The staff reading taken along a levelling operation are given below the instrument shifted after taking 5th, 10th , 14th and 19th reading.

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written 6.3 years ago by

teamques10 ★ 68k

Station	B.S	I.S	F.S	Rise	Fall	R.L	remark
1	1.355					185.205	1st RL
2		1.605			0.25	184.955
3		2.125			0.52	184.435
4		0.685		1.44		185.875
5	2.015		1.365		0.68	185.195	CP1
6		1.355		0.66		185.855
7		-1.385		2.74		188.595	Inverted staff reading
8		0.685			2.07	186.525
9	1.685		2.105		1.42	185.105	CP2
10		1.155		0.53		185.635	BM 185.635
11		1.105		0.05		185.685
12	1.085		2.015		0.91	184.775	CP3
13		1.345			0.26	184.515
14		1.355			0.01	184.505
15		-2.015		3.37		187.875	Inverted staff reading
16	1.655		1.305		3.32	184.555	CP4
17		1.685			0.03	184.525
18			1.455	0.23		184.755	Last RL
	∑B.S = 7.795		∑F.S = 8.245	∑RISE = 9.02	∑FALL = 9.47

Step1. Calculate rise and fall:

1. BS of point 1- IS of point 2 = 1.355- 1.605 = - 0.25 (-ve means fall)

2. IS of point 2 – IS of point 3 = 1.605 – 2.125 = -0.52 (- ve means fall)

3. IS of point 3 – IS of point 4 = 2.125 – 0.685 = + 1.44 (+ve means rise)

4. IS of point 4 – FS of point 5 = 0.685 – 1.365 = -0.68

5. BS of point 5 – IS of point 6 = 2.015- 1.355 = +0.66

6. IS of point 6 – IS of point 7 = 1.355-(-1.385)= +2.74

7. IS of point 7 – IS of point 8 = -1.385- 0.685= - 2.07

8. IS of point 8 – FS of point 9= 0.685- 2.105= - 1.42

9. BS of point 9 – IS of point 10 = 1.685 – 1.155=+0.53

10. IS of point 10 – IS of point 11= 1.155-1.105=+0.05

11. IS of point 11 – FS of point 12=1.105-2.015= -0.91

12. BS of point 12 – IS of point 13=1.085 – 1.345= -0.26

13. IS of point 13 – IS of point 14 =1.345-1.355=-0.01

14. IS of point 14 – IS of point 15=1.355-(-2.015)=+3.37

15. BS of point 16 – IS of point 17=1.655-1.685= -0.03

16. IS of point 17 – FS of point 18=1.685-1.455=+0.23

Step.2 - Calculate R.L:

note: (*upward direction sign,rise-ve,fall=ve)

(*downward direction rise+ve,fall-ve)

1.RL of 10th reading =185.635(given)

2. RL of 9 point= 185.635 – 0.53 = 185.105

3. RL of 8 point=185.105+1.42=186.525

4. RL of 7 point =186.525+2.07=188.595

5. RL of 6 point=188.595- 2.74=185.855

6. RL of 5 point=188.855+0.66=185.195

7. RL of 4 point=185.195+0.68=185.875

8. RL of 3 point=185.875-1.44=184.435**

9. RL of 2 point=184.435+0.52=184.955

10. RL of 1 point=184.955+0.25=185.205

11. RL of 11 point=185.635+0.05=185.685

12. RL of 12 point=185.685-0.91=184.775

13. RL of 13 point=184.775-0.26=184.515

14. RL of 14 point=184.515-0.01=184.505

15. RL of 15 point=184.505+3.37=187.875

16. RL of 16 point=187.875-3.32=184.555

17. RL of 17 point=184.555-0.03=184.525

18. RL of 18 point=184.525+0.23=184.755

check:

∑B.S - ∑F.S = ∑RISE - ∑FALL

(7.795 – 8.245 )=( 9.02 – 9.47) =(184.755 – 185.205)

    -0.45         =        -0.45       =       -0.45

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