Surveying - objectives, principles, classification
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The document provides an overview of surveying in civil engineering, covering its definition, objectives, principles, classifications, and various applications. It discusses the history of surveying methods, from ancient civilizations to modern technology, emphasizing the importance of accuracy and precision in measurements. Additionally, the document categorizes different types of surveying, including plane and geodetic surveying, and outlines the various tools and techniques used in this field.
Surveying - objectives, principles, classification
- 2. Topics Surveying Definition Objectives Principles of Surveying Classification Plan and Map Scales used for Maps and Plans Accuracy Precision
- 3. Definition: Surveying is the science and art of determining the relative positions of various points above, on or below the surface of the earth. The relative positions can be determined by measuring: Horizontal Distance Vertical Distance Horizontal Angle Vertical Angle Surveying H V VA HA
- 4. Surveying Various Stages of Surveying in Big Projects: To survey the land and prepare Plans Plans are used in the preparation of the detailed drawing, design and estimate of the project After finalising the drawings, setting out is done by establishing various points and lines on the ground from the drawing
- 5. History of Surveying The Babylonians practiced some type of surveying as early as 2500 B.C. Surveying in some forms was used in India and Egypt to divide the land for taxation purposes from 1400 B.C. Surveying methods were used for Control points in Nile civilization. Romans developed improved methods of surveying during Roman period. They used odometers and groma (for measuring Right angles) In Twentieth Century, precise levelling instruments, modern optical theodilites and EDM were invented.
- 6. Objectives 1.To prepare a plan/map to show the relative position of the object on the surface of earth. 2.To collect essential data for the earthwork. 3.To measure the area and volume of the site. 4.To construct any structure on the ground according to it’s drawing. 5.To determine fields parameter and properties, for planning and execution of various projects. 6.To estimate the quantity of the products to be used and its cost 7.To record property lines of private, public & government lands, which helps in avoiding unnecessary controversies.
- 7. Uses of Surveying To prepare a topographical map which shows hills, valleys, rivers, forests, villages and towns etc. To prepare a cadastral map which shows the boundaries of fields, plots, houses and other properties. To prepare an engineering map which shows the position of engineering work such as buildings, roads, railways, dams, canals. To prepare a contour map to know the topography of the area to find out the best possible site for roads, railways, bridges, reservoir, canals, etc
- 8. Uses of Surveying Surveying is also used to prepare military map, geological map, archaeological map etc. For setting out work and transferring details from the map on the ground.
- 9. Principles of Surveying Always work from the whole to part First establish accurately a large main framework consisting of widely spaced control points Between the large main framework, subsidiary small framework can be established by relatively less accurate surveys Thus the errors will be localised and are not magnified A D G E J H B F C
- 10. Principles of Surveying Always make provisions of adequate checks There is always possibility of making errors while taking the measurement, recording the observations, computing and plotting the results There should be suitable provision for checks Adopt a method which automatically reveals the mistakes Same party should measure in reverse direction Two different parties should take the measurements independently A Check Line B D C
- 11. Principles of Surveying Always choose the method of survey that is the most suitable for purpose Cost of surveying increases an increase in accuracy High accuracy requires very costly precise instruments, more fieldwork and more extensive computations Eg: Land survey in rural area where the cost of land is low, can be done with accuracy of 1 in 1000, using a chain Eg: Survey of residential plot in big city where the cost of land is high, accuracy of 1 in 10000 or more is required and done with steel or invar tape
- 12. Principles of Surveying Always record field data carefully Measurements taken in the field must be recorded in proper field book instantly Record must be in standard form and clearly written with black ball pen or hard pencil 3H or 4H It may be in the form of tables, sketches, description or all In case of mistake, a line should be drawn to cross it
- 13. Classification of Surveying Primary Divisions of Surveying is made on the basis of: Curvature of the Earth is Considered Earth is assumed to be Flat Shape of the earth is Oblate Spheroid. Length of Polar Axis = 12713.168 Km Length of Equatorial Axis = 12756.604 Km Difference = 43.434 Km (0.34%) For understanding consider Earth as Sphere Due to the curvature of earth’s surface, the measured distances are actually curved. However, when the distances are small, curvature can be neglected and there is no difference between curved distance and straight line distances.
- 14. Classification of Surveying Surveying is Primarily divided into: Plane Surveying Geodetic Surveying Plane Surveying Curvature of Earth is neglected and assumed as flat surface. Horizontal distances and angles are projected onto a horizontal plane. A horizontal plane at a point is the plane which is perpendicular to the vertical line at that point. The vertical line is indicated by a freely suspended plumb bob. Used for small areas i.e. Less than 250 sq. Km.
- 15. Classification of Surveying Geodetic Surveying Curvature of earth is taken into consideration. High standard of accuracy is maintained. Main object of Geodetic Survey: Determine the precise location of a system of widely spaced points on the surface of the earth. These points are used as control stations.
