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ENGINEERING SURVEYING : COMPASS SURVEYING

CIVIL ENGINEERING STUDIES

NAME : SITI HAJAR BT. MD. JAMIL

CLASS: 5 CIVIL 4

IC NO.:960310-56-5284

TEACHER NAME : PN ZATUL HIDAYAH BT. MOHD SAPIAN

5.3 COMPASS SURVEYING

INTRODUCTION Compass surveying is a method of

surveying by taking bearings and linear distance to produce plan . Bearing is measured using chain survey or measuring tape . Bearing in compass surveying means angle is made by chain line which is made by chain line or survey line by referring it to the magnetic meridian or magnetic north . This survey line will be series of line which is called traverse .

5.3.1 PRINCIPLE OF COMPASS SURVEYING

I. True North or Magnetic North In compass surveying , bearing is an angle

measured clockwise between one survey line with the north direction. Bearing refers to true north known as true bearing , while bearing which refers to magnetic north is known as magnetic bearing . True north is a direction of earth’s north to north pole from any point on earth surface , while magnetic north is the direction of north shown by the magnetic needle in the prismatic compass

5.3.2.INSTRUMENT USED IN COMPASS SURVEYING

EXAMPLE

II. Compass Traverse Traverse is a survey line which is

continuous from one to another . Traverse is divided into 2 types . OPEN & CLOSED traverse . Bearing reading for compass surveying work is taken using prismatic compass.


OPEN AND CLOSED TRAVERSE

STEPS :1.Set up of station A2.Direct the compass to station B3.Take the bearing reading .4.Set up at station B5.Direct the compass to station A6.Take the bearing reading. The difference between forward & backward bearing is 180 degree.

=260-80=180 degree

7.Then measure the distance between the distance AB .


5.3.1 PRINCIPLE OF COMPASS SURVEYING EXAMPLE :

5.3.1 PRINCIPLE OF COMPASS SURVEYING Other than identification of

distance & bearing for survey line , prismatic compass can also be used to determine relative position of an object . The position of an object is identified after bearing and distance of survey line are taken .


Instruments used in compass surveying are , chain , measuring tape , chaining arrow , ranging pole , prismatic compass , plumb bob , book and recording stationaries


Prismatic compass is used to measure the bearing of the survey line and others details referring to the magnetic north . Prismatic compass is a graduated compass card attached too magnetic needle and placed on to steel pivot . The graduated compass dial has bearing reading from 0 to 360 degree in a clockwise direction ,

A CROSS SECTION OF PRISMATIC COMPASS


II. Plumb Bob A plumb bob is used to center any

surveying instruments on to survey station . The instrument is made of metal reverse cone shape and tired with thread on the upper part of the plumb bob so as it easy to hang on the tripod .


EXAMPLE

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