Part - 1 (Introduction)

1. SURVEYING
INTRODUCTION
Presented by -
Md. Mohotasimur Rahman (Anik)
Jr. Structural Design Engineer
Associated Builders Corporation Ltd.

2. DEFINITION
 Surveying is the art of finding the relative positions of
different features above, on or beneath the surface of
the earth by taking measurements of distances,
directions and elevations, and finally representing
them as plans, maps and sections.
 A plan or map represents the horizontal projection or
an area surveyed. This representation is called a map
if the scale is small, while it is called a plan if the
scale is large.
 Vertical distances are correctly shown by drawing
vertical sections (or simply sections).
 Surveying is the first step for the execution of any
project and the success of any engineering project
depends upon the accurate and complete survey work.
 The application of surveying requires the knowledge
of mathematics, physics and. To some extent,
astronomy.

3. GENERAL PRINCIPLE
 The general principle of surveying is to
work from the whole to the part, not from
the part to the whole.
 In extensive surveys, the entire area to be
surveyed is first divided into large triangles
which are surveyed with the greatest
accuracy. The large triangles are then
subdivided into small triangles which are
surveyed with less accuracy.
 The object of this system of working is to prevent the accumulation of errors. If there is any error in the
measurement of any side of a triangle. it will not affect the whole work. The error can always be detected
and eliminated Out. if we work from the part to the whole, the minor errors in measurement arc magnified
in the process of expansion of survey and a stage comes when these errors become absolutely
uncontrollable

4. PRIMARY DIVISIONS OF SURVEYING
 The surveying may primarily be divided into two divisions:
 1. Plane surveying.
 2. Geodetic surveying.
Figure: Plane surveying. Figure: Geodetic surveying

5. PLANE SURVEYING
 Surveys in which the earth surface is assumed to be plane
and the curvature of the earth is ignored are known as plane
surveys. Surveys covering an area up to 260 𝑘𝑚2
may be
treated as plane surveys.
 In dealing with plane surveys, the knowledge of plane
geometry and trigonometry is required.
 It is to be noted that the difference in length between the arc
and, the subtended chord on the earth surface for A distance
of 18.2 km is only 0.1 m.
 Plane surveys are used for the layout of highways, railways,
canals, fixing boundary pillars, construction of bridges,
factories, etc.
 Scope and use of plane surveying:
 Majority of engineering projects, plane surveying is
the first step to execute them. For proper, economical
and accurate planning of all engineering projects,
plane surveys are basically needed and their practical
significance cannot be over-estimated. Figure: Chain

6.  Plane surveying may again be subdivided in the following ways:
 1. Chain Surveying: It is the simplest type of surveying in which the area to be surveyed is divided
into a number of triangles. The lengths of the sides are measured and the interior details are
recorded. The whole area is then plotted on a drawing sheet to a suitable scale to prepare a map.
 2. Traverse Surveying: (Compass and Theodolite Surveying): It is a type of surveying in which the
plot of land to be surveyed is enclosed by a series of straight lines making angles with one another.
The length of the lines and the angles are measured and plotted with all interior details on a
drawing sheet to a suitable scale to produce a map.
 3. Plane Table Surveying: It is a method of surveying in which observations and plotting are done
simultaneously.
 4. Ordinary Leveling: It is a type of surveying in which the relative elevations of different points
on the surface of the earth are determined.
PLANE SURVEYING

7. GEODATIC SURVEYING
 The surveys in which the curvature of the earth is taken into account and higher degree of accuracy in
linear and angular observations is achieved, are known as geodetic or trigonometric surveys.
 The geodetic surveys extend over large areas and lines connecting any two points on the surface of the
earth are treated as arcs.
 For calculating their projected distances on the plans or maps, the correction for the earth's curvature is
applied to the measured distances.
 A knowledge of spherical trigonometry is necessary for making measurements for the geodetic surveys.
 Scope and use of geodetic surveying:
 Geodetic surveys are conducted with highest degree of accuracy to provide widely spaced control
points on the earth surface for subsequent plane surveys. Provision of such control points is based on
the principle of surveying from the whole to the part and not from the part to the whole, as stated
earlier.
 Geodetic surveys require the use of sophisticated instruments, accurate methods of observations and
their computation with accurate adjustment.
 To eliminate the errors in observations due to refraction, angular observations are generally restricted
to night and arc lamps are used as signals on the survey stations.

