# civil engineering -jaja

Post on 27-Jun-2015

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presentation of my spm assignment

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• 1. 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

2. 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 . 3. 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 earths 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 4. 5.3.2.INSTRUMENT USED IN COMPASS SURVEYING EXAMPLE 5. 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. 5.3.1 PRINCIPLE OF COMPASS SURVEYING 6. OPEN ANDCLOSEDTRAVERSE 7. 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 . 5.3.1 PRINCIPLE OF COMPASS SURVEYING 8. 5.3.1 PRINCIPLE OF COMPASS SURVEYING EXAMPLE : 9. 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 . 10. 5.3.2.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 11. 5.3.2.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 , 12. A CROSS SECTION OF PRISMATIC COMPASS 13. 5.3.2.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 . 14. 5.3.2.INSTRUMENT USED IN COMPASS SURVEYING EXAMPLE