In third order, class II geodetic control, the average triangle closure should not exceed how many arcseconds?

In third order, class II geodetic control, the average triangle closure should not exceed how many arcseconds?

• A. 3 arcseconds
• B. 4 arcseconds
• C. 5 arcseconds
• D. 6 arcseconds

Answer: (C)

In a third-order Class II geodetic control network, triangle closure is a key quality check. When you measure directions and distances and compute coordinates to form triangles, the path should close exactly back to where you started. In practice, there is a small residual, an angular misclosure, measured in arcseconds, that tells you how much error remains in the closed loop. The aim is to keep this misclosure small enough across the network to ensure reliable results after adjustment and to maintain consistency with the reference frame. The standard target for this order and class is to have the average triangle closure not exceed five arcseconds. This value reflects a balance: it’s tight enough to indicate a high-quality network with realistic measurement noise and refraction effects, yet achievable with proper field procedures and instrumentation. If the average closure rose above this threshold, it would signal systematic or random errors that could bias the network and would typically prompt reobservations or reweighting. Values well below five arcseconds are better but often harder to achieve consistently in routine practice.

In a third-order Class II geodetic control network, triangle closure is a key quality check. When you measure directions and distances and compute coordinates to form triangles, the path should close exactly back to where you started. In practice, there is a small residual, an angular misclosure, measured in arcseconds, that tells you how much error remains in the closed loop. The aim is to keep this misclosure small enough across the network to ensure reliable results after adjustment and to maintain consistency with the reference frame.

The standard target for this order and class is to have the average triangle closure not exceed five arcseconds. This value reflects a balance: it’s tight enough to indicate a high-quality network with realistic measurement noise and refraction effects, yet achievable with proper field procedures and instrumentation. If the average closure rose above this threshold, it would signal systematic or random errors that could bias the network and would typically prompt reobservations or reweighting. Values well below five arcseconds are better but often harder to achieve consistently in routine practice.