Introduction to surveying | Engineering Surveying-I

Chapter:1 Introduction

1.1 Definition of surveying

The science and art of determining the relative position of various point above on the below the surface of the earth by means measuring distance, direction and elevation, using different instrument. surveying is the first step of executing of any project. The main purpose of surveying is the preparation of maps and plan showing the relative position.

1.2 Objective of surveying

(a) To preparation plan and maps of area.

(b) To collect field data.

1.3 Uses of surveying

(a) To prepare an engineering map.

(b) To prepare topographic map which show the hill, river, town of a country.

(d) To prepare contour map.

(e) To determine the best possible routs of railways, road etc.

(f) To determine the capacity of reservoirs.

(g) To prepare archaeological map.

1.4 Classify surveying

(a) According to the Nature of ground

i. Land survey: The survey which is carried out on the earth is called land survey. Land survey is further classified into topographic cadastral and city survey.

ii. Hydrographic Survey: The survey which is carried out further studies of large water bodies is called hydrographic survey.

iii. Astronomic survey: The survey which is carried per determining absolute location and direction of any land on the surface of the earth by making observation heavenly body (march, sun, moon, star etc.) is called astronomical survey.

(b) According to the purpose of survey

i Mine survey: This survey used for the exploring mineral wealth.

ii. Geological survey: This survey used for determining different stra in the earth crust.

iii. Military survey: This is carried out for preparation of maps of area of military importance.

iv. Engineering survey: To collect required data for planning, design and executing of engineering projects.

(c) According to instrument

i Chain survey

ii Compass survey

iii Plain table survey

iv Leveling survey

v Theodolite survey

vi Traverse survey

(vii) Aerial survey

Mainly Survey are divided into two types

(a) Plane survey

The survey in which the curvature of earth is ignored and survey area is less than 260km2 then the survey is called plane survey.

(b) Geodetic survey

The survey in which the curvature of earth is consider and survey area is more than 260km2 then the survey is called plane survey.

1.5 Principles of surveying

(a) Work from whole to part

The survey in which the curvature of earth is ignored and survey area is less than 260km2 then the survey is called plane survey.

(b) Location of a point by measurement from two control

points.

(d) accuracy/precision required

(e) independent check

1.6 Definition of scale:

(a)Full size scale

The scale in which the actual measurement of object are drawn to same size of drawing is known as full size scale. It is also called equal size scale. The proportion of full size scale is 1:1 etc.

(b)Reducing scale

The scale in which the actual measurement of object are reduce to some proportion is known as reducing scale. The strandard proportion of Reducing scale is 1:5, 1:10 etc

(c)Enlarge scale

The scale in which the actual measurement of object are increase to some proportion is known as Enlarge scale. The strandard proportion are 10:1, 2:1, etc.

1.7 Representative Factor (RF)

The ratio of distance on a map or drawing to the corresponding actual distance on the ground which have same unit is called Representative factor. It is denoted by RF.

RF= Distance on drawing of object (Same unit)/Corresponding actual distance on ground

For example:

If a scale is 1cm= 10m then,

Representative fraction (RF) = 1/10*100 = 1/100

1.8 Types of scale:

A. Plain scale

A plain scale on which it is possible to measure only two dimension. For example centimeters (cm) and millimeters (mm) etc.

B. Diagonal scale

It is on which possible to measure three dimension such as kilometer (km), hectometer (hm) and decimeter (dm) etc.

C. Vernier scale

A device used for measuring the fractional part of one of the smallest divisions of a graduated scale. It usually consists of a small auxiliary scale which slides alongside of the main scale.

D. scale of chord

The scale of chord used to measure or to set of angular. It is marked either on rectangular protractor or ordinary wooden box scale.

1.9 Numerical practice

Q. Find the representative fraction (RF) of the following scales.