Azimuth closure at an azimuth check point for a second-order, class I geodetic network is given by which formula?

• A. 1.7√N
• B. 3.0√N
• C. 4.5√N
• D. 10.0√N

Answer: (B)

Azimuth closure tests quantify how closely measured azimuths around a check point conform to the computed values, and the acceptable misclosure grows with the number of azimuth observations due to random errors. For a second-order, class I geodetic network, the standard tolerance for azimuth closure at an azimuth check point is proportional to the square root of the number of azimuths, with a constant of 3.0. Therefore the allowable azimuth closure is 3.0√N, typically expressed in seconds of arc. This reflects that angular errors accumulate roughly with √N and that the 3.0 factor corresponds to this network’s accuracy class.