Pretty much one way. They are a cheat. Guests need a reason to use them and the choices are food, drink, fun, gift, bathroom, and energy. I forget offhand what they used on these but unless the guests need whatever they used they will not cross another bridge. This also is the same for the pontoon bridge and the tunnels by them. With any of these types of things there should always be an alternative way off the island or cliff or whatever. For flat areas I would suggest using these as an alternative. There should be a tutorial around for using these as they require a little bit of thinking and land raising.
If you use search in the downloads there are other bridges there as well.