Politically, from my own personal experience, most infrastructure projects are sold to the public with a much lower price tag than what they know to be the actual costs, because people are incredibly price sensitive when approving important infrastructure projects.

What we need is a true accounting of the cost of things, and the political willingness to do them. This way we don't have to worry about politicians 'underbidding' their projects just to get enough popular support. It becomes a rigged game when that happens, where the public approves projects that everyone on the project side knows will costs several times that early estimate.

If we want the bridges and the tunnels and the shared transportation, sanitation, etc. We need to understand that these projects cost money, and we need to be able to have t true accounting of them, not one that is politically convenient.

Otherwise, we'll just have this, with 2x and 3x being common run ups, ad infinitum.

Good numbers, on all projects, would help us better allocate our future dollars. Big numbers shouldn't kill meaningful and worthwhile projects. Bad ideas should.

The Swiss seem to be able to do it.

https://en.wikipedia.org/wiki/Gotthard_Base_Tunnel

On time and on budget.