land surveying using auto level leveling

8/20/2019 Land Surveying Using Auto Level Leveling

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Objectives

To learn to apply a system approach to a plan, execute and manage a survey given

specification as a group

To learn and undertake site measurements and calculations using proper equations

To learn how to analyze data with respect to error theory and produce scale plots

To learn how to work in a team

Read information from maps and plans

To learn how to use the survey equipment such as total stations and auto level

To learn how to interpret the data obtained and how to use the spread sheets to reduce,

adjust and analyze the data


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Introduction

According to J. Uren’s and W.F.Price’s book, Surveying for Engineers, they describe surveying

as an art of determining the relative positions of different object on the surface of the earth by

measuring the horizontal distance between them and by preparing a map to any suitable scale.

Engineering surveying involves the following:

Investigating land, using computer based measuring instruments and geographical

knowledge, to work out the best position to construct bridges, tunnels and roads.

Producing up-to-date plans which form the basis for the design of a project.

Setting out a site, so that a structure is built in the correct location and to the correct

size.

Monitoring the construction process to make sure that the structure remains in the rightposition and recording the final as-built position.

Providing control points by which the future movement of structures such as dam and

bridges can be monitored.

J. Uren & W.F. Price (2006)


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We carried out the task at Lanjut Resort (4.210484, 101.9755766) Latitude and Longitude of the

place. We spent one week over there and one task was carried out every day. It usually began

after breakfast at 9-10am and we were usually done by 2-3pm. We had rain interruption on

Friday which was why our readings for task 4 had a little more margin of error.

The report is separated into four different tasks:

Task 1: Polar radiation survey

Task 2: Closed loop traverse survey

Task 3: Setting out of building outline (levelling)

Task 4: Curve re-alignment survey


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General Introduction

A dictionary definition of engineering surveying is that:

The measurement, definition and portrayal, either digitally or graphically in the form of

maps or plans, of the physical features of, and the structures on the Earth’s surface. The

ability to understand engineering design information and from this provide dimensional

control for all stages of construction work.

So in simple words, surveying is used in engineering to measure the heights, angles and

distances between two or more points on a landmark.

Heribert Kahmen & Wolfgang Kaig (1988)

In this assignment, we have carried out four different tasks. After collecting initial results, I have

used trigonometry equations and other basic surveying formulas to calculate various different

readings and values.

I have used the basic designing skills to draw Auto Cad 2D and 3D drawings which were

required for the tasks one to four.

I have also discussed the different sources of errors which took place during the surveying and

how to improve those errors and the discussion of the accuracy of the readings obtained.

I have also noted down what was my experience from the surveying camp and the surveying

assignment which I have produced as a result. What I have learnt from the experience and how

this has expanded my knowledge of civil engineering.


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We took the reading of the hotel lobby. We took measurements of all the columns at the hotel

lobby. We will use the readings to obtain X, Y and Z using trigonometry equations.

Civil engineering – The design and construction for engineering projects, such as public andprivate works, such as infrastructure (roads, railways, water supply & treatment etc), pipelines,

dams & reservoirs, bridges & tunnels, and buildings.

Engineering surveying covers the detailed surveys required for design of engineering projects

(roads, bridges, dams, buildings, tunnels etc) as well as the setting out and monitoring of the

subsequent construction or structures.

C.L. Berger Sons (2010)

Construction surveying setting out involves staking out reference points & markers that will

guide the construction of new structures such as roads or buildings for subsequent construction.

Building or construction projects relates to specific structures e.g. low level; medium to high rise

buildings, stadiums; residential buildings; standard & odd shaped structures, etc. It can include

civil structures, (such as bridges, tunnels, dams, drainage facilities such as treatment plants,

pump stations) with significant structural elements involved.



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SURVEY TYPES

Engineering surveys

• Engineering surveys are conducted to obtain data essential for planning, estimating, locating

and layout for the various phases of projects. The objectives of engineering surveys include

obtaining preliminary data required for selecting suitable routes and sites and for preparing

structural designs, establishing a system of reference points, and marking lines, grades and

principal points.

David Allen (2010)

Principles of Surveying

• There are a few rules that apply to all categories and whenever field work is being carried out

& should be adhered to at all times.

David Allen (2010)

Accuracy

Use of instruments to measure angles, distances and level (requires techniques & procedures

to be mastered). Important to realise that Absolute precision can never be obtained, despite

ideal conditions and the use of the best equipment & techniques

Errors

Much of what is done in surveying is prone to errors

Gross (mistakes), systematic & random (unavoidable)

Mistakes arise from inattention, inexperience and carelessness. Important to adopt procedures

or independent checks that eliminate or isolate such errors. Systematic errors are those which

may exist but whose pattern and effects are known, can be monitored and compensated for by

application of appropriate corrections. (e.g. EDM distance; - also measure temp & pressure)

David Allen (2010)

Random errors are unavoidable & due to imperfections in instruments used, human elements

such as eyesight, & inconsistent conditions that cause such errors.


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Survey methods

Surveys can usually be executed in several ways by a combination of instruments and methods.

Main factors to consider when deciding upon technique to be used:

Purpose & extent of the survey

Degree of accuracy required

Control of errors

Nature of the country (i.e. topography, vegetation, visibility & access issues, etc)

Commercial issues (i.e. budget & programme considerations)


Good survey practice (As a general guide)

Use equipment which is well maintained, regularly checked and “calibrated”

Analyse acceptable error limits for each component of the survey (i.e. set the target accuracy

specification). Be aware of likely error sources; resolve existing & underlying errors (don’t

introduce new ones)

Confirm with defendable marking, measuring, recording and processing methods.

ALWAYS take check (‘redundant’) measurements.

Be careful & objective when collecting, assessing and recording measurements & data, & while

documenting and analysing results. (Don’t cook the books!!)


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Setting Out

Definition

Setting out is the establishment of marks & lines to define the position & level of elements of the

construction work so that works may proceed with reference to them. This process may be

contrasted with the purpose of Surveying which is to determine by measurement the positions of

existing features.-


Alternate definition is that setting out is the reverse of Surveying. (i.e. surveying is a process of

producing a plan or a map of a particular area, setting out begins with the plan and ends with

the various elements of an engineering project correctly positioned in the area.

(Uren, J. et al 2006)

Attitudes to setting out vary from site to site, with generally insufficient importance attached to

the process.

It tends to be rushed (time constraints & pressure from contractors), often leading to errors & in

some cases resultant costly corrections.

Good work practices & techniques in setting out essential to minimise errors & to ensure the

construction process proceeds smoothly.

Good knowledge is vital, as the setting out phase is one of the most important stages in any civil

engineering construction project.

Setting out aims

The aims of setting out are to position the works in their correct relative spatial and absolute

positions, & to ensure that they proceed smoothly and that their costs are minimised. (Uren,

J. et al 2006)

Chances of this aim being achieved will be greatly enhanced by the use of suitable control

methods, availability & reference to correct plans, and where good working practices are

adopted.


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Two main aims:

Various elements of the scheme must be correct in all three-dimensions both relative and

absolute (i.e. correct size, plan position & reduced level).

