Traverse Calculations
Traverses are used to transfer “control” from one point to another. This implies measurements to and from
several station setups. Four different types of traverse are recognised, namely:
Closed (Loop) – starts and finishes at the same point, which must be know. The orientation is taken
from a fixed (typed) bearing between first and last points on the traverse. The reading to this point is
initially taken.
Control - starts and finishes at fixed control points with opening and closing bearings.
Pipe – like the Control traverse but has no closing bearing. ie the last point on the traverse is not
occupied.
Open – like a Pipe traverse, but does not observe to a known point for closure. No adjustments for
misclosure can therefore be made, but BS and FS readings to and from the same points will be
meaned.
GPS Link – this is a separate option and is used to traverse between two known points, which are not
occupied. The traverse is simply rotated in the direction of the two points and scaled to fit.
In all cases “known” or fixed points must be identified. Both angles and distances are measured from these
“fixed” to “unknown” points. The purpose of traverse adjustment is to calculate coordinates of the unknown
points.
If you start at a known point and calculate the coordinates of points along the traverse using measured
angles and distances to another known point this will create a “closing error”. Another purpose of these
calculations is to distribute these misclosures, or small measuring errors, throughout the
traverse. Bowditch and Transit adjustment methods are supported. Corrections for Scale Factor, Curvature
& Refraction and Mean Sea Level can be applied.
In the example shown above, the traverse starts at STN22 and finishes at STN20. Angles and distances are
measured between each station. Since we know the coordinates of fixed points a back bearing and forward
bearing can be determined.
It doesn’t matter if you measure horizontal angles clockwise or anticlockwise, provided you are consistent.
Tools are available in the Traverse Wizard to switch BS and FS readings to make Horizontal angles wholly
clockwise or anticlockwise.