In third-order, class I geodetic control, the maximum triangle closure should not exceed how many arcseconds?

In third-order, class I geodetic control, the maximum triangle closure should not exceed how many arcseconds?

• A. 3 arcseconds
• B. 5 arcseconds
• C. 10 arcseconds
• D. 1 arcsecond

Answer: (B)

Triangle closure is about how well the measured angles in a triangle agree with a perfect closed figure. In third-order, class I geodetic control, the standard tolerance for this angle misclosure is five arcseconds. This limit represents a practical balance: it's tight enough to ensure high internal consistency of the network, yet achievable with typical surveying instruments and procedures of that order. If the triangle closure exceeds five arcseconds, it signals inconsistent observations or biases that should be corrected or re-observed before final adjustments, so the resulting coordinates meet the desired accuracy. Tolerances much smaller, like one or three arcseconds, would be overly stringent for this level, while a larger tolerance such as ten arcseconds would allow too much inconsistency and degrade the network’s quality.

Triangle closure is about how well the measured angles in a triangle agree with a perfect closed figure. In third-order, class I geodetic control, the standard tolerance for this angle misclosure is five arcseconds. This limit represents a practical balance: it's tight enough to ensure high internal consistency of the network, yet achievable with typical surveying instruments and procedures of that order. If the triangle closure exceeds five arcseconds, it signals inconsistent observations or biases that should be corrected or re-observed before final adjustments, so the resulting coordinates meet the desired accuracy. Tolerances much smaller, like one or three arcseconds, would be overly stringent for this level, while a larger tolerance such as ten arcseconds would allow too much inconsistency and degrade the network’s quality.