Transcript:

This staircase, the metallic staircase that you are seeing is actually a double helix. There's one flight of stairs that go up and another flight of stairs that come down.

Here's the flight of stairs that come down all the way from the top. So we walk down, and we walk down, and we take the turn, we walk down the helix coils and here is the set of stairs that goes up. We're walking down, walking down, here's the stairs that go up and notice as we turn the corner walking down; this is the staircase that goes up. This is the final exit. We walk down, and this end of the ramp is firmly attached to this staircase.

The other end of the ramp, though, we'll just see it in a moment; yeah, here, the other end of this ramp is on wheels. Notice the tracks. This end is on wheels, and there's a reason for it. The reason it's on wheels is because this ship can move to the left or right depending on whether the tide is coming in or going out; and if the end that is on the dock is not on wheels, the extreme stresses would simply break the coupling.

This is practical engineering.