Well even if it weren't higher capacity, it has other advantages -- no parking/leaving the car, potentially no ticket gates or waiting for a train... etc.
Trying new ideas isn't a waste of everyone's time, it's research.
>and if it doesn't work out, it can always be converted to rail
Or worst case likely office, manufacturing or even residential space, I mean... that's a LOT of square footage that just got created in an area with very expensive real estate.
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.
oh i don't doubt that it can fit. but i can't imagine it being popular.
japan has small apartments out of necessity. not because they like living in small spaces.
add that working or living under artificial light is not exactly healthy. this idea strikes me as something for an emergency shelter, backup workspace, but not for normal operation/living.
right, it might not work for a regular sized train, but if it can fit a car, it can fit rails and a custom designed rail carriage with the same advantages of a regular train.
it might not even need regular rails. there are trains that work with rubber wheels (paris subway had that for decades already), so it would really just be fancy busses with guide-rails.
EDIT: pretty much the same idea is mentioned by several others in this discussion, so it seems not to be to far fetched.
of course, given the popularity of public transportation in LA, it makes sense that they are going for the ability for people to use one vehicle from their home all the way to their destination. i just hope they focus on actually getting the most use out of the tunnels, even if their initial vision doesn't work out the way they intend.
IIRC the main heat source is the breaking of the trains combined with the high frequency of them. I suspect that using many cars will still release a lot of heat into the tunnels.
The trains in the narrow tunnels push air around, so recent stuff like full height platform screen doors help improve conditions (allowing platforms to be air conditioned without having to air condition the tunnels)
Trying new ideas isn't a waste of everyone's time, it's research.