Thought I might start a thread on Musk's Boring Company after his release of the video at the TED2017. Here is a great, bit old, article on boring at WSJ (subscription required). The High-Tech, Low-Cost World of Tunnel Building Cost only $19,000 per foot per that article for a train, by my math that is $100M per mile. Boring companies tunnels will be much smaller of course and cheaper, but only single lane. Four lane highway costs are quite a bit cheaper, $10M per mile. I'm not sure how this becomes financially possible?