Hey man just a quick few crits, you should try to run multiple 48 or 64 unit brushes down the center of the hallway floor to break up the repetative sections. (imo) Play around with textures similar to a dark brown metal diomand plate for example, try metal/metalfloor001a or metal/metalfloor005a for the center of the floor. Also, for the cieling try a 32 unit brush with a different texture(s) such as facility/ceiling04.
Also, try to add ventalation. Maybe some "decals/decalmetalgrate001a" decals placed every 128 or 196 (try the 196 so it is does not appear to be too repetative). And dont be afraid to knock out some lights in one or two sections.
I like how you tryed to use different colores and hues for the lighting, but I would try to make them a little stronger each way, such as deeper blues and oranges. For some easy detail, in the areas that you knock out some lights, add one or two env_sparks (small sparks and short falling distances). Adding some wires (thin ".5") would also add easy detail.
Try those out, I would like to see what ideas you can add too.