Once set-out begins, it must proceed quickly & with little or no delay so the works can proceed

smoothly and costs can be minimised.

David Allen (2010)

Apparatus

The following apparatus were used for the first task

Traverse booking sheet

Levelling booking sheet

Total station

Prism

Tripod

Measurement tape

Field record book

Pen

Recording sheet

Staff

(Assignment Brief)


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Procedure

There are three main steps to follow when setting up the total station:

Centering the total station

Levelling the total station

Elimination of parallax

The first step is to set up the tripod over the peg. The legs of the tripod are placed an equal

distance from the peg and are extended to suit the observer’s height.

The total station is then taken out of its case, and carefully placed on top of the tripod. It is

screwed onto the tripod.

The ground mark (peg) is focused now through the optical plummet. The three foot screws are

adjusted until the peg can be seen in clear focus.

The circular bubble on the upper part of the total station is now adjusted till it is centered by

adjusting the individual tripod legs.

The final step is to centre the plate level bubble which is done by adjusting the foot screws.

Once the bubble is in the center, the instrument is turned 90° and the bubble is checked again.

If it is still in the centre, then the instrument is ready for measurements to be taken.

Wilfred Schofield & Mark Breach (2007)


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Fig 1.2 The drawing explains the angle we were measuring at the hotel lobby room

(Wilfred Schofield & Mark Breach (2007)

ST Line Face left Face right


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XK1 34 01 40 214 01 10

XK2 34 01 40 214 01 10

XL1 89 16 20 269 16 41XL2 89 16 20 269 16 41

After we found the face right and face left from the site, we shall use equations to find the other

data which we need:

Mean

There are two conditions when we are finding the mean:

If face left is bigger than the face right:

ℎ 180°2

If face left is smaller than the face right:

ℎ − 180°2

Mean in radians form

We use the following formula to convert the means from degrees to radians

Angle x °⁄

The next step is to obtain the HD which we can get by using the measuring tape. We measure

from the centre of the tripod to the point. The readings are in metres.

Calculation of WCB

Back Bearing = Forward Bearing - 180° if the forward bearing is greater than 180°

Back Bearing = Forward Bearing + 180° if the forward bearing is less than 180°


Line Mean Reduced angle Whole circle bearing


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Degree Minutes Seconds Degree Minutes Second Degree Minutes SecondXA1 223 10 31 00 00 00 00 00 00XA2 223 10 31 00 00 00 00 00 00

XD04 223 57 4.5 00 46 33.5 00 46 33.5XD03 223 57 4.5 00 46 33.5 00 46 33.5

XD01 229 58 06 06 47 35 06 47 35XD02 229 58 06 06 47 35 06 47 35

XB3 238 59 21.5 15 48 50.5 15 48 50.5XB2 239 06 3.5 15 55 32.5 15 55 32.5

XB1 239 21 37 16 11 06 16 11 06

XB4 278 14 57.5 55 04 26.5 55 04 26.5XB5 278 14 57.5 55 04 26.5 55 04 26.5

XC1 281 14 47 58 04 16 58 04 16XC2 281 14 47 58 04 16 58 04 16

XD1 301 30 32.5 78 20 1.5 78 20 1.5XD2 301 30 32.5 78 20 1.5 78 20 1.5

XE1 271 10 40 48 00 09 48 00 09XE2 271 10 40 48 00 09 48 00 09

XF1 208 02 55.5 344 52 24.5 344 52 24.5XF2 208 02 55.5 344 52 24.5 344 52 24.5

XG1 142 36 06 279 25 35 279 25 35XG2 142 36 06 279 25 35 279 25 35

XH1 339 45 24.5 116 34 53.5 116 34 53.5XH2 339 45 24.5 116 34 53.5 116 34 53.5

XI1 333 26 36 110 16 05 110 16 05XI2 333 26 36 110 16 05 110 16 05

XJ1 347 58 32.5 124 48 1.5 124 48 1.5XJ2 347 58 32.5 124 48 1.5 124 48 1.5

XJ3 01 25 17.5 138 14 46.5 138 14 46.5XJ4 01 25 17.5 138 14 46.5 138 14 46.5

XJ5 22 46 12 159 35 41 159 35 41XJ6 22 46 12 159 35 41 159 35 41

XK1 34 01 25 170 50 54 170 50 54


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XK2 34 01 25 170 50 54 170 50 54

XL1 89 16 30.50 226 05 59.50 226 05 59.50

XL2 89 16 30.50 226 05 59.50 226 05 59.50

The next step is to find the ∆E Easting and ∆N Northing using the following formula:

Northing ∆N Equation used

HD x Sin Angle x °⁄

The calculator should be in radians form

11.66 x Sin 00°46’33.50” x °⁄ = 11.658

8.78 x Sin 15°48’50.5” x °⁄ =8.447

The triangle shows the ∆N and ∆E and how it is used for the trigonometric valuesobtained

Easting ∆E Equation used


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HD x Cos Angle x °⁄


11.66 x Cos 00°46’33.50” x °⁄ = 0.15791

8.78 x Cos 15°48’50.5” x °⁄ = 2.3926

The triangle shows the ∆N and ∆E and how it is used for the trigonometric valuesobtained

After this, we shall obtain the ∆E and ∆N using last three digits of my passport numberplus 100. My passport number is so for X it will be 106, Y is 100 and Z is 100.

X = 106 + ∆E

X = 106 + 0.1579 = 106.1579

Y = 100 + ∆N

Y = 100 + 11.65893 = 111.65893

Line Degree Radians Length ∆E ∆N X Y

106 100


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XA1 0 0 12.2 0 12.2 106 12.2

XA2 0 0 12.2 0 12.2 106 12.2

XD04 0.775972 0.013543 11.66 0.15791 11.65893 106.1579 111.6589XD03 0.775972 0.013543 11.66 0.15791 11.65893 106.1579 111.6589

XD01 6.793056 0.118561 11.8 1.395747 11.71716 107.3957 111.7172XD02 6.793056 0.118561 11.8 1.395747 11.71716 107.3957 111.7172

XB3 15.81403 0.276007 8.78 2.392689 8.447688 108.3927 108.4477

XB2 15.92569 0.277956 8.78 2.409148 8.443009 108.4091 108.443

XB1 16.185 0.282482 11.42 3.183207 10.96739 109.1832 110.9674

XB4 55.07403 0.961223 11.1 9.100806 6.354945 115.1008 106.3549

XB5 55.07403 0.961223 11.1 9.100806 6.354945 115.1008 106.3549

XC1 58.07111 1.013532 15.4 13.07006 8.144541 119.0701 108.1445XC2 58.07111 1.013532 15.4 13.07006 8.144541 119.0701 108.1445

