No extensions seem appropriate. Shenfield is the natural limit of operators on its branch, as are Reading and Heathrow.
Far from easy. It involves electrification, a complete redesign of Old Oak Common Station, more rolling stock, platform extensions and the suggestion it can be justified for 2 or 4tph isn't going to result in its funding. Mind you more than 2tph would also need more tracks on the Chiltern line. Probably a non starter.
Why?
"probably" is quite the understatement. The NNML has been severed for OOC, you've mentioned the redesign that would be needed but also you'd need a grade-separated junction for which there is no space over or under the GWML.
No. A two platform station on a congested two-track railway isn't ideal for terminating services. There isn't exactly scope for building extra platforms on the viaduct either.
The flat junction at Forest Gate couldn't cope with the extra traffic. There is enough demand on the Shenfield route as far as Romford to justify all of the services via Stratford going there in any case.
Not possible at all. There is no connection from the tunnel portal to the Tottenham Hale line and it wouldn't be possible to engineer one either.
It’s official enough to be mentioned quite a few years ago, in the last Western and Wessex route studies? But I think via Staines towards the SWML is much more likely than towards Windsor, and far more likely to be a HEx replacement than a CR extension.
It's always going to be mentioned in the strategic papers, but Windsor would never have sufficient business and Staines needs a solution for the Level Crossings.
There are still people who would prefer the terminus of Reading to Didcot services to be Oxford. A four car 387 shuttle between platform 3 at Reading using the Festival Line and a bay platform at Oxford is probably the right service once the wires reach Oxford with passenger services on the relief lines to Reading wholly turned over to Crossrail.
I agree with all your reasoning, but the last time I checked the OOC Crossrail platforms, the centre two tracks were designed in such a way that the western turn-back sidings will point towards Northolt.
No, the Up Relief will cut off the access to the NNML. Any proposal I have seen for Chiltern to reach OOC has involved constructing additional bays in the V between the GWML and HS2 stations.
Howabout the Windsor central/Slough shuttle; is the capacity available on the GWML to add that to the core routes?
A major destination you'd take an inner-suburban service to? everythin stops there amyway, slow or fast. I'd have said Heathrow rather than Maidenhead maybe, but certainly sending what's not far removed from LU subsurface trains to Reading is too much. Plus, what investment do TfL have in outer Thames valley journeys? what do they care about someone going from Taplow to Reading?
No. There is no sensible manner in which it would be possible to run Crossrail to the Windsor branch as it is on the wrong side at Slough with no space to build grade separation.
But that’s exactly why it would never have been considered a reasonable possibility.
Not least because an underground platform would be needed under Slough's existing station on that diveunder and then a steep incline to get back to the level of the Windsor branch.