I saw on the TfL website earlier today that the line was suspended between Abbey Wood and Heathrow/Reading due to an obstruction with the overhead power lines at Paddington. When writing this, this has now been downgraded to severe delays.
I've just checked the GWR website which is saying nothing about issues at Paddington, so it seems the issue was confined to the Elizabeth line section only. If this is the case. Can I ask why an issue at Paddington would cause a suspension of the entire COS, as well as the western section? would it not be possible for trains from Abbey Wood to terminate at Tottenham Court Road, and for trains from Heathrow/Reading to terminate at Paddington High Level?
There are only two crossovers in the tunnels between Royal Oak and Custom House/Pudding Mill Lane: A trailing crossover approximately midway between Farringdon and Tottenham Court Road and a facing crossover immediately west of Whitechapel. These are vastly insufficient to operate a safe and useful service through the core. There are crossovers at Custom House so it might be possible to run a shuttle service from there to Abbey Wood, but this would depend on signalling allowances, whether detrainment is required at Custom House (and whether there are staff to do it). I don't know how much notice is required to run trains into the high level stations - I would expect the platforms to be scheduled for other services. The nature and position of the obstruction relative to current sections will also likely be relevant.
The essential things in life are seen not with the eyes, but with the heart. --Antoine de St. Exupery
Great Western Railway were affected by last night's incident which I'm assuming was in the vicinity of Westbourne Park Sidings/Paddington mainline throat. With overhead lines being involved, the isolation area (if that's what was required) on a section of railway as dense as this would be particularly disruptive