It would be interesting to see what Network Rail are proposing for the "full renewal in a couple of years". Might some of this be work to upgrade the junction with the Portishead line?
According to
WECA» 's "Year Rail Delivery Plan for Investment: 2020 – 2030" (2020), one of the things they and are looking at is: "Increase capacity and improve resilience for new MetroWest services between Portishead and
BTM▸ ". This is said to require:
Bristol to Exeter CMSP.
Bristol West Junction Enhancement.
Four tracking Bristol Temple Meads to Parson Street.
Passenger and train capacity at Bristol Temple Meads.
Two points about that - it comes under "New schemes to be developed in the 10 Year Rail Delivery Plan and delivered 2030 to 2045"; and in that first step CSMP means a "Continuous Modular Strategic Planning" study. Somehow I don't find that sounds reassuring.