TOPOGRAPHIC SURVEYS
The purpose of a TOPOGRAPHIC SURVEY
is to gather survey data about the natural and
man-made features of the land, as well as its
elevations. From this information a three-
dimensional map may be prepared. You may
prepare the topographic map in the office after
collecting the field data or prepare it right away
in the field by plane table. The work usually
consists of the following:
1. Establishing horizontal and vertical control
that will serve as the framework of the survey
2. Determining enough horizontal location
and elevation (usually called side shots) of ground
points to provide enough data for plotting when
the map is prepared
3. Locating natural and man-made features
that may be required by the purpose of the survey
4. Computing distances, angles, and
elevations
5. Drawing the topographic map
Topographic surveys are commonly identified
with horizontal and/or vertical control of third-
and lower-order accuracies.
ROUTE SURVEYS
The term route survey refers to surveys
necessary for the location and construction of
lines of transportation or communication that
continue across country for some distance, such
as highways, railroads, open-conduit systems,
pipelines, and power lines. Generally, the pre-
liminary survey for this work takes the form of
a topographic survey. In the final stage, the work
may consist of the following:
1. Locating the center line, usually marked by
stakes at 100-ft intervals called stations
2. Determining elevations along and across
the center line for plotting profile and cross
sections
3. Plotting the profile and cross sections and
fixing the grades
4. Computing the volumes of earthwork and
preparing a mass diagram
5. Staking out the extremities for cuts and fills
6. Determining drainage areas to be used in
the design of ditches and culverts
7. Laying out structures, such as bridges and
culverts
8. Locating right-of-way boundaries, as well
as staking out fence lines, if necessary
SPECIAL SURVEYS
As mentioned earlier in this chapter,
SPECIAL SURVEYS are conducted for a specific
purpose and with a special type of surveying
equipment and methods. A brief discussion of
some of the special surveys familiar to you
follows.
Land Surveys
LAND SURVEYS (sometimes called cadastral
or property surveys) are conducted to establish
the exact location, boundaries, or subdivision of
a tract of land in any specified area. This type of
survey requires professional registration in all
states. Presently, land surveys generally consist
of the following chores:
1. Establishing markers or monuments to
define and thereby preserve the boundaries of land
belonging to a private concern, a corporation, or
the government.
2. Relocating markers or monuments legally
established by original surveys. This requires
examining previous survey records and retracing
what was done. When some markers or monu-
ments are missing, they are reestablished following
recognized procedures, using whatever informa-
tion is available.
3. Rerunning old land survey lines to deter-
mine their lengths and directions. As a result of
the high cost of land, old lines are remeasured to
get more precise measurements.
4. Subdividing landed estates into parcels of
predetermined sizes and shapes.
5. Calculating areas, distances, and directions
and preparing the land map to portray the survey
data so that it can be used as a permanent record.
6. Writing a technical description for deeds.
Control Surveys
CONTROL SURVEYS provide “basic con-
trol” or horizontal and vertical positions of points
to which supplementary surveys are adjusted.
These types of surveys (sometimes termed geodetic
surveys) are conducted to provide geographic
positions and plane coordinates of triangulation
and traverse stations and the elevations of bench
marks. These control points are further used as
references for hydrographic surveys of the coastal
waters; for topographic control; and for the
control of many state, city, and private surveys.
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