Peter Masson wrote:
"D7666" wrote in message
...
On Dec 19, 5:01 pm, Mr Thant
wrote:

This is relevant because every train to Moorgate is one less to/
through London Bridge (unless you can find somewhere new to start
them from), undermining the purpose of the scheme.

Holborn Viaduct ;o)

City TL out of St.Pauls sdgs.

For each train turned back in St Pauls Sidings you lose two paths to
Farringdon, one as it goes into the sidings and one as it comes out.
To avoid this you'd have to remodel the sidings so that they are
between the up and down lines. Even then you'd lose capacity when
trains don't turn up at the right time. I doubt that you could
lengthen the platforms at Moorgate for 12-car trains - down trains
didn't call at Barbican because the platform was too short. As others
have pointed out, you couldn't operate Farringdon at 24 tph with SDO.
If you retain the Moorgate branch you can't lengthen the Farringdon
platforms south of the station, because that's where the junction is.
You can't extend them to the north because of the gradient of the
diveunder under the LUL lines. So you'd have to rebuild the gridiron
so that the Thameslink line stays level and the LUL line dives
underneath it. All in all completely unaffordable, and quite
unnecessary, as passengers can change at Farringdon to LUL (or in
future, Crossrail) to reach Moogate or Liverpool Street. Or walk.

I'd also suggest [with hindsight] that they had a pretty good idea that it
wasn't just the Farringdon platform lengthening that would go over the
junction, but the combined Thameslink/Crossrail station, and I believe the
Crossrail construction access is to use the disused track bed. Was this all
assumed to be happening by the original decision makers?

Paul S