Outdoor Advertising Cleaning 12-15

I have been asked by a billboard company to bid on washing billboards they have on the interstate. This is a national company with local offices. Is anybody doing this kind of work. If so, can you help with an idea of how to price it? They are asking for pricing on regular cleaning of existing signs as well as thorough cleaning as needed to remove adhesive.
Thanks for the help

Keith Reid
Central Texas Pressure Washing

Wow, Billboards, never thought about that before, but consider they charge
16.90 a day or $507 per 30 day's per customer and the amount of billboards
they need cleaned, and I have know idea, but it could be worked out maybe
by sq ft, plus the remote location's, height and simply pita, it should pay well
I hope some one with experience has imput because there must be a need!
Zinisser makes a prouduct that removes wallpaper paste and work easily with hot water. I wonder? Good Luck, Let us know how it works out.

I saw a company doing them on I-95 about two months ago. Based upon the equipment present I would guess there is good money in it. 60+ foot boom truck with articulating platform lift. One full rig with two 20 hp driven hot water units. Four man crew two in the air, two on the ground. Two lanes of traffic were blocked about 100 feet north and south of where they were working.