The process of making only those measurements that are consistent with the accuracy
level that is required.
c. Accuracy Levels. Measurements must not be accepted as correct without verification.
Verification, as much as possible, must be different from the original measurement method used. The
precision of measurement must be consistent with the accuracy level that is required for the surveying
type being conducted. The higher the accuracy level, the more time that is required to make the
measurement, since greater care and more observations must be taken.
The purpose and type of a survey are the primary factors in determining the accuracy level that is
required. This, in turn, will influence the selection of instruments and procedures. First-order
triangulation, which becomes the basis or "control" of future surveys, requires a high level of accuracy.
At the other extreme, cuts and fills for a highway survey require a much lower accuracy level. In some
construction surveys, inaccessible distances must be computed. The distance is computed by means of
trigonometry, using the angles and the one distance that can be measured. The measurements must be
made to a high degree of precision to maintain accuracy in the computed distance.
d. Maintenance. Fieldwork also includes adjusting instruments and caring for field equipment.
Do not attempt to adjust any instrument unless you understand the workings or functions of its parts.
Adjusting instruments in the early stage of your career requires close supervision from an experienced
e. Factors Affecting Fieldwork. The surveyor must constantly be alert to the different
conditions encountered in the field. Physical factors, such as terrain and weather conditions, will affect
each field survey in varying degrees. The following are some of these conditions:
Measurements using telescopes can be stopped by fog or mist.
Swamps and floodplains under high water can impede taping surveys.
Sighting over open water or fields of flat, unbroken terrain creates ambiguities in
Bright sunlight reduces light-wave measurements.
However, reconnaissance will generally predetermine these conditions and alert the surveying party to
the best method to use and the rate of progress to be expected.
f. Training. The training status of personnel is another factor that affects fieldwork.
Experience in handling the instruments being used for a survey can shorten surveying time without
introducing errors that would require resurvey.
1-8. Measurements. Fieldwork in surveying consists mainly of taking and recording measurements.
The operations are as follows:
Measuring distances and angles for the purpose of-