuit breakers will pop out before anyone is fried. So it typically takes an hour after a possession is taken before it is safe to work. "Normal short circuiting devices" are being installed at 3rd rail sub stations, these have reduced the number of short circuit straps needed when setting up a possession, but it is still a time consuming and expensive process. However the 3rd rail is cheap to install, robust and a lot more reliable than overhead electrics, so as a railway worker and Kent commuter i'm really glad it was installed. Money well spent. (Jonathan a Siemens employee, we do really good electrification equipment and installation, shameless plug!)

[@hughs591]

A nice concise history, thank you. A friend who was a third rail fan used to amuse me by comparing 25kv overhead locomotives to “moving substations.” NB, could you have solved your flickering shot by taking it as a still frame?

[@Lolwutfordawin]

And they wouldn't even be that far off! In one of Budapest train stations there is a locomotive permanently wired into building with it's pantograph raised humming along as it's now a stationary substation.

[@jamez6398]

It still blows my mind that there are trains for getting around certain metropolitan areas because they are just that vast, like in Greater London, Paris, and Rome whilst having trains for going to other cities and trams for going around the city centre because the city centre itself is that vast. Where I live, the city is small enough that, to get around the city centre, you can just walk, and you use the tram network to get around the whole city, and the trains are only for going to other cities, we only have 2 levels of transport rather than 3 levels. I never been to parts of London outside the city centre when I visited so when I flew to Rome, and then Paris and got a train to the city centre that floored me because where I live you get tram from the airport if you want to get into the city including the city centre and you only take the train if you are coming from elsewhere. In Malta, you use the bus for the whole country because it is that small, yet in Paris, Rome and Greater London you have to use the train just to leave the city centre and go to another part of the city, there are some cities that are bigger than some countries, which I find shocking. In Malta I could probably get between the 2 furthest points of the country in a 45 minute drive...

[@chrisadye1590]

Just a quick correction - overhead wires are more weather resistant. The only conditions which affects the overhead more than third rail is the wind, although now that we tend to use higher tension on the wires that is very unlikely to cause an issue directly - it's more that trees and other things which are blown onto the railway will bring down the power lines. Third rail is badly affected by frost and snow. The solution is to spray the rail head with what I think is a thin solution of oil. The current can still pass to the collector shoe on the train, but the oil stops ice freezing to the rail, so the collector shoe just knocks it off. In cold conditions they may also run ghost trains overnight (trains without passengers) so the powered rail is regularly swept to avoid the build up of ice. In snowy conditions the extra rail makes clearing snow from the tracks less effective as it gets in the way.

[@andrewpinner3181]

Thanks Jago ! I'd never really given much thought as to 3rd rail vs overhead, except the tube.

[@brianfretwell3886]

Nice to see the South Western Railway class 707s that still haven't been replaced with the newer class 701s, even thought the 710s have been moved on and the 701s are 4 years late!! The other trouble with overhead wires is the time taken to re-wire after an accident (or dodgy pantographs) pull them down. If a shoe pushes a third rail off the insulators (and that did happen to a train I was on near Balham some years ago). a track gang can quickly put it back after the power has been isolated. They had arrived and started work before we were evacuated from the train, a class 319!

[@GooseWaffe]

I believe we still have two of them!

[@Mitch-Hendren]

Merseyrail is also 3rd rail . But theres a ban on new installs unless its between two existing 3rd rails. So new extension to Headbolt lane from Kirkby had to be done by battery traction..... its not working very well.

[@AndreiTupolev]

I suppose this was a government decision, or was it Network Rail? Either way they're equally stupid

[@Mitch-Hendren]

@@AndreiTupolev government wouldn't you know !

[@SteamboatWilley]

Daft decision. Extending the 3rd rail would have been a better solution.

[@Mitch-Hendren]

@@SteamboatWilley it might happen yet . The battery section is painfully slow and unreliable .