8.  Geodetic surveying may again be subdivided in the following ways:
 1. Triangulation: In this type of surveying a network of well-defined triangles are formed on the plot
of land to be surveyed. Only one line known as base line and all other angles are measured very
carefully.
 2. Reciprocal Leveling: This type of surveying is required to obtain the difference in levels between
two points which are separated by obstacles.
 3. Stadia or Tachometric Surveying: It is a type of surveying in which vertical and horizontal
distances are computed from stadia readings without using chain or tape.
 4. Astronomical Surveying: It is a branch of surveying in which the meridian, azimuth, latitude,
longitude, time, etc. of a place on the surface of the earth are determined by observation of some
heavenly bodies like the sun and the fixed stars.
 Photographic Surveying: This is a method of surveying in which plans or maps are prepared from
photographs taken from suitable camera stations.
GEODATIC SURVEYING

9. DIFFERENCE BETWEEN PLANE SURVEYING AND GEODATIC SURVEYING
Geodetic surveyingPlane surveying
 Effect of the curvature of the earth surface is
ignored.
 The earth surface is assumed to be plane, i.e.
two dimensional.
 Involves smaller areas less than about 260 𝑘𝑚2
.
 Lower degree of accuracy.
 Done locally by the individual organization.
 Effect of the curvature of the earth surface is
included.
 The earth surface is assumed to be spherical, i.e.
three dimensional.
 Involves large areas more than about 260 𝑘𝑚2
 Higher degree of accuracy.
 Done by the concerned state or government
department.

10. CLASSIFICATION OF LAND SURVEYS (BASED ON THE NATURE OF THE FIELD)
 1. Topographical surveys: The surveys which are carried out to determine the natural features of a country
such as hills, valleys, rivers, lakes, wooded areas, etc. and the artificial features such as roads, railways,
towns, villages, canals, buildings, etc. are called topographical surveys.
 2. Cadastral surveys: The surveys which are generally plotted to a larger scale than topographical surveys
and are carried out to determine the boundaries of fields, houses, estates and other properties are called
cadastral survey. These are also sometimes used for surveying the boundaries of municipalities,
corporations and cantonments.
 3. City surveys: The surveys which arc carried out for the construction of roads, parks, water supply
system, sewer system and other constructional works for any developing township arc called city surveys.
The city maps, which arc prepared for the tourists, are known as Guide Maps.

11. CLASSIFICATION OF HYDROGRAPHIC SURVEYS (BASED ON PURPOSE OF SURVEY)
 The surveys which deal with the measurement of water bodies like seas, rivers, lakes. gulfs, etc. for the
purpose of navigation, development of port facilities, prediction of tides and determination of mean sea
level arc called hydrographic surveys.
 1. Engineering or Project Surveys: The surveys which are carried out to collect data for planning, design
and construction or an engineering project like highways, railways, irrigation canals. water supply,
sewage disposal. tunnels, dams, reservoirs, etc. are called engineering or project surveys.
 2. Military or Defense Surveys: The surveys which are carried out for preparation of maps of the areas of
strategic or military importance are called military surveys.
 3. Mine or Exploratory Surveys: The surveys which are carried out for exploration or hidden mineral
wealth beneath the surface or the ground, i.e., coal, copper, gold mines, etc. arc called mine surveys.
 4. Geological Surveys: The surveys which arc carried out to ascertain the composition of the earth crust,
i.e. different strata or rocks or the earth crust, arc called geological surveys.
 5. Archaeological Surveys: The surveys which are carried out to prepare maps of ancient culture, i.e.
antiquities, are called archaeological surveys.
 6. Marine or Navigation Surveys: The surveys which are carried- out to determine the positions of
harbors and the courses of ships are called marine or navigation surveys.
 7. Reconnaissance Survey: A preliminary survey to inspect the area before the actual detailed survey to
ascertain how the survey works can be executed in the best possible ways called reconnaissance survey.

12. CLASSIFICATION OF SURVEYS (BASED ON INSTRUMENT)
 Chain Surveying
 Compass Surveying
 Plane Table Surveying
 Theodolite Surveying
 Stadia or Tachometric Surveying
 Triangulation Surveying
 Photogrammetric Surveying.

