Massively cool cutting edge technology, even before Elon involvement. ;-)
There is also a huge amount of interesting videos on Youtube about these projects, all the way from the initial tunnel boring/blasting all the way to final outfitting (imagine installing rails & electric equipment in a 57 km long tunnel - no wonder it took 6 years of multi shift daily work, etc.).
>>A 2002 report by Michitsugu Ikuma described, for the undersea section, that "the tunnel structure appears to remain in a good condition." The amount of inflow has been decreasing with time, although it "increases right after a large earthquake".
You can of course submit any tunneling articles/media you think are interesting.
Just look at the abundance of Atlas Obscura articles -- few are tech based.