Oops again. I see what you did there: your Alderpoint Bridge IS the Cain Rock Bridge.
Oops, Cain Rock Bridge is SOUTH of Alderpoint, CA. Upstream, yes.
I believe info and photo here is for the downstream Eel River Bridge,not Cain Rock Bridge. Neat website! No Cain Rock Bridge info? You can see it on Google Earth by searching for Alderpoint, CA then panning a few miles north, upriver. Td