Figure 14-5.-A control point sheet.
shown in figure 14-5. Traverse and base line sheets give
the locations of traverse or base line stations, the latitude
and departure of each course or baseline, and the
coordinate location of each traverse or base line station.
For a traverse sheet or base line sheet, the computational
sheet used to compute latitudes, departures, and
coordinates usually provides a satisfactory abstract.
Procedures for Checking Field Notes
You are already familiar with field and office work
and therefore realize the ever-present possibility of
errors in surveying. As supervisor, you should be aware
that a large part of your job is checking to ensure that
errors are detected. In the field, as mentioned before,
you must keep the measurement situation in hand by
ensuring that the measuring methods used are those that
reduce the possibility of error to a minimum. For
example, when tape corrections are called for, you must
ensure that correct tension is applied, that temperatures
are taken, and that temperature corrections are applied
accurately.
You are also responsible for error-free com-
putations. Obviously, you cannot check all
computations by performing all the calculations
involved; this would be the equivalent of doing all the
computing yourself. You can, however, require
computing procedures that will, if they are followed,
reveal the existence of errors. For example, you can
require that areas be obtained both by double meridian
distance and by double parallel distance. There are, of
course, numerous other computations in which the use
of two methods will give results that can be checked
against each other.
Finally, you must develop skill in the weighing of
results for the probability of error. This is a skill that
cannot be taught; it comes with experience. For
example, after you have had a good deal of experience
with contour mapping, you develop the ability to get the
“feel” of the ground when you study contour lines. This
often helps you spot a misdrawn contour line
arrangement because the
with real-life probability.
Survey Crew Training
arrangement is inconsistent
The techniques of the actual operation of surveying
instruments are, for the most part, fairly easy to learn;
and a crew member learns these quickly in the field.
These techniques, however, are a small part of the
knowledge involved in the art and/or science of
surveying. If a field crew member is shown only how to
set up and level an instrument, how to hold a rod, and
the like, he is receiving only a minimal amount of
training.
14-10
