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FUNDAMENTAL   LEVELING Procedure
METHODS  OF  LEVELING

Engineering Aid 3 - Beginning Structural engineering guide book
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as Figure  14-11 .-Procedure for direct leveling. Figure 14-12.-Turning points. “Balancing shots” means equalizing as much To balance distances for a setup, you will find possible  BS  and  FS  distances  by  selecting that  using  the  same  number  of  paces  for  BS  as turning  points  that  are  approximately  an  equal distance  from  both  the  BS  and  FS  points. No  matter  how  carefully  you  level  a  level telescope, it is likely to be still slightly out of the horizontal. The error this causes increases with the length of the sight taken. If the BS distance differs  from  the  FS  distance,  the  BS  and  FS errors  will  also  differ.  If  the  distances  are  the same, the errors will be the same. Balancing shots therefore  eliminates  the  effect  of  instrumental error and also of curvature and refraction, other errors that increase with distance. for FS is helpful. In general, BS and FS distances should be kept under 300 ft except when necessary to  pass  or  cross  an  obstacle. Establishing Turning Points Suppose you want to determine the elevation of a point at the summit of a long slope, and the nearest BM is at the foot of the slope some 30 ft or  so  below  the  summit.  Obviously,  you  cannot sight a rod held on the BM and another held on the summit from the same instrument setup point. You must work up the slope in a series of steps, as shown in figure 14-12, by establishing as many 14-11







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