CEVB 211

SURVEYING PRACTICAL TRAINING

LABORATORY EXPERIMENT NO 6

TACHYMETRY

SECTION : 03

NAME : Zulaika Binti Mohd Fauzi : CE087587

GROUP NUMBER : 03

GROUP MEMBERS

1. Norshamirra Binti Mohd. Hijazzi CE087565

2. Antar Ali CE087529

3. Mohammed Noaman CE088674

4. Mohammad Ali Moayed CE088416

5. Haithm Awadh CE087546

6. Raziq Ahmad CE087570

7. Khaled Omar CE087550

DATE OF LABORATORY SESSION : 27.12.2012

DATE OF REPORT SUBMISSION : 26.12.201 2

LAB INSTRUCTOR : SIVADASS A/L THIRUCHELVAM

CriteriaScalePoor Acceptable Excellent

A. Appearance, formatting and grammar/ spelling.

1 2 3 4 5

B. Introduction, objective & theory 1 2 3 4 5C. List of apparatus & procedure 1 2 3 4 5D. Results: data, figures, graphs, tables, etc. 1 2 3 4 5E. Discussion 1 2 3 4 5

F. Conclusions 1 2 3 4 5

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Table of Contents

Title Page

Abstract 3

Objective 3

Instrument 3

Procedure 3

Data Collected and Results 4-5

Calculations 6-7

Discussion / Analysis 8 -9

Conclusion 9

Appendix 9 -10

Reference 10

2

Abstract

Tachymetry is a geodetic method enabling to measure angles and distances. The aim of this

practical training is to obtain the distance indirectly by using Tachymetry (stadia method). Our

lab instructor was told us to do this tachymetry at the same location as before when we are doing

theodolite surveying which is at BJ building. All measurement from one station to another

station had been measured before. Tachymetry was performed by the means of polar method in

local coordinate system with relative heights. The advantage of this method is its good regional

availability even at places far from the workplaces.

Objective

The objective of this practical training is to obtain the distance indirectly by using Tachymetry

(stadia method). This method is derived from optic principal.

Instrument

1) Digital theodolite (1 unit).

2) Tripod (3 units).

3) Target (2 units).

4) Staff (2 units).

5) Measurement tape (1 unit).

6) Hammer/nail/spray.

Procedure

1) Racky the area and the suitable location of the stations are determined.

2) The digital theodolite is set up on station 1 and the bearing is set from station 1-2. This

will be the datum for beginning the work.

3) The observation data is recorded i.e bearing, vertical angle and the staff readings (upper,

middle and lower stadia). The codes for each surveyed features is noted.

4) Once complete, the digital theodolite is shifted to the next station and the back bearing is

set (bearing 1-2). Step 3 is repeated.

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Data collected and result

Tachymetry Booking Form

Inst

.

Stn.

And

Ht.

of

inst.

Axis

Staf

f

stn.

Horizontal

angle

Vertical

angle, θ

Uppe

r

Stadi

a (m)

Middl

e

Stadia

(m)

Lower

Stadia

(5.297m

)

Horizontal

distance

H=100 scos2θ

(m)

Vertical distance

V=12

. 100 s sin 2θ

(m)

±V −Mid .

Reading

(m)

Ht.

of

inst

.

R.L. at

staff

(m)

Remark

s

A1 25º56’45” 1.484 1.461 1.438 4.600 0.046 -1.415 100.000

A2 87º32’14” 1.470 1.449 1.425 4.500 0.045 -1.404 100.011

1 A3 108º43’11” 00º34’04”

1.342 1.320 1.297 4.500 0.045 -1.275 1.52 100.140

A4139º35’06” 1.600 1.575 1.550 5.000 0.050 -1.525 99.900

A5 169º51’56” 1.544 1.515 1.485 5.899 0.058 -1.457 99.968

4

B1 28º12’44” 1.330 1.315 1.300 2.999 0.063 -1.252 99.895

B2 49º44’50” 1.120 1.100 1.080 3.998 0.084 -1.016 100.131

2B3

80º31’87” 01º11’57”

1.266 1.247 1.229 3.698 0.077 -1.170 1.45 99.977

B4 119º09’50” 1.292 1.277 1.260 3.199 0.067 -1.210 99.957

B5145º02’36” 1.379 1.362 1.343 3.598 0.075 -1.287 99.880

C123º07’20” 1.230 1.225 1.210 1.999 0.047 -1.178 99.697

3C2

55º55’43” 1.088 1.069 1.050 3.798 0.090 -0.979 99.896

C375º17’38” 01º21’24

”0.930 0.910 0.889 4.098 0.097 -0.813 1.34 100.06

2

C485°34′48″ 0.942 0.921 0.889 5.299 0.125 -0.796 100.07

9

C5112°00’37

”0.869 0.841 0.816 5.297 0.125 -0.716 100.15

9

5

D119º26’47” 0.702 0.679 0.657 4.407 0.651 -0.028 99.535

D254º14’01” 0.502 0.478 0.449 5.190 0.766 0.288 99.851

4D3

70º08’11” 08º17’13”

0.484 0.461 0.433 4.994 0.737 0.276 1.39 99.839

D4101°35′55″ 0.878 0.862 0.849 2.840 0.419 -0.443 99.120

D5132°47′19″ 0.871 0.858 0.844 2.644 0.390 -0.468 99.095

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Sample calculation

The horizontal and vertical angles as well the upper, middle and lower stadia readings are

determined directly from the theodolite during the survey process.

