Find a way to access it? The signallers must have some way of getting to it. More of a problem would be finding a use for it.
Route for signalmen probably involves track access making other uses even more problematic.
A box like Severn Bridge deserves preserving complete with frame, interlocking, instruments etc. somewhere else (Bids?). It would need quite a big site.
It would be possble to interface it with a computer to simulate how it worked.