XD1 78.33375 1.367182 11.35 11.11553 2.295089 117.1155 102.2951

XD2 78.33375 1.367182 11.35 11.11553 2.295089 117.1155 102.2951

XE1 48.0025 0.837802 6.25 4.644838 4.181864 110.6448 104.1819

XE2 48.0025 0.837802 6.25 4.644838 4.181864 110.6448 104.1819

XF1 344.8735 6.019178 6.42 -1.67531 6.197559 104.3247 106.1976

XF2 344.8735 6.019178 6.42 -1.67531 6.197559 104.3247 106.1976

XG1 279.4264 4.876911 3.4 3.35409 0.556853 102.6459 100.5569XG2 279.4264 4.876911 3.4 3.35409 0.556853 102.6459 100.5569

XH1 116.5815 2.034732 3.1 2.772325 -1.38716 108.7723 98.61284

XH2 116.5815 2.034732 3.1 2.772325 -1.38716 108.7723 98.61284

XI1 110.2681 1.924541 9.9 9.287014 -3.42949 115.287 96.57051

XI2 110.2681 1.924541 9.9 9.287014 -3.42949 115.287 96.57051

XJ1 124.8004 2.178178 10.1 8.293565 -5.76427 114.2936 94.25373

XJ2 124.8004 2.178178 10.1 8.293565 -5.76427 114.2936 94.25373

XJ3 138.2463 2.412852 5.9 3.92899 -4.40148 109.929 95.59852XJ4 138.2463 2.412852 5.9 3.92899 -4.40148 109.929 95.59852

XJ5 159.5947 2.785453 8.35 2.911298 -7.82604 108.9113 92.17396

XJ6 159.5947 2.785453 8.35 2.911298 -7.82604 108.9113 92.17396

XK1 170.8483 2.981866 7.17 1.140377 -7.07873 107.1404 92.92127

XK2 170.8483 2.981866 7.17 1.140377 -7.07873 107.1404 92.92127


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XL1 226.0999 3.946187 7.3 -5.26001 -5.06185 100.74 94.93815XL2 226.0999 3.946187 7.3 -5.26001 -5.06185 100.74 94.93815

Vertical Data

Line Face Right Face Left

XA1 97 16 0 262 44 10

XA2 81 17 0 278 43 20

XDO4 87 15 0 272 45 30

XDO3 97 27 20 262 32 50

XDO1 97 24 20 262 35 30

XDO2 87 18 20 272 41 10

XB3 92 16 20 267 43 50

XB2 99 47 40 260 12 20

XB1 92 4 0 267 56 20

XB4 97 49 20 262 10 30

XB5 91 48 0 268 12 20

XC1 95 41 20 264 18 10


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XC2 83 8 40 276 51 50

XD1 97 40 0 262 20 30

XD2 80 42 0 279 18 40

XE1 103 43 40 256 16 50

XE2 73 21 26 286 38 0

XF1 103 29 0 256 31 10

XF2 73 58 20 286 1 0

XG1 114 22 40 245 37 30

XG2 60 40 0 299 20 50

XH1 116 14 40 243 45 0

XH2 58 29 20 301 30 0

XI1 98 49 0 261 11 40

XI2 79 26 20 280 33 50

XJ1 98 40 0 261 20 40

XJ2 84 48 20 275 11 20

XJ3 104 31 20 255 28 20

XJ4 81 57 20 278 2 0


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XJ5 100 29 40 259 30 10

XJ6 84 36 40 275 23 10

XK1 102 7 0 257 53 50

XK2 75 21 0 284 40 30

XL1 101 51 20 258 8 40

XL2 76 39 20 284 20 0

Mean

To calculate the mean, the following equation was used:

(90° − ) ( ℎ − 270°)

2

XA1

(90° − 97°16′00") (262°42′10" − 270°)

2

= - 7°15’55”

Reduce Face Left

90° - Face Left

90° − 97°16′00"

= -7°16’00”

Reduce Face Right

ℎ − 270°

262°42′10" − 270°


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=--7°17’50”

The next step is to obtain the vertical distance. In this case, the distance is found by the

following equation:

VD = Tan Mean Angle x Length

VD = Tan -7°15’55” x 12.2

VD = -1.555

The next step is to add the VD to 100 to find Z

VD + 100 = Z

-1.555 + 100 = Z

99.975 = Z

Reduced Face Right Reduced Face Left MEAN


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7 16 0 7 15 50 7 15 55

8 43 0 8 43 20 8 43 10

2 45 0 2 45 30 2 45 15

7 27 20 7 27 10 7 27 15

7 24 20 7 24 30 7 24 25

2 41 40 2 41 10 2 41 25

2 16 20 2 16 10 2 16 15

9 47 40 9 47 40 9 47 40

2 4 0 2 3 40 2 3 50

7 49 20 7 49 30 7 49 25

1 48 0 1 47 40 1 47 50

5 41 20 5 41 50 5 41 35

6 51 20 6 51 50 6 51 35

7 40 0 7 39 30 7 39 45

9 18 0 9 18 40 9 18 20

13 43 40 13 43 10 13 43 25


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16 38 34 16 38 0 16 38 17

13 29 0 13 28 50 13 28 55

16 1 40 16 1 0 16 1 20

24 22 40 24 22 30 24 22 35

29 20 0 29 20 50 29 20 25

26 14 40 26 15 0 26 14 50

31 30 40 31 30 0 31 30 20

8 49 0 8 48 20 8 48 40

10 33 40 10 33 50 10 33 45

8 40 0 8 39 20 8 39 40

5 11 40 5 11 20 5 11 30

14 31 20 14 31 40 14 31 30

9 2 40 9 2 0 9 2 20

10 29 40 10 29 50 10 29 45

6 23 20 6 23 10 6 23 15

12 7 0 12 6 10 12 6 35

14 40 0 14 40 30 14 40 15


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11 51 20 11 51 20 11 51 20

14 20 40 14 20 0 14 20 20

VD = Tan Mean Angle x Length

VD = Tan -7°15’55” x 12.2

VD = -1.555

The next step is to add the VD to 100 to find Z

VD + 100 = Z

-1.555 + 100 = Z

99.975 = Z


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Length HI V.D Z

100 100

12.2 101.53 -1.555 99.975

12.2 101.53 1.871 103.401

11.66 101.53 0.561 102.091

11.66 101.53 -1.526 100.004

11.8 101.53 -1.534 99.996

11.8 101.53 0.554 102.084

8.78 101.53 0.348 101.878

8.78 101.53 -1.516 100.014

11.42 101.53 -0.413 101.117

11.1 101.53 -1.525 100.005

11.1 101.53 -0.348 101.182

15.4 101.53 -1.535 99.995

15.4 101.53 1.853 103.383

11.35 101.53 -1.527 100.003

11.35 101.53 1.86 103.39


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6.25 101.53 -1.526 100.004

6.25 101.53 1.868 103.398

6.42 101.53 -1.539 99.991

6.42 101.53 1.844 103.374

3.4 101.53 -1.541 99.989

3.4 101.53 1.911 103.441

3.1 101.53 -1.529 100.001

3.1 101.53 1.9 103.43

9.9 101.53 -1.535 99.995

9.9 101.53 1.846 103.376

10.1 101.53 -1.538 99.992

10.1 101.53 0.918 102.448

5.9 101.53 -1.529 100.001

5.9 101.53 0.939 102.469

8.35 101.53 -1.547 99.983

8.35 101.53 0.935 102.465

7.17 101.53 -1.538 99.992


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7.17 101.53 1.877 103.407

7.3 101.53 -1.532 99.998

7.3 101.53 1.866 103.396

The height of the instrument is 1.53m.