[@grassytramtracks]

There's not a total ban, small infill extensions are not banned, albeit there's a lot of regulation to jump through, having batteries for the last mile to Headbolt lane is just stupid

[@91Durktheturk]

Interestingly, as mentioned in the video, there were overhead wires on the Brighton line, which were converted to 3rd rail by the Southern Railway to ensure standardisation across the Southern network

[@manomaylr]

I’m surprised. It should have stayed and been converted to 25kV. We may have had 125mph on there by now.

[@91Durktheturk]

@@manomaylr Yes, well I guess its a trade off between standardisation and having a superior system. In many countries they actually have similar issues. In the Netherlands they use 1500 Volt dc overhead wires, which is far from superior compared to 25kv ac. However, the benefits of having a standardised system outweigh the costs of having a somewhat outdated system. I guess this must have been the reasoning at Southern back then as well.

[@iankemp1131]

@@91Durktheturk Yes, best available technology changes with time. In the 1920s third rail was more reliable and proven than overhead (and cheaper for quick expansion). The LNER and BR used 1500V DC overhead lines from the 1940s (Shenfield. Woodhead) and got very high reliability, the initial switch to 25 kV AC in the 1960s caused lots of problems (also in Glasgow) but it was better after the teething troubles had been gradually ironed out. NL has relatively short distances and modest speeds, so less incentive to swap.

[@robfinch1522]

My father worked on the railways and said that sometimes walking back from the depot after a night shift and between two tracks, especially after rain, and he was carrying his raincoat over his arm, if the raincoat flicked the live rail it gave him enough of a wakeup call to watch his step..

[@GazK71]

Great video! Just one correction: third rail is more expensive than overhead, not cheaper. This is because the low voltage constraint means more frequent substations, and they are more expensive per unit because they have rectifiers and very large high current circuit breakers.

[@andrewrevans8496]

Thanks

[@JagoHazzard]

And thank you!

[@jgodfrey546]

Another joule, Jago! Electrification promoters of the day likely got a charge out of the potential revenue it could generate. Resistence among others seemed myopic despite the number of terminals in London. Cheerio

[@vincenthuying98]

Dear Jago, great vid! The third and fourth rail lead the way. In catenary pulling and pushing power it’s indeed a bliss of travel. Nevertheless, it would be interesting to hear on the clearance issue for tube trains and even over land transport. Especially where some British rail companies in the past have chosen to use the minimum overhead clearance to cut costs on bridge, tunnel and other infrastructure construction. As always I’m feeding your third, fourth and overhead electric potential. Cheerio

[@chrisadye1590]

When the DLR was electrified they hung the conductor from above so it was a bottom contact system. This meant that it was much less susceptible to ice, and also they put it under an insulated cover, so it can't be stepped on by track workers or trespassers. You have to lie down next to the rail and reach up under the cover to come into contact with it.

[@A-Trainspotter-From-Berkshire]

The North London Line was once fully third rail then British Rail converted it mostly to OLE for freight.

[@henrybn14ar]

It was 4th rail until about 1970.

[@interstat2222]

In autumn 1996 if I remember correctly.

[@JaapFilius]

Every system has it pro and contra. But I do like the 3-rail concept because it blends so well in the landscape. And in particular in Kent that's a huge "pro": imagine that beautiful landscape full of catenary portals.....

[@henrybn14ar]

Like the procession of gallows and goalposts from London to Swindon.

[@lars7935]

Only Europeans will find overhead line ugly. I'm so sad that we seem to be stuck in preserving 'good views' over good infrastructure.

[@interstat2222]

3rd rail is antiquated and unsafe and also expensive and inefficient as it needs constant boosting and substations. I like 80s and 90s OLE infrastructure. 2010s designs are a bit ugly (eg GWR mainline).

[@bighamster2]

​@@lars7935Especially since the alternative is usually a multi-lane road, which is far bigger, noisier, uglier, more polluting etc. Plus trains are a great way for people to actually get to enjoy the view.

[@dougmorris2134]

Stepping on “The Third Rail.” A mistake that is only made once! ⚡️💥 Remember the old electrician’s saying: It’s the Volts that jolts but the mills (milliamperes mA) that kills. The current from the third rail exceeds over 1000 Amps.

