Seven Sisters

[NSE]

Hey, was at Euston last night, at 22:20 exactly as I recall it, and the next two trains where Walthamstow Central-bound and the third one for Seven Sisters, nothing strange there (other than the fact a Walthamstow one was coming when I needed it ) On arrival at Seven Sisters on platform 3, I glanced at the display, and it said after the Walthamstow train behind me, the next one was for Seven Sisters. This is different, as the Seven Sisters trains turn in the middle platform, number 4, and I've never seen a train turn in 3. As I understand it, a train can't turn in 3, it can only go to Walthamstow, Number 4 is used for turning (it goes northbound, crosses over to the Southbound depot line, and returns to the southbound platform) or can be used as a through to Walthamstow, and 5 is for all Southbound trains.
Now, did I just see a cock-up on the screen at Seven Sisters and the train was going into 4 as usual, or do they somehow turn back in platform 3? which by my reckoning involves a reversal (on the main running line) back to platform 4? or was it going to run empty to Walthamstow?

Anyway, any one with any knowledge I'd be interested to know if 3 is used as a turning platform, I go through Seven Sisters multiple times a day, and was wondering Well done if you managed to keep up with question :P

 

[EM2]

There is an excellent article on London Reconnections about Seven Sisters:
http://www.londonreconnections.com/2012/the-secret-life-of-seven-sisters/
But it doesn't answer the question

 

[NSE]

An excellent article, many thanks But as someone who (virtually) lives on the Victoria Line, its nothing I don't know already

 

[DavyCrocket]

They may have been doing a stock and crew reformation in order to get a defective or priority stable train to the depot.
Train trip data may not have yet been changed so the platform display would display the previous information.
As I'm not all that clued up on the reversing capabilities that's an operational reason I can give!

 

[superdrive1]

3 cannot be used for turning trains, it's a through Walthamstow platform, 4 is mainly a terminating platform but can if required be used as the through Walthamstow platform, 5 is the only southbound platform and used for trains from Walthamstow as well as those leaving the depot to enter service. So in short, 3 can't be used as a turning platform. One possible answer to this may be that the line had suffered earlier delays and there were substantial gaps in southbound service from Walthamstow so normal Seven Sisters terminators were sent into 3, cleared of passengers and sent empty to Walthamstow to form more southbound trains from Walthamstow to Seven Sisters and down to Brixton, I don't know if there was any such disruption, but if there was that logic may make a bit of sense! Honest answer is I haven't got a clue though!

 

[EM2]

Ah, that could be it. There was a one-under at Tottenham Hale earlier in the day on Thursday, and they were still saying 'severe delays' when I was considering KXSP-SS at about 22:20.