Report Ukur Aras

CENTRE FOR DIPLOMA STUDIES DEPARTMENT OF CIVIL ENGINEERING GEOMATICS LABORATORY Subject Code Practical Name Course Code Practical Date Group Group Leader Group Member

Levelling DAC20503 07.10.2015 2

Lecturer name Marks

Comments

Introduction Objective Theory Instrument Procedure Data/ Table Data Analysis Discussion Presentation/ Plotting Conclusion/ Recommendation Reference Total mark Accepted Seal

/ 5% / 5% / 10% / 5% / 5% / 10% / 20% / 15% / 10% / 10% / 5% / 100%

CONTENTS

No. 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10. 0

Content Introduction Objective Theory Instrument Procedure Data / Table Data Analysis Discussion Conclusion / Recommendation Reference

Page 1-3 4 4 5–6 7 – 10 11 12 – 18 19 20 21

1.0

INTRODUCTON

Leveling may be the art of determining the relative heights or elevations of points are objects on the earth’s surface. It deals with measurements in a vertical plane. Definitions of terms used in Leveling: 1. A level surface: It is any surface parallel to the mean spheroidal surface of the earth e.g. surface of a still lake. Since the earth is a oblate spheroid, a level surface may be regarded as a curved surface, every point on which is equidistant from the center of the earth. It is normal to the plumb line at all points. 2. A level line: It is line lying in a level surface. It is therefore, normal to the plumb line at all points. 3. A horizontal plane: It is a plane tangential to the level surface at that point. It is perpendicular to direction of gravity (plumb line). 4. A horizontal line: It is any line lying in the horizontal plane. It is a straight line tangential to a level line. 5. A vertical line: It is a line normal to the level surface through that point e. g. a plumb line. 6. A vertical plane: It is a plane containing a vertical line. 7. A vertical angle: Angle between two intersecting lines in a vertical plane, one of the two lines is commonly taken as horizontal in surveying. 8. A datum surface or line: It is any arbitrarily assumed level surface or line from which vertical distances are measured in India the datum adopted for G.T.S. bench marks is the mean sea level at Karachi now in Pakistan.

9. The elevation: It is vertical distance of a point above or below the datum. It is also known as the reduced level (R.L.) The elevation of a point is plus or minus according as the point is above or below the datum. 10. The difference in elevation (H): It is the vertical distance between the level surfaces passing through the two different points. 11. A bench mark (B.M.): It is fixed reference point of known elevation. 12. The line of collimation: It is the line joining the intersection of cross hairs of the optical center of the object glass. It is also called the line of sight. 13. An axis of the telescope: It is a line joining the optical center of the object glass to the center of the eye piece. 14. Foresight: (Also called a foresight reading) It is a staff (or rod) reading on a point whose elevation is to be determined or on a change point. It is also termed as minus sight. It is the last staff reading denoting the shifting of the instrument. 15. An Intermediate sight (I. S.): It is any other staff reading taken on appoint of unknown elevation from the same set up of the level. All sights taken between the back sight and the fore sight and the foresight are intermediate sights. 16. A change point (C. P): It is appoint denoting the shifting of the level. It is a point on which is the fore and back sights are taken. Any stable and well defined object such as a boundary stone, curb stone rail, rock etc. is used as a change point. A bench mark may also be taken as a changer point. It is also called a turning point (T. P).

17. A Station: It is a point whose elevation is to be determined. It may be noted that it is a point where the staff is held not the point where they leveled is set up. 18. The height of instrument (H. L): It is the elevation (or the R.L.) of the plane of collimation (or plane of sight) when the instrument is correctly leveled. It is also called the height of plane of the collimation. To determine elevation of points two instruments are required, viz. 1. A level 2. A leveling staff or rod. The level: Level consists of essentially 1. Leveling head 2. The limb 3. Telescope 4. bubble tube Types of level: 1. Dumpy level 2. y level

2.0

OBJECTIVE

1. To get the perfect reading on the instrument 2. Recalibrate levelling instrument and staff so, the reading levelling is suitable to the height of the earth surface 3. Diffrentiate the damage instrument on value reading for send to the supplier 4. The first procedure to prevent the error in the process of leveling gone wrong.

