SURVEYING Er Vishal Manghnani Department of Civil Engineering

SURVEYING Er. Vishal Manghnani Department of Civil Engineering SSCE, Udaipur

SURVEYING Surveying is the art of determining the relative positions of different objects on the surface of the earth by measuring the horizontal distance between them. It is reletated only in horizontal plane. LEVELLING Levelling is art of determining the relative vertical distances of different points on the surface of the earth. It is reletated only in vertical plane. SSCE DEPARTMENT OF CIVIL ENGINEERING 2

1. 2. 3. 4. Object of surveying The main object of surveying is to prepare a map or plan to show the relative positions of the objects on the surface of the earth. To determining the boundaries of land. It is very useful for the purpose of designing projects, such as dams, canals, roads, railways etc. The successful completion of any engineering project mainly depends upon the accurate surveying. SSCE DEPARTMENT OF CIVIL ENGINEERING 3

1. 2. 3. 4. 5. Uses of surveying It is useful for measurement of areas. To prepare different types of maps such as topographical map, cadastral map, engineering map, military map, contour map, geological map etc. It is very useful for the purpose of designing projects, such as dams, canals, roads, railways etc. It is used for making of plans in connection with legal documents. In case of dispute of property, certain plans may be used as a legal documents. SSCE DEPARTMENT OF CIVIL ENGINEERING 4

1. 2. Principles of surveying To work from the whole to the part. To locate a new station by at least two measurement ( linear or angular ) from fixed reference points. SSCE DEPARTMENT OF CIVIL ENGINEERING 5

1. To work from the whole to the part. According to the first principle, the whole area is first enclosed by main stations (controlling stations) and main survey lines (controlling lines). The area is then divided into a number of parts by forming well -conditioned triangles. The main survey lines are measured very accurately with a standard chain and then the sides of triangles are measured. SSCE DEPARTMENT OF CIVIL ENGINEERING 6

1. To work from the whole to the part. The purpose of this process of working is to prevent accumulation of error. During this procedure, if there is any error in the measurement of any side of a triangle, then it will not affect the whole work. The error can always be detected and eliminated. But, if the reverse process (from the part to the whole) is followed, then the minor error in measurement will be magnified in the process of expansion and these errors will become absolutely uncontrollable. SSCE DEPARTMENT OF CIVIL ENGINEERING 7

2. To locate a new station by at least two measurement ( linear or angular ) from fixed reference points. According to the second principle, the new stations should always be fixed by at least two measurement from fixed reference points. Linear measurements refer to horizontal distances measured by chain or tape. Angular measurements refer to the magnetic bearing or horizontal angle taken by a prismatic compass or theodolite. SSCE DEPARTMENT OF CIVIL ENGINEERING 8

Classification of surveying A) Primary classification 1. Plane surveying, 2. Geodetic surveying. B) Secondary classification 1. Based on instruments a) Chain surveying, b) Compass surveying, c) Plane table surveying, d) Theodolite surveying, e) Tacheometric surveying, f) Photographic surveying 2. Based on methods a) Triangulation surveying, b) Traverse surveying 3. Based on object a) Geological surveying, b) Mine surveying, c) Archaeological surveying, d) Military surveying SSCE DEPARTMENT OF CIVIL ENGINEERING 9

Classification of surveying 4) Based on nature of field a) Land surveying, b) Marine surveying, c) Astronomical surveying, Land surveying divided into following classes i) Topographical surveying : - to determine the natural and artificial features of country such as rivers, lakes, hills, roads, railways, towns etc. ii) Cadastral surveying : - to determine the boundaries of fields, estates, houses, etc iii) City surveying : - to locate the premises, streets, water supply and sanitary system etc. iv) Engineering surveying : - to collect data for designing of engineering works such as roads, reservoirs, railways etc. SSCE DEPARTMENT OF CIVIL ENGINEERING 10

Difference between Plane surveying & Geodetic surveying Plane surveying Geodetic surveying 1. The effect of curvature of earth is not considered. 1. The effect of curvature of earth is considered. 2. The surface of the earth is taken as plane. 2. It involves spherical trigonometry. So it is called trigonometrical survey. 3. The area to be surveyed less than 250 km 2 3. The area to be surveyed more than 250 km 2 4. The degree of accuracy is low. 4. The degree of accuracy is high. 5. Plane surveying is conducted by 5. Geodetic surveying is state agencies like Irrigation conducted by Survey of India (GTS) department, Railway department. 6. SSCE DEPARTMENT OF CIVIL ENGINEERING 11

REPRESENTATIVE FRACTION (R. F. ) It is the ratio of plan distance to corresponding ground distance. In R. F. both the numerator and denominator should be in the same units. If 10 m on the ground represents 1 cm on the drawing paper, the scale is 1 cm = 10 m. So R. F. = 1 cm / 10 x 100 cm = 1/ 1000. SSCE DEPARTMENT OF CIVIL ENGINEERING 12

CONVENTIONAL SYMBOL SSCE DEPARTMENT OF CIVIL ENGINEERING 13

Prismatic compass SSCE DEPARTMENT OF CIVIL ENGINEERING 14

Compass traversing: Important Definition True meridian: Line or plane passing through geographical north pole and geographical south pole Magnetic meridian: When the magnetic needle is suspended freely and balanced properly, unaffected by magnetic substances, it indicates a direction. This direction is known as magnetic meridian. The angle between the magnetic meridian and a line is known as magnetic bearing or simple bearing of the line. SSCE DEPARTMENT OF CIVIL ENGINEERING 15

Arbitrary meridian: Convenient direction is assumed as a meridian. Grid meridian: Sometimes for preparing a map some state agencies assume several lines parallel to the true meridian for a particular zone these lines are termed as grid meridian. Designation of magnetic bearing Whole circle bearing (WCB) Quadrantal bearing (QB) WCB: The magnetic bearing of a line measured clockwise from the North Pole towards the line is known as WCB. Varies 0 -360 SSCE DEPARTMENT OF CIVIL ENGINEERING 16

Quadrantal Bearing: The magnetic bearing of a line measured clockwise or anticlockwise from NP or SP (whichever is nearer to the line) towards the east or west is known as QB. This system consists of 4 -quadrants NE, SE, NW, SW. The values lie between 0 -90° QB of OA = N a E Reduced Bearing: When the whole circle bearing of a line is converted to quadrantal bearing it is termed as reduced bearing. Fore and Back Bearing: In WCB the difference between FB and BB should be exactly 180° BB=FB+/-180° Use the +ve sign when FB<180° Use the –ve sign when FB> 180° SSCE DEPARTMENT OF CIVIL ENGINEERING 17