E. Traverse Adjustment

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:

Equations D-5 and D-6
  Figure E-1
Loop Traverse Misclosure

On an adjusted (balanced) traverse:


Equations D-3 and D-4
  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


Most simple surveying projects use total stations which measure distances and angles with comparable quality. The Compass Rule is an appropriate adjustment method for these traverses. Although least squares would provide a "better" adjustment solution, it is generally overkill for a basic traverse. For more information on traverse adjustment by least squares see XVIII. Least Squares Lite.

We will concnetrate on the Compass Rule.