3.0

THEORY The purpose of the test is to know the accurancy of the leveling instrument. It also can

find the error and the damages on the instrument. Other than that, before doing the test, we must make sure the calibration of the instrument is perfect. So, the real distance does not have big difference than the distance that taken during the test. Distance from the front view to the leveling instrument must not be too far to reduce the error on collimation. Besides, this test will be succeed and granted if the real distance smaller than the limit distance allowed. The minimum distance after the front view staff is 6m and the maximum is 66m. Front view staff is the last before tranfering the instrument from the CP to the next CP. BM which is Benchmark is the fixed station on the earth surface.

4.0

INSTRUMENTS

There were several instruments that used for running Two Peg Test and Levelling. Two Peg Test :1. Level and Tripod ( 1 set )  A level is required to define the reading of vertical distances on the staff. 2. Staff ( 2 set )  A levelling staff is needed to measure vertical distances. 3. Staff bubble ( 2 set )  Staff bubble is fitted to the staff to make sure the staff stable to the ground. 4. Measuring Tape  A tape is used to measure distances between the level and staff.

Levelling :1. Level and Tripod 

( 1 set )

A level is required to define the reading of vertical distances on the staff.

2. Staff ( 2 set )  A levelling staff is needed to measure vertical distances. 3. Staff bubble ( 2 set )  Staff bubble is fitted to the staff to make sure the staff stable to the ground. 4. For measuring distances for levelling, not using tape but using foot step. 5. Hammer 6. Nail / Thumbtack

Level and Tripod

Staff

Staff bubble

Measuring tape

5.0

PROCEDURE

Two Peg Test procedure :1. Measure out 3 points (Point A, B and C) which is 30m apart, and mark them on the ground. Point A as back sight and point C as foresight. 2. Set up the level instrument at point B, the centre and put the staff at point A and point C. 3. To set up the level, first set up the tripod. Ensure the top is level. Push legs firmly into the ground. Then, attach level. Use the foot screws to centralise the circular bubble. Test to see if the compensator is working and the remove the parallax to see clearly. 4. Make sure the stuff bubble is at centre of the circle to get the right readings.

A

B 30

30

C

6m

5. Read the staff vertical distance at point A, record the data and read again. 6. Rotate the level to point C, read the staff reading at point C, record the data and read again. 7. Move the level instrument to 6m beyond point C on the line point A,B and C. 8. Set up the level, read the staff at point A and record the data. Then, read the staff at point C and also record the data.

9. Calculate height difference.

Levelling procedure. Observing procedure :1. Levelling depends on area given. For group 2, the area involve are K4, K5, K6, K7 and K8.

(Practical Area) 2. Start at TBM 1 area K4, put the staff at TBM 1. Using footsteps, 39 steps as 30m. From TBM 1, measure 39 steps and set up the level instrument at the point. Measure another 39 steps and it will be the change point, (Point A). Put another staff at Point A. 3. Read the first staff at TBM 1, it is a back sight reading and record the data in the Levelling Observation form. Rotate the level to Point A, it will be foresight reading. Read the staff at Point A and record the data. 4. Next, move the level instrument 39 steps from Point A and measure Point B. Put the staff from TBM 1 at Point B. The staff at point A will

stay. Set up the level, read the staff at point A and record the data as back sight reading. Rotate the level towards Point B, read the staff and record the data. 5. Move the level instrument with the same distance from Point B. Set up the level and measure Point C. Put the staff from Point A to Point C. Read the staff at Point B, record the data. Rotate the level to Point C, read the staff and record the data. 6. Move again the level instrument with the same distance from Point C. Set up the level and measure Point D. Point D is the TBM point. Mark the Point D using the hammer and nails given. Put the staff from point B to Point D. Read the staff at Point C, record the data. Rotate the level to Point D, read the staff and record the data. 7. Move the level instrument with the same distance from Point D. Set up the level and measure Point E. Put the staff from Point C to Point D. Read the staff at Point D, record the data. Rotate the level to Point E, read the staff and record the data. 8. Next, move the level instrument with the same distance from Point E. Set up the level and measure Point F. Put the staff from Point D to Point F. Read the staff at Point E, record the data. Rotate the level to Point F, read the staff and record the data. 9. Move the level instrument with the same distance from Point E. Set up the level and measure Point F. Put the staff from Point D to Point F. Read the staff at Point E, record the data. Rotate the level to Point F, read the staff and record the data. 10. Next, move the level instrument with the same distance from Point E. Set up the level and measure Point F. Put the staff from Point D to Point F. Read the staff at Point E, record the data. Rotate the level to Point F, read the staff and record the data. 11. Move the level instrument with the same distance from Point F. Set up the level and measure Point G. Put the staff from Point E to Point G. Read the staff at Point F, record the data. Rotate the level to Point G, read the staff and record the data. 12. Lastly, move the level instrument with the same distance from Point G. Set up the level and the other Point H is back to the TBM 1. Put the staff from Point F to TBM 1. Read the staff at Point G, record

