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Chapter 1
Introduction of Basic Surveying
What is Surveying?
Surveying has to do with the determination of the relative spatial location of
points on or near the surface of the earth. It is the art of measuring horizontal
and vertical distances between objects, of measuring angles between lines, of
determining the direction of lines, and of establishing points by predetermined
angular and linear measurements.
Along with the actual survey measurements are mathematical calculations.
Distances, angles, directions, locations, elevations, areas, and volumes are thus
determined from the data of the survey. Survey data is portrayed graphically by
the construction of maps, profiles, cross-sections, and diagrams.

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Types of surveys:
1. Geodetic Surveying:
- The type of surveying that takes into account the true shape of the
earth.
- These surveys are of high precision and extend over large areas.
2. Plane Surveying:
- The type of surveying in which the mean surface of the earth is
considered as a plane (in which its spheroidal shape is neglected) with
regard to horizontal distances and directions.
- Measurements are made as if the lines of force due to gravity were
everywhere parallel to each other, as if underneath the irregular
ground surface there existed a flat, horizontal reference plane.

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Operations in Surveying:
i. Control survey Made to establish the horizontal and vertical
positions of arbitrary points.
ii. Boundary survey Made to determine the length and direction of land
lines and to establish the position of these lines on
the ground.
iii. Topographic survey Made to gather data to produce a topographic map
showing the configuration of the terrain and the
location of natural and man-made objects.
How do we define scale?
Large scale: 1:100 - 1:5000
Medium scale: 1:5000 - 1:50000
Small scale: 1:50000 - 1:200000

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iv. Hydrographic survey The survey of bodies of water made for the purpose
of navigation, water supply, or subaqueous
construction
v. Mining survey Made to control, locate and map underground and
surface works related to mining operations.
vi. Construction survey Made to lay out, locate and monitor public and
private engineering works.
vii. Route survey Refers to those control, topographic, and
construction surveys necessary for the location and
construction of highways, railroads, canals,
transmission lines, and pipelines.
viii. Photogrammetric
survey
Made to utilize the principles of aerial photo-
grammetry, in which measurements made on
photographs are used to determine the positions of
photographed objects.
ix. Engineering Survey Embraces all the survey works required before,
during and after any engineering (construction)
work, such as:
• producing plans (large scale) or
numerical data for engineering
projects
• determining areas and volumes (e.g.
earthwork)
• providing permanent control points
for other surveying tasks
• setting out engineering constructions
• supervising the correctness of
construction
• recording final as-built position of
construction

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Reliability of a Survey
Every measuring technique is subject to unavoidable error.
A surveyor must know the accuracy of their measurements, and the fact whether
it fulfills the requirements.
How can we determine the accuracy requirements?
- From the map scale: a good draftsperson can plot a line within 0.25
mm on the map (in real units). In case of a map scale 1:1000 this
corresponds to 0.25m.
- From engineering tolerances: in engineering surveying the accuracy
requirements depend on the given tolerances of structures.
Types of errors
There are several types of error that can occur, with different characteristics.
(i) Mistakes
Such as miscounting the number of tape lengths when measuring long distances
or transposing numbers when booking.
Can occur during the whole surveying process, including observing, booking,
computing or plotting.
Solution:
Creating suitable procedures, and checking the measurements.

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(ii) Systematic errors
Systematic errors arise from sources that act in a similar manner on
observations.
Examples:
- Expansion of steel tapes due to temperature changes
- Frequency changes in electromagnetic distance measurements
These errors are dangerous, when we have to add observations, because they act
in the same direction. Hence the total effect is the sum of each error.
Solution:
Calibrating the instruments – comparing the observations with other
observations made by other instruments.
(iii) Random errors
All the discrepancies remaining once the mistakes and systematic errors have
been eliminated. Even when a quantity is measured many times with the same
technology and instrumentation, it is highly unlikely that the results would be
identical.
Although these errors are called random, they have the following characteristics:
- Small errors occur more frequently than large ones
- Positive and negative errors are equally likely
- Very large errors occur rarely
Due to this, the normal statistical distribution can be assumed.
Solution:
Repetitions of observations.
Eliminating or handling the errors
Suitable procedures must be followed:
• The survey area is always covered with the simplest possible framwork of
high quality measurements (control network). If we work within this
control network, the possible accumulation of errors is limited.
• Observing procedures are designed so that:
• most mistakes can be discovered immediately
• possible sources of systematic errors are eliminated
• Additional and redundant measurements should be taken.
Example: measuring three angles of a triangle.
• Repeat the measurements