chapter 1 and 2 @etconp.pdf

Addis Ababa University Ethiopian Institute Of Architecture, Building
Construction And City Development
Compiled by Ebisa Tesfaye (Msc.) Page 1
Chapter One Introduction
1.1 Definition and uses of Surveying
Surveying: - is the art of making measurement of the location of points on or near the surface of
the earth.
The location of the points in the horizontal and vertical planes involves the relative distance and
height between adjacent points. When these measurements area drawn to scale the correct
horizontal and vertical relationships among the various manmade and natural feature are
obtained.
1.2 Important of surveying
Survey is required before planning and construction, during planning and construction, and after
planning and construction of any road, railway, bridge, water supply and drainage systems,
pipelines, high voltage lines, irrigation and transportation channels, dams, urban land
subdivisions etc.
Hence we can to conclude that practically no engineering activity can be planned, designed,
executed and maintained without the active participation of the surveyor.
1.3 Branches of surveying
There are various criteria on which classification of surveying could be based. The primary
division is
a. Based on how the curvature of the earth is considered
i. Geodetic surveying:- a branch of surveying which takes into account the shape and size
of the earth. The main objective of geodetic surveying is to determine the precise location
of a system of widely spaced points on the surface of the earth. The point’s so located
are used as control points (stations) of the primary surveys.
Geodetic surveying is used in all cases when the area of the land to be surveyed exceeds
250 km2
.
The Ethiopian mapping authority (EMA) makes uses of geodetic surveying to produce and
print the whole map of Ethiopia.
ii. Plane surveying:- the branch of surveying in which the main surface of the earth is
considered as plane in which the spheroid shape of the earth is neglected.
Plane surveying is
 Used for relatively small areas (less than or equal to 250km2
 The standard of accuracy is lower than in geodetic surveying
 The direction of the plumb line at various points are considered to be parallel to
one another
 A curved line on the surface of the earth is considered mathematically straight
b. Based on the purpose for which the survey is conducted.
A. Topographic Survey:- are used in order to produce maps and plans on which the natural
features like mountain, river etc and manmade features like cities, road etc are shown.
B. Control Survey: - as the name indicates a network of horizontal and vertical monuments on
a national basis is established by control surveys. The network of monuments serves as a
reference frame work for the other types of surveys.
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C. Photogrammetric survey:- as indicated by the name itself, this branch of surveying makes
use of data obtained by camera or other types of sensors mounted on airplanes or satellites.
D. Construction Survey:- also called engineering survey before any type of construction
is started, the surveyor acquires all the necessary data of the site which are daily processed.
E. Cadastral survey: - are invariably known as property surveys, land surveys or boundary
surveys. These surveys are undertaken by municipal authorities for producing plans of property
boundaries, establishing property corners and computation of areas of land parcels.
F. Route survey: - these surveys are for highways, rail road’s, pipelines, transmission lines and
other project of long linear development.
G. Hydro graphic surveying: - these are made to produce maps of shore lines and bottom
depth of lakes, streams, reservoir and other large bodies of water.
H. Cartographic surveying: - is a combination of topographic and hydrographical surveying.
The art of drawing maps and charts is called cartographic and its duty of the cartographer to
prepare chart or maps from data supplied by a hydrographical and/or topographical land
surveyor.
1.4 Accuracy, precision & Error
Accuracy: - the measure of nearness or closeness to the true value E.g. given a true length to be
50 .00m and measured values of 50+0.01, 50+0.03, the value 50+0.01 is more accurate.
Precision:- the measure of nearness to each other of the measured values; the degree of
refinement in measurement (units)
Error: the difference between the true value or most probable value & the measured value of the
same quantity.
An error is either systematic or random error.
A systematic error is an error which magnitude and algebraic sign can be theoretically
determined.
A random error is an error which magnitude and sign cannot be predicted. Random
errors tend to be small and tend to distribute themselves equally on both side of Zero.
Mistakes are blunders (also called gross error) made by survey personnel. Taking the
wrong count of paces or wrong number of tape measure, Transposing figure, say for example
taking 54 for 45 are example of mistakes, mistakes must be discovered &eliminated,
preferably by the people who made them.
1.5 Duties of a surveyor
The duties of a surveyor can be broadly divided in to four main parts. They are
a. Field work
b. Office work
c. Construction work and
d. Care and adjustment of instruments.

