He is an engineer, not an architect, or even a civil construction engineer. He has noted a few times, he has no idea, and did no calculations, his modus operandi is just to (hopefully) overbuild any requirements of strength. He is probably overbuilding some strength 10x what worst case scenario could be, but it still leaves an avenue for error since he doesnt entirely plan it out fully with simulations.
He did a video after the first part of the tunnel being built with an inspection.
That being said he’s an engineer he knows how to keep things to code
He is an engineer, not an architect, or even a civil construction engineer. He has noted a few times, he has no idea, and did no calculations, his modus operandi is just to (hopefully) overbuild any requirements of strength. He is probably overbuilding some strength 10x what worst case scenario could be, but it still leaves an avenue for error since he doesnt entirely plan it out fully with simulations.