Skip to main content

Balancing traverse, methods, independent coordinates

Short answer

Balancing distributes closing errors so that latitude and departure sums equal zero. Methods: Bowditch (correction proportional to length, assumes equal precision), Transit (proportional to lat/dep, precise angles), Graphical, Axis, Least squares. Independent coordinates reference all stations to one origin, preventing accumulation of plotting errors and allowing direct distance, bearing, and area computations.

What do you mean by the term "balancing the traverse"? Explain the types of balancing method you know with proper logic behind their uses. Why there is need of using independent coordinates instead of consecutive coordinates?

Meaning of balancing the traverse

Because of errors in angles and lengths, a closed traverse does not close exactly: ΣLat≠0\Sigma\text{Lat}\ne0 and ΣDep≠0\Sigma\text{Dep}\ne0. Balancing (adjusting) the traverse means distributing these closing errors over the lines (and angles) by a rational rule, so that the corrected latitudes and departures sum to zero and the traverse closes mathematically.

Methods of balancing, with the logic

MethodLogic of use
Bowditch (compass) ruleAngles and lengths of equal precision; linear error assumed proportional to l\sqrt{l} and angular error to 1/l1/\sqrt{l}, which makes the correction proportional to the length ll. Most common.
Transit ruleAngles are measured more precisely than lengths (transit or precise theodolite); the correction is proportional to the latitude (departure) of each line.
Graphical methodA graphical form of Bowditch's rule, applied on the plot itself; no calculation, so it suits compass and plane-table traverses and rough work.
Axis methodAngles are accurate and the error lies mainly in the lengths; only the lengths are corrected, using the closing-error line as the axis.
Least squaresRigorous method for important control networks; it weights all the observations.

Before using any of these, the angular misclosure is distributed equally among the angles.

Why independent coordinates are used

  • All stations are referred to one origin, so each station's position is independent of the others and plotting errors do not accumulate (consecutive coordinates are measured from the previous station).
  • An error at one station affects only that station, so it is easy to detect.
  • Lengths, bearings, areas and offsets between any two stations can be obtained directly from the coordinates.
  • They can be tied to the national grid or to other surveys, and used for setting out.

✓ Answer checked by Claude Opus 5.5 (high effort)

All Surveying II chapter 1 questions →