I really don't remember the chapter, its either right before On a rail, during Blast pit, or during forget freeman. Basically: a nuclear power facility suspended in the air several meters, and the main deck has a rotating tram that moves from the right spot of the main platform, to the center (halting to allow the player to access the ladder), the proceeding to finish at the left, then repeats the cycle in a U shape. I want to do something similar for my power generator room on my map, whereing the player can smack a panel (press button) and go to the other side of the room, or access the up and down one to gain access to main control panel (objective)