Question

make a peg adjustment for the following notes:

When the wye level is at 1, the rod readings on P and Q are 0.750m and 2.766m respectively.

When the wye level is at 2, the rod readings on P and Q are 1.906m and 3.798m respectively.

Point 1 is on the same line PQ and midway between P and Q. Point 2 is on the same line as P and Q but not between them. Point 2 is 40m from P and 260m from Q. With the wye level at point 1

Determine the following for a level sight:

a.) Rod reading (m) at P

b.) Rod reading (m) at Q

Answer 1

Solution;- the values given in the question are as follows:

instrument is at point-1, so the reading on P and Q are 0.750 m and 2.766 m respectively

instrument is at point-2, so the reading on P and Q are 1.906 m and 3.798 m respectively

distance between P and point-2 is 40 m

distance between point-2 and Q, shown in figure given below.

(a), Calculating rod(staff) reading at point-1:-

let difference in elevation point P and point Q is ELPQ

difference in elevation point P and point Q (ELPQ)=2.766-0.75

difference in elevation point P and point Q(ELPQ)=2.016 m

let(assume) the ground is continuously sloping ground-

difference in elevation point P and point Q is 2.016 m occur in length 220 m

difference in elevation in the length 220 m is 2.016 m

so the difference in elevation in the length 110 m=2.016/2

difference in elevation in the length 110 m=1.008 m

point-1 in between the point P and Q

distance from point P to point-1 is 110 m

reading on staff at the point-1=reading on staff at point P+difference in elevation in the length 110 m  

reading on staff at the point-1=0.750+1.008

reading on staff at the point-1=1.758 m

(b), Calculating rod(staff) reading at point-2:-

difference in elevation point P and point Q (ELIPQ)=3.798-1.906

difference in elevation point P and point Q(ELIPQ)=1.892 m

let(assume) the ground is continuously sloping ground-

difference in elevation point P and point Q is 1.892 m occur in length 220 m

difference in elevation in the length 220 m is 1.892 m

so the difference in elevation in the length 40 m=1.892*(40/220)

difference in elevation in between the point P and point-1=0.344 m

reading on staff at the point-2=reading on staff at point P-difference in elevation in the point-P and point-2 m  

reading on staff at the point-2=1.906-0.344

reading on staff at the point-2=1.562 m

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