Recursive Escalator Sign

The sign is comical in itself: stick figure hits his head on overhanging sign. Beware!

 

But this is a SIGN ABOUT THE SIGN. The logic behind its existence escapes me: without the sign there, there would be no need to warn about it.

 

W

T

F?!?

 

(Pic taken while going down the escalator opposite. Original story here.)

Done