[@RogersRamblings]

Some moons ago I was LT train crew. Unusually I was wearing leather soled shoes one day, it was also raining. I'd been instructed to stable a train in sidings. Leaving the cab through the door in the front, I stepped from the cab floor to the coupler, from the coupler to the neg rail and then to the ground. With one foot on the ground, the other still on the neg rail and one hand on the grab rail I felt a decidedly tingling sensation. Releasing the grab rail and moving my foot from the neg to the ground caused the sensation to stop. I never wore anything except rubber soled shoes again.

[@johnchurch4705]

@@RogersRamblingsdid the rubber soled shoes have a thicker sole? I knew someone that worked at Upminster Bridge, his doc martins had a thinker sole just incase you accidentally touched a live rail.

[@RogersRamblings]

@@johnchurch4705 I normally wore ex army rubber soled boots or occasionally rubber soled shoes. It was only the leather soles that allowed current to pass.

[@corinheathcote9868]

When my dad worked out of Hornsey on Eastern Region with a diesel on to the Slade Green Depot on the Southern region via Snow hill tunnel, he did forget about the 3rd rail and step on it climbing off a loco. One can think his boots insulated him.

[@julianaylor4351]

The now Lioness Line, has always been third rail from Euston to Watford Junction since the death of steam trains, especially since it shared the line with the Bakerloo from Queens Park to Watford Junction, although this was ended in 1979/80, now going only to Harrow and Wealdstone. The mainline in the area, has been diesel and overhead lines since the end of steam. The local main steam depot at Willesden is now a Freightliner depot. The lines from Liverpool Street were electrified in the 1950s and currently the Paddington main lines are being electrified, with overhead lines.

[@melanierhianna]

The NER had a pretty significant third rail commuter system north of the Tyne. But they also used overhead. The E1 loco you very briefly displayed is actually both third rail and overhead. It used overhead the river Tyne quayside but third rail up to and on to the commuter lines. The overhead was because it was considered somewhat dangerous to have live rails in a shouting yard.

[@stewartellinson8846]

Might be worth mentioning a few additional reasons why the post- war sr went with the third rail . 1) the LBSCs elevated electric lines used Siemens technology and they, being German, had been out of favour since 1914. 2) the SECR had been planning it's own electrification based on a tube type 4 rail system and 3) LSWR / SECR engineering staff dominated the higher echelons of SR management. Add that to the cost of the overhead system and the straightened circumstances of the early SR and the technologically better LBSC system was always going to lose to the cheaper and simpler 3rd rail The LBSC were right in the long term tho....

[@contrapunctusmammalia3993]

they were really really right tho, interestingly. Because they used an AC OLE system which was quite forward looking of the time and would have put them in a really good position throughout the 20th c

[@adrianbaron4994]

This is quite true, and in the end, the decision came down to AC mileage versus DC mileage, but it wasn't as clear-cut as it seems. The LBSCR was so pleased with the turnaround in fortunes of the South London line after AC electrification that they eventually extended the system to other suburban lines south of London; they got about 1/3rd of the way to Brighton and planned to extend the wires all the way there, which would have given Britain its first electrified mainline. Keeping with the continental feel of the LBSCR AC system, they would have used Swiss-style coupled wheel AC electric locomotives for non-stop express services from Brighton to Victoria and London Bridge, including Pullman services. We could have had an electric Brighton Belle 10 years before the DC one came along, and they were planning for it to be fast...well under 55 minutes, just enough time for kippers, toast, marmalade and tea. The arguments against abandoning the technically superior overhead AC for DC third rail still ring true today...dangerous to staff, vulnerable to snow, ice, and heavy rain, numerous substations required every few miles, not suitable for long distances and high speeds.. but just as with HS2, short-termism overcame everything else.