the data. Rotate the level towards Point H (TBM 1), read the staff and record the data.

Booking procedures :1. The Rise and Fall Method The terms that are commonly used in the Rise and Fall Method are:    

BS = Back sight, FS = Foresight, IS = Intermediate Sight, and RL = Reduced Level.

2. Height of Collimation  Height of Collimation (HOC) = Reduce Level (RL) + Back sight 

(BS) Height of Collimation (HOC) – Foresight (FS) = Reduce Level (RL)

Calculation procedures :1. Checks survey accuracy, and should be within tolerances given below. 2. The following check the arithmetic of your level reductions and must be exact:  ∑ BS - ∑ FS = ∑ Rise - ∑ Fall  (Back sight) – (Foresight) = (RL) (last BM) – RL (start BM)

3. Misclosure should be: ± (20 √ D) mm, where D is the length of the traverse in  km.

7.0

DATA ANALYSIS

BS – Back sight FS – Foresight RL – Reduced Level ∆h = BS – FS (+∆h) @ (-∆h) Reduced Level B = Reduced Level A + ∆h (Rise) Reduced Level C = Reduced Level B - ∆h (Fall) Difference = ∑ Back sight - ∑ Front sight = ∑ Rise - ∑ Fall = Final RL – Initial RL Ht. Col = RL A + BS reading CENTRE FOR DIPLOMA STUDIES GEOMATIC LABORATORY (LEVELLING)

Correction = Difference / Total Number of Foresight Data: TBM 1 = 2.782 m ∑ Distance = 480 m = 0.48 km    TBM 1 = 2.782 m (Initial RL) BS = 1.221 Ht. Col = TBM 1 + BS reading, TBM 1 = 2.782 + 1.221 = 4.003    TBM 1 to A BS, TBM 1= 1.221 FS, A= 1.248 BS – FS = ∆h ∆h, A = 1.221 – 1.248 = -0.027 = 0.027 (fall) RL A = RL TBM 1 - ∆h, A = 2.782 – 0.027 = 2.755

6.0DATA / TABLE

Ht. Col A = RL A + BS reading, A = 2.755 + 1.252 = 4.007

   A to B BS, A = 1.252 FS, B = 1.285 BS – FS = ∆h ∆h, B = 1.252 – 1.285 = -0.033 = 0.033 (fall) RL B = RL A - ∆h, B = 2.755 – 0.033 = 2.722 Ht. Col B = RL B + BS reading, B = 2.722 + 1.324 = 4.046    B to C BS, B = 1.324 FS, C = 1.390 BS – FS = ∆h ∆h, C = 1.324 – 1.390 = -0.066 = 0.066 (fall) RL C = RL B - ∆h, C = 2.722 – 0.066 = 2.656 Ht. Col C = RL C + BS reading, C = 2.656 + 1.481 = 4.137    C to D, TBM K2 BS, C = 1.481 FS, D, TBM K2 = 1.345 BS – FS = ∆h ∆h, D TBM K2 = 1.481 – 1.345 = +0.136 = 0.136 (rise)

