z-levels are stable, and https://github.com/CleverRaven/Cataclysm-DDA/pull/41135 doesn’t work with z-levels disabled and I refuse to maintain two different versions of bridges, one that is awesome and one that is pathetic.
Now that ground vehicles can go up and down ramps, there is space for a lot of new features, like highway overpasses, hills, and possibly railroads.