The following readings were obtained during differential levelling. The reduced Level (RL) of point A is 240.000 m. The foresight and back sight between points A and TPI is 1.420 m and 2.024 m, respectively.
The following readings were obtained during differential levelling.
The reduced Level (RL) of point A is 240.000 m. The foresight and back sight between points A and TPI is 1.420 m and 2.024 m, respectively. Fore sight and back sight between points TP1 and TP2 is 2.100 m and 1.986 m, respectively. The back sight from B is 1.722 m. These are marked on the given figure. What is the RL at turning point-2 (TP2)? All values are in meters.
Right Answer is:
240.490 m
SOLUTION
The operation of levelling to determine the elevation of points at some distance apart is called differential levelling and is usually accomplished by direct levelling.
Start with A (+ve for up and –ve for down)
Elevation of TP2 compare to A
= +2.024 + (1.986 – 1.42) – 2.1
= + 0.49
∴ RL of TP2 = 240 + 0.49 = 240.49 m