china built a massive triple decker tunnel underneath the yellow river, it's only 4 miles long but is 53m in diameter, and they built it with a tunnel machine in 111 days or something like this
i'm more convinced than ever that russia used chinese tunnel machines to dig behind hohol positions
anyway china #1 btw
also make sure you check out the video on the highway china is building through the himalayas to nepal which requires like a million miles of tunnels and they're going to finish it all within 2 years
tl;dr china #1
>https://youtu.be/-Q9ZJSTRu30?si=eDtUoUB-AS0hjn-B