In message , John Rowland
writes

Paul Terry wrote:

I guess it would be possible for trains to reverse at Clapham Junction
and continue round the circle, but I imagine that it could produce all
sorts of operating problems.

I can't think of any, unless you mean "reverse *promptly* at Clapham
Junction and continue round the circle".

Clockwise and anticlockwise services would have to cross on the level
just outside the station if they were not to terminate at Clapham
Junction.

Pathing on the WLL will be difficult because it is shared with a number
of other services, so there is likely to be little or no flexibility to
schedule services to make optimum use of such a crossover - and delays
on the WLL leg would then have a bad knock-on effect on the ELLE leg.

Pathing on the ELLE should be easier, but it is likely that the line
will have to be shared with some sort of SLL service to Victoria, so
there is all sorts of potential for circle-line-like delays - breaking
the service at Clapham Junction should help mitigate that.

It should produce a more robust service if the trains *do* continue
around the circle, after a suitable wait... that way problems which
affect the clockwise can't affect the anti and vice versa.

I don't think that the Orbirail project will ever run a fully circular
service, because of the potential for serious delays (like the circle
line but infinitely worse). Nothing's decided, AFAIK, but clockwise
services from Clapham Junction may terminate at Stratford for the
Olympics, and at Barking thereafter, although it has also been suggested
that they may (as at present) go no further than Willesden Junction.
Anticlockwise may only go as far as Surrey Quays.
--
Paul Terry