RL D, TBM K2 = RL C + ∆h, D = 2.656 + 0.136 = 2.792

Ht. Col D, TBM K2 = RL D, TBM K2 + BS reading, D, TBM K2 = 2.792 + 1.136 = 3.928    D, TBM K2 to E BS, D TBM K2 = 1.136 FS, E = 1.220 BS – FS = ∆h ∆h, E = 1.136 – 1.220 = -0.084 = 0.084 (fall) RL E = RL D, TBM K2 - ∆h, E = 2.792 – 0.084 = 2.708 Ht. Col E = RL E + BS reading, E = 2.708 + 1.242 = 3.950    E to F BS, E = 1.242 FS, F = 1.254 BS – FS = ∆h ∆h, F = 1.242 – 1.254 = -0.012 = 0.012 (fall) RL F = RL E - ∆h, F = 2.708 – 0.012 = 2.696 Ht. Col F = RL F + BS reading, F = 2.696 + 1.450 = 4.146

   F to G BS, F = 1.450 FS, G = 1.420 BS – FS = ∆h ∆h, G = 1.450 – 1.420 = +0.030 = 0.030 (rise)

RL G = RL F + ∆h, G = 2.696 + 0.030 = 2.726 Ht. Col G = RL G + BS reading, G = 2.726 + 1.460 = 4.186    G to H, TBM 1 BS, G = 1.460 FS, H, TBM 1 = 1.411 BS – FS = ∆h ∆h, H, TBM 1 = 1.460 – 1.411 = +0.049 = 0.049 (rise) RL H, TBM 1 = RL G + ∆h H, TBM 1 = 2.726 + 0.049 = 2.775 Ht. Col H, TBM 1 = 2.775 (Final RL)

∑ Back sight, BS ∑ Front sight, FS

= 1.221 + 1.252 + 1.324 + 1.481 + 1.136 + 1.242 + 1.450 + 1.460 = 10.566 = 1.248 + 1.285 + 1.390 + 1.345 + 1.220 + 1.254 + 1.420 + 1.411 = 10.573

Difference

= ∑ Back sight, BS - ∑ Front sight, FS = 10.566 - 10.573 = -0.007

∑ Rise

= 0.136 + 0.030 + 0.049 = 0.215 = 0.027 + 0.033 + 0.066 + 0.084 + 0.012 = 0.222

∑ Fall

Difference

= ∑ Rise - ∑ Fall = 0.215 – 0.222 = -0.007

Final RL = 2.775 Initial RL = 2.782 Final RL – Initial RL = 2.775 – 2.782 = -0.007 Difference = ∑ Back sight - ∑ Front sight = ∑ Rise - ∑ Fall = Final RL – Initial RL = -0.007 Correction = Difference / ∑ Number of Foresight = 0.007 / 8 = 0.0009 Explanation: First (FS) correction = 1 × value of correction Second (FS) correction = 2 × value of correction Third (FS) correction = 3 × value of correction And so on. Misclosure Limits

√ D mm = ± 20 √ 0.48 = ± 20

= 13.86 mm The Difference value is less than the Misclosure Limit. Difference < Misclosure Limit So, the Levelling work is accepted.

GEOMATIC LABORATORY (LEVELLING) Back sight

Intermediate sight

Foresight

Rise (+VE)

Fall (-VE)

1.221 1.252

1.248

1.324

1.285

1.481

1.390

1.136

1.345

1.242

1.220

1.450

1.254

1.460

1.420 1.411

1.221-1.248 = 0.027 1.252-1.248 = 0.033 1.324-1.390 = 0.066 1.481-1.345 = 0.136 1.136-1.220 = 0.084 1.242-1.254 = 0.012 1.450-1.420 = 0.030 1.460-1.411 = 0.049

Ht. col 2.782+1.221 = 4.003 2.755+1.252 = 4.007 2.722+1.324 = 4.046 2.656+1.481 = 4.137 2.792+1.136 = 3.928 2.708+1.242 = 3.950 2.696+1.450 = 4.146 2.726+1.460 = 4.186

Reduced Level

Correction

2.782

0

2.782-0.027 = 2.755 2.755-0.033 = 2.722 2.722-0.066 = 2.656 2.656+0.136 = 2.792 2.792-0.084 = 2.708 2.708-0.012 = 2.696 2.696+0.030 = 2.726 2.726+0.049 = 2.775

