End of Third rail?

[Metroland]

In the latest issue of Rail:

According to Network Rail, third-rail lines have no long term future and will need to convert to OHL. Peter Dearnan, NR head of electrification says the current system is at the limits of it's capabilities in terms of power and train speeds it can support.

As for trains, Siemens Desiros and Bombardier Electrostars can easily have pantographs fitted, this is already the case in other parts of the country.

 

[SS4]

I'm not surprised, doesn't third-rail leak a fair amount of current into the ground (Earth)? Plus if it's DC you need more substations than for AC power.

Third rail will be here whilst I'm travelling though because it's too expensive to replace

 

[M60lad]

Out of interest if this is true what will happen to the Merseyrail system which used 3rd Rail, is there enough room to convert the underground sections to OHL

 

[radamfi]

I presume the NR man is talking principally about the higher speed lines in southern England. Low speed metro type systems like Merseyrail are OK. Third rail is widely used on metro systems across the world but not on 80+ mph lines as used south of London.

 

[Xenophon PCDGS]

Out of interest if this is true what will happen to the Merseyrail system which used 3rd Rail, is there enough room to convert the underground sections to OHL

This is a specific "island" of 3rd rail electrification that can be viewed as a seperate entity, away from discussions on 3rd rail electrification on a national basis. The tunnel section under the river Mersey and the city centre of Liverpool have been subject to discussion for even longer than I have been alive!! The only real extension to the system in recent years was the line extension to Chester.

 

[NightatLaira]

Replacing all the third rail southern metals will be a massive undertaking! Clapham Junction would look crazy if the wires ever came in!! 25kV OHL and 3rd rail DC can't coexist over the same stretch of track due to shorting issues, so the whole lot would have to be completely changed overnight: i.e. buidling of all the stanchions, catenaries, substations etc. in situ over the third rails and then an overnight switch from DC to AC, with the switched-off 3rd rails then being picked up for scrap over the forthcoming months... You'd probably need to start ordering the bi-mode stock now to replace all the DC only stuff

If they do it I hope they'll consider upping the speed and maybe introducing some tilters at the same time. I can already picture a cascaded pendolino in SWT colours doing 125mph though Wimbledon under the wires en-route to Poole in about 2025

 

[ralphchadkirk]

25kV OHL and 3rd rail DC can't coexist over the same stretch of track due to shorting issues

Eh? 3rd rail and OHLE do coexist at a number of locations.

 

[jopsuk]

I did wonder when the ELL was converted to Overground whether that could have had OHL, using a solid conductor rail (as found in other locations) through the tunnels- I'd guess that if the south London network was converted to OHL, this would be seriously looked at.

I'd assume though that this is very much an aspiration of NR though, not a solid plan- after all, better to get more of the network using some form of electrification first before "tinkering". Plus, whilst the 313/319/375/376/377/378/395/444/450 fleets are all dual-voltage capable (plus, with more work, possibly the 458 and 460s?), the 455/456/465/466 fleets would be much more of a challenge.

I'd guess they'd start though with the Thameslink routes, possibly the Croydon-Milton Keynes route and the Southeastern High-speed extension routes.

 

[ANorthernGuard]

Eh? 3rd rail and OHLE do coexist at a number of locations.

Yep they do

 

[Barn]

Replacing all the third rail southern metals will be a massive undertaking! Clapham Junction would look crazy if the wires ever came in!! 25kV OHL and 3rd rail DC can't coexist over the same stretch of track due to shorting issues, so the whole lot would have to be completely changed overnight: i.e. buidling of all the stanchions, catenaries, substations etc. in situ over the third rails and then an overnight switch from DC to AC, with the switched-off 3rd rails then being picked up for scrap over the forthcoming months... You'd probably need to start ordering the bi-mode stock now to replace all the DC only stuff

If they do it I hope they'll consider upping the speed and maybe introducing some tilters at the same time. I can already picture a cascaded pendolino in SWT colours doing 125mph though Wimbledon under the wires en-route to Poole in about 2025

You sure? There are some stretches with both systems, like City Thameslink to Farringdon.