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Discussion and Analysis

The experiment was successfully carried out. We found the face right and face left of the whole

reception at Lanjut Resort and then we proceeded for the calculations part using the equations

as shown above for mean, whole circle bearing, X, Y and Z.


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The precise observation of angles is dependent on the perpendicularity of the primary axes of

the total station. The plate level vial axis must be perpendicular to the vertical axis. The vertical

axis must be perpendicular to the horizontal axis. The axis of the line of sight must be

perpendicular to the horizontal axis.

There are many different types of errors which have occurred at the sight:

Instrumental : Plate level vial out of adjustment

Detection: Level instrument in two directions as per typical setup. Rotate instrument 180° from

either of these directions, and bubble should remain centred. Any mis-centering indicates that

the plate level vial axis is not perpendicular to the vertical axis.

Correction: Level instrument with bubble not centred by 1/2 of the detected error (bubble run),

or follow manufacturer's procedure for removal of error.

Horizontal axis not perpendicular to vertical axis

This error causes errors in both horizontal and vertical angles since telescope travels in inclined

plane instead of vertical plane.

Error can be removed by observing angles in both direct and reversed mode, and averaging.

Dual-axis compensators can remove this error is the instrument is properly calibrated.


Axis of sight not perpendicular to horizontal axis


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This error causes the telescope to scribe out a cone when it is plunged.

Corrected by using double-centering technique when extending a line, and by doubling

angles (measuring in both direct and reversed modes.)

Vertical indexing error

Eccentricity of the plates-Occurs when vertical axis of instrument does not coincide with centre

of plates. Compensated for by taking several readings about the plates and averaging. This

happens automatically in surveying grade instruments.

Circle graduation errors - Caused by irregularities in marking of plates. Take many reading

about the plates and average. This is generally handled by modern total stations.

Errors caused by peripheral equipment - Be sure that tripods and targets are mechanically

sound and in adjustment. Use targets that are appropriate for sight distances.

Natural errors

Wind. Vibrates tripod and target in windy condition. When this happens you can (1) protect

instrument from wind by using shield, or (2) Wait until wind speed reduces.

Temperature

It can cause uneven expansion of tripod and instrument parts resulting in instrument

mislevelling. When this happens you can shield instrument using umbrella.

Refraction

Causes bending of sight line. Avoid having sight line close to objects (within 0.5 m) that can

create microclimates such as the ground, cars, and large trees. When this cannot be done,

postpone observations until better conditions exist.

Tripod setting


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Avoid situation where legs are placed on different surfaces, and extreme soft-ground

conditions. When this cannot be avoided such as in marshes and swamps, pound long wooden

stakes flush with surface and set tripod on stakes. Most total station instruments have sensors

to suspend observations when mislevelling becomes too great.

Personal errors-

Instrument not centred

Can cause observed angle to be too large or small. Carefully centre and level instrument. Size

of error is reduced when angles have long sight lengths.

Target not centred

Can cause observed angle to be too large or small. Use long sight distances to reduce effect

on observed angles.

Improper use of clamps and tangent screws

Practice in formation of good observing habits and familiarity with equipment will reduce these

errors.

Poor focusing

One of the most common errors. Be sure parallax is removed before taking observation. Avoiddifferent operators during observation procedure.

Overly careful sights

This is a common beginner error. Take careful sights on targets, but do not redo procedure.

Beginners tend to observe, then reobserve, then reobserve ... before taking sight. This process

results in unsettling instrument and reducing pointing accuracy. Trust your eyes.



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Autocad Drawings

Figure 1.9: 3D drawing of the Lobby Room from the top front

Fig 1.94: Another top view showing the columns and hotel reception with entrance and

door


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Fig 1.95: Showing the columns and reception from front top view

Fig 1.96: Shows the columns and front reception from side top view


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Fig 1.97: Shows the columns and reception from reception view

Sketches


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ConclusionSo I can further conclude that the experiment was successfully carried out and all of the

requirements for this task were completed as scheduled.

I have learnt from this task on the methodology involved with setting out, how it is carried out,

and what the necessary precautions which have to be taken are and at the same time the errors

involved with setting out.


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Task 2 Close loop traverse of a control survey

According to J. Uren and W.F. Price, a traverse is defined as a chain of straight lines which is

used as a basis for the measurement of details. A traverse is produced and developed by

measuring the internal angles and distances between points forming a boundary of the site. We

shall be measuring close traverse in this task, where area will be found of a piece of land. Each

of these straight lines is called a traverse leg and each point is called a traverse station.

Figure 2.0: Close Traverse

Close traverse

A close traverse begins and ends at the same point whose position is known. The closed

traverse is mostly used for locating the boundaries at lakes, woods, or grasslands.


Open traverse

An open or free traverse contains a series of linked traverse lines which do not return to the

starting point. They are mainly used for road constructions.

Fieldwork

In a traverse, there are three stations which are considered to be of importance. The stations

are referred to as the rear station, the occupied station and the forward station.


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Rear station: it is the one from which the person who is performing the traverse has just moved

to or a point to which the azimuth is known. It is the starting point.

Occupied station: it is the station at which the angle-measuring instrument is set up. This is the

point which the person is measuring.

Forward station: it is the next station which the person will measure in succession.

During the traverse, the horizontal angles, vertical angles and horizontal distances are

measured.

Fig 2.2: It shows the basic concept behind traversing

Horizontal angles: these are determined from instrument readings made at the occupied

station by sighting the instrument on the rear station and turning the instrument clockwise to the

forward station. When measuring horizontal angles, the instrument is always sighted at the

lowest visible point of the station markers designated the rear and forward stations. It is done in

order to avoid errors and have a more accurate drawing. Horizontal angles are used in

determining bearings.

Vertical angles: these are determined from instrument readings made at the occupied station

to the height of instrument on the station marker (using a staff) at the forward station. Vertical

angles are used in determining the difference in height between stations.

Distance: the distance was measured by using a 30 meters measuring tape. The distance is

very important as it helps to determine coordinates and heights.


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The equipment used was the total station. A total station is defined as a device which in

combination with a theodolite and an EDM together with an inboard computer or

microprocessor, has the capacity to perform various computations such as determining the

horizontal and vertical components of slope distances, computing elevations and coordinates of

sighted points.


Errors in traverse method

Inaccurate centering of the theodolite, total stations or target

Non-verticality of targets

Inaccurate bisection of targets

Parallax not eliminated

Lateral refraction, wind and atmospheric effects

Theodolite or total stations not level or not in adjustment

Incorrect use of the theodolite or total stations

Mistakes in writing the readings and bookings


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Levelling work

Equipment used

Auto level is used to carry out levelling. It is set up on a tripod and a staff is used to take the

measurements. The staff bubble should be accurately centered in order to obtain a highly

accurate reading. After use, all the equipment used should be carefully stored with care.

Setting it up

Setup your tripod as level as possible, step on tripod legs to drive into the

ground.

Attach auto level to the tripod.

