Are there public toilets at the Nine Arch Bridge?
There aren’t any official public toilets directly on the Nine Arch Bridge. Still, visitors often use the toilets inside the little hillside cafes and guesthouses. Usually, there is a small fee, or it is enough to buy a drink, and then you are let in, with no big fuss.
Since the bridge is more about transit infrastructure than a managed tourist zone, public civic amenities basically don’t exist here. So plan ahead and take advantage of the facilities at your hotel, or use the nearby private places. That is the most practical path, for real.