 

[Xenophon PCDGS]

If they do it I hope they'll consider upping the speed and maybe introducing some tilters at the same time. I can already picture a cascaded pendolino in SWT colours doing 125mph though Wimbledon under the wires en-route to Poole in about 2025

Sorry, I just can't resist the need to comment upon the need for for "Northern" British rolling stock being cascaded to the South of England. Is it not usually "cascadation" in the other direction?:cry::cry:

If the northern part of the rail network were to have its own theme song, I can think of none better than Second Hand Rose sung by Barbra Streisand. (You will note that due to extreme self-control, I have avoided detailed "trans-shipment comment" on Class 142 Pacer units).

 

[jopsuk]

Eh? 3rd rail and OHLE do coexist at a number of locations.

Indeed- how much dual-electrified track exists at Euston? Plus, obviously, there are the transitional sections at Farringdon, in West London, Ebbsfleet, Ashford, Drayton Park and Dollands Moor

 

[Yew]

Sorry, I just can't resist the need to comment upon the need for for "Northern" British rolling stock being cascaded to the South of England. Is it not usually "cascadation" in the other direction?:cry::cry:

If the northern part of the rail network were to have its own theme song, I can think of none better than Second Hand Rose sung by Barbra Streisand. (You will note that due to extreme self-control, I have avoided detailed "trans-shipment comment" on Class 142 Pacer units).

Im sure pacers could be used as an intrim measure down south whilst the ohle infrastructure goes up

 

[ukrob]

Replacing all the third rail southern metals will be a massive undertaking! Clapham Junction would look crazy if the wires ever came in!! 25kV OHL and 3rd rail DC can't coexist over the same stretch of track due to shorting issues, so the whole lot would have to be completely changed overnight: i.e. buidling of all the stanchions, catenaries, substations etc. in situ over the third rails and then an overnight switch from DC to AC, with the switched-off 3rd rails then being picked up for scrap over the forthcoming months... You'd probably need to start ordering the bi-mode stock now to replace all the DC only stuff

If they do it I hope they'll consider upping the speed and maybe introducing some tilters at the same time. I can already picture a cascaded pendolino in SWT colours doing 125mph though Wimbledon under the wires en-route to Poole in about 2025

As others have pointed out, you are very wrong, but I'm interested in where that information came from?

 

[WestCoast]

Im sure pacers could be used as an intrim measure down south whilst the ohle infrastructure goes up

I have a mental image of 6 Pacers coupled up providing a peak-hour Southeastern service

There are numerous examples of OHLE and Third Rail coexisting so that, fortunately (or unfortunately) won't have to happen!

 

[Nym]

I'd just like to see that round Manchester...

Would be fun to see a 12 car pacer pull into Bolton in the morning high peak

 

[swt_passenger]

The problem with dual electrification is that the two systems have fundamentally different earthing and return current arrangements.
In the DC system the return current passes through one or both rails and they are not intentionally earthed, although there is leakage. In OHLE systems it is different, the track and structures such as the gantries are all cross bonded and are earthed. This leads to additional complexity where both systems are present - and the new system through the Thameslink dual voltage area has a very complex system that automatically switches the return current system between the two modes as trains progress through.

Up until recently, track circuit design was different in the two areas, the DC area used AC track circuits, and vice versa. This was another area of complexity when both supplies were present, however axle counters have now reached a reliability level where they would be the natural solution.

SO dual voltage installations are kept as short as reasonably practicable to avoid the additional costs of all the extra kit.

Somewhere along the line Nightatlaira has probably picked up on this and inadvertently remembered it simply as 'shorting issues'.

--- old post above --- --- new post below ---

I presume the NR man is talking principally about the higher speed lines in southern England. Low speed metro type systems like Merseyrail are OK. Third rail is widely used on metro systems across the world but not on 80+ mph lines as used south of London.

It's almost certain that Rail will have the wrong end of the stick. Re-electrifying the 'Southern' route mileage in its entirity (and look at the amount of four or more tracks there is) would never achieve a strong enough business case.

Wouldn't there be many more overall benefits in electrifying all the non electrified lines first?

 

[Caped Crusader]

Im sure pacers could be used as an intrim measure down south whilst the ohle infrastructure goes up

I would pay good money to see a Pacer roll up on a Monday to form a peak service in third rail land! Please, please, please make it somewhere like Haslemere, East Grinstead or Oxshott and then film it.

 

[radamfi]

the new system through the Thameslink dual voltage area has a very complex system that automatically switches the return current system between the two modes as trains progress through.

