Suveying Chain Method

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Suveying Chain Method

  1. 1. What is Surveying ? Surveying is a method of determining accurately, points and lines of direction (bearings) on the earth's surface and preparing from them, maps or plans. Boundaries, areas, elevations, construction lines, and geographical or artificial features are determined by the measurement of horizontal and vertical distances and angles and by computations based on geometry and trigonometry.
  2. 2. What is Surveying? <ul><li>Surveying can be defined as: </li></ul><ul><ul><li>The art of making measurements of the relative positions of natural and man made features on the earth’s surface and the presentation of this information either graphically or numerically Bannister, A. Raymond, S., and Baker, R., 1998, Surveying </li></ul></ul><ul><li>The basics of surveying haven’t changed. </li></ul><ul><ul><li>Egyptians and Greeks measured using differential leveling, distance, and angles. </li></ul></ul><ul><li>There are two types of surveying: </li></ul><ul><ul><li>Geodetic and Plane Surveying </li></ul></ul>
  3. 3. Types of Surveying <ul><li>Geodetic </li></ul><ul><ul><li>Accounts for curvature of the earth. </li></ul></ul><ul><ul><li>Used mostly for national mapping programs. </li></ul></ul><ul><ul><li>Needs to be highly accurate. </li></ul></ul><ul><li>Plane Surveying </li></ul><ul><ul><li>Treats the earth’s surface as a flat plane. </li></ul></ul><ul><ul><li>The instrument is always leveled according to the center of the earth (gravity level/plumb bob). </li></ul></ul><ul><ul><li>Only appropriate for smaller areas. (less than 250 km 2 ) </li></ul></ul>
  4. 4. Why might you want to survey? <ul><li>It is a handy skill: </li></ul><ul><ul><li>You may rent a level & rod if you don’t own one. </li></ul></ul><ul><ul><li>May use it to lay out foundations or driveways. </li></ul></ul><ul><ul><li>To arrange contours in your fields. </li></ul></ul><ul><li>To understand what professionals are doing. </li></ul><ul><ul><li>When you see a surveying crew at work. </li></ul></ul><ul><ul><li>When a crew is surveying your land. </li></ul></ul>
  5. 5. SURVEYING EQUIPMENTS The Gunter's chain (known also as the surveyor's chain), which is 20 m long and divided into 100 links links
  6. 6. The engineer's chain, 30 m long and also consisting of 100 links The tape, usually of steel
  7. 7. THEODILITE ROD OR STAFF
  8. 8. FIELD BOOKS DIGITAL FIELD BOOK
  9. 9. Basic principles of plane surveying Consider a simple survey situation as shown on the left. To plot the area accurately it is essential to establish a base line first. Once a base line is established, the points can be located relative to the line by taking two measurements with the following possible combinations:
  10. 10. Two distances Two angles One distance and one angle One distance at 90 , offset Basic CHAIN SURVEY – two distances. AC and BC are measured. Point C is drawn by intersecting Radii AC and BC.
  11. 12. Basic TRIANGUALTION – two Angles ABC and BAC are taken. Point C is located using the Intersection of the angles.
  12. 14. Basic TRAVERSE – distance and angle. Point C is located by the measured distance of AC and the angle ABC.
  13. 16. Basic OFFSET – distance at 90 degrees. Point C is located by the distance on a line perpendicular to base line AC through C.

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