Adjust level so bubble is centred in vial.

Adjust recital until crosshairs are clear.

Adjust the objective lens until object you are sighting on is clear.


Care of Auto Levels

If the instrument becomes wet leave it unpacked. Wipe down instrument, clean and dry

transport case. Pack up instrument only when it is perfectly dry. Never touch the glass

with fingers, use soft clean lint-free cloth to clean lens.

Checking Auto Level Accuracy

Set up instrument in an area that is as level as possible and which is about 65

metres long. Place two matching level rods or two pieces of strapping in the

ground about 15 meters apart with the faces toward each other. Position and

level the instrument so that the distance from the instrument to each rod is the

same measure.

Take a reading on each rod with the instrument (or mark each piece of strapping

where the crosshair is sighted).


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Move transit to another spot on the line and take readings and mark both rods

again.

The difference between the marks on the rod will be the error of the instrument.

The error needs to be corrected by a competent repair technician.


Parallax Error

It occurs when the image of the staff doesn’t fall exactly on the plane of the diaphragm or when

the focal point is not found in the plane of the diaphragm.

In our case, parallax error was avoided by using two different group members; they moved their

eyes to different parts of the eyepiece when viewing the staff held by another group member.

There was a slight change in the positions of the target and it was concluded that parallax error

is present and since it couldn’t be completely eliminated, it was found in acceptable range.

Bookings

Details of the site, work, date, observer, weather, wind, instrument and all other

important information should be recorded

Levelling sheets were printed and used for recording the measurements and all of them

were numbered accordingly in order to keep track and not get recordings mismatched

Reduced level

HPC method and Rise and fall method are used to find the reduced level. The height of the

instrument used is 1.53m.



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Apparatus used



Total station Prism

Tripod

Automatic level

Measurement tape

Wooden peg

Field record book

Health and safety equipments

Pen

Recording sheet

Nails

Spray paint

Staff

Procedure

a. First, we set up the bench mark. By referring to it, we placed the tripod on the ground

and opened its legs. We first placed two legs into the ground and then the third one.

Each of them were equally apart from each other roughly.

b. We placed the theodolite on top of the tripod and then centred the bubbles to obtain

accurate readings. Adjust recital until crosshairs are clear.

c. We remove the black casing from the front lens and then switch on the theodolite. We

reset it to zero. The nail with the spray paint is seen using the lens on the ground and

until it is visible, the theodolite is then set up to be used.

d. We take the reading of the bench mark and the point 20 from behind. We then set it to

zero again and take the point number 2 in front.

e. We take the horizontal distance by using the measuring tape. Every group member was

assigned a different role in order to complete the task on time and more accurately.

f. The total angles for our case was 3240° since the equation is (n-2)*180°. After doing the

calculations, the angles were re-aligned while maintaining the same distance due to

errors.


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Calculation of WCB and Back Bearing

We then have to calculate the Whole Circle Bearing and Back Bearing of each point. Theback bearing is defined as the angle from the south line of the same point.

Back Bearing = Forward Bearing - 180° if the forward bearing is greater than 180°

Back Bearing = Forward Bearing + 180° if the forward bearing is less than 180°

The whole circle bearing is added with my last two digits of passport number. My passportnumber is so the last two digits are 00.


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Calculating Northing ∆N and Easting ∆E

Now we find the Northing and Easting using the basic trigonometry equations which have sine,

cosine and tangent together with the lengths recorded.

The WCB is converted to radians form which is found using the formula below. The calculator is

changed from degrees to radians.

Angle x °⁄

177°56’21.97” x °⁄ = 3.105

144°08’41.34” x °⁄ = 2.515

Northing ∆N Equation used

HD x Cos Angle x °⁄


34.25 x cos 130°07’23.13” x °⁄ = -22.069

18.15 x cos 105°01’21.26” x °⁄ = -4.704


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Easting ∆E Equation used

HD x Sin Angle x °⁄


34.25 x sin 130°07’23.13” x °⁄ = 26.1918

18.15 x sin 105°01’21.26” x °⁄ = 17.5297


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Autocad Drawing


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HPC and Rise and Fall Method

There are two ways of calculating reduced levels – the rise and fall method and the height plane

collimation method.

The arithmetic checks must be done for all levelling calculations.

BS – FS = Rises – Falls = Last Initial RL – First RL

When establishing the new heights of new TBMs and other important points, the BS and FS

should be taken and the rise and fall method of calculation should be used.

The HPC method of calculation can be much quicker when a lot of intermediate sights have

been taken and it is a good method to use when mapping or setting out where many readingsare often taken from a single instrument position.

A disadvantage of the HPC method is that the check on reduced levels calculated from IS can

be long and there is a tendency for it to be omitted.

Calculation checking

Height of Collimation Method

BS – FS = Last Initial RL – First RL

27.72 – 27.73 = 100.00 – 99.99

0.01 = 0.01

Rise and Fall Method


27.72 – 27.73 = 9.52 – 9.53 = 99.99 – 100

0.01 = 0.01 = 0.01


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Discussion & Analysis

The total station.

The plate level vial axis must be perpendicular to the vertical axis.

The vertical axis must be perpendicular to the horizontal axis.

The axis of the line of sight must be perpendicular to the horizontal axis.

Errors

Instrumental -

Plate level vial out of adjustment


either of these directions, and bubble should remain centred. Any miscentering indicates that


Correction:

Level instrument with bubble miscentred by 1/2 of the detected error (bubble run), or follow

manufacturer's procedure for removal of error.








This error cause the telescope to scribe out a cone when it is plunged.




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Eccentricity of the plates-

Occurs when vertical axis of instrument does not coincide with centre of plates. Compensated

for by taking several readings about the plates and averaging. This happens automatically in

surveying grade instruments.


Circle graduation errors –

Caused by irregularities in marking of plates. Take many reading about the plates and average.

This is generally handled by modern total stations.

Errors caused by peripheral equipment –

Be sure that tripods, tribrach, and targets are mechanically sound and in adjustment. Use

targets that are appropriate for sight distances.


Natural errors -

Wind

Vibrates tripod and target in windy condition. When this happens you can (1) protect instrument

from wind by using shield, or (2) Wait until wind speed reduces.

Temperature

Can cause uneven expansion of tripod and instrument parts resulting in instrument mislevelling.

When this happens you can shield instrument using umbrella.

Refraction


create microclimates such as the ground, cars, large trees. When this cannot be done, postpone

observations until better conditions exist.


Tripod setting


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to suspend observations when misleveling becomes to great.

Personal errors-

Instrument miscentering



Target miscentering


on observed angles.



errors.

Poor focusing

One of the most common errors. Be sure parallax is removed before taking observation. Avoiddifferent operators during observation procedure.



Beginners tend to observe, then re observe, then re observe ... before taking sight. This process




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Sources of error in levelling

Collimation error

Collimation error is produced when sight lengths from one instrument position are not equal,

since the collimation error is proportional to the difference in these.

In our site work carried out at Lanjut Resort, I believe the collimation error was avoided to its

acceptable limits since we kept sight lengths equal, especially focusing on the BS and FS.

