Installing swings in public spaces like on Billy Goat Hill is a time-honored San Francisco pastime. Ironically, the emblem for the SF Rec and Parks Department is a child on just such a tree swing, though that agency appears bent on removing exactly these unsanctioned park improvements. In that spirit — adding wonderment to unexpected places, public agencies be damned — artist Hunter Franks has put a swing in the aisle of BART cars, reprising a similar and well documented scene from 2009. Curbed took note of the underground playground, which Franks posted to Instagram.

Franks writes on his website that he recently declared himself BART's "Artist-In-Residence," an unofficial, self-appointed position that's relatively humble in comparison to, I don't know, declaring oneself an emperor. Anyway, congratulations on the job to Franks, who also installed hopscotch lines in front of ticket machines and a "missed connections" board.

"I threw on a yellow construction vest to look more official and carried out a week of unsanctioned creative interventions to insert joy, spontaneity, and connection into the drab world of the BART system," Franks explains.

It remains to be seen if BART will actually try to punish him for this.

"Swings are childhood, freedom, air, fun," Franks writes, "So there can't be any better place for a swing than a subway train where hordes of adults commute to and from work stuck in a small screeching steel box. I made a simple swing with some rope, a drill, and wood and hung it on the BART train. People were thrilled and the number of smiles on the train increased 100%. One rider remarked that BART should turn all the seats into swings." Add that to the list of BART demands.

This is all, the "Artist-in-Residence" explains, a gentle reminder that we're lucky to be here — even if "here" is on BART.

Related: Local Artist Puts A Bunch Of Bart Simpsons On BART Because Why Not