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

What’s the buzz?

[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.

[abzzeus]

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

[josephturner]

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'.

[pjelbro]

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.

[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.

[jamesgilbart]

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.

[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.

[kerimbozkurt]

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,

[southcalder]

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

[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.

[MidlandMark]

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.

[simonwinter]

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 !!

[SiVlog]

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

[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.

[neilcrawford]

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.

[jadeboswell-rzly]

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.

[Thommygun-qvum]

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.

[SheeplessNW]

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!

[r.markclayton]

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.

[haweater]

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.