Message posted by Joerg (Webmaster) on April 07, 2017 at 17:31:45 PST:
I finally remembered to look for these mystery signs. Turns out they are posted along Hwy 93 and along Hwy 375 between Hiko Jct and Mailbox Road, only in the northbound direction. They are posted on the left (!) side of the road and reflect changes in the highway center divider pattern (no passing zones). I could not find any info on them online, but it appears to be some sort of trial. Not very effective as far as I am concerned. I never paid much attention to them before the OP mentioned them here.
In Reply to: Odd road signs around Area 51? posted by Bob in Gilroy on March 20, 2017 at 20:25:52 PST: