https://pedestrianobservations.wordpress.com/2012/04/20/quick-note-how-much-tunnels-really-cost/ https://pedestrianobservations.wordpress.com/2012/04/20/quic...

https://pedestrianobservations.wordpress.com/2012/04/20/quick-note-how-much-tunnels-really-cost/ https://pedestrianobservations.wordpress.com/2012/04/20/quic... $250 million for a water tunnel that goes 3km. It's simpler than a hyper loop tunnel. Also I'm not sure Crossrail is a good counter example. That's a 30 billion dollar project to go 73 miles. Saying the TBM cost $20 million is like quoting the cost of a truck without including the price of the driver or diesel fuel.