In a classical triangulation, the procedure for first order and second order (class I) accuracy positioning requires how many directions?

• A. 8
• B. 16
• C. 4
• D. 2

Answer: (B)

Redundancy in angular observations and a well‑distributed network around each station are essential for accurate triangulation. For first order and second order (Class I) accuracy, the observations must over‑constrain the solution so that a least‑squares adjustment can separate random measurement errors from true positions and detect any blunders. In classical triangulation this is achieved by collecting a large set of directions from each station to multiple reference points spread around the station. Sixteen independent directions provide a strong, well‑balanced set of observations, giving good geometric strength for the adjustment and the required precision. Using fewer directions (like eight or four) would reduce redundancy, making the solution more sensitive to instrument biases and local errors and failing to meet Class I standards. Observing two directions is clearly insufficient to determine reliable positions.