"D7666" wrote

But if you slightly displaced the suggested regulation locations
clockwise around the Circle, you could use *Barbican* and South Ken.
The latter has I think room for 4 tracks still within the existing
structure/cutting, although it would need some shifting around of
trackside kit.

Thus a more sensible use of the redundant ''widened lines'' going east
of Farringdon would be to diverge from the Met-City to 4 platforms
through Barbican and converge back to 2 through lines through
Moorgate. I suggest there is enough space to do this but would need a
certain amount of significant work east of Barbican to achieve.

Ideally for bifurcating working you need an island for each direction
with both platform faces going the same way - neither South Ken nor
Barbican would offer this, so any trains being recessed or tipping out
would cause passenger to have to use crossways, but I suggest overall
this is an advantage : it train X is in the existing platform train Y
is stuck in tunnel behind. With 2 platform tracks, Y might get in
allowing passengers to cross to X while Y recesses. Overall it keep
passengers moving even if one train does not.

The whole point of this suggestion is to address the fundamental weak
point of the Circle - it has zero resilience. If you have 4 track
locations it allows sort of elasticity for the operators.

Far too subtle a point for uk.railway ''but we've always done it his
way'' die hards of course.

I can just about remember South Ken with 4 District/Circle platforms. What
would be possible, and probably not too difficult, would be to put in an
additional westbound (clockwise)track and platform at South Kensington, so
that District trains have their own track, separate from the Circle, from
here through Gloucester Road. Useful when Earls Court is blocked, perhaps
with trains waiting for a change of driver, as Circle trains could overtake
the queue. Exceptionally a District train could use the Circle track to
overtake a queue if this helped regulating the service.

If the westbound (anticlockwise} track through Barbican was diverted to the
former Up Moorgate Widened line trains would simply call at the other side
of the island platform. The existing westbound line could then be used as a
recess line, or as a turnback line in either direction. At worst passengers
on an eastbound train which was being turned back would be advised to change
at Farringdon if they were travelling beyond Barbican, or have to cross the
bridge at Barbican if they weren't given or didn't heed this advice. No
worse than trains turning back at Mansion House or Tower Hill.

Peter