CONCLUSIONES PERSONALES

E=a1 (

0.3233+0.4033 2

) × 5 =

1.8165m²

=a2 (

0.4033+0.5833 2

) × 5 =

2.4665m² A2=4.283

A

T2

= 𝐛𝐡 𝟐⁄ = 𝟎. 𝟓 𝐱 𝟏 𝟐⁄ = 𝟎. 𝟐𝟓𝐦²

A2 + A

T2

= 4.283 + 0.25 + 0.25 = 4.783m

2

Since there are two triangles, so we add 0.25m

2

_twice.

D=a1 (

0.3433+0.0833

2

) × 5 =

1.0665m²

=a2 (

0.0833+0.4733

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A

T3

= 𝐛𝐡 𝟐⁄ = 𝟎. 𝟓 𝐱 𝟏 𝟐⁄ = 𝟎. 𝟐𝟓𝐦²

A3 + A

T3

= 2.458 + 0.25 + 0.25 = 2.958m

2

Since there are two triangles, so we add 0.25m

2

_twice.

C=a1 (

0.3067+0.3600 2

) × 5 =

1.6085m²

=a2 (

0.36+0.37 2

) × 5 =

1.825m² A4=3.4918

A

T4

= 𝐛𝐡 𝟐⁄ = 𝟎. 𝟓 𝐱 𝟏 𝟐⁄ = 𝟎. 𝟐𝟓𝐦²

A4 + A

T4

= 3.4918 + 0.25 + 0.25 = 3.9918m

2

Since there are two triangles, so we add 0.25m

2

_twice.

B=a1 (

0.2867+0.35169 2

) × 5 =

1.6085m²

=a2 (

0.3567+0.3767 2

) × 5 =

1.8335m² A5=3.442

A

T5

= 𝐛𝐡 𝟐⁄ = 𝟎. 𝟓 𝐱 𝟏 𝟐⁄ = 𝟎. 𝟐𝟓𝐦²

A5 + A

T5

= 3.442 + 0.25 + 0.25 = 3.992m

2

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A=a1 (

0.0767+0.3169₂

) × 5 = 0.984m

=a2 (

0.3169+0.4₂

) × 5 = 1.7923m

Therefore A6=2.7763

A

T6

= 𝐛𝐡 𝟐⁄ = 𝟎. 𝟓 𝐱 𝟏 𝟐⁄ = 𝟎. 𝟐𝟓𝐦²

A6 + A

T6

= 2.7763 + 0.25 + 0.25 = 3.2763m

2

Since there are two triangles, so we add 0.25m

2

_twice.

V1= (

4.603+4.783 2

) × 9

= 42.237m

3

V2= (

4.783+2.958 2

) × 9 =

34.8345m

3

V3= (

2.958+3.9918 2

) × 9=

31.2741m

3

V4= (

3.9918+3.992 2

) × 9=

35.9271m

3

V5= (

3.992+3.2763 2

) × 9 =

32.70735m

3

Total= V1+V2 + V3 + V4 + V5 = 𝟏𝟕𝟔. 𝟗𝟖𝟎𝟎𝟓m

3

Total= (

4.603+3.2763 2

)× 45 = 𝟏𝟕𝟕. 𝟐𝟖m

3

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.

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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.

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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

Detection: Level instrument in two directions as per typical setup. Rotate instrument 180° from either of these directions, and bubble should remain centred. Any miscentering indicates that the plate level vial axis is not perpendicular to the vertical axis.

Correction:

Level instrument with bubble miscentred 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

This error cause 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.)

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.

89 | P a g e 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

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, large trees. When this cannot be done, postpone observations until better conditions exist.

Tripod setting

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 misleveling becomes to great.

Personal errors-

Instrument miscentering

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 miscentering

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. Avoid different 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 re observe, then re observe ... before taking sight. This process results in unsettling instrument and reducing pointing accuracy. Trust your eyes.

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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

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 member, 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.

91 | P a g e

Figure 4.7

 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

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

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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 camp last week:

 Reading the staff incorrectly

 Writing the wrong value for a reading in the recording sheet  Making mistakes in calculations

Conclusion

Therefore I would like to conclude task 4 by saying it was properly carried out. We managed to get all the necessary points required for the road curve. The road was properly designed and even a slight margin of error was taken in consideration since when it comes to designing of roads, there is always the issue of health and safety involved.

In document Electric master. info:eu-repo/semantics/bachelorthesis (página 137-149)