A technology that links cities across the globe, the Vactrax network seems to be based on the 'vacuum railway' theory developed by Isambard Kingdom Brunel in the nineteenth century. It was to use air pressure or vacuum to drive trains at high speeds with little friction and therefore with great efficiency.
Travel by Vactrax appears to be fast and inexpensive, though it is probably funded by corporations in Stark. It seems to be representative of post-Collapse transport, unreliant on anti-gravity technology.
In response to concept art of a Vactrax station that did not appear in-game, Ragnar made the following response:
"The Vactrax stations were actually removed from the game. Why? They didn’t serve much purpose other than to throw off the pacing. We cut a number of other locations as well, but we haven’t thrown anything away. I strongly believe in reuse."
This may indicate its future reappearance in a Stark section of Dreamfall Chapters.