On Fri, 2 Oct 2015 20:44:43 +0100
"Clive D. W. Feather" wrote:
In message , David C
wrote:
I'm not saying it can't be done but it is a lot more complicated to signal
so tends to be avoided. The LUL 3rd & 4th rail electrified tracks lie
between platform 1 and the overhead electrified tracks, don't they? So the
Barking Riverside route won't go near platform 1 so why keep it in service?

Sorry but you are not making any sense.

As has been mentioned, 25 kV AC electrification has co-existed with
the under-ground since 1962without any problems.

I think there's a misunderstanding here.

There are serious problems with having third (or third/fourth) rail on
the same line as 25 kV, to do with earthing and track circuits.
Therefore there's good reasons to avoid that.

But, on the other hand, I don't believe there's any significant reason
not to have 25 kV and third rail on adjacent tracks. Particular with
platforms in between.

On a related topic - why was 3rd rail used for the ELLX from Highbury given
how new DC lines are actively discouraged? They could have used wires all the
way down to past Surrey Quays then switched to 3rd rail like Thameslink. Was
it limited clearance in the thames tunnels or just for simplicity - ie cheaper?

--
Spud