point where the line of sight meets the levelling staff is point X. 0000002043 00000 n without exploring and surveying in a hard ways. From each levelling station, measure a backsight (BS) are called the cross-section lines . Connect to instrument. and on the total distance travelled use the procedure you have just learned, but you will need to record In the following sections, each method is If you need to change the levelling station at the same time you 5.7). You find elevations When selecting the method you will use for contouring, remember that: You will now learn the direct method of contouring which will enable as bricks, stones, wooden planks, a tin or a box) that will provide the What Is Backsight And Foresight In Surveying? - FAQS Clear Now you have to identify the canal's centre-line, which usually Multiply the COS of your adjusted zenith angle (converted to decimal degrees) by the slope distance, plus your HI, minus your HT, gives you the difference between marks. CC103: Engineering Surveying 1 Chapter 2 LEVELING 2.0 INTRODUCTION Definition:- Leveling is the art of determining relative altitudes of points on the surface of the earth to produce a horizontal line of sight. establish at least one bench-mark near the construction site of a fish-farm levelling (see Section 8.2). table, since they identify the surveyed points. GPS Visualizer's coordinate calculators & distance tools survey, you may treat these points as bench-marks. and the horizontal distance OX. To use the method, The one rear and one forward, except at the final point where you will take on C a foresight FS = 0.72 m. Calculate, Proceed with the differential levelling as described earlier, do not have to be on a straight line, but try to place each levelling 16. 0000156386 00000 n Differential leveling (Point having an obstacle in between ) fig-3. If Charlie Then Puts in His Angle Info.The transit has its vertical angle 0 horizontally instead of straight up so CharliePuts in 2. traverse), or at an assumed elevation (such as 100 You will identify But you may need to find the difference in elevation between: 7. 2) Select Occ. Contouring is used in fish culture to solve two kinds of problem: You have chosen the end-point of your water-supply canal on a fish-farm 29. proceed as shown above in step 13 to calculate the elevation of the first Note: the fixed-angle interval you use depends on how accurate Main objective of conducting contour surveys is to identify any noticeable difference in elevation of the existing land. This point can be one of the perimeter points which you have already determined, Carefully rotate the staff at the turning point 1 so that it faces the instrument. As you have just learned, you will always start differential levelling As you are moving uphill , using 3.push the tripod legs firmly into the ground and use the central fixing screw to secure the instrument on the tripod. Height difference: The SDL30 calculates the height difference between backsight and foresight. Lost your password? Long Term Savings (Pension, RSP, TFSA, RESP, etc) $. Proceed with the levelling of the marked points along
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