Just a little suggestion I want to float. There doesn't seem to be any concensus on how the modules tie together or how we get to the hub. so How about this. It keeps in line with the original ship design by BD.
The rings are connected by fore and aft running sections that pass between the module ends. Each deck of the module has a door at each end in to this section, you can either cross straight ahead in the next module of the same ring, or walk down the corrider to another ring. At the end of each of these sections is an elevator that will take you to a different deck.
On the eft side of this diagram note that the elevator goes down one more level. This allows access (via airlock) to a tram that runs up and down the snorpler tube that ties the rings to the axis. ( This diagram only shows the one leading to the cargo bays. There are three sections that have also have trams to the engine area. )
The diagram show rings 1 & 4 in transparency to show to help illustrate the layout.
