Your humble blog poster has commuted to/from town including this intersection since the very beginning of this Century. Literally thousands of trips. He’s never noticed this sign (signage) before, so it’s either new or he’s been too busy paying attention to traffic (i.e., staying alive) to notice before.
Regardless, this “Bosque Tr” (WITH ARROW!!!) sign has got to be one of, perhaps, one such sign in the entire area. Have these been popping up elsewhere? If so, send us a photo. Spotting sign/signage this rare needs to be shared in the same way that new birds are added to sighting websites.