Andrews Smashed in Latest Poll, page-119

''...highly skilled workers undertaking high risk operations such as tunnel-boring...''

No different to driving a train albeit 1000 times slower.
You just push buttons and watch gauges.
It's the technical staff that should be earning the big bucks, the surveyors and mechanics, they're the ones that ensure the machine heads in the right direction and keeps going.
When I worked on underground hydro's in the 70's a favourite saying of the tunnellers was ... "you send, we'll bend it".