1. Field work
 Site investigation:- before the actual surveying work is started the surveyor must carry
out preliminary site investigation. The site investigation will enable to acquire on overall
view of the site and how best to arrange the work.
 Decision Making:- after the site has been investigated, the surveyor must select the
survey method to be adopted, the instrument and equipment to be used; and the
survey party to be deployed for the successful completion of the survey.
 Data Acquisition: - this step involves measurement of distance, angles and recording
them in the field. Usually the measurement operation is accompanied by rough sketches
drawn in the note books.
2. Office work
 Data processing: is computing the data acquired in the field for determining relative
position of points. Areas and volumes etc.
 Data representation: is called mapping, the processed data must be interpreted
graphically and can also be show in tabular form or computer format.
3. Construction
 Setting out:- consists in driving pegs or stakes in to the ground to mark out
boundaries or to guide construction activities.
 Construction supervision:- at times the surveyor is called upon to carry out construction
supervision to check whether the construction of the project has been effected according
to the design and specification.
4. Care and Adjustment of instruments
The surveyor must study carefully the manufactures catalogue which accompanies each
surveying instrument. The catalogue contains short instruction on how to handle, adjust & use
the instrument. The instruction must be rigorously followed and applied.
Field work Office work Construction work
Data
Acquisition
Site
investigation
Decision
making
Supervision
Setting out
Data
processing
Data
Representation

CHAPTER TWO
UNITS OF MEASUREMENT
All surveying measurement is based on the following five kinds of measurements.
A. Horizontal distance
B. Horizontal angle
C. Vertical distance
D. Vertical angle and
E. Slope distance
2.1 Units of length & Angles
1. The international unit of measurement for length is meter (m) and subdivided into the
following units.
A. Units of length-millimetre (mm), Centimetre (cm), decimetre (dm), Meter (m),
Kilometre (km)
10mm=1cm
10cm=1dm
10dm=1mt
1000mt=1km
1 Us inch=1 British inch=2.54cm
1Us foot=30.48cm
B. Units of area= square meter (m2
)
C. Units of Volumes=cubic meter (m3
)
2. Units of angles:- most surveying instrument measure the angular distance between points in
degrees (o
), minutes (‘) ,second (”) and some countries in grad(g) systems.
10
=60’ and 1g=100c
1’=60’’ 1c=100cc
900
=100g
In which c is centesimal minutes & cc is centesimal seconds.
e.g. 1. Work out the following question
410
54’27’’ 910
42’30’’
+ 560
36’45’’ - 220
52’42’’
2. Convert the following degree to grad system
400
22’45’’
2.2 Scale
It’s obvious that we cannot plot length on a piece of paper to their full length or size. But using a
ratio we can determine their length or sizes and this can be done using scales.
Scale is a ratio of distance on the drawing to the corresponding distance on the ground or object.
Scale may be expressed in the following three ways:-
1. By a statement: - such as 1cm to 100mts and so on (i.e. 1cm to 10mts meaning 1cm on the
paper represents 10mts on the ground.)

2. By representative fraction (R.F):- such as 1: R, the denominator being the number of units
represented by one scale unit. These 1:5000, 1:1000 or 1/5000, 1/1000 this is the most commonly
used in map surveying.
N.B in this method the unit of measurement is the same
3. By dividing a line: - usually 1and 2 are combined to express the scale for example 1cm to
10mts or 1:1000.
2.3 Linear (method of distance) measurements
Linear measurement can be obtained in three different ways
1. Direct method
2. Indirect Method
3. Electronic distance measurement method
1. Direct method
Direct measurement can be obtained by the following methods
 Applying a tape to a line for measuring its length directly.
 Applying a protractor to an angle or by turning on angle with surveying instrument.
 Counting the number of pacing between points and multiplying with the average
length of the pacing, approximately equal to the horizontal distance.
2. Indirect method
It is obtained when it’s not possible to apply the unit of measurement directly to the distance or
on angle to be measured. The quantity is therefore determined by its relation to some measured
quantities.
For instance, because of the river between two points A and B it’s difficult to measure by direct
measurement method. In this case we can apply indirect measurement either by observing the
vertical angles to a known vertical distance; then applying trigonometry.
3. Electronic distance measurement method.
The distance being found by timing electro-magnetic radiation transmitted from the instrument
station A to the reflector station B and back to the instrument. Comparing the transmitted and
received waves the instrument is able to compute and display the required distance.
2.4 Equipment used in taping
Equipment used for taping consists of a steel tape, Plumb bobs, one or more line rods (range
poles), a set of taping pins and a hand level. (Spring balance also used to measure tension force).
1. Line rods (ranging poles):- they are used for alignment of the measurement if the distance to
be measured is greater than the length of tape.
2. Taping pins: - used to mark the end position of the tape on the ground while the
measurement is in progress.
3. Hand level: - used to keep the two ends of the tape in the same horizontal plane.
4. Plumb bob: - used to project points from the tape down to the ground.

