I just watched the 10-minute video posted in this thread, and learned something new. His final process step was to spray a light mist of gray paint over the entire sign, to mimic the patina of the other ones sharing the gantry.

To me, that's when this went from guerilla engineering to art. Or better yet, both.

> Is artist the right term here? Seems more like guerrilla engineer or guerilla highway management person.

The name "Harry Tuttle" comes to mind. [0]

[0] https://www.youtube.com/watch?v=dht_3NziwSw