13. IMPORTANTS OF SURVEYING
 Surveying is of vital importance in any engineering project. The object of surveying is the preparation of
plans, maps and sections of the area to be covered by the project. In the absence of accurate maps, it is
practically impossible to layout the best possible alignments of roads, railways, canals, tunnels,
transmission power lines and microwave or television relaying towers. Detailed plans, maps and sections of
the area to be covered by an engineering project are necessary for the establishment of sophisticated
instruments, the measurement of land, the fixation of boundaries, the estimation of amount of earthwork
and other necessary details depending upon the nature of the project. The success of any engineering
project depends upon the accurate and complete survey work. We can never think or .a project like
railways, highways, tunneling, irrigation, dams, reservoirs, water works, sewerage works. airfields, ports,
massive buildings, etc. without proper surveying. Also. the economic feasibility or the engineering
feasibility of a project cannot be properly ascertained without undertaking a survey work.

14. SCALE
 Since the area that is surveyed is vast, it is never possible to make the drawings to full size, and therefore,
drawings of an area are made to a smaller scale. The operation is generally known as drawing to scale ..
Scales earl be represented by the following two method
 Numerical scales: These scales arc further subdivided into (i) engineer's scales, and (ii) fraction scales.
 Engineer's scale: One cm in the-plan represents some whole number of meters on the ground, such as 1 cm
= 12 m, 1 cm = 100 m, etc. This type of scale is known as the Engineer's scale.
 Fraction scale: One unit of length on the plan represents some number of the same unit or length on the
ground, such as I :500 or 1/500, I: I 0000 or 1/10000, etc. This type of scale is known as the fraction scale
the ratio of map (or drawing or plan) distance to the corresponding ground distance is known as the
representative fraction. (abbreviated as R.F).The representative fraction can be easily found for an
engineer's scale. For example, if the scale is 1 cm = 50 m, then 𝑅𝐹 =
1
50 ×100
=
1
5000
. In a similar way, the
fraction scale can be converted to engineer's scale. For example, if the fraction scale is 1:10,000, then 1 unit
on plan = 10,000 units on the ground, 1 cm on plan = 10,000 cm on the ground or 1 cm Oil plan = 100 m
011 the ground, Hence, the engineer's scale is 1 cm = 100 m.
 Graphical Scales: A graphical scale is a line subdivided into plan distances corresponding to some
convenient units of length on the ground, i.e.

15. STAGES OF SURVEY OPERATIONS
 The entire work of a survey operation may be divided into the following three stages:
 1. Field work
 2. Office work
 3. Care and adjustment of instruments
 1. Field work: The field work consists of the measurements of all the necessary horizontal and vertical
distances, horizontal and vertical angles, elevations, etc. and keeping a systematic record of what has been
done in a field book. Field work is further subdivided into (i) reconnaissance, (ii) field measurements or
observations, and (iii) field record .
 Reconnaissance: During reconnaissance, the surveyor examines the area to be surveyed in order to
know how the survey work can be performed in the best possible ways. He will fix a number of
stations to establish a- system of horizontal controls. He will also make a rough sketch of the area
showing the stations and same permanent features including the. north line. The sketch is not
prepared according to scale, but it should represent the approximate positions of different features in
the area so that it becomes a good guide for further work.
 Field measurements: The surveyor takes all linear and angular measurements with survey
instruments. The measurements include horizontal and vertical distances, horizontal and vertical
angles. etc. Method of measurement depends upon the nature of the terrain, type of instruments and
the method of surveying.

16. SCALE
 1. Field record: All the measurements are recorded in a field book. The field records may be
numerical values, sketches and explanatory notes. Every care is made to ensure correct entries of all
the observations, otherwise the survey may be useless. The competency of a surveyor is judged by
his field records.
 2. Office Work: The office work of a surveyor consists of (i) drafting, (ii) computing, and (iii) designing,
based on the field records.
 Drafting: This process consists of preparation of plans, longitudinal sections and cross sections by
plotting the field measurements to the desired scale.
 Computing: This process consists of calculating data necessary for plotting and determining the areas
and volumes of earthwork.
 Designing: This process consists of selecting the best alignment of roads, railways, canals, etc. on
the plotted plan.
 3. Care and Adjustment of Instruments
 A great care is required to handle the survey instruments both in field and office. A beginner should
always be made familiar with care and adjustment of the instruments and their limitations. Precise
instruments like theodolite, level, prismatic compass, etc. need more care than the equipment such as
chains, arrows, ranging rods, etc.
Ref: Surveying, Prof. Abdul Halim