My latest megaproject involves clearing levels out around my fortress, which I'm doing by the ol' collapsing support method.
The last section I went to collapse didn't... and when I checked I realised it was at the bottom of a stairwell and was basically hanging off the up-stairs. So I re-built the support and then removed that section of stairs. (Then realised it'd be a bad idea to collapse it anyway, 'cos I had bedrooms on the floor underneath. D'Oh!)
The odd thing is that I decided to rebuild those bottom stairs to give my dorfs access to channel it out, removing it that way instead, but when I went back to designate them there were half-a-dozen confused dorfs milling around on the cleared level!
Odd! How'd they get there? I
think they came in to remove stones by dropping down through the down-stairs in the level above, but couldn't get out again because there were no matching up stairs.
I decided to remove the stairwell altogether, and build a new one off to one side of the area I wanted gone. So I removed all the rest of the up/down stairs, except for the down-stair at the highest level. Then I went back down to the lowest level to build a floor across a channel to get the dwarfs trapped there out and back to work...
...and I'll be buggered! Even more dwarfs are appearing there as I watch! I flick back up through the other z-levels... no stairs, no ramps, no dwarves in sight... Until at the very top, the only section of stairs I didn't remove... there's a queue of dwarfs all waiting for their turn.
In they go... and miraculously appear almost instantly some 8 z-levels down where the stairway
used to finish. No injuries, no complaints. So they haven't fallen all the way.
Glitch? Probably. There's no way out, so they wouldn't path there deliberately. [shrug]
But it's funny as hell to watch.
Wish I could build one that worked the other way... an express elevator in which a dwarf walks in at the bottom and appears at the top of my Goblin Liberation Tower.
"Beam me up, McScotty!"