In case you haven't noticed, Japan dug 62 miles of tunnels.  You yourself said tunneling is expensive. Yet Japan was able to tunnel 3x more miles then what Honolulu's rail will be in length, along with another 25 miles of above ground guideway (92 miles total) and still cost less then 5 billion dollars.  Give it up, you're just digging yourself into a hole that's getting deeper and deeper the more you comment on rail.