Why?
The current tram system takes up a lot of surface space, that would be more well used for other things. Also metros are cool
How?
Simple build a couple of metro stations and connect them with tunnels. We can also move some water elevators to the metro stations which will make the surface (especially blair mountain str) look much nicer.
Who?
i can do most of the world
Layout
here is a layout of my suggestion for a metro system https://imgur.com/AQdYYWG
How deep does the metro go? According to your layout, the ‘beach mine’ might come in the way between Revolution square and Blair mountain street. There is also a ‘machine testing lab’ near Lenin Street, but I don’t remember where exactly. Otherwise I think this could be expanded. From Castro square stop a path could go to the Iron farm and from Lenin street to the new storage house. What kind of metro system are you building transporting-wise? Ice boat, piston bolt or a mix of both?
Whatever, we can just build walls whenever we hit some empty space.
Those thing shouldn’t be a problem, the beach mine will be below it anyways and going thru it isn’t a problem either. The machine room will be moved a bit, but there is not much in there yet so it will be a small amount of work to move it.