SURVEYING - 1

 CHAPTER – 1

SURVEYING

DEFINATION

SURVEYING CAN BE DEFINED AS “THE SCIENCE AND ART OF DETERMINING THE RELATIVE POSITIONS OF VARIOUS POINTS ABOVE, ON OR BELOW THE EARTH SURFACE WITH THE HELP OF MEASURING DISTANCE, DIRECTION AND ELEVATION USING DIFFERENT INSTRUMENTS.

IMPORTANCE OF SURVEYING IN CIVIL ENGINEERING

v  PLANNING PHASE

v  DESIGNING PHASE

v  CONSTRUCTION AND LAYOUT PHASE

PRIMARY DIVISION OF SURVEYING

1.      PLANE SURVEYING

ü  THE SURVEYING IN WHICH EARTH SURFACE IS ASSUMED AS A PLANE AND THE CURVATURE OF THE EARTH IGNORED, IS KNOWN AS PLANE SURVEYING.

ü  AREA IS LESS THAN 260 Sq.km.

ü  LOW DEGREE OF ACCURACY

ü  THE EARTH SURFACE IS ASSUMED TO BE PLANE THAT IS TWO DIMENSION.

ü  DONE LOCALLY BY THE INDIVIDUAL ORGANIZATION.

2.      GEODETIC SURVEYING

ü  THE SURFACE IN WHICH THE CURVATURE OF EARTH SURFACE IS CONSIDERED IS KNOWN AS GEODETIC SURVEYING.

ü  THE MAIN OBJECTIVE OF GEODECTIC SURVEYING IS TO DETERMINE VERY PRECISELY THE RELATIVE OR ABSOLUTE POSITION ON THE EARTH’S SURFACE OF A WIDELY POINTS.

ü  AREA IS GREATER THAN 260 sq.km.

ü  HIGH DEGREE OF ACCURACY

ü  THE EARTH SURFACE IS ASSUMED TO BE SPHERICAL THAT IS THREE DIMENSION.

ü  DONE BY CONCERNED STATE OR GOVERNMENT DEPARTMENT.

DIFFERENCE BETWEEN PLANE SURVEY AND GEODETIC SURVEY

S.NO.	PLANE SURVEY	GEODETIC SURVEY
1.	EARTH CURVATURE IGNORED.	EARTH CURVATURE IS TAKEN INTO ACCOUNT
2.	AREA IS LESS THAN 260 Sq.km.	AREA IS GREATER THAN 260 Sq.km.
3.	LOW DEGREE OF ACCURACY.	HIGH DEGREE OF ACCURACY.
4.	THE EARTH SURFACE IS ASSUMED TO BE PLANE THAT IS TWO DIMENSIONAL.	THE EARTH SURFACE IS ASSUMED TO BE SPHERICAL THAT IS THREE DIMENSIONAL.
5.	DONE LOCALLY BY INDIVIDUAL ORGANIZATION.	DONE BY THE CONCERNED STATE OR GOVERNMENT DEPARTMENT.
6.	ALL TRIANGLES FORMED BY SURVEY LINES ARE CONSIDERED AS PLANE TRIANGLE.	ALL LINES LAYING IN THE SURFACE ARE CURVED LINES AND THE TRIANGLES ARE SPHERICAL TRIANGLES HENCE INVOLVED SPHERICAL TRIGNOMETRY.
7.	CARRIED OUT FOR ENGINEERING WORKS.	ALL GEODETIC SURVEY INCLUDES WORK OF LARGER MAGNITUDE AND HIGH DEGREE OF PRECISION.
8.	THE LEVEL LINE IS CONSIDERED AS STRAIGHT.

 PLUMB LINE ASSUMPTIONS PLANE AND GEODETIC SURVEY

Plumb Bob Line is an imaginary line passing longitudinally through its centre.

P.B.L. is parallel in case of Plane Surveying.

P.B.L. always intersect at the center of earth in case of Geodetic Surveying.