Hence, obtained for staff station A1:

Horizontal angle, = 87º32’14” Upper stadia = 1.470m

Vertical angle, = 00º34’04” Middle stadia = 1.449m

Lower stadia = 1.425m

Horizontal distance , H = 100s cos2

where s = upper stadia – lower stadia, = vertical angle ; 00º34’04”

Hence, horizontal distance for A1 = 100x (1.470-1.425) cos2 (00º34’04” )

= 4.500m

Vertical distance, V= ½ x 100s sin 2

where s = upper stadia – lower stadia, = vertical angle ; 00º34’04”

Hence, vertical distance for A1 = ½ x 100 (1.470-1.425) sin 2(00º34’04”

= 0.045m

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±V −Mid .reading = Vertical distance – middle stadia reading

Hence, V-midreading for 1 = 0.045 -1.449

= -1.404 m

Reduced Level (RL) of staff = Known RL1 + height of instrument ± (V-mid.reading)

Here the known RL at point 1 given is 100.000m and the height of instrument measured at point

2 is 1.52m.

First, we have to find the RL of station 2 based on RL on station 1:

RL at station 2 = RL at point 1 + m ±V - HI

= 100 +1.415-1.52

= 99.895 m

Therefore RL at station 3 = RL at point 2 + HI + V – m

= 99.895 + 1.252 -1.45

= 99.697 m

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Discussion

Generally, horizontal distances are measured by direct methods, for an example laying of chains

or tapes on ground. These methods are not always convenient if the ground is undulating, rough,

difficult and inaccessible. Under these circumstances, indirect methods are used to obtain

distances. One such method is Tacheometry. Using tacheometric methods, elevations can also be

determined. It is in fact a branch of angular surveying in which both the horizontal and vertical

positions of points are determined from the instrumental observations, the chain surveys being

entirely eliminated.

The horizontal distance that we obtained indirectly which means from the calculation are 4.600,

4.500, 4.500, 5.000 and 5.899 m at the staff station of A1, A2, A3, A4, A5 respectively. Then,

the horizontal distance at the staff station of B1, B2, B3, B4, B5 are 2.999, 3.998, 3.698, 3.199,

and 3.589 m respectively. Same goes to staff station C1, C2,C3, C4, C5 the horizontal distance

are 1.999, 3.798, 4.098, 5.299, and 5.297 m. last but not least at the staff station D1,

D2,D3,D4,D5 the horizontal distance are 4.407, 5.190, 4.994,2.840, and 2.644 m respectively.

Meanwhile, the vertical distance at the staff station A1, A2, A3, A4, A5 are 0.046, 0.045, 0.045,

0.050, and 0.058 m respectively. For the staff station at B1, B2, B3, B4, B5 the vertical distance

are 0.063, 0.084, 0.077, 0.067, 0.075 m. Then for the staff station at C1, C2,C3, C4, C5 the

vertical distance are 0.047, 0.090, 0.097, 0.125, and 0.125 m respectively. Last but not least, at

the staff station D1, D2,D3,D4,D5 the vertical distance are 0.651, 0.766, 0.737, 0.419, and 0.390

respectively.

There are a lots of difficulties faced and errors that might occurred when the experiment is

conducted means that, all distance, angle and measurements taken have errors. The problems we

have faced in this practical training like the location we have choose got many obstacle that

block our vision besides the climate was not good when we are doing this tachymetry because its

raining. Apart from that, the instrument also may not correctly leveled, means the bubble most

likely is not be in the center, then it will affect the telescope to not correctly focused. This may

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come out with the presence of parallax. Parallax results when the optics are out of adjustment.

The parallax may be determined by nodding the head up and down while looking through the

telescope. There is no movement of the image relative to the cross hairs. Movement indicates

parallax is present and adjustment is needed. The parallax may be eliminated by properly

focusing the telescope. Furthermore, the staff is incorrectly read or not held vertical. All the

above are mistakes (blunders) and cannot be corrected unless the work is repeated.

Conclusion

In conclusion, the objective of this experiment has been satisfied. By doing this practical training

we are able to explain the principle of tachymetry, as well as we have already the stadia

principles. Overall, the results obtained from this experiment are satisfactory considering that it

meets its main objectives.

Appendices

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Reference

1) www.tachymeter_online_tachymetry_unskilled_191773.html2) http://www.safetylit.org/citations/index.php?fuseaction=citation3) Notes given by Dr. Birima4) http://vedyadhara.ignou.ac.in/wiki/images/e/e0/UNIT_2(CRC).pdf

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