Jefferies tubes, that lead around decks to various parts of the ship, these ones are located in main engineering at the lower part of the warp core. these will run thoughout the ship, making good alternate routes for players to get from point A-B especially of doing a team gamemode, each deck corridor will have an access hatch, and major rooms such as sickbay, bridge, mess hall, shuttle bay, etc will have them, at least in 2 hatches per room on opposing sides Ingame shots of engineering, I know its bland atm and baren.