 

SECONDARY CLASSIFICATION OF SURVEYING

1.      ACCORDING TO THE NATURE OF FIELD

I)                    LAND SURVEY :

THE LAND SURVEY MA BE FURTHER SUB DIVIDED INTO THE FOLLOWING TYPES WHICH MAY BE DESCRIBED BELOW.

a)      TOPOGRAPHIC SURVEY

Ø  THIS SURVEY IS CARRIED OUT FOR DETERMINING THE NATURAL FEATURES OF THE COUNTRY SUCH AS HILLS, VALLEYS, RIVERS, FOREST, LAKES etc.

Ø  SCALE = 1:25000 TO 1:1000000 (1:10 LAKHS)

b)      CADASTRAL SURVEY

Ø  CADSTRAL SURVEY IS DONE TO FIX THE PROPERTY LINE OF PERSONAL, MUNICIPALITIES, STATES etc.

Ø  SCALE = 1:1000 TO 1:5000

c)      CITY SURVEY

Ø  CITY SURVEY IS DONE FOR CONSTRUCTION OF STREETS, WATER SUPPLY SYSTEM, SEWER etc.

II)                  HYDROGRAPHIC OR MARINE SURVEY

Ø  IT DEALS WITH THE MAPPING OF LARGE WATER BODIES FOR THE PURPOSE OF NAVIGATION, CONSTRUCTION OF HARBOR, PREDICTION OF TIDES AND DETERMINATION OF MEAN SEA LEVEL.

III)               ASTRONOMICAL SURVEY

Ø  ASTRONOMICAL SURVEY DEALS WITH THE DETERMINATION OF ABSOLUTE LOCATION AND ABSOLUTE DIRECTION OF HEAVENLY BODIES LIKE SUN, MOON etc.

2.      ACCORDING TO THE PURPOSE OF SURVEYING

I)                    MINE SURVEY : THIS IS USED FOR EXPLORING THE EARTH’S MINERALS SUCH AS GOLD, COPPER, COAL, SILVER, etc. BETWEEN THE EARTH’S CRUST.

II)                  GEOLOGICAL SURVEY: Geological  Survey is carried out by geologists. It is usually for the study of the earth’s rock structure. It helps to determine different strata in the earth’s crust.

III)                Archaeological Survey: As the name suggests, the Archaeological Survey is carried out by the Archaeologists for their study concerning the past. This survey helps to trace the relics of the past.

IV)               Military Survey: The Military Survey is carried out by every country worldwide. A military survey is based on a broader spectrum. Military Survey helps in determining the points of strategic importance for the country.

V)                 ENGINEERING SURVEY

Ø  This Survey Is Performed For Determining And Collecting Data For The Design Of Engineering Works Such As Road, Railways, Reservoir, Water Supply, Sewerage Etc.

Ø  The Engineering Survey May Be Further Sub Divided Into The Following Classes:

A)     RECONNAISSANCE SURVEY : It Is Used For Determining The Feasibility And Rough Cost Of Scheme.

B)      PRELIMINARY SURVEY: It Is Used For Collecting More Precise Data To Choose The Best Location Of The Works.

C)      LOCATION SURVEYS: It Is Used For Setting Out The Work On The Ground.

3.      ACCORDING TO THE INSTRUMENT USED

A)     CHAIN SURVEY

Ø  It Is Simplest Type Of Surveying In Which Only Linear Measurement Are Done With The Help Of Chain Or Tape.

B)     COMPASS SURVEY

Ø  In Which Horizontal Angles And Direction Of Lines Are Measured With Compass And Length Of Line Are Measured With Chain Or Tape.

C)      PLANE TABLE SURVEY

Ø  IN WHICH PLAN OR MAP IS PRODUCED BY DETERMINING DIRECTION OF VARIOUS POINT AND A LINEAR MEASUREMENT WITH CHAIN OR TAPE.

Ø  THE METHOD OF SURVEYING IN WHICH FIELD WORKS AND PLOTTING ARE DONE SIMULTANEOUSLY, IS KNOWN AS PLANE TABLING.

D)     LEVELLING

Ø  SURVEYING IN WHICH ELEVATION OF VARIOUS POINTS ARE MEASURED WITH A LEVELLING INSTRUMENT AND VERTICAL STAFF.

E)      THEODOLITE SURVEY

Ø  SURVEYING IN WHICH HORIZONTAL AND VERTICAL ANGLES ARE MEASURED WITH THEODOLITE AND LENGTH IS MEASURED WITH CHAIN OR TAPE.