You don't need to compare to the "Bay Bridge". The Queensferry Crossing was recently completed and it sits right next to the Forth Bridge, it cost an estimated

You don't need to compare to the "Bay Bridge". The Queensferry Crossing was recently completed and it sits right next to the Forth Bridge, it cost an estimated 1.35bn and it 2.7km long making it about £500 million per KM. So there is a significant additional cost, however only one person was killed building it vs 73 for the forth bridge. It was also (of course) bitterly opposed by the green party, the friends of the earth, nimbies etc but thankfully these usual suspects were defeated. You can't easily compare different bridges (especially on different continents!) with the different terrain. I assume the queensferry crossing is on the "3rd best" location to build a bridge on that part of the Forth, the Forth Bridge will have been able to choose the easiest route. The queensferry crossing is regarded as quite well managed when it comes to costs: https://www.constructionnews.co.uk/sections/news/queensferry-crossing-cost-management-praised-despite-delays-02-08-2018/ https://www.constructionnews.co.uk/sections/news/queensferry...