# Traverse calculations

In a conventional survey, if you have surveyed a series of points using traverse stations, then you can use the Traverse function to calculate closed‑loop traverses or open traverses that start and end on pairs of known points.

A valid traverse station has one or more backsight observations to the previous traverse station, and one or more observations to the next traverse station. To compute a traverse closure, there must be at least one distance measurement between successive points used in the traverse.

If the software calculates a misclosure then you can adjust it using either a Transit or Compass (also known as Bowditch) adjustment. The software calculates an angular adjustment and then a distance adjustment.

The Azimuth fields do not have to be completed for points used in the traverse. If the foresight azimuth is null in a loop traverse but all angles have been observed, you can compute an angular and distance adjustment. However, if the backsight azimuth is null, the traverse cannot be oriented, adjusted coordinates cannot be stored, and an angular adjustment cannot be computed on an open traverse (you must compute a distance adjustment).

To calculate the traverse closure

1. Tap and select Cogo / Adjust / Traverse.
2. Enter the Traverse name.
3. In the Start station field, tap List.

4. From the list of valid traverse points, select the point to use as the start station. Tap Enter.

   A valid start station has one or more backsights and one or more observations to the next traverse station.

5. Tap Add.

   When there is only one valid traverse station, it is added automatically.

6. If there is more than one valid traverse station, select the next station in the traverse.

   - To view the observed azimuth and distance between two points in the list, select the first point and tap Info.
   - To remove points from the list, select the point and tap Remove. All points after the selected point are also removed.

7. Continue to add points until all points in the traverse have been added.

   A valid end station has one or more backsights, and one or more observations to the previous traverse station.

   - You cannot add more points after selecting a control point.
   - You can use station setup plus type station setups within a traverse. However, the averaged orientation computed as part of the station setup is not used in the traverse computation and the resulting adjusted coordinates for the station means that the station orientation is changed.

   - You cannot include a resection station setup (including a standard resection, Helmert resection or Refline station setup) within a traverse, but it can be used as the start or end station in a traverse.

8. Tap Close to compute the traverse closure.

9. To store the closure results, tap Store.

To adjust the traverse

1. To select the adjustment method, tap Options. Select the Transit or Compass method (also known as Bowditch) then select the error distribution method for angles and elevations.
2. To adjust the angular misclosure, tap Adj. Ang.
3. To store the angular adjustment details, tap Store.
4. To adjust the distance misclosure, tap Adj. dist.
5. To store the distance adjustment details, tap Store.

When the adjusted traverse is stored, each point used in the traverse is stored as an adjusted traverse point with a search classification of adjusted. If there are any previously adjusted traverse points of the same name, they are deleted.

Traverse options

Use these options to specify how a traverse calculation is adjusted.

Field | Option | What it does
--- | --- | ---
Adjustment method | Compass | Adjusts the traverse by distributing the errors in proportion to the distance between traverse points
Transit | Adjusts the traverse by distributing the errors in proportion to the northing and easting ordinates of the traverse points
Error distribution
Angular | Proportional to distance | Distributes the angular error among the angles in the traverse based on the sum of the inverses of the distances between traverse points
Equal proportions | Distributes the angular error evenly among the angles in the traverse
None | Does not distribute the angular error
Elevation | Proportional to distance | Distributes the elevation error in proportion to the distance between traverse points
Equal proportions | Distributes the elevation error evenly among the traverse points
None | Does not distribute the elevation error

The Compass option is the same as the Bowditch method of adjustment.