Engineering surveying : Compass surveying CIVIL ENGINEERING STUDIES Engineering surveying : Compass surveying NAME : SITI HAJAR BT. MD. JAMIL CLASS: 5 CIVIL 4 IC NO.:960310-56-5284 TEACHER NAME : PN ZATUL HIDAYAH BT. MOHD SAPIAN

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 .

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

instrument used in compass surveying EXAMPLE

5.3.1 principle of compass surveying 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

principle of compass surveying STEPS : 1.Set up of station A 2.Direct the compass to station B 3.Take the bearing reading . 4.Set up at station B 5.Direct the compass to station A 6.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 .

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 .

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

instrument used in compass surveying 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

instrument used in compass surveying 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 .

instrument used in compass surveying EXAMPLE