Traverse and traverse computation process

A traverse is a series of connected survey lines whose lengths and directions (angles or bearings) are measured in the field. The ends of the lines are traverse stations.

Computation process

1. Adjust the angles: for a closed traverse the sum of interior angles must be $(2n-4)\times90^\circ$; distribute the error equally if it is small.
2. Find bearings of all lines from the known bearing of one line and the adjusted angles.
3. Latitudes and departures: $L\cos\theta$ and $L\sin\theta$ for each line.
4. Closing error: $e=\sqrt{(\Sigma\text{Lat})^2+(\Sigma\text{Dep})^2}$ and relative error $e/\Sigma L=1/N$; compare it with the allowable value.
5. Balance the traverse by Bowditch's rule (or transit rule) to get corrected latitudes and departures.
6. Independent coordinates: add the corrected latitudes and departures successively to the coordinates of the starting station.
7. Final lengths and bearings from the corrected quantities, then plot by coordinates.

All the steps are arranged in a Gale's traverse table.

Layout of Gale's traverse table

One row per station and line, so that angles, bearings, latitudes, departures, corrections and coordinates are tabulated in one place, with the sums checked at the foot of each column.