I rewatched that scene and yeah.... so Scotland road was a very long very industrial hallway without a lot of "landmarks" if you will. None of the doors were marked, and the only signage just shows "eck" likely marking "D Deck" meaning that hallways lead to some stairs. There were a few different sets of stairs like that. That being said, the furthest set back was infront of boiler casing 3 which had a wall further back in the hallways which you don't see. Later in the scene you see Jack yelling at a man on the other side of a gate in a hallway that runs the width of the ship with stairs in it. That would of been infront of boiler casing 2. But... there was not a set of double stairs like is seen in the movie.

tl;dr I highly doubt James Cameron made the hallways scene blueprint accurate and likely just made a long section of hallways that looked like scotland road as a set piece.