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:

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Eqn (E-1)
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  Figure E-1
Loop Traverse Misclosure

On an adjusted (balanced) traverse:

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Eqn (E-2)
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  Figure E-2
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.

Table E-1

Method Premise Advantage Disadvantage
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.