[@stewartellinson8846]

@@adrianbaron4994 I seem to recall that the LBSC used some motor luggage vans which were effectively elective locomotives and some became the SR express brake vans in the the thirties, after conversion

[@Jimyjames73]

Thanks for that Jago - Every day is a School day with Jago!!! Thanks for sharing 🙂🚂🚂🚂

[@dodgydruid]

My late father had a jolt from a third rail one windy stormy night crossing over Blackfriars bridge from the signalbox, they used the leftermost line to cross the bridge which was next to the disused bridge. Well he caught the hem of his trouser leg on the rail and it threw him over to the disused one and for the second time in his life he was hanging on for dear life over the rampaging waters of the Thames below him (the first time was when he thought to use the disused bridge instead of walking trackside and a floor beam disappeared right under him) and he had to pull himself to a metal section to gain safety. People see it as a lowish number at 750v but the amperage behind it was extremely high hence why you had to do the ministry of silly walks over the live rails esp in wet weather as they would arc to you fatally, he only got a belt from his wet trousers and was lucky.

[@bucephalus00]

Unrelated, but I'm sorry to hear about the passing of your father ❤

[@bobdeverell]

One benefit of 3rd rail over overhead wire is that it is less obtrusive. Bridges do not have to be raised. But with the traditional open rail design there are dangers from electrocution, foliage and snow. This is overcome by arranging the top surface and sides of the rail to be covered by a plastic cover and arranging the pick-up shoe to connect from underneath. This gives safer operation and allows a higher traction voltage. Today several metros across the world use this design.

[@cd0u50c9]

6:03 - speak of loop lines - having a look at loop lines around London (past and present), and routes from one London terminus to another would I think be a great video!

[@philipbrailey]

I often wondered.

[@nua1234]

London underground four rail systems improves readability, because if there is a ground fault (eg drinks can between running and power rail). One rail will go to earth potential and the other will move away from earth, so the voltage between the two power rails will be unchanged, allowing the trains to continue running. The fault can be fixed overnight during the maintenance window

[@FarmYardGaming]

I love these videos in particular for some reason. The perfect video one might watch when eating for example.

[@Gordanovich02]

When electrifying the lines into Edinburgh through the Mound and Haymarket tunnels, limited clearance necessitated the use of solid overhead conductors, rather than flexible cables which might be pushed up into the tunnel roof. As a consequence, steam engines are no longer allowed to operate through those tunnels; steam hauled railtours have to go around the old Edinburgh South Suburban line. One imagines much of the Southern Region would face similar clearance issues.

[@johnkeepin7527]

There are also several stretches of the GW that have overhead conductor rail inside tunnels, e.g. the Severn Tunnel, and Chipping Sodbury tunnel on the Badminton line. Most of them use copper contact rail mounted in an aluminium structure, but not the Severn Tunnel part - they fell foul of salt water using two different metals, so had to use aluminium contact - no doubt with increased wear and tear.

[@lassepeterson2740]

Another reason for 3rd rail was was weight of train . With low voltage DC you could run the train using only series , parralel and resisters , no tranformers on board that is . Weight saving in the old days before solid state . Overhead was mostly originally brought in to run higher voltages AC to be transformed onboard .

[@johnledingham852]

If some wayward pedestrian should inadvertently step on a third rail providing power to electric locomotives, would it be "Goodnight Irene?"

[@Clavichordist]

This was an interesting topic. Thank you for uploading. In the US, the rail lines in and out of New York City are both third-rail and overhead. When electric power was introduced, New York City banned steam power from within the city due to the pollution. The New York Central went with third-rail into its yards and the famous Grand Central Terminal. The New Haven Railroad (New York, New Haven, and Hartford) opted for overhead into Pennsylvania Station via the famous Hells Gate Bridge. At the same time, the Long Island Railroad chose third rail power and ran initially into Penn Station and now more recently into Grand Central Terminal. Since the New Haven served both Penn Station and Grand Central, they developed dual-mode electrics with wires up to Woodlawn Junction where the New Haven joined the New York Central Harlem division which ran third-rail up north to Brewster or a bit more than that now. In the 1950s, the New Haven developed the FL9, a dual-mode diesel electric-third rail full electric locomotive. While a bit sketchy initially, these proved to be reliable workhorses and this same technology is used today by commuter railroads worldwide. The New York Central had some interesting box cab electric switchers it used to shunt trains around the underground Grand Central Terminal. The locomotives were third rail powered but had pantographs fixed in the upright position to power the locomotives over crossovers and switches.

