Hypothetical Severn Tunnel Replacement

[Peter Kelford]

So how about a bridge then?

 

[option]

Would this be;
replacement because the existing one is approaching end of life
additional capacity

If it's the first, then it needs to be somewhere next to the existing tunnel, as that's where all the existing infrastructure is.
If the second, then it could be elsewhere, as you'd also be looking at improvement works to rail infrastructure at each end.