Puckety Underpass

If someone can please explain this wording on an illuminated temporary highway sign we passed last night on our way back from Pittsburgh, please let me know. I'm assuming it's a Pennsylvania thing, but George is just as baffled as I am!

Just for the record, our family power chant, courtesy of life with Danny:

WE NEVER SLEEP!
WE NEVER STOP!
WE WON'T GIVE UP
UNTIL WE DROP!

DO SUMPIN' ELSE!
DO SUMPIN' ELSE!