I do know that tunnel boring machines can disturb the surface, and that substantial effort goes into minimizing this. (That is, minimal surface disturbance isn'

I do know that tunnel boring machines can disturb the surface, and that substantial effort goes into minimizing this. (That is, minimal surface disturbance isn't automatic on account of the fact that you're boring.) I believe it sometimes has to do with how much pressure they need to apply to the tunnel face; the ideal pressure for cutting can lead to sink or swell on the surface. Presumably this is less of an issue the deeper you go. I don't know much about this stuff though. This is maybe relevant: > This thesis summarizes and evaluates the performance of Tunnel Boring Machine (TBM) construction in Singapore's MRT network. Surface settlement induced by the tunneling process can cause damage to underground utilities and foundations and buildings and/or disrupt daily life by damaging roads and pavements, and is used in this thesis as a measure of performance. https://dspace.mit.edu/handle/1721.1/82809 https://dspace.mit.edu/handle/1721.1/82809