jonmcity said:
Think it is possible to build the new turrets first, leaving the roof in place then secure the roof to the new turrets while extending the north and south stands.
I don’t think it is
As I have mentioned, numerous times in this thread, the roof is a mono-structure, primary support is the PRE-TENSIONED cable net. The roof design is light weight, therefore the foundations will be designed for this so any replacement roof would have to be light Think about the roof as a tent with the guide ropes representing part of the cable net imagine cutting away part of the tent including the guide ropes and putting a new piece in!
Look at the stadium in plan view and observe where the turrets and cable anchors are in relation to the outer wall and you will see how difficult this makes building new structure