A two peg test was also carried out in order to check the collimation error. We first placed pegs

on both sides of the total station and then found the difference in elevation. Then, we moved the

level 30cm past both pegs and then took the readings again. There was a slight difference in

elevation from both readings and it was concluded that it is in the acceptable range.


Compensator not functioning

To check the compensator, gently tap the total station, move the foot screw slightly off level or

push the compensator check lever to make sure whether the reading remains constant.

In our case, the compensator was functioning perfectly since the total station used was in good

condition.

Parallax



In our case, parallax error was avoided by using two different group members, they moved their






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Defects of the staff

The total station used was fairly new so this error is eliminated from the readings. Another error

which arises from staff defects is the zero error. It usually occurs when two staffs are used for

the same series of readings, and it is advised to use only one staff for all the readings which is

what we followed for our tasks.


Field or on-site errors

Staff not vertical

The bubble was checked before every reading was taken and it was made sure that the bubble

was in the centre. The staff is held vertically straight as well since we are measuring the vertical

height of the ground.

Unstable ground


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Task three and four were carried out on the beach. The staff was inserted into soft sand which

is why there was trouble keeping the bubble on the centre for long since the sand kept the total

station and the staff move a little.

To keep the accuracy in the readings, the measurement was taken quickly.

Handling the instrument and tripod

Though constant warnings were given to other group members, someone always ended up

coming into contact with the tripod legs. To avoid this, a circle was made around the tripod and

no one was allowed to enter the circle except the one using the total station. Fingertips were

used to focus the total station and not the complete hand.


Reading and booking errors

Readings were immediately recorded into the recording sheets and the reading was repeated

twice loud so that there is no mistake in recording the measurements taken.

Human error

Humans also tend to make error and there are three which I have experienced in survey camplast week:

Reading the staff incorrectly

Writing the wrong value for a reading in the recording sheet

Making mistakes in calculations



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Conclusion

Overall, the traverse method was successfully completed and the margin of error obtained was

3240° - 3239°53’57.5” giving us 00°06’2.5”.

There were a lot of errors and mistakes in this task but it was successfully completed and such

a small margin of error states that from a student of civil engineering, we are on the right verge.

We worked as a team for this task and everyone was given different tasks to complete. My skills

for working as a team were tested for this task. We all made new friends and got closer to each

other individually then we were before.

The best part was that I learnt a lot from this task. It improved my knowledge on whole circle

bearing, how to obtain mean, and how to draw a closed traverse using pen and paper and in

autocad.

The autocad part was very challenging in the beginning but slowly as I managed to see some

videos on You Tube and learn from the Auto Cad help section, I managed to make the drawings

required for this task.


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Task 3

The task 3 involves setting out at given points. The figure is provided and the task was to

produce the same figure on the beach and then measure the face right and face left and

levelling measurements from stations 1, 2 and 3.

The readings were then used to calculate the mean, whole circle bearing, Northing and Easting

and the x and y using last two digits of the passport number. The height of collimation method

and rise and fall method were used for the levelling calculations.

This report will explain the research methodology used, procedure, data, analysis of data,

discussion, conclusion, recommendation and reference and appendix in the order stated.

Objective

The objective of carrying out this task is to carry out:

Levelling activities

Determine the contour lines

Plot the design building in AutoCAD

Carry out Setting out on the building outline provided

Apparatus



Total station

Prism

Tripod

Automatic level

Measurement tape

Wooden peg

Field record book

Health and safety equipment

Pen

Recording sheet

Nails

Spray paint

Staff


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Procedure

There are three main steps to follow when setting up the total station:

Centering the theodolite

Levelling the theodolite Elimination of parallax

The first step is to set up the tripod over the peg. The legs of the tripod are placed an equal

distance from the peg and are extended to suit the observer’s height.

The total station is then taken out of its case, and carefully placed on top of the tripod. It is

screwed onto the tripod.

The ground mark (peg) is focused now through the optical plummet. The three foot screws are

adjusted until the peg can be seen in clear focus.

The circular bubble on the upper part of the theodolite is now adjusted till it is centered by

adjusting the individual tripod legs.

The final step is to centre the plate level bubble which is done by adjusting the foot screws.

Once the bubble is in the center, the instrument is turned 90° and the bubble is checked again.

If it is still in the centre, then the instrument is ready for measurements to be taken.


Since we have to follow the following map, we set it out first by using the wooden pegs provided

and then carried out the measurements using the total station.

A total station can measure both horizontal and vertical distances and at the same time the

slope distances. Using the vertical angle, the total station can calculate the horizontal and

vertical distance components of the measured slope distance and display these.


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A total station is used by setting it up over one end of the line and a reflector is held by the

person at the measuring point. The instrument is pointed towards the reflector and part of the

signal returns and is processed and in a few seconds, gives the slope distances with the

horizontal and vertical distances.


After setting up the total station, the first point taken was north, 10 meters and it was marked as

point 1. After this, since our XY was 50, the next point was north 12.50 meters from point 1.

The measurements of face right and face left were taken at every point until the whole figure

was sketched out at the field using the wooden pegs and the rope was used to connect all the

points.


Then, a contour plan was set up by establishing wooden pegs every 2 by 2 meters. The auto

level was used to carry out the levelling measurements at every point as one group member

was holding the staff.


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Calculations

After taking the readings above, the next step was to calculate the reduced level and

Misclosure, and then find the corrected reduced level values. This was done using height of

collimation method and rise and fall method.

The first bench mark was taken as 102 plus last two digits of my passport number. Since my

passport number is, the TBM remained as 102. Therefore, the first HPC was 102 + 0.555 and

that is 102.555. Microsoft excel was used to insert the data and do the calculations.

To make sure there are no mistakes done, the answer was checked using the following

equation:

BS – FS = Last Initial RL – First RL

The value obtained was 0.003 which proved that the calculation was correctly carried out and

that there were no mistakes. The error obtained is divided by the number of stations and then

the value is distributed over the stations.

Rise and Fall Method

For the rise and fall method, there is also an arithmetic equation provided which can show us

whether the equation used is correct or not.


4.664 – 4.667 = 1.409 – 1.412 = 101.997 – 102.000

0.003 = 0.003 = 0.003

Therefore the following calculation is correct since all the values are the same.


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Collimation error

Collimation error is produced when sight lengths from one instrument position are not equal,

since the collimation error is proportional to the difference in these.












condition.

Parallax



In our case, parallax error was avoided by using two different group members, they moved their





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Defects of the staff

The total station used was fairly new so this error is eliminated from the readings. Another error

which arises from staff defects is the zero error. It usually occurs when two staffs are used for

the same series of readings, and it is advised to use only one staff for all the readings which is

what we followed for our tasks.


Field or on-site errors

Staff not vertical

The bubble was checked before every reading was taken and it was made sure that the bubble

was in the centre. The staff was held vertically straight as well since we are measuring the

vertical height of the ground.

Unstable ground


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Task three and four were carried out on the beach. The staff was inserted into soft sand which

is why there was trouble keeping the bubble on the centre for long since the sand kept the total

station and the staff move a little.

