Comment by hinkley
Metros are in tunnels.
There’s only so much gridlock you can avoid without going above or below grade. I was shocked when I moved to Seattle and they had no subway system. It was made even worse by being crammed up against a tall hill with a ridiculously deep lake behind it. They are finally changing it now but I’d spent time in Tokyo before, and time in London and Paris shortly after and it was a real head scratcher. One bus tunnel helped, as was evidenced when they shut it down for a couple years, but cmon.
Seattle also is a great example of "why tunnels for cars are not tantamount to a public transport network".
As well as all the impediments to the glorious vision of the parent commenter's "tunnels everywhere" as a panacea.