Well that's the thing, see: according to S&TE's excellent diagram, the current lines from Temple Meads to Narroways - the reliefs, in the new scheme of things - don't appear to be affected by the remodelling. So I'm assuming that the closure is for safety reasons.
The current up and down lines will be breached on Filton Bank where the lines are slewed to run from the original formation of the relief line to the original main lines so as to connect the new tracks to run through the new platform and the added 3rd platform and for the new relaid tracks from Dr. Days Junction tracks can be connected through the original Abbey Wood platforms.
In the olden days of semaphore signalling the box controlling what SandTEngineers excellent diagram labels as HORFIELD
JCN▸ was FILTON INCLINE SIGNAL BOX.
I spent many an hour in the next box up the line, FILTON JUNCTION, with my school chum whose father was a signalman there, sat on an old cushion on an upturned metal milk crate.
One day when I got time I'll put down some memories of my adventures in the late 50's with my school chum which at one point included a footplate ride on
GWR▸ 3440 CITY OF TRURO from Filton Junction to Swindon when the loco was working the Bristol - Swindon via Badminton all stops diagram in 1958 I think it was.
