I don't think you've seen a London Underground deep tube line, you ain't getting two levels of cars in that space. No overtaking either, as they use separate tu

I don't think you've seen a London Underground deep tube line, you ain't getting two levels of cars in that space. No overtaking either, as they use separate tubes for each direction. Even the larger, shallower subsurface lines are UK loading gauge, which isn't big enough for double decker trains. I doubt any double decked traffic on existing UK railway land without extensive expensive rebuilding. As for "robotic underground construction", it's not like they have a load of Navvies digging by hand nowadays, a modern tunnel boring machine is pretty damn robotic, but it still costs a fair chunk of change to tunnel.