[@jacksugden8190]

Hi Tom, after reviewing your video, the City & South London Railway King William Street (near Bank) to Stockwell was the first tube railway, followed by, in 1900 by the Central London Railway (Central line) between Shepherds Bush and Bank was the second tube railway.

[@iankemp1131]

No, Waterloo and City line was 1898 so was indeed the second tube railway. It sometimes gets forgotten because it was nearly 100 years before it became part of the London Underground.

[@PaulSmith-pl7fo]

Hi Jago. Electrifying!

[@davelewthwaite]

That F-- *rewinds* Oh, FLICKER. Yes, it is a bit.

[@polyvg]

I used to live on the Waterloo to Southampton and Bournemouth line. That was electrified with third rail in the 1960s. But still needed diesel for the Basingstoke to Reading branch, etc. Given how late that was, it is a shame they didn't go for overhead. And don't neglect the Class 73 electro-diesel locomotives. They were unusual also because they were required to be narrower than standard to permit operation in some of the sub-sized tunnels (e.g.in Kent). A truly specialised loco.

[@aoilpe]

Some systems take the current from above ( like in the UK ), some from underneath (like the Berlin S-Bahn) which makes protection of people and snow/ice simple… The overhead wires can be replaced with a overhead rail in tunnels too…

[@paulhollis8879]

Overhead rails as in the Elizabeth Line.

[@MarioFanGamer659]

Some are even side contact like the Hamburg S-Bahn.

[@Tevildo]

6:15 - That must be one of the last Red Star signs in the country! It looks like it's pre-NSE, although I suppose it's possible they removed the NSE branding but kept the Red Star sign. Can individual signs rather than buildings be listed?

[@rkhayden]

I don't think it's pre NSE as Guildford station was rebuilt 1988-89 during the NSE era.

[@Tevildo]

@@rkhayden That sounds like a reasonable date for the sign, considering its general condition. I assume it would originally have had NSE branding, but I've not been able to find a contemporary photo of the totem, only the platform signs.

[@pmichael73]

You are the pantograph to my overhead wire.

[@mountainview547]

For all its limitations, the world's first electrified main line was London to Brighton using 3rd rail.

[@spectro742]

I was just about to write: I was just looking at a map of eletrification in the UK and was puzzled about 3rd rail in the south east vs overhead electrification everywhere else, and was wondering my my train from Brighton to Cambridge made it all the way; it must be able to utilise both technologies, and it seems my suspicion is correct. And then the volks railway comes on the screen haha. I love the volks railway, a fun ride, although I haven't been on it in ages.

[@armandoperez7967]

Here in NYC, they use the third rail. In Connecticut and New Jersey they use the overhead wires. I could be wrong but it probably has to do with clearance issues.

[@andybrice2711]

1:14 You can remove that sort of flicker quite easily in editing software. Layer a second copy of the video clip over the first. Offset the timing by one frame. And set the compositing blend mode to "brighten".

[@zetectic7968]

Interesting but some points to add about Southern: government won't stump up the money to convert to overhead power lines; too many NIMBYs against "unsightly wires & gantries" ; every frosty night trains have to be run dispensing de-icing fluid to try & prevent the 3rd rail from freezing ( in the past this has been thousands of litres of vegetable oil).

[@henrybn14ar]

Overhead wires are always falling down and need constant attention. It is probably best to confine electrification to busy routes.

[@SteveW139]

@@henrybn14arOnly if the electrification was done on the cheap (like the East Coast Main Line.

[@SocieteRoyale]

Merseyrail is entirely a third rail enclosed system, there is talk of extending the operations to Wigan, Wrexham and Warrington, but Network rail are reluctant to allow them to install more third rail along the tracks. So far the trial battery powered services to Headbolt Lane (not on the third rail) have been... mixed

[@mdhazeldine]

There's been talk about converting the Norths Downs Line to electric. If they do, I imagine that might get third rail as it's completely within the third rail area and shares tracks with other trains for quite a bit of the route. That would be one of those rare exceptions.

