...700s will be quicker still, and do it automatically, ie the driver doesn't have to do anything.
They'll also be able to do it while moving
So what happens now is of little or no relevance to the final procedure at all.
on the ECML side of Thameslink I do not understand how they are going to deliver the trains at the right time and order to Thameslink core. I image confusion as trains arrive out of sequence.
I wonder why they didn't extend the wires and/or 3rd rail out of the core to somewhere with more space to reduce the effect of the switchover delay.
It was to avoid having to AC immunise the DC lines and their signalling that cross underneath the Thameslink route heading to/from Waterloo East. It was explained in one of the early Thameslink 2000 papers. (I think subsequently it also meant the physical design of Blackfriars station's new roof would be simpler all round.)
Even if it were less electrically or technically challenging, once you get past the core section southbound you have two routes, so you'd have to double the amount of hardware at the very least.
There is a highly complex set of contactors and switchgear (at Ludgate Cellars - between Blackfriars and City T/L) that controls the trackside aspects of the AC/DC changeover system - that system would have to be doubled up to cover two areas. The up and down track sections between City and Farringdon stations inclusive have both AC and DC power supplies, and the earth and traction return systems are switchable between AC and DC modes - this can happen progressively as a train moves between the two stations, there isn't an existing system of such complexity anywhere, as far as I am aware.
Makes sense.
I presume there is an equally good reason why the 3rd rail couldn't be extended northwards
The same reason as not extending the wires south, it would mean installing another set of contractor kit or some other method of switching the earthing. Even where it is now, with all the protection kit in, is a pain; the return current from trains on DC is constantly trying to get to the AC section (the DC substation is between Blackfriars and City TL) This burns out the insulated block joints in the rails at Blackfriars every 6 months or so.
Also, for those of us who have managed both third rail and OLE railways, the former is a right royal pain in the derrière across the business, from staff safety to track maintenance to signal engineering complications to quantity of distribution kit etc etc.
What gets me with the tube trains is when there's another one in 1 minute, and another in 2... Why struggle to get on when the next one (or one after) may be much quieter and give a more comfortable ride? Especially true if there was a gap in service before and the crowding was due to that.
But, for the TV core, not every next train will stop at the same places so people won't want to wait. They'll take as long as possible to board and hold the doors as necessary. I can almost guarantee chaos in the peaks or during special events with more numbers than normal.