To keep the accuracy in the readings, the measurement was taken quickly.


Handling the instrument and tripod

Though constant warnings were given to other group members, someone always ended up

coming into contact with the tripod legs. To avoid this, a circle was made around the tripod and

no one was allowed to enter the circle except the one using the total station. Fingertips wereused to focus the total station and not the complete hand.

Reading and booking errors

Readings were immediately recorded into the recording sheets and the reading was repeated

twice loud so that there is no mistake in recording the measurements taken.

Human error

Humans also tend to make error and there are three which I have experienced in survey camplast week:

Reading the staff incorrectly

Writing the wrong value for a reading in the recording sheet

Making mistakes in calculations


The total station.




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The axis of the line of sight must be perpendicular to the horizontal axis.


Errors

Instrumental -

Plate level vial out of adjustment


either of these directions, and bubble should remain centred. Any miscentering indicates that



Correction:

Level instrument with bubble miscentred by 1/2 of the detected error (bubble run), or follow

manufacturer's procedure for removal of error.







This error cause the telescope to scribe out a cone when it is plunged.





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Eccentricity of the plates-

Occurs when vertical axis of instrument does not coincide with centre of plates. Compensated

for by taking several readings about the plates and averaging. This happens automatically in

surveying grade instruments.

Circle graduation errors –

Caused by irregularities in marking of plates. Take many reading about the plates and average.

This is generally handled by modern total stations.

Errors caused by peripheral equipment –

Be sure that tripods, tribrach, and targets are mechanically sound and in adjustment. Use

targets that are appropriate for sight distances.


Natural errors -

Wind



Temperature



Refraction


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create microclimates such as the ground, cars, and large trees. When this cannot be done,

postpone observations until better conditions exist.


Tripod setting




to suspend observations when misleveling becomes too great.

Personal errors-




Target miscentering

Can cause observed angle to be too large or small. Use long sight distances to reduce effecton observed angles.




errors.

Poor focusing

One of the most common errors. Be sure parallax is removed before taking observation. Avoid

different operators during observation procedure.



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Contour drawing for task 3


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Conclusion

I come to the conclusion that the error obtained was 0.03. The different sources of error were

discussed in order to explain how surveyors encounter the different errors and the best part was

that most of the errors we had experienced them at the surveying camp so it gave us a verygood description and made it easy for me to explain on the errors section.

I used Auto Cad for this task as well but it was the 2D figure which was required so I didn’t have

much trouble making it.

The Contour lines came out properly and they do not meet which is an essential requirement in

contour drawing. The Points seem to be parallel to each other.


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Task 4

Road Curve

This task involves the making of a road. The survey is carried out in order to establish the points

required and to ensure that the road is properly produced. Now the making of a road curve

involves extension of the tangent lines. You can understand the drawing properly by checking

the figure below:

We are carrying out the survey in order to check the health and safety issues involved with the

road. If the proper dimensions are not used, even a small margin of errors can cause accidents

which can cost us human lives and damage of infrastructure and vehicles. In other words, it canbe the reason of major transportation crisis. This is why highway engineering is respected by

the whole engineering society because they hold one of the most difficult jobs in the world and

even a slight error is not affordable.


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Total Station

Capable of measuring angles in both the

horizontal and vertical planes, slope distances

Can trigonometrically convert slope distances to

their horizontal and vertical components of distances

Can compute XYZ coordinates of points using

observations. (Z is elevation)

All information can be digitally recorded

Can be used to stake-out engineering projects using

coordinates

Can measure multiple angles and average the results

Displays measurements on liquid crystal displays


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All total stations have

standards

telescopes

objective lens and focus

eyepiece lens and focus

both lenses must be focused to avoid parallax

define axis of sight

EDM

horizontal axis

vertical axis

levels (many instruments use digital levels today)

keypad

display

battery

angle measurement system

horizontal circle

vertical circle

horizontal and vertical motion screws

lock screw

tangent screw

automatic compensator to correct for mislevelment - not on all instruments

collimator - used to roughly sight on target

Communication port

optical/laser plummet

base - permit interchange of equipment with tribrach


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Procedure for setup over a point

Remove tribrach from instrument in case, and place on tripod if it has an optical

plummet.

Place legs such that two are downhill and are not in the lines of sight. This will prevent

you from having to lean over legs in most instances.

Extend legs so that the shortest person in your crew can comfortably use total station

without standing on tiptoes.

Roughly centre and level tripod over point. You can use a coin or stone to check

centring. Drop it from the centre of the tripod and observe where it hits.

Place instrument on tripod if required. Make sure tribrach is centred on tripod head to

ensure maximum flexibility in centring.

Focus optical plummet eyepiece and objective lens to bring ground and centring wires

into sharp focus. Make sure parallax is removed.

Using levelling screws, centre optical plummet over point

Using adjustable legs, carefully level circular bubble.

Steps 8 & 9 should bring the instrument roughly centred and levelled over the point. If

not, repeat steps.

Use precise level to roughly level instrument.

Loosen tribrach and centre instrument over point. Be careful not to rotate instrument

when sliding on head of tripod.

Fine level instrument using precise level, and tribrach levelling screws.

Check instrument centring

Check level.

Repeat steps 10-13 until instrument is precisely centred and levelled over point. (If it

takes more than the first attempt, you are doing something wrong!)


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Relationships between Distances and Angles

From Euclidean geometry we know that

S = R q

Where S is the arc length on a circle of radius R subtended by

and angle q in radian units.

Thus

1' of arc = 0.03 ft at 100 ft

1" of arc = 1 ft at 40 mi, or 0.5 m at 100 km, or 1 mm at 200 m

1" of arc = 0.000004848 radians

1 radian = 206,264.8" of arc

A traverse that requires a precision of 1:20,000 implies an angular accuracy of

Important to pick a target that matches the accuracy of your instrument, and desired resulting

angle.

Example

A chaining pin is used as a site on a station that is 100 ft from the instrument. The chaining pin

is 0.01 ft wide. It is estimated that the operator can centre the sight within ±0.005 ft, or 1/2 of the

pin. What resultant angular error can occur with this target? Would this be an appropriate target

when using an instrument that has a specified accuracy of ±3"?


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Measuring Horizontal Angles

The procedure for measuring angles is dependent on the total station used.

There are two basic procedures for angle measurement.

Repetition method: This method can only be done by some instruments.

Direction method : Can be performed using any total station.

An angle must be turned at least once direct, and reverse to ensure that instrumental errors are

compensated. A set of each is known as a position.

(1DR) means an angle turned once direct and once reverse. - 1 position

(2DR) means an angle turned twice in the direct and reversed. 2 positions.

General Procedures for Measuring Angles by Repetition Method

1. With instrument at I sight on J (back sight)

2. Zero display

3. Turn instrument to K (foresight).

4. Read and record display.

5. Press button to hold value of angle on display. (Note: Not all instruments have this

button.)6. Plunge scope, and sight J.

7. Release angular value on display by pressing button. (Again, not all instruments have

this feature.)

8. Turn instrument and sight on K.

9. Repeat steps 5-8 until desired number of turnings is obtained. (There must be an even

number of angles to correct for instrumental errors.)

