Four dc / ac locations (or is it five)?

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Railcar

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Any Thameslink drivers reading this? A quiz question has this wording
'Between The North Pole (a real pub in 2012) and Wormwood Scrubs is a railway bridge.
At that point on the line something happens that only happens at three other places in London. All those other places are stations. How many can you name?
'

The 'official' answer is Drayton Park, Farringdon and Acton Central.
However, I was on a Thameslink train yesterday (Sunday 16th May). On Sundays, trains do not call at City Thameslink. However, my train came to a halt in the station and the driver explained (I paraphrase) that it was to do the changeover from dc to ac. My later return train did the changeover at Farringdon and did not stop at City Thameslink.
Is it standard practice for the northbound services to changeover at City Thameslink and the southbound at Farringdon?
If it is, the 'official' answer to the question is not quite right.
 
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Irascible

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Used to switch at Dalston Kingsland, not sure these days. Not Thameslink obviously, but your question doesn't specify Thameslink? ( Edit well Acton isn't on Thameslink either, so :D ).
 

alistairlees

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Any Thameslink drivers reading this? A quiz question has this wording
'Between The North Pole (a real pub in 2012) and Wormwood Scrubs is a railway bridge.
At that point on the line something happens that only happens at three other places in London. All those other places are stations. How many can you name?
'

The 'official' answer is Drayton Park, Farringdon and Acton Central.
However, I was on a Thameslink train yesterday (Sunday 16th May). On Sundays, trains do not call at City Thameslink. However, my train came to a halt in the station and the driver explained (I paraphrase) that it was to do the changeover from dc to ac. My later return train did the changeover at Farringdon and did not stop at City Thameslink.
Is it standard practice for the northbound services to changeover at City Thameslink and the southbound at Farringdon?
If it is, the 'official' answer to the question is not quite right.
I'm pretty sure that's normal northbound, and there are signs on the platform at City Thameslink (in both directions) reminding drivers to change from 3rd Rail to AC Electric (or vice versa).
 

zwk500

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Yes it is. This allows services that fail to changeover correctly to be reversed with the functioning power supply. There is a scissors crossover between City TL and Farringdon that allows trains to use either platform and reverse back to the 'right road' line. Both platforms at both stations and both lines between themare provided with both systems. Not sure if Smithfield sidings are 3rd-rail only or not.
 

zwk500

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Used to switch at Dalston Kingsland, not sure these days. Not Thameslink obviously, but your question doesn't specify Thameslink? ( Edit well Acton isn't on Thameslink either, so :D ).
No longer happens, NLL is OLE from Stratford all the way through to Acton Central so there's only 1 changeover.

Trains will also change traction from DC to OLE at Camden Junction when the 3rd rail into Euston is isolated but the OLE is not, although that's only for engineering works or after an incident so I guess the quiz may not be counting that.

EDIT: Somewhat sadly, I've just found out the old North Pole pub is now a Tesco Express.
 

Need2

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Not sure if Smithfield sidings are 3rd-rail only or not.
3rd rail only. The driver MUST stop at City TL and switch the power supply to DC only before or there will be a whole world of trouble ahead
 

Egg Centric

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There is a way to make the quiz master correct though. Make the answer start with "Change power supply, whilst the train is heading between 90 and 270 degrees" ;)

Since the other locations this applies to trains heading in one direction they all still apply, but it rules out City because it's only northbound ones there.

Hopefully I got the bearings right!
 

Val3ntine

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On the NLL also going to the Watford-Euston DC line there is a changeover from AC to DC just before crossing the junction into the DC platforms at willesden junction. And DC to AC the opposite.

Although at a depot; willesden depot is AC throughout. A train going from the depot needs to change from AC to DC, then unto the DC lines, then if needing to go unto the NLL line once again changing from DC to AC.
 

Beebman

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There's also a changeover possible at the old Primrose Hill station for any trains routed from Willesden Jct to Camden Road via the DC lines through South Hampstead.
 

Bald Rick

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The quiz is horribly wrong.

There are the New Lines at Willesden (connection between the D.C. lines and the NLL)

Also at Primrose Hill (connection between the D.C. lines and the link to the NLL)

And at Highbury and Islington (connection between the ELL and NLL, although not in use)

Then at Watford the connection between the D.C. lines and WCML fast line (although I thought that had been removed, all the maps I have show it still there). Noting that Watford is not in London.
 

norbitonflyer

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If the answer is "a change from AC to DC" this does only happen, in regular passenger service at least, at the said four locations within Greater London (at City TL they only change from DC to AC). Neither Primrose Hill nor the "New Lines" connection at Willesden Junction see regular passenger services.
 

