Which term describes stations appearing in two survey sessions?

• A. Pivot Sites
• B. Control Stations
• C. Boundary Sites
• D. Pivot Stations

Answer: (D)

Stations that appear in two survey sessions are called pivot stations. The idea is that a point measured in both sessions acts as a bridge, tying the two sets of observations together. With these common points, you can determine how the second session relates to the first by solving a rigid-body transformation (translation and rotation, and sometimes scale). This anchors the two surveys to a shared reference frame, reducing misalignment and enabling a consistent combined network.

Other terms don’t convey this bridging role as clearly. Control stations are known reference points within a single survey network and aren’t inherently about linking two sessions. Boundary sites describe markers marking edges or limits, not the specific function of linking sessions. Pivot sites isn’t the standard term used in this context.