covered If controlled photographs are available, the
survey engineer can locate points by pricking or keying
them to the photographs. An uncontrolled photograph
may be satisfactory for the surveys of low-order
accuracy mentioned in the preceding paragraph.
According to the soils analyst’s instructions, the survey
party chief prepares maps or overlays upon which he
plots the control and ties them to the pedological
features. The pedological interpretation of aerial
photographs is the responsibility of the terrain analysts.
Plane Table Traverse
The plane table traverse is best adapted to relatively
open country for the preparation of the basic sketch upon
which the soils engineer plots pertinent data. In the
absence of detailed instructions from the soils engineer,
the following procedures are generally satisfactory for
preparing a sketch of an area of several square miles (3
miles by 3 miles maximum for initial exploration):
1. SCALE: 1:12,500 or 1:25,000.
2. TRAVERSE CONTROL. Run in circuits or
between known positions of a higher order of accuracy.
3. SIGHTING. Use a peep sight or telescopic
alidade.
4. DISTANCE MEASUREMENTS. Pace or
obtain a rough measurement with tape. When a
telescopic alidade is available, use stadia measurements
where possible (to reduce the time required for the
survey, rather than to increase the accuracy).
5. BASE DIRECTION. To determine a base
direction, select known bases: railroad or highway
tangents, recognizable features, or reliable topographic
maps. In the absence of these known bases, use
magnetic north as determined by compass observations.
6. COMPASS. Use military compass, forestry
compass, or pocket transit.
7. DISTANCE BETWEEN BASIC CONTROL
POINTS. Maintain 3 miles as the extreme maximum
distance between stations.
8. ACCURACY. Distances should be measured in
such a manner that points can be plotted within 25 feet.
For the scales suggested, measurements to 1 part in 100
will suffice. Take sights with peep-sight alidade
carefully to maintain directions of an accuracy
comparable to distances.
9. TOPOGRAPHY. Topography is usually not
required on reconnaissance surveys for pedology,
particularly in areas of low relief. Where suitable
deposits of sand, gravel, or stone have been located
route surveys from the site to the point of use may be
required for the location of haulage roads, conveyors, or
other means of transporting the material. In hilly terrain,
a rough topographic map, obtained by clinometer,
pocket transit, or stadia, may be required to make the
location of a favorable route easier.
Compass Traverse
In heavily wooded areas, compass traversing is
more convenient than plane table traversing; however,
more time is required for plotting by the compass
traverse method. Traverse lines between stations should
be long to reduce the number of observed bearings.
Points between stations are located by offsets from the
traverse lines. Where local attraction affects compass
readings, points are plotted by intersection. Survey
readings may be plotted in the field. Notes should be
kept in case the traverse must be retraced. In the absence
of detailed instructions from the soils engineer, the basic
guides for plane table traverse apply.
Field Sheets and Site Plans
The survey engineer must furnish the soils analyst
with suitable maps, overlays, and sketches for the
plotting of pedological data. After the preparation of a
reconnaissance field sheet of an area of several square
miles, the soils analyst may require a sketch of a
particular site in which many samples are taken for a
more detailed study. In the absence of detailed
instructions, the surveyor prepares a sketch on a scale
of 1 inch = 400 feet and provides ranges and reference
points to aid in plotting or tieing in specific positions of
auger holes, drill holes, and lines of exposed rock or
other pedological features. For plotting the data of a
range, cross section, or series of boreholes, the soils
analyst may require the surveyor to provide a basic plot
on a scale of 1 inch = 100 feet or of 1 inch = 200 feet.
Survey measurements will be conducted accordingly.
SOIL SURVEYS
The survey of soil conditions at the site of proposed
military construction provides information about the
nature, extent, and condition of soil layers; the position
of the water table; drainage characteristics; and sources
of possible construction materials. The survey of soil
conditions is vital to both the planning and execution of
military construction operations.
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