. Well, my justification for that catwalk was the 'intermix console' - note that it's directly tied into those very large pipes exiting the top of the chamber (and yes, they do connect to the top run of those big manifolds behind the 'cage'
; I figured it has to have that direct connection, for mechanical reasons - really, I just wanted a cool catwalk in there to take advantage of the height of the room, and it had to have some
sort of workstation to make it appear worthwhile. In terms of the TV show - not necessarily 'real' engineering - it's there to add an additional range of filming locations, whether on the catwalk itself, or to look down into the space, an angle we rarely ever saw. Plus, one can add additional crewmen to a scene, who can either be checking the console, walking the catwalk, using the crosswalk to move from the second level on one side to the second level on the other, or climbing the tri-ladder without interrupting a scene on the floor.
Basically, it was a response to BreweryPrise: catwalks = good; giant obvious beer vats = bad