I can think of infinitely better ideas than this ridiculous one. But the question is always where is the money coming from.

If you can get an Elon Musk type to pay for the building of a stupid bridge, then suddenly it's viable, even if high speed rail between already land-connected regions is such a better value for money.

I haven't heard who proposed this particular idea. But all the news I've heard recently from the UK is brexit related so I've probably missed a lot.