Fiberglass signs are used in dozens of demanding applications. The photos below show typical applications:
 

		Signs for zoos and water parks.
		Signs for ski areas. Here they must take abuse from skiers and successive freeze/thaw cycles.
		Subway and bus signs. Graffiti can be cleaned from the sign.
		Here the dam sign is subjected to constant water immersion.
		Gas pipeline signs (fiberglass must pass the rifle/shotgun test).
		Substation signs.
		The relative lightweight of fiberglass has an enormous advantage when installing a large sign such as this one. You shouldn't need a crane to install a cable crossing sign!

Also see...
    Should I use an Aluminum Sign?