> Yes, the larger machine would have to have larger material removal rates just to keep up with the smaller machine. But that makes it more expensive, not less.

> Yes, the larger machine would have to have larger material removal rates just to keep up with the smaller machine. But that makes it more expensive, not less. More expensive than one, potentially less expensive than two. Happens in manufacturing and industry all the time. Transport cost alone could be enough to account for it. > Call me stubborn, but I need a better theory to explain why the bigger TBM would be cheaper. Sounds like you should have a chat with the project lead.