Landscaped metro stations

I've been researching house plants and humidity. It would seem that one needs the other, but also that the first does a rather nice job of regulating the second. This has gotten me thinking. Plants like humidity. Some metro stations in Montreal are so humid that they literally have stalactites extending from their ceilings. What's the clever, humidity regulating, life enriching solution to this problem? Obviously, the STM needs to turn metro stations into giant, beautiful terrariums. Plants would make the metro stations more comfortable for passengers. And they'd be significantly less drippy, too. The only major retrofit involved would be switching the florescent lights for something a little more grow light-y. Landscaped metro stations? Oh yes.