Unfortunately "big engineering" is 10% fun and 90% filling out paperwork - and with a few exceptions the paperwork part is the only bit that offers any career progression.
Documentaries rarely bother filming the 200 guys who spend years working in office parks on P6 plans and CAD models to plan everything to the Nth degree!
And even the "fun" is 90% boring. The tunneling itself is maintaining the TBM as it's doing its thing and crawling along at ~30ft/day. Seeing them in action for 10mn is fun (I did and the scale is awe-inspiring) but I'd expect working on them to be more on the boring side.
Documentaries rarely bother filming the 200 guys who spend years working in office parks on P6 plans and CAD models to plan everything to the Nth degree!