survey, for example, is a route survey required in the
design and construction of a particular road or highway.
The initial activities included in a route survey are as
follows: reconnaissance survey, preliminary-location
survey, and final-location survey.
On the other hand, a long established Navy base
might already have well-marked horizontal and vertical
control networks and up-to-date topographic maps
available. Then perhaps neither a reconnaissance nor a
preliminary survey would be required. The road could
probably be designed by using the existing design data,
and the fieldwork would begin with making the final
location survey. In summary, the extent to which data
is already available is an important factor in
determining what field operations have to be
RECONNAISSANCE SURVEY. A recon-
naissance survey provides data that enables design
engineers to study the advantages and disadvantages of
a variety of routes and then to determine which routes
are feasible. You begin by finding all existing maps that
show the area to be reconnoitered. In reconnaissance,
studying existing maps is as important as the actual
Studying these maps and aerial
photographs, if any exist, will often eliminate an
unfavorable route from further consideration, thus
saving your reconnaissance field party much time and
Contour maps give essential information about the
relief of an area. Aerial photographs provide a quick
means for preparing valuable sketches and overlays for
your field party. Direct aerial observation gives you an
overview of an area that speeds up later ground
reconnaissance if the region has already been mapped.
Begin the study of a map by marking the limits of
the area to be reconnoitered and the specified terminals
to be connected by the highway. Note whether or not
there are any existing routes. Note ridgelines, water
courses, mountain gaps, and similar control features.
Look for terrain that will permit moderate grades
without too much excavating. Use simplicity in
alignment and have a good balance of cuts and fills; or
use a profile arrangement that makes it possible to fill
depressions with the cut taken from nearby high places.
Mark the routes that seem to fit the needs and that
should be reconnoitered in the field. From the map
study, determine grades, estimate the amount of
clearing required, and locate routes that will keep
excavation to a minimum by taking advantage of terrain
conditions. Mark stream crossings and marshy areas as
possible locations for fords, bridges, or culverts.
Have the reconnaissance field party follow the
route or routes marked earlier during the map study.
Field reconnaissance provides you with an opportunity
for checking the actual conditions on the ground and for
noting any discrepancies in the maps or aerial
Make notes of soil conditions,
availability of construction materials, such as sand or
gravel, unusual grade or alignment problems, and
requirements for clearing and grubbing. Take
photographs or make sketches of reference points,
control points, structure sites, terrain obstacles,
landslides, washouts, or any other unusual
Your reconnaissance survey party will usually carry
lightweight instruments that are not precise. Determine
by compass the direction and angles. Determine the
approximate elevations by an aneroid barometer or
altimeter. Use an Abney hand level (clinometer) to
estimate elevations and to project level lines. Other
useful items to carry are pocket tapes, binoculars,
pedometer and pace tallies, cameras, watches, maps,
and field notebooks.
Keep design considerations in mind while running
a reconnaissance survey. Remember that future
operations may require further expansion of the route
system presently being designed. Locate portions of
the new route, whenever possible, along roads or trails
that already exist.
Locate them on stable, easily
drained, high-bearing-strength soils. Avoid swamps,
marshes, low-bearing-strength soils, sharp curves, and
routes requiring large amounts of earthmoving.
Keep the need for bridges and drainage structures
to a minimum. When the tactical situation permits,
locate roads in forward combat zones where they can
be concealed and protected from enemy fire.
The report you turn in for the reconnaissance field
party must be as complete as possible; it provides the
major data that makes the selection of the most feasible
route or routes possible.
PRELIMINARY SURVEY. A preliminary
survey is a more detailed study of one or more routes
tentatively selected on the basis of a reconnaissance
survey report. It consists essentially of surveying and
mapping a strip of land along the center line of
tentatively selected route.
Some of the activities associated with
preliminary survey are as follows: running