Twickenham possible extra platform provision

[Wokingham]

Is this tunnel for a service or something in the future?


additional

It appears a photo I thought I had attached has not worked.

Underneath the new flats a gap has clearly been left to allow trains to run through, past platform two, was curious if this would just be for a additional platform or new service.

 

[JonathanH]

Is this tunnel for a service or something in the future?

Which tunnel?

Are you talking about passive provision on the north side of the layout which would allow a through connection to the bay platform in the future?

A different layout at Twickenham allowing fast trains to pass slower trains would be great but not aware of any current plans for it to ever happen.

 

[Snow1964]

The original plan when station rebuild other side of road was two island platforms and London facing bay for rugby extras.

Didn't quite end up like that, as the centre platform at St Margarets can't be used as reversible fast. The centre line doesn't become two middle tracks just west of St Margarets either, and the up slow was never realigned to allow up fast to be laid in (which would have been reversible, so it could be used as holding line for trains using the bay.

When the old station was demolished (which was 1950s), the slow lines were not connected as independent tracks to the Strawberry Hill (Kingston loop), or rather they are, but can't be bypassed by trains on the fast lines. So fast and slow trains can't do cross platform at Twickenham and run parallel to the junction.

The mid 1970s Feltham area resignalling never completed the plan, and nowadays 2 of the 5 new platforms at Twickenham are dead. But seem to have sensibly decided not to block the trackbed.

 

[TSG]

A different layout at Twickenham allowing fast trains to pass slower trains would be great but not aware of any current plans for it to ever happen.

Resignalled to Basingstoke at Easter 2021. The Up Twickenham became bidirectional between a new down main to up main (or twickenham as they are now known) crossover at the country end of St Margarets and a new Up to Down crossover between the Strawberry Hill flyover and Whitton. I don't see any reason why slow trains can't be passed in either direction now. They can now run parallel to the junction, just not in both directions at once.

The mid 1970s Feltham area resignalling never completed the plan, and nowadays 2 of the 5 new platforms at Twickenham are dead. But seem to have sensibly decided not to block the trackbed.

The new signalling has provision for the platform 2 bay to be used, subject to other works on the bay track being completed before these routes are enabled.

 

[30907]

I don't see any reason why slow trains can't be passed in either direction now. They can now run parallel to the junction, just not in both directions at once.

The main issue would be that in the down direction a slow would be delayed by about 5min at Twickenham, so you might as well send it on to Hounslow. The Up direction is OK (and was before).

 

[WAO]

I don't think that you could pass four, up and down trains simultaneously without four through roads, i.e re-instating platform 2 as through, although I concede that the new layout is clever. The flyover is a bit of a waste otherwise and I've known this to be a consistent limitation over the years for down trains trying to be semi-fast. It would not be tolerated on the SW main line I imagine.

The Island is a bit slim for an East facing bay.

WAO

 

[TSG]

The main issue would be that in the down direction a slow would be delayed by about 5min at Twickenham, so you might as well send it on to Hounslow. The Up direction is OK (and was before).

Realistically this about as good as you're going to get without widening the Thames bridge from Richmond. I think there may be physical constraints around the London end of St Margarets that would have made the marginally better positioning of the crossover parallel to P1/2 converging points very difficult.
You'd knock too much capacity out of the up line going any further west with the bidirectional. As it is, it gives you the parallel junction going down.

I don't think that you could pass four, up and down trains simultaneously without four through roads, i.e re-instating platform 2 as through, although I concede that the new layout is clever. The flyover is a bit of a waste otherwise and I've known this to be a consistent limitation over the years for down trains trying to be semi-fast. It would not be tolerated on the SW main line I imagine.

As alluded to above, I'm not sure you could get them there on the down anyway. If the flyover could be moved to Woking I suspect they would but there you go...