INTRODUCTION OF ENGINEERING SURVEY

TOPIC 1 (INTRODUCTION)

COURSE LEARNING OUTCOME
- Describe briefly types of surveying

1.0 INTRODUCTION

Definition:
 Is a science and art of measuring, recording and drawing to scale, the location, the size and shape of natural and man-made features on a surface of the earth.
 Determine the relative position of distinctive features on the surface/beneath the surface of earth, by means of measurement of distance, direction and elevation
 Surveying can be defined as the art and science of making measurements of the relative positions of natural and manmade features on the earth’s surface, and presentation of this information either graphically (in the form of a map or plan) or numerically.
 Basically, surveying is a process of measuring distance, height differences and angles at construction site

1.1 PURPOSE OF SURVEYING
The main purpose of surveying work is to obtain data of the earth surface to:
 Produce plan, cross and longitudinal sections of proposed project area to be built.
 Determine boundary and area of site to determine ownership and permission to enter the site.
 Determine volume of soil that may be required during construction.
 Ensure the project to be constructed is in the correct position.
 Obtain soil profile of the area and later, to determine the required cut and fill.
 Determine the site level as well as the location of construction such as gradient of drainage and others.
 Record the final location of construction including any adjustment to it.

1.2 PRIMARY DIVISIONS OF SURVEYING
Can be devided into two groups which are:-
1.2.1 Plane Surveying
 Which the mean surface of earth is regarded as plane survey and not curved as it really is.
 Survey area cover up to 260sq. Km
 Used for layout of highways, railways, canals, tunnel, fixing boundary pillars, construction, construction of bridges and factories.
1.2.2 Geodetic survey
 Curvature of the earth is taken into account.
 Demand higher degree of accuracy in linear as well as angular observations is achieved.

1.3 CLASSIFICATION OF SURVEY
Classification can be done based on its use and also purpose of survey
1.3.1 Classification based upon the nature of the fields

a. TOPOGRAPHIC SURVEY
 Depict the topography of the mountainous terrain, rivers, water bodies, wooded areas and other cultural details such as roads, railways, townships etc.

b. CADASTRAL SURVEY
 Carried out for fixing the property lines, calculation area of landed property and preparation of revenue maps of state.

c. CITY SURVEY
 Carried out for the construction of roads, parks, water supply system, sewer and other constructional work for any developing township.

d. HYDROGRAPHIC SURVEY
 Mapping of large water bodies for the purpose of navigation, construction of harbour work, prediction of tides and determination of mean sea level.
 Consist of preparation of topographical maps of the shores and banks, by taking sounding and determining the depths of water at a number of places
.
e. ASTRONOMICAL SURVEY
 Carried out to determine absolute location e.g. latitude of different places on the earth surface and the direction of any line on the surface of the earth by making observations to heavenly bodies.
1.3.2 Classification based on the purpose of survey

a. ENGINEERING SURVEY
 Determine of quantities on to afford sufficient data for designing engineering works such as roads, sewage disposal and water supply.

b. MILITARY/ DEFENCE SURVEY
 Preparation of maps of the areas of military importance

c. MINE SURVEY
 Exploration of mineral wealth’s beneath the surface of the ground

d. GEOLOGICAL SURVEY
 To ascertain the composition of the earth crust

e. ARCHAEOLOGICAL SURVEY
 To prepare maps of ancient culture.

1.3.3 Classification based on instrument used
a. Chain survey
b. Compass survey
c. Plane table survey
d. Theodolite survey
e. Tacheometric survey
f. Photogrammetric survey

1.4 BASIC PRINCIPLES
 Measure distance
 Measure distance at right angles
 Measure distance and angle
 Measure angles

The fundamental rule in surveying project is WORK FROM THE WHOLE TO THE PART.
1.5 THE STAGES OF SURVEY OPERATION
The entire work may be devided into three stages:-

1.5.1 Field work
Consist of measurement of distance and angles required for plotting to scale and keep systematic record in the form or field book
a. Reconnaissance - the surveyor goes over the area to fix a number of stations to ensure intervisibility.
b. Observation – also includes determination of difference in elevations between the stations and surveying contours of land areas and bathymetric contours of water bodies.
c. Field records - all the measurements are recorded in the field book.

1.5.2 OFFICE WORK
The field notes are brought to the office and necessary drafting, computing and designing work are done by draftsmen and computer.

1.5.3 CARE & ADJUSTMENTS OF INSTRUMENTS
A great care is required to handle survey instruments. A beginner should always be made familiar with care and adjustments of the instruments and its limitations.

1.6 UNDERSTANDING MAP AND PLAN
1.6.1 Plan – will accurately define widths of roads, size of building etc. every features are exactly true to scale
1.6.2 Map – Is a representation, no matter how accurately it may be shown.
1.7 ERROR
Every measurement contains errors of unknown magnitude due to several reasons and hence no measurement in surveying is exact.

1.7.1 SOURCES OF ERRORS
a. Natural errors: - Result from the temperature, refraction, obstacles to measurement, magnetic declination
b. Instrumental errors:- Result from the imperfect construction and adjustment of the instrument
c. Personal errors:- Arise from the limitation of the human senses such as sight, touch and hearing

1.7.2 TYPES OF ERRORS
a. Systematic errors:- Errors which occur from well understood causes.
b. Accidental errors:- Due to combination of cause and are beyond the control of surveyor