Thameslink northbound traction changeover

[Pdf]

Why do trains through Thameslink core switch to AC traction at City Thameslink while going north, but switch to DC at Farrinngdon while going south? As far as I can tell, third rail goes all the way to Farringdon. Surely a minute could be saved by not stopping at City Thameslink when it is closed (Sundays and late evenings). I assume there's some kind of operational reason for the switchover offset. Anyone know what that is?

 

[JonathanH]

I assume there's some kind of operational reason for the switchover offset. Anyone know what that is?

The northbound switchover is at City Thameslink because if the switchover fails, an 8-car can be put in Smithfield sidings, and if a 12-car fails it is easier to ensure it can take the crossover to return south.

Basically, it is best to do a changeover at the first available opportunity for a reliable railway.

Some more here
https://www.railforums.co.uk/thread...r-disruption-04-04.230034/page-7#post-5609847
https://www.railforums.co.uk/threads/operational-incident-at-blackfriars.221214/page-4#post-5270520
https://www.railforums.co.uk/threads/four-dc-ac-locations-or-is-it-five.217517/page-2#post-5141386

This is particularly relevant about having the changeover as close to the substation at City Thameslink as possible.
https://www.railforums.co.uk/thread...-to-overhead-lines.210166/page-2#post-4829753

Surely a minute could be saved by not stopping at City Thameslink when it is closed (Sundays and late evenings).

No time saving as the paths north of Farringdon and south of Blackfriars wouldn't be changed. Therefore the only saving is getting to Farringdon slightly earlier.

City Thameslink is closed early on a Saturday morning as well.