Given my first official volunteer signmaking task of carving some colorcore signs for the local conservation folks, I consulted with one of my font experts (a benefit of working at a newspaper) after carving a prototype.
This led to some research online and I ran across this interesting resource which lists fonts used for public signage around the globe:
List of public signage typefaces
The US Park Service also has written a lot on the topic including this document (not the official version but it points to the official pages):
Park Service Typography Overview Article