This image shows the Lowest Largest U-Turn being installed, 22 October 2017.
The Lowest Largest U-Turn feeds into The First Track, and is fed by the Snake Plate U-Turn.
The Lowest Largest U-Turn is only used by the large marble, and is its last turn before arriving at the large marble resting point on the bottom of the track. The Lowest Largest U-Turn lies just above the first track, which had its first test on 9 October 2017 (skip forward to 50 seconds).
In the future, the lowest point of the Outer Spiral will be right above the Lowest Largest U-Turn.