Hello to everyone here!
What if those vehicles were designed to use already existing tunnels underground? I know, they're equipped with drilling features and so, but this topic reminded me about this thing i was researching not long time ago.
I have read a lot about very old intercontinental tunnels, sometimes described as made from glass, connecting whole world. Unfortunately all sources I can find are not in english, but there is surely a lot to talk about.
Have you heard about this? Ancient underground tunnel system, connecting all the continents? I dont want to hijack this thread, but if you want I can try to translate some informations I've read.
(pardon my english, I am not a native speaker)