Recieved "Totally Tubular" achivement without even having built a Transit Tube

Same for me: Loaded a 16 cycle old save and got the achievment. It happened directly after the load, so I suspect it has something to do with that.

Try loading the added save file.

Panopticon.sav

Same, a little later than cycle 16. But tubes not even researched.

Not even 10 days into my current save and the achievement was awarded to me, too.

I feel like this achievement is incorrectly going by the actual distance traveled by the Dupes regardless of how they do it at the moment.

Changed Status to Dupe