[@princessdaisy6]

9:08 the southern to watford also has this problem

[@SantaFe19484]

Nice video! This is the first time I heard of a fourth rail.

[@GeorgeChoy]

Very informative as usual, have a great weekend.

[@garycard1456]

That particular EMU train design in your thumbnail....I remember travelling on them in the 1990s to Richmond or Kew Bridge (for visits to the botanic garden). They were used by South West Trains to serve the SW London suburbs, and they look slightly different, design-wise, to those serving the S/SE London suburbs (Network South East).

[@norbitonflyer5625]

That's a 455. Still the mainstay of the SWR suburban services because of the dealy in commissioning the new class 701s. very different toi the slightkly newer Networkers (class 465) on South Eastern, or indeed the class 377 Electrostars on Southern. Network South East was the brand name in late British Rail days for all suburban services operating out of London, as far as Kings Lynn, Northampton, Oxford, and East Devon - not just those in SE London.

[@sglenny001]

Good to see some Doncaster footage

[@annabelholland]

I can name a few sections of new third rail. These are the new London Bridge and Reading station developments, the Bermondsey dive under and the new Merseyrail extension, the connections to HS1 (but not HS1 itself) plus those tracks that were renewed. Like with new level crossings, are there any regulations related to the installation of new third rail infrastructure since almost all new electrification projects are 25 kv AC OLE?

[@kevanhubbard9673]

I think that outside of London and the wider south east and a tiny bit of the south west as Weymouth is hardly the south east the only other place in England to have third rail is the Merseyrail system.The Manchester to Bury line had some kind of rail pick up too but obviously that's replaced by a tram now.

[@henrybn14ar]

Tyneside was 3rd rail

[@adrianbaron4994]

The Glasgow Subway, a true oddity, uses a 600 V DC third rail system and a track gauge of 4 feet and has a single circular line around the city. As I'm not a Scot I cannot possibly explain this.

[@iankemp1131]

Yes, Manchester to Bury was electrified way back in time by the Lancashire and Yorkshire Railway and had a third rail with side contact that was non-standard all its life. When train/track renewal was needed it was an obvious candidate to be one of the first lines to we switched to trams, along with the Altrincham route.

[@iankemp1131]

@@henrybn14ar Yes, and Tyneside suffered the curious fate of being de-electrified in the 1960s before re-electrifying with overhead wires for the Tyne and Wear Metro in the 1980s. At least it survived.

[@teessidetrainspotter]

Don't know if this is mentioned but the first electric suburban railway was the 1904 Tyneside electrics which ran on the North Tyneside Loop which is now run by the Tyne And Wear Metro using overheads

[@jacobf4702]

As someone who works in rail not in the southern region, the prospect of working around live 3rd rail is terrifying. Very easy for it to be game over when carrying long metal objects (tools, survey gear etc) around which most rail workers do. Also efficiency wise the 750V DC system loses almost 30% of the inputted energy to heat and other losses. Compared with about 2% loss on the 25KV AC wires. Very much Edison v Tesla in modern day.

[@paulking9734]

The old slammers had resistance grids for acceleration control which must have added considerably to the heat/resistive losses of the third rail. Modern trains 377s et al with electronic control wizardry may well have cut these losses significantly, be interesting to see by how much if anybody has studied this.

[@roberthuron9160]

New York has a triple power system! In order,the Long Island,over-running third rail. Next,the Metro-North[ex-NYC],under running third rail,and finally the Metro-North- New Haven lines,a combination of under- running third rail,and now,25,000 volt AC overhead! Those voltages were inherited from the New Haven,as that company was pioneering the AC network,that everyone takes for granted! The genius of Tesla,and the indomitable will of Westinghouse made that system possible,and Amtrak fulfilled the dream of the New Haven,and finished the electrification to Boston! A very long and complicated history,as all three lines,contributed to the ultimate outcomes! Thank you,for the forum,Jago,as your insights are always welcome! Thank you 😇 😊!

