The video clip tells you why China can build subways fast, with good quality

[Hamartia Antidote]

TBM is certainly not new and I knew about it when I was in kindergarten, but building hundred subway lines in 40+ cities at the same time is something we have never seen before. The scale and the efficiency of China's infrastructure building are impressive, and I think that's the message OP tried to convey.

Seems Elon Musk thinks current TBM tech sucks. He wants to improve speed by 500 to 1000%.

http://www.dailymail.co.uk/sciencet...tweets-photo-giant-tunnel-boring-machine.html