>in a tight tunnel? unlikely. 12ft diameter gives you at least 8ft of internal space x a mile. Japan for example has 100sqft apartments. I've worked in an offi

>in a tight tunnel? unlikely. 12ft diameter gives you at least 8ft of internal space x a mile. Japan for example has 100sqft apartments. I've worked in an office, in Indianapolis, that wasn't even 8ft across and there were 20ish of us with desks against the wall so little space you had to slide all the way in for someone to walk down the aisle. You could cut a channel down the center for plumbing and electrical conduit, probably only have a foot of clearance on one side, then have a walkway down the other side and make quite a bit of comparable office space. Most THOW, tiny homes on wheels, are less than 8.5 feet wide to remain legal trailer width in most states so you've already got people living like that in the US. Here you could cut elevator shafts every eighth of a mile and just make the freight elevators. Say after fire suppression, pumps etc, you only have 4500ft of length to rent/lease/sell you could have 200+ small offices/apartments/artists spaces/climate controlled storage units. I mean a Type IXC submarine (like U-505 at the Museum of Science and Industry in Chicago) had a pressure hull beam (width) of 14ft 5in and you still had material between the crewed area and that hull. Having been in U-505, and being 6'1 300lbs, even with a full tour I found it had plenty of room to move about and would have happily lived on it. Especially if it didn't have pipes/gauges/equipment/cabinets/cots etc hanging off the walls. Those things ran with crews of 50-60 people for months at a time, small offices or flats for 1-2 people would sell quite well I'm sure. Hell, I've been in escape rooms that weren't wide enough for me to lay down in. I'd live in the tube.