[@johnplampin7274]

And the LIRR overrunning third rail has a cover over it, which seems odd when you look at it but may make it safer and less likely to collect ice. Also I think the New Haven electrification history was more complicated.

[@roberthuron9160]

@@johnplampin7274 Yes,the New Haven's electrification story is EXTREMELY complicated,but space is short,so,that I could only put hints in! As an aside,the IRT,BMT Subways also had/have covered third rail,and the Long Island ran over the BRT lines,via Chestnut Street Incline,and that's a tale for another time! Thank you for the attention 🙏! Thank you 😇 😊!

[@Andrewjg_89]

Not just Thameslink Class 700 that are dual voltage and swap voltage at Farringdon & City Thameslink. But Great Northern Class 717 are dual voltage and swap power at Drayton Park and Southern Class 377/2 and Class 377/7. That also dual voltage and use the West London Line when operating the East Croydon-Watford Junction service via Kensington Olympia. And Southeastern Class 395 Javelin also change voltage at Ebbsfleet International and Ashford International as they use HS1 from St. Pancras International.

[@davidstone408]

Jago here is one for you. GWR (current franchise) runs trains from Reading to Gatwick which are Diesel the in part over SWR tracks with I think some sections not electrified (although might be wrong) - however because Reading with exception to three bay platforms (which are third rail SWR services to Waterloo and the GWR Gatwick) is Overhead power the GWR units can not return to the maintenance yard. Something has to change

[@norbitonflyer5625]

The reason diesels are used is because two sections of the route are not electrified - Wokingham to Ash, and Giuldford to Reigate to Gatwick. There is no reason why diesels cannot run under the wires to and from Reading depot, and indeed they do every night.

[@blameless_hyperborean8638]

I suppose one of the other reasons that 3rd rail was easier to install in the first place is that you have less lineside furniture, which means that it's easier to justify retaining mechanical signalling -- overhead line projects almost always involve re-signalling to ensure visibility.

[@neilbain8736]

This is a bit weird. I was thinking about just this last night, but more in terms of why the 4th rail was necessary as a -ve instead of using the rails as a -ve. I believe it has to do with earth leakage but other systems got around this. This all started with a solar charger I got in a charity shop that can generate about 18v on a sunny day and some videos by BigClive about power regulation, distribution and a tremendous regret at not having paid enough attention at college.

[@TheEulerID]

The reason for 4th rail is that the tube is lined with cast iron segments, and if the running rail was used as the return, stray currents would promote galvanic corrosion in the liners, which are often in damp soil. Running rails can't be fully isolated from ground, unlike the power rails, which use ceramic insulators. With one rail at -210V and the other at +420V the current runs between the two and is well isolated from the ground and doesn't promote corrosion. That said, world-wide, 4th rail electrification is fairly rate.

[@RayM53]

Here in East Sussex we still await electrification. The line to Uckfield is still diesel and partially single track as well. Perhaps in the future we may return to a pre-Beeching level of service.

[@TheEulerID]

Services on pre-Beeching rural lines were often very patchy indeed, so don't necessarily set that as the target. Pre-Beeching rural lines were often very infrequent, not particularly reliable and used very old stock. On many lines you would be lucky to get one two carriage train every two hours. There is something of a sentimental attachment to lines back in the 1950s, but it was not a golden age. By that time, a lot of passenger traffic had already been lost (it had started with buses, which were often more convenient before private transport became really popular). Also, steam-operated rural lines in the 1950s were really bad.

[@adrianbaron4994]

Keep an eye on the GWR ex Vivarail D stock battery train experiment on the Ealing to Greenford shuttle route. This started quite recently and GWR is betting big on this, having paid £25 million for the Vivarail trains, technology etc, and hiring the former Vivarail specialist engineering staff. What is really needed is to reconnect the Uckfield line to Brighton via Lewes, but that's a different matter.

