1. Adjusting a Traverse
Adjusting a traverse (also known as balancing a traverse) is used to distributed the closure error back into the angle and distance measurements.
Summing the latitudes and departures for the raw field traverse:
Loop Traverse Misclosure
On an adjusted (balanced) traverse:
Adjusted (Balanced) Loop Traverse
The condition for an adjusted traverse is that the adjusted Lats and Deps sum to 0.00. As with other survey adjustments, the method used to balance a traverse should reflect the expected error behavior and be repeatable. Table E-1 lists primary adjustment methods with their respective advantages and disadvantages.
|Ignore||Don't adjust anything.||Simple; repeatable||Ignores error|
|Arbitrary||Place error in one or more measurements||Simple||Not repeatable; ignores error behavior|
|Compass Rule||Assumes angles and distances are measured with equal accuracy so error is applied to each.||Simple; repeatable; compatible with contemporary measurement methods.||Treats random errors systematically|
|Transit Rule||Assumes angles are measured more accurately than distances; distances receive greater adjustment.||Simple; repeatable; compatible with older transit-tape surveys.||Treats random errors systematically; not compatible with contemporary measurement methods.|
|Crandall Method||Quasi-statistical approach. Angles are held and errors are statistically distributed into the distances.||Allows some random error modeling; repeatable.||Models only distance errors, not angle errors.|
|Least squares||Full statistical approach.||Allows full random error modeling; repeatable; can mix different accuracy and precision measurements; provides measurement uncertainties.||Most complicated method|
The Compass Rule works sufficiently well for simple surveying projects and is the one we will apply.
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