2.5 Errors in tape measures & their correction
There are various factors contributing to introduction of errors while carrying out tape measures.
A. Incorrect tape length (standardization):- a source of error and calibration is essential.
It must be checked with a standard tape.
Cs=L(La-Ln) /Ln,
Where Cs= correction for standardization
L=measured length.
Ln=nominal length of one full tape
La=actual length of one full tape.
B. Tape not horizontal (sloping land):- the distance measured along the slope between two
stations is always greater than the horizontal distance. The correction required is known
as slope correction. This is always negative since all surveying calculation, plans, and
setting out designs are based in the horizontal plane, any sloping distance measured must
be reduced to horizontal before sign in calculation. The inclination angle between the
horizontal line and the slope tape is measured using clinometers; then the slope correction
can be calculated.
Correction for slope=L-D
Cos θ=D/L
Cs=L-L Cosθ
=L (1-Cosθ)
Where Cs= correction for standardization
L= distance measured along the slope between two stations
θ= inclination angle b/n the horizontal line and the slope tape
C. Change in temperature:- the length of the tape increase while the temperature is
increased & decreased if temperature is lowered. The amount of correction for
temperature can be determined by the formula
Ct=Lα (T-Ts)
Where Ct= Correction to be applied
L=Measured length
α= Coefficient of thermal expansion
T= Temperature at which the measurement is made
Ts=temperature at which the tape was standardized
D. Incorrect tension (forces applied at the end of the tape): when the correct tension is not
applied to the tape incorrect lengths are obtained. The correction to the measured length
can be obtained from the equation.
Cp=(p-Ps) L/AE
Where Cp=correction per measurement
P=Tension applied
Ps=standard tension

L= measured length
A=X-sectional area
E=modulus of elasticity
E. Sag (downward bending of the tape):- the effect of sag must be considered for more
accurate work. The tape will sag under its own weight in the shape of a catenaries curve.
The correction for sag is given by the formula
Cs=-nw2
L3
/24P2
=W2
L3
cos2
.θ/24P2
Where Cs=correction for sag in m.
w=weight per unit length of the tape , kg/m or N/m.
n= number of unsupported length
L= unsupported length in m( length between supports)
P= tension applied in the field, kg or N.
Assignment 1
1. A steel tape is standardized at 200
c under a tension of 44.5 N when supported
throughout its entire length and distance between the zero mark and the 30m mark is
30.014 m the tape weight 0.17N/m and has a x-sectional area of 2mm2
.In the field this
tape is used under 120 N and is supported at the ends only and temperature of the tape is
recorded as 50
c. The tape is used to measure line AB and the measured length of the line
is 29.872m. The difference in elevation between A and B is 1.9m. If E=200KN/mm2
and
α =0.0000112/0
c, determine the corrected length of AB.
2. The standardized length of the tape was known to be 50.013m at 200
c and 20N
tension. The nominal length of the tape was 50m and the tape was used to measure a line
AB suspending it between supports. The tape weights 0.17N/m and has x-sectional area
of 2mm2. The following measurements were recorded.
Calculate the horizontal distance of line AB if young’s modulus (E) for a tape material is
200km/mm2
and the coefficient of thermal expansion (α) is 0.0000112/0
c.

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