Bald Rick

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If the answer is "a change from AC to DC" this does only happen, in regular passenger service at least, at the said four locations within Greater London (at City TL they only change from DC to AC). Neither Primrose Hill nor the "New Lines" connection at Willesden Junction see regular passenger services.

From D.C. to AC there is a regular passenger service from Willesden LL to Stratford with the changeover on the new lines.

Regular as in once a day!
 

AlterEgo

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The quiz is horribly wrong.

There are the New Lines at Willesden (connection between the D.C. lines and the NLL)

Also at Primrose Hill (connection between the D.C. lines and the link to the NLL)

And at Highbury and Islington (connection between the ELL and NLL, although not in use)

Then at Watford the connection between the D.C. lines and WCML fast line (although I thought that had been removed, all the maps I have show it still there). Noting that Watford is not in London.
Watford connection is still there, as is the third rail stub on the down fast.
 

Kite159

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From D.C. to AC there is a regular passenger service from Willesden LL to Stratford with the changeover on the new lines.

Regular as in once a day!

More than that, although it tends to be at the extremes of the day where some trains terminate at the low level platforms from Stratford to head to the depot, and at least the "2L99 0902 Willesden Junction to Stratford (London)" service on a Sunday morning going the other way
 

zwk500

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I know it's not London, but is there any interchange between DC and AC lines at Reading?
No. The connecting spurs are not electrified either way.
Can they not change over on the move?
Some can. 378s do for LO services between Shepherd's bush and North Pole Jn. It's just easier to do it in a station in case the changeover fails for any reason.
 

zwk500

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I know it's not London, but is there any interchange between DC and AC lines at Reading?
For the sake of completeness, connections between AC & DC on the Southern outside London only take place where HS1 meets the classic lines at Ebbsfleet, Fawkham Jn (Not used but think it's still in place), Ashford and Dollands Moor.

Somebody else will have to fill in Merseyrail but I think Hunt's Cross/South Liverpool Parkway has a short length of dual systems.
 

AverageTD

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Can they not change over on the move?
378s can and pretty much always do on any WLL services to/from Clapham Junction. Interestingly, the Class 377s on the WLL stop and sit for a minute near North Pole to complete the change which makes me wonder if it's limited by stock too. At any other locations though there is a platform where the change can occur. However I'd be very surprised if the 700s or the 717s couldn't do it on the move if they wanted to.
 

zwk500

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378s can and pretty much always do on any WLL services to/from Clapham Junction. Interestingly, the Class 377s on the WLL stop and sit for a minute near North Pole to complete the change which makes me wonder if it's limited by stock too. At any other locations though there is a platform where the change can occur. However I'd be very surprised if the 700s or the 717s couldn't do it on the move if they wanted to.
The 377s stopping where the 378s do it on the move is because GTR and LO have different policy, not stock restrictions.
 

D365

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The 377s stopping where the 378s do it on the move is because GTR and LO have different policy, not stock restrictions.
Yep it’s based on what the respective fleet are authorised to do.
 

Beebman

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For the sake of completeness, connections between AC & DC on the Southern outside London only take place where HS1 meets the classic lines at Ebbsfleet, Fawkham Jn (Not used but think it's still in place), Ashford and Dollands Moor.

Somebody else will have to fill in Merseyrail but I think Hunt's Cross/South Liverpool Parkway has a short length of dual systems.

Yes there was a short length of track there of dual systems, however the OHLE has recently been cut back to Hunts Cross West Junction and I doubt that there's anything more now other than the very briefest of overlaps. Having said that, I have reason to believe that there never was a possibility of a changeover happening there as I understand that the OHLE was de-energised at the same time as the DC was extended to Hunts Cross and the eastern access to Allerton Depot (which is why the OHLE was there in the first place) was removed.
 

zwk500

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Yes there was a short length of track there of dual systems, however the OHLE has recently been cut back to Hunts Cross West Junction and I doubt that there's anything more now other than the very briefest of overlaps. Having said that, I have reason to believe that there never was a possibility of a changeover happening there as I understand that the OHLE was de-energised at the same time as the DC was extended to Hunts Cross and the eastern access to Allerton Depot (which is why the OHLE was there in the first place) was removed.
Cheers. Am I right in thinking that all other Merseyrail lines only meet non-electric lines so there are no traction current boundaries on the Merseyrail system now?
 

Taunton

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In the days when the North London ran through to North Woolwich, services which had started in the 1980s as 3rd rail throughout later used to change four times along the way, there being two separate overhead sections which had replaced DC along the way. Can't recall the exact stations, but if you were sat under the pantograph there was a periodic considerable bang from the circuit breaker as it went up/down.

Certainly back in 313 days, DC trains arriving at both Euston and Watford would occasionally change over and return empty to depot on the AC lines (at Watford using that stub on the Down Fast line). It was described in Modern Railways at the time. Does it still happen?
 
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