So, Zürich: you remember the tunnel that comes out half way to Adliswil, under Uetliberg?

What did it cost as a tunnel, what would that have cost as a surface road in reality, and what would it have cost as a surface road if the area had been flat? *That* is why you're being called out by loads of people for "a smaller geographic footprint".

Tunnels are expensive: https://www.bbc.com/future/article/20220621-what-if-roads-we...