Thameslink Core pantograph strike

[MCR247]

Back on topic, and as we see on Thameslink, with 4 (and a half) sets of crossovers in less than three miles from just north of St Pancras to Blackfriars South, it can sustain at best a quarter if the normal service if one section is out and even that will incur delays.

Out of curiosity, where abouts are these located?

 

[jdp30]

One before St Pancras on the Bedford branch, one between St Pancras and Farringdon, half between Farringdon and City Thameslink(Allowing going wrong direction northbound out of City Thameslink along the southbound track and changing back to the northbound before Farringdon) , One between City Thameslink and Blackfrairs, and one south of Blackfriars.

There's also a half one on the Finsbury Park branch, allowing wrong direction northbound out of St Pancras back to the actual northbound track - @Bald Rick doesn't seem to be counting this one?

Can see them here: https://www.opentraintimes.com/maps/signalling/tlk_core




I'd be interested to know why the halves are only halves - Space constraints?

 

[miklcct]

In theory yes, in practice I think they're very hesitant to do it and as above says it absolutely kills the service on the branches.

There is a contingency plan on the Elizabeth line to run the service back in 3 separate railways if needed. Is such plan available on Thameslink (to terminate all trains at Kings Cross / St Pancras High Level / Blackfriars / London Bridge) if the core is blocked?

 

[Bald Rick]

One before St Pancras on the Bedford branch, one between St Pancras and Farringdon, half between Farringdon and City Thameslink(Allowing going wrong direction northbound out of City Thameslink along the southbound track and changing back to the northbound before Farringdon) , One between City Thameslink and Blackfrairs, and one south of Blackfriars.

There's also a half one on the Finsbury Park branch, allowing wrong direction northbound out of St Pancras back to the actual northbound track - @Bald Rick doesn't seem to be counting this one?

Can see them here: https://www.opentraintimes.com/maps/signalling/tlk_core




I'd be interested to know why the halves are only halves - Space constraints?

The other ‘half‘ of the crossovers on the ECML branch of the core is on the slow lines in Copenhagen Tunnel. I was including but not counting them, but they do effectively the same job as the Midland Road Junction crossovers in Kings Cross Tunnel on the Midland side.

The half crossover between City TL and Farringdon is only there to enable a train that fails to change voltage to go back where it has come from. The changeover is always at Farringdon (southbound) and City TL (northbound). If the changeover doesn’t work there, the driver contacts the signaller to advise what’s happening, then advances to the next station to attempt there. The signaller must then set signals to prevent any trains following the troublesome one from departing Farringdon (southbound) or City TL (northbound). If the train fails to change over at the next station on the second attempt, it is cancelled, tipped out, and driven by the same driver from the other end through the crossover and straight to depot.

 

[Meerkat]

Bit late to this but if its a case of the ADD not being fast enough and you don't want to mess with the signaling could you hang a non-conductive rail ramp under the relevant building so that the pantograph was forced down rather than getting knocked off (I am assuming this wouldn't cancel the ADD, and the ADD triggers lights and bells so the train will be stopping)?
Any fancy detection system would need to be able to distinguish a pantograph from a pigeon or windborne rubbish. Bods who supply the OD radars for level crossings might be able to knock something up.....for a price.

 

[norbitonflyer]

Bit late to this but if its a case of the ADD not being fast enough and you don't want to mess with the signaling could you hang a non-conductive rail ramp under the relevant building so that the pantograph was forced down rather than getting knocked off (I am assuming this wouldn't cancel the ADD, and the ADD triggers lights and bells so the train will be stopping)?

Possible, but then wherever that ramp ends the pantograph would spring up again. The ceiling in the station roof is quite low (to preserve sightlines to the cathedral) and you would get the same problem there instead. And there is a signal gantry just beyond the roof which would be hit if your rail ramp (or indeed the catenary) continued the full length of the roof.

 

[twpsaesneg]

Bit late to this but if its a case of the ADD not being fast enough and you don't want to mess with the signaling could you hang a non-conductive rail ramp under the relevant building so that the pantograph was forced down rather than getting knocked off

That's pretty much what the face of Snow Hill tunnel had when the wires ended at Farringdon... plus ca change

 

[Meerkat]

Possible, but then wherever that ramp ends the pantograph would spring up again. The ceiling in the station roof is quite low (to preserve sightlines to the cathedral) and you would get the same problem there instead. And there is a signal gantry just beyond the roof which would be hit if your rail ramp (or indeed the catenary) continued the full length of the roof.

I'm assuming that
a) the ADD is getting triggered but can't act fast enough before the train gets to the building
b) once triggered the ADD wont let the pantograph go back up without a driver override - and a driver who did that would be getting a meeting with no chair, let alone tea and biscuits!