- 16. Classification of Surveying Classification is done based on: Function Instruments Used Functional Classification of Surveying: Control Surveying: Establishing the horizontal and vertical positions of widely spaced Control points using principles of geodetic survey. In India it is done by Survey of India.
- 17. Classification of Surveying Land Surveying: To determine the boundaries and areas of tracts of the lands. Also known as property survey, boundary survey or Cadastral survey City Survey: Conducted within limits of a city for urban planning for layouts of streets, buildings, sewers, pipes etc. Topographical survey: Topography is defined as the shape or configuration of the earth’s surface. Information pertaining to reliefs and undulations on the earth’s surface is generally shown in the form of contours of equal elevations.
- 19. Classification of Surveying Route Survey: Special type of topographical survey conducted along a proposed route for a highway, railway, sewer line etc. Mine Survey: To determine the relative positions and elevations of mines, shafts, adits, bore holes etc. for underground works. Hydrographic Survey: Conducted on or near the body of water, such as lakes, rivers, bays, harbours etc. For locating shore lines, estimation of water flow and determination of shape of area beneath the water surface. Engineering Survey: To collect data for the designing and planning of engineering works such as building, bridges, roads, dams, reservoirs, sewers and water supply lines.
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- 21. Classification of Surveying Astronomic Survey: To determine the latitudes, longitudes, azimuths, local time etc. for various places on the earth by observing heavenly bodies (the sun and stars) Satellite Survey: To obtain intercontinental, interdatum and interisland geodetic ties all over the world through artificial earth satellites. Geological Survey: To obtain information about different strata of earth’s surface for geological studies (Geological Maps). Construction Survey: This is the final survey. The points and lines are established on the ground, and the layout plan of the structure is marked on the ground. Stakes are driven for setting out.
- 23. Classification of Surveying Miscellaneous Surveys: Archaeological Survey: To unearth relics and antiquity Military Survey: To determine the routes and points of strategic importance Gravity Survey: To measure the intensity of the gravitational force at various points General Survey: To acquire and accumulate qualitative information and quantitative data for a specific purpose by observing, counting, classifying and recording according to the need. Eg: Traffic Survey
- 25. Classification of Surveying based on Instrument Classification based on Instruments used: Chain Survey: Simplest survey used for linear measurements Chain or Tape is used Accuracy is low Compass Survey: Horizontal angles are measured Magnetic Compass is used Accuracy is low but better than Compass survey
- 26. Classification of Surveying Levelling: Relative elevations (levels) at various points are determined with respect to reference plane (datum) Dumpy Level, Auto Level Accuracy is Medium Plane Table Survey: A map is prepared in the field while viewing the terrain after determining the directions of various lines and taking the linear measurements Plane Table, Alidade, Chain or Tape are used Accuracy is low
- 27. Classification of Surveying Theodilite Survey: Horizontal and Vertical angles can be determined. Classified as: Traverse and Triangulation Vernier or Transit Theodilite is used Accuracy is high Tacheometric Survey: Horizontal angles, distances and Elevations can be measured Tacheometer is used Tacheometer is a Theodilite fixed with Stadia Diaphragm having two horizontal cross hairs in addition to one vertical cross hair Accuracy is Medium
- 28. Classification of Surveying Photogrammetric Survey: Measurements are taken with help of Photographs and are used for topographic mapping of vast areas Drones, Satellites and Aeroplanes were used Accuracy is High EDM Survey: Used for determining horizontal, vertical angles and distances Works on Trilateration principle Accuracy is High
- 29. A Plan and A Map Plan: A graphical representation of features on or near the Earth’s surface projected on a horizontal plane Plan represents the area on a horizontal plane, horizontal distances are measured between various points on the earth’s surface. A plan is drawn relatively on a large scale Map: Map is a Plan whose scale of the geographical projection on a horizontal plane is small Map depicts additional features such as reliefs, harchures and contour lines to indicate undulations of the ground Difference b/w Plan and Map Large scale representation of a small area are called Plans Small scale representation of a large area are called Maps
- 30. Map
- 31. Plan
- 32. Plan
- 33. Scale of a Map Scale: Ratio of distance on the map with the corresponding distance measured on the ground Scales are represented as: Engineers Scale: One Cm on the plan represents whole number of meters on the ground Eg: 1Cm = 1 Km Representative Fraction (R.F.): Ratio of map distance to the corresponding ground distance is independent of units of measurement Eg: 1: 1000 (1Cm = 10m, 1Cm = 1000Cm, 1: 1000) Graphical Scale: It is a line sub divided into plant distance corresponding to convenient units of length
- 34. Accuracy & Precision Accuracy: Closeness of a measurement to its true value Precision: Closeness of a measurement to previously measured value. It may or may not be accurate. A good surveyor should achieve both accuracy and precision