I am attempting to model the London eye and I have made an edge where there should be two. Is there an easy way to split my edges into faces the whole way round the ring?
Select your object and delete everything but one "segment". Then use one of these ways to create a circular array of it.
Then editing just one segment will affect all others. It will also result in a lighter model, and future changes will be much easier.
To actually split the edge select it and then use Bevel in edit mode. It depends on the topology of your mesh but from what I can see, it looks like it should do what you intend.