0.0009 × 1 = 0.0009 0.0009 × 2 = 0.0018 0.0009 × 3 = 0.0027 0.0009 × 4 = 0.0036 0.0009 × 5 = 0.0045 0.0009 × 6 = 0.0054 0.0009 × 7 = 0.0063 0.0009 × 8 = 0.0072

∑BS = 10.566

10.566 -10.573 = -0.007

∑FS = 10.573

∑Rise = 0.215

∑Fall = 0.222

Final RL =2.775 Initial RL = 2.782 0.215 2.775 -0.222 -2.782 = -0.007 = -0.007 Difference = ∑BS - ∑FS = ∑Rise - ∑Fall = Final RL - Initial RL = -0.007 Correction = 0.007 / 8 = 0.0009 Misclosure Limit = ± 20 √ D mm = ± 20 √0.48 mm = 13.85 mm *Difference < Misclosure Limit. So, the Levelling work is accepted.

8.0

DISCUSSION Before the levelling activity is carry out, our group carried out Two

peg test to determine whether levelling bubble and telescope line-of-sight are parallel. The height difference for the first set up and the second set up are 0.010m and 0.013m respectively. The difference between the height difference for the first set up and the second set up is 3mm, and the value is less or within the acceptable error which is 5mm. The route we used for the levelling was from TBM1 to Area 8 and then back to TBM 1. We had marked down the spot we set up the levelling equipment and also the stuffs to make sure that the reading obtained are more accurate. Our group had done the levelling activity twice. We failed the first levelling. The formula of misclosure limit was given by

±(20 √ D)mm ,

where D= length of traverse in km. The length of traverse of our first set up was 0.476km. The misclosure allowed is ±13.80mm. The reading is not acceptable because our group get the misclosure more than allowed which is 27mm. This happened because of several factors: 1 The tripod is not in the stable state and the bubble at the level is not in the centre. 2 Reading is taken, while the crosshair are not visible. 3 Observer is inexperienced in handling the equipment 4 The weather are too hot making the observer less motivated during the levelling process. 5 No cooperation between the group members. The second levelling or second set up was successful. The misclosure for the second set up was 7mm. The length of traverse of our second set up was 0.480km and by using the formula of misclosure limit, the misclosure allowed is ±14.00mm. 7mm is within the misclosure allowed. The second set up was successful because our group have overcome the factor-factor stated above. During the process of levelling, precaution that needs to be considered while carrying out the levelling includes:

1 The tripod must be in the stable state and the bubble at the level must be in the centre. 2 While reading the measurements, make sure that the crosshair are visible. 3 Put a nail below the staff for more precise readings. 4 Put the level in its case before move to the next point.

9.0

CONCLUSION / RECOMMENDATION In conclusion, our study did have achieved the intended objectives. For the two peg

test, the allowable different that is accepted due to the set up is 5 mm. Hence, our difference value is 3mm. So the instrument was in good condition. For the levelling, the important thing that we must follow is the distance between two points that must be accurate in order to prevent from getting error that can be occur. The differences that we have obtained is 0.007. Besides, the correction are 0.0009 for a total distance of 480 m. Therefore, the value of allowed are significant differences between the values obtained of not more than 13.86 mm. Since the difference value is less than the allowed reduced level, the levelling work is accepted. For the recommendation, student must know how to conduct the basic and manual operations of this equipment. Then, make sure the distance between the staff and tripod is same. Besides, carefully consider where to set up the level, first set up the tripod. Ensure the top is level and attach level. Use the foot screws to centralise the circular bubble. Test to see if the compensator is working and the remove the parallax to see clearly. Lastly, we must check the staff bubble is at centre of the circle to get the right readings.

10.0 REFERENCE 1 Kejuruteraan Geomatik 1, Hj. Masiiri Kaamin, Abd. Shukor Sarif. Panel Kejuruteraan Geomatik, Jabatan Kejuruteraan Pengangkutan, Geoteknik dan Geomatik, Fakulti Kejuruteraan Awam dan Alam Sekitar, UTHM. 2 Lab sheet Levelling, Geomatics Laboratory. Centre for Diploma Studies. 3 https://www.scribd.com/doc/261201512/Geomatic-LevellingReport# 4 http://www.boeingconsult.com/tafe/ss&so/survey1/level/notessur1.htm