Angles observed clockwise from a backsight on the “rearward” traverse station to
a foresight on the “forward” traverse station [see Figures 9.1(a) and (b)] are called
angles to the right. According to this definition, to avoid ambiguity in angle-to-theright
designations, the “sense” of the forward traverse direction must be established.
This is normally done by consecutive numbering or lettering of traverse
stations so that they increase in the forward direction. Depending on the direction
of the traversing, angles to the right may be interior or exterior angles in a polygon
traverse. If the direction of traversing is counterclockwise around the figure, then
clockwise interior angles will be observed. However, if the direction of traversing
is clockwise, then exterior angles will be observed. Data collectors generally follow
this convention when traversing.Thus, in Figure 9.1(b), for example, the direction
from A to B, B to C, C to D, etc., is forward. By averaging equal numbers of
direct and reversed readings, observed angles to the right can also be checked and
their accuracy improved. From the foregoing definitions of interior angles and
angles to the right, it is evident that in a polygon traverse the only difference
between the two types of observational procedures may be ordering of the backsight
and foresight stations since both procedures observe clockwise angles.