Does that mean there will be no long dwell time at Farringdon to change from DC to AC?

Wouldn't there be many more overall benefits in electrifying all the non electrified lines first?

The possible future scarcity and expense of diesel does seem a more pressing issue than capacity issues in the south of England, but it is an issue nevertheless. However, some people may argue that capacity on third rail lines IS more important than electrifying some rural lines, and would prefer to close such rural lines when diesel is no longer practical if it means that third rail to OHE conversion could take place instead.

 

[yorksrob]

Sounds like an expensive waste of money to me. Exactly how many more trains are they planning to fit through lines such as London bridge - Charing Cross or Clapham Jnc - Victoria, which, last time I looked were already electrified by third rail?

Do they have a signalling system in mind that would be able to support all of these shorter headways and will they install it at the same time as the catenary?

Shouldn't someone be looking at designing lighter and cheaper trains for the next replacement in 30 - 40 years time?

I think NR are in a bit of a dream world on this one.

 

[swt_passenger]

Does that mean there will be no long dwell time at Farringdon to change from DC to AC?

On the new units the changeover specification says it must be fast enough to happen during a normal station dwell time, but it must also be equally possible whilst moving.

Northbound changeover will normally be at City Thameslink once the new Blackfriars bay platforms are back in use, but at the moment the northbound track's OHLE is partly isolated because certain SE units are out of gauge to the OHLE when leaving Smithfield sidings - from next year some time (April maybe) they'll become limited to terminating at Blackfriars.

It's set up so that in either direction changeover is attempted at the first of the two stations, but if changeover isn't achieved the trains will run through to the next station and reverse - hence the trailing crossover just south of Farringdon. Also in the specific case of northbound 8 car trains they can run into Smithfield Sidings and reverse from there later.

So in normal circumstances the dual voltage stretch will be operating as an AC railway northbound and DC southbound - which again increases the complexity because the return curent switching condition will be different on each of the two tracks.

 

[A-driver]

I would think that before any serious plans could be made about converting 3rd rail to over heads they would have to electrify routes such as north west, mml, gwml etc. Can you Imagen the outcry if they spent all that money on 're-electrification'? All new trains with DC must have a recess on the roof of an intermediate carriage for future pantographs though.

 

[swt_passenger]

I think NR are in a bit of a dream world on this one.

I'll reserve judgement - it's exactly the sort of thing where Rail will misinterpret the details. I guess this latest issue is the one out next Wednesday for non-subscribers?

--- old post above --- --- new post below ---

All new trains with DC must have a recess on the roof of an intermediate carriage for future pantographs though.

That's probably so that when they come to about 30 years old they can be cascaded up north, replaced by brand new state of the art trains down here...

 

[SouthEastern-465]

I can only imagine it would happen after the 750v DC only units are withdrawn for exsample Class 465s/456s/455s?

 

[ukrob]

All new trains with DC must have a recess on the roof of an intermediate carriage for future pantographs though.

Must have? Or happen to be designed to have?

 

[jones_bangor]

I'm not surprised, doesn't third-rail leak a fair amount of current into the ground (Earth)?

Victorian technology, but as many people have said, would be expensive to replace, but certainly do-able.

 

[Aictos]

What about FCC's Class 313s when they run into Drayton Park on the way into Moorgate, the 3rd rail pickup shoes don't retract as far as I know as there is both AC and DC from Drayton Park as far as Highbury and Islington.

 

[northwichcat]

I'd just like to see that round Manchester...

Would be fun to see a 12 car pacer pull into Bolton in the morning high peak

A 12 car Pacer would arrive 15 minutes late and then it'd take 5 minutes to get all the doors unjammed.

 

[WestCoast]

A 12 car Pacer would arrive 15 minutes late and then it'd take 5 minutes to get all the doors unjammed.

Out of interest how many 142s can run in multiple? I know 2 can, but are any more than that permitted?
I can see any form of re- electrification being expensive and subject to intense criticism.

 

[Failed Unit]

What about FCC's Class 313s when they run into Drayton Park on the way into Moorgate, the 3rd rail pickup shoes don't retract as far as I know as there is both AC and DC from Drayton Park as far as Highbury and Islington.

I was also thinking would the tunnels have clearance for overhead anyway? I am sure merseyrail is 3rd rail for clearance reasons.