One idea I keep returning to is a "laned" system for elevators/lifts. Two shafts for going up, and two for going down. One of the two in each direction is the "passing lane"-- and you fit dozens of elevator "cars" in the whole system. For very high altitudes it may even make sense to have a third, high-speed lane.
Obviously this would require a completely different mechanism as you can no longer have cables attaching each car to the roof. In fact I have no clue how it could work! This is what I keep pondering...
You might be able to do it with linear motors. The problem there would be the reliance on the safety brakes in the event of power outages (not really a problem with counterweight elevators).
Mount what amounts to an elevator system on the linear motor, but it never goes up and down. So you suspend a standard otis elevator from the linear motor.
Power fails, linear starts to fall, lands on top of the traditional otis with its emergency brakes holding the whole works up. There's no reason the cable between the otis and the linear has to be 200 feet for the linear to build up speed... make it, perhaps, 3 inches and a nice spring arrangement.
I bet it would still be pretty scary to be in one of those during a power failure. So put hybrid batteries on the linear motor so it can just keep on running during a power fail, perhaps programmed to do nothing but a normal controlled descent to the bottom doors. if ($powerfail == 'Y') { ignore_all_floor_selection_buttons_higher_than_this_floor; }
I remember hearing that elevators took up a quarter of the floor space of the old World Trade Center - only because they used express and local elevators, it would have otherwise been half the floor space. So it would seem a "vertical train" system could be quite valuable for saving real estate.
Obviously this would require a completely different mechanism as you can no longer have cables attaching each car to the roof. In fact I have no clue how it could work! This is what I keep pondering...