[@dj_paultuk7052]

*Heres a question for the experts.. So i get the fast Hitachi trains from Reading into Paddington most days. Q. Why is it, sometimes the Hitachi 125 trains (sorry dont know the name), sometimes sit in Paddington with the Diesel engines running. And yet the Pantograph is up and touching the overhead cables. In sure there is a technical reason.

[@leoroverman4541]

Hi Jago, just a couple of points, if you'll excuse the Pun. Grouping came about as a less expensive means of Nationalising. The War had worn the railways out and the proposal to nationalise it by the Government because it would cost too much to buy out the shareholders. It was trading on Government costs from 1914 which was never adjusted. ( Ring a Bell? ) Because Nationalisation was what happened in 1948 to the Groups after Word war 2 for exactly the same reasons. By that time the thermal efficiency of Steam Locomotives had in fact risen considerably. I worked on the early Eurostar and it needed to be compatible with three systems. UK third rail, then SNCF and from Lille it would be on Belgian system. This caused delays in introduction. Once St P opened it could drop the third rail requirement but I don't know if the Overhead system here is compatible with SNCF. The last point is of course that both Steam and Electric used the same base of coal as we had no oil of our own. Steam was cheaper to produce.

[@StuartClary]

I'm sure I read somewhere that there are restrictions on 3rd rail electric systems these days. They can extend an existing system, but not equip a new one, like the Chiltern Line. The DLR has a third rail but it's hidden underneath plastic to get round this

[@henrybn14ar]

Yes, sabotage by civil servants.

[@001mrbbb001]

I believe it is to do with UK H+S law about a working environment with easily accesible unprotected live conductors not being permitted.

[@lordmuntague]

Very decent attempt at simplifying a very complicated topic Jago, and very much better than any others I've seen. Doubt if I could have done any better without getting very techie, I fear this is one of those subjects where a certain amount of basic physics is essential to gain a reasonable understanding much of what's going on here. There's no easy comparison in saying whether (either now or historically) third rail is or has been cheaper than OHL. And that's not even taking into account the equally important distinction between AC and DC OHL systems. Very much "how long's a piece of cable?" territory here. While AC is truthfully the better system today, third (and fourth) rail still have a great deal of importance, and its not like AC electrification was without its problems - see the history of the Glasgow Blue Trains in the early 1960s, a tale of mercury arc rectifiers and transformer explosions.

[@SeverityOne]

Funny to see the Class 76. It's six-axle sister class, the Class 77, was smaller, with just seven locos. But contrary to the single Class 76 that was preserved, three of the Class 77 were preserved: one in the Netherlands, and two in Britain - the one in Manchester in its Dutch livery.

[@12crepello]

It was lucky the Dutch National Railways bought the fleet of 77's for further use, otherwise there would be none preserved.

[@SeverityOne]

@@12crepello When I first started travelling by train, at the end of the 1980s, intercity trains in the Netherlands would be pulled by an 1100, 1200, occasionally 1300, or 1600 series locomotive. So the obvious question was: where are the 1400 and 1500 series? Bear in mind that there were no online resources back then. You had to get your information from magazines or books, and they could be expensive for a student. Turns out that the 1400 series was never built (although some people have made a model based on sketches), and the 1500 series was retired in 1985. The latter was the British Class 77. Finally, in 1989, when the Dutch railways celebrated 150 years of railways in the Netherlands (IIRC), I saw one in Utrecht, together with some more stuff I didn't even know about, such as the 1000 series. There was also the German ICE-E: the experimental one.

[@davidfalconer8913]

The London Underground uses ( more expensive ? ) FOUR rails to keep the running tracks totally isolated from the traction electricity ... this is to prevent SERIOUS electrolytic corrosion of the tunnel rings .... simple ! ........ DAVE™🛑

[@PrograError]

Funny enough, even for third rail there are differences. The common in UK seems to be top contact third rail. In other metros, underside contract third rail is more common. eg. Singapore's mainline metros, NSEWL. Which the third rail is covered with a protector on the top side while the bottom is for the shoe to contact... Tho from what I heard, the maintenance is more tedious since the shoe is to have a pressure on the third rail more than the top contact ones, where it can rely on gravity. Just needing care not weld it to the rails...