10. Record final angular value.

11. Take average of final value, and compare with first recorded reading to check

consistency of angle turning. Repeat angle measurement procedure, if necessary.


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General Procedure for Measuring an Angle Using the Directional Method (SMI)

1. To complete the observation of the angle and distance.

2. Sight the back sight station K and zero the instrument. For most instruments, zeroing

can be done from the SETUP soft key menu.

3. From the Setup soft key menu find the SHOTS submenu. Press SETUP, NXT, SHOTS.

4. Press the BS soft key. This will read the instrument's horizontal and zenith angles and

set the values in the BSDIR: line of the screen.

5. Sight the instrument on your foresight station K, and press SHOT from the SHOTS

submenu.

6. Plunge the scope and re sight the foresight station K. Press the SHOT soft key to read

the circle in the reverse position.

7. Re sight the back sight station J and press the BS soft key.

8. To measure the angle 2DR, press the SET1 soft key to toggle the data collector to

SET2, and repeat steps a-f.

9. Press the EVAL soft key in the SHOTS submenu. This will display the average of the

two pointing and the error. If the error is less than 1.96´DIN of your instrument accept the

shots by pressing the STPTS (store points) key. If the error is too large you can delete a

pointing and repeat the shot.

Once you willing to accept your observations press the STPTS (store points) button. The data

collector will prompt to determine if this is a traverse point (TRAVR) or a side shot (SIDES).

Press TRAVR soft key. The data collector will accept the shots, move the occupied point to

station 2 (the next station in the traverse), and the back sight point to station 1 (the previous

occupied point).


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General Procedure for Measuring an Angle Using the Directional Method

1. The advantage of this method is that it allows you to sight on multiple stations with little

additional effort.

2. With instrument at P, sight on Q.

3. Zero display.

4. Turn instrument to R. and read and record display.

5. Turn instrument to S and read and record display.

6. Plunge telescope.

7. Turn instrument to sight on Q.

8. Zero display.

9. Turn instrument to R. and read and record display.

10. Turn instrument to S and read and record display.

11. Repeat step 5-9 until angle(s) are measured desired number of times.

Vertical Angles

Zenith/altitude angles are angles measured in the vertical plane.

Zenith angles have zero pointing toward the instrument's zenith.

All total stations measure zenith angles.

Altitude angles have zero pointing toward the instrument's horizon

; "+" when above the horizon and "−" when below the horizon

Altitude angles were predominant with transits older transits.

Relationship between zenith angle (z) and altitude angle (a) is

Direct mode a = 90° - z

Reversed mode a = z - 270°

Indexing error is an error caused by the zero point on the vertical circle not truly being at the

zenith.


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The concept involved is that we shall increase the tangent length which allows us to

have a larger curve radius and a larger curve distance which allows for a greater

distribution of deflection angles at each given point.

All roads are designed according to road speeds. This is the reason why every road has

a different speed limit. The emphasis is given to the vehicle so it can be as comfortable

and safe with the velocity and weight that it is carrying on the specific road.

This is why, the smaller the radius of the curve, the greater is the radial force acting on

the vehicle. In our case, the radius is 20°08’45” which is normal.

In a road, we can notice something an engineer will call as a super elevation. It

shouldn’t exceed a certain limit because then the road will have more curve and the

vehicles on it will slip off the way.

Curves are aligned to provide smooth changes in direction in the form of deflection

angles that will sum up to a certain amount by the end of the curve. It is often the case

that the ratio between deflection angles and longest chord length are to be made in

such a way that the angle is small over greater distance.

The curve given for us was a horizontal curve with a constant radius.


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Volume of the road curve

Now, we need to find the volume of the road curve. We shall use the figure above plus the CorrRL values to find the area and then multiply it with the chord length to find the volume.

Calculations

The formation level given for group 1 is 101.XYZ. XYZ are the last three digits of my passportnumber so in my case, the formation level is 101.600.

The following are the autocad drawings for the cut and fill part.


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Figure 4.1 : It shows the Cut and Fill for Task 4


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Figure 4.2 : Shows the cut for road curve




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The drawing of the new road using the Autocad and Microsoft Office Design

Calculations for the volume


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Cut and Fill

F=a1 (.+.

) × 5 = 1.864m²

=a2 (.+.

) × 5 = 2.239m² (Triangle 0.25m² on both sides) A1=4.103

AT1 = ⁄ =.

⁄ = .²

A1 + AT1 = 4.103 + 0.25 + 0.25 = 4.603m2

Since there are two triangles, so we add 0.25m2 twice.

E=a1 (.+.

) × 5 = 1.8165m²

=a2 (.+.

) × 5 = 2.4665m² A2=4.283

AT2 = ⁄ =.

⁄ = .²

A2 + AT2 = 4.283 + 0.25 + 0.25 = 4.783m2


D=a1 (.+.

) × 5 = 1.0665m²

=a2 (.+.

) × 5 = 1.3915m² A3=2.458


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AT3 = ⁄ =.

⁄ = .²

A3 + AT3 = 2.458 + 0.25 + 0.25 = 2.958m2


C=a1 (.+.

) × 5 = 1.6085m²

=a2 (.+.

) × 5 = 1.825m² A4=3.4918

AT4 = ⁄ =.

⁄ = .²

A4 + AT4 = 3.4918 + 0.25 + 0.25 = 3.9918m2


B=a1 (.+.

) × 5 = 1.6085m²

=a2 (.+.

) × 5 = 1.8335m² A5=3.442

AT5 = ⁄ =.

⁄ = .²

A5 + AT5 = 3.442 + 0.25 + 0.25 = 3.992m2



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A=a1 (.+.

) × 5 = 0.984m

=a2 (.+.

) × 5 = 1.7923m

Therefore A6=2.7763

AT6 = ⁄ =.

⁄ = .²

A6 + AT6 = 2.7763 + 0.25 + 0.25 = 3.2763m2


V1= (.+.

) × 9= 42.237m3

V2= (.+.

) × 9 = 34.8345m3

V3= (.+.

) × 9= 31.2741m3

V4= (

.+.

) × 9= 35.9271m3

V5= (.+.

) × 9 = 32.70735m3

Total= V1V2 V3 V4 V5 = . m3

Total= ( .+.

)× 45 = . m3

The important point to note is that since the formation level is 101.600, all the points are to cut.

This actually made it easier for me to calculate the area and the volume.

The total volume to cut is 177.28m3.


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The total station.




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Wind



Temperature



Refraction


create microclimates such as the ground, cars, large trees. When this cannot be done, postpone

observations until better conditions exist.

Tripod setting




to suspend observations when misleveling becomes to great.

Personal errors-




Target miscentering


on observed angles.



errors.

Poor focusing

One of the most common errors. Be sure parallax is removed before taking observation. Avoid

different operators during observation procedure.






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Collimation error

Collimation error is produced when sight lengths from one instrument position are not equal,since the collimation error is proportional to the difference in these.











condition.

Parallax



In our case, parallax error was avoided by using two different group member, they moved their


There was a slight change in the positions of the target an

land surveying using auto level leveling

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