CONTENTS

Introduction to leveling 3

Definitions and terms used in leveling 4-8

Methods of leveling 9-10

Equipment 11-15

Objectives 16

Leveling fieldwork Data 17-20

Conclusion 21

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INTRODUCTION TO LEVELING:

DEFENITION OF LEVELING:

Leveling is a type of surveying, the objective of which is: i) to find the elevations of given

points in relation to a set or assumed datum, and ii) to establish points at a given or

assumed datum. The first operation is required to enable the works to be designed while

the second operation is required in the setting out of all types of engineering works.

Levelling deals with measurements in a vertical plane.

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DEFINITIONS AND TERMS USED IN LEVELING:

Level surface: A level surface is defined as a curved surface which at each point is

perpendicular to the direction of gravity at the point. The surface of a still water is a truly

level surface. Any surface parallel to the mean spheroidal surface of the earth is, therefore,

a level surface.

Level line: A level line is a line lying in a level surface. It is, therefore, normal to the plumb

line at all points.

Horizontal plane: Horizontal plane through a point is a plane tangential to the level surface

at that point. It is, therefore, perpendicular to the plumb line through the point.

Horizontal line: It is a straight line tangential to the level line at a point. It is also

perpendicular to the plumb line.

Vertical line: It is a line normal to the level line at a point. It is commonly considered to be

the line defined by a plumb line.

Datum: Datum is any surface to which elevation are referred. The mean sea level affords a

convenient datum world over, and elevations are commonly given as so much above or

below sea level. It is often more convenient, however, to assume some other datum,

specially, if only the relative elevation of points are required.

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Elevation: The elevation of a point on or near the surface of the earth is its vertical distance

above or below an arbitrarily assumed level surface or datum. The difference in elevation

between two points is the vertical distance between the two level surfaces in which the two

points lie.

Vertical angle: Vertical angle is an angle between two intersecting lines in a vertical plane.

Generally, one of these lines is horizontal.

Mean sea level: It is the average height of the sea for all stages of the tides. At any

particular place it is derived by averaging the hourly tide heights over a long period of 19

years.

Bench Mark: It is a relatively permanent point of reference whose elevation with respect to

some assumed datum is known. It is used either as a starting point for levelling or as a point

upon which to close as a check.

5

DIFFERENTIAL LEVELING:

Differential leveling is the establishment of differences in elevation between two or more

points with respect to a datum. Differential leveling is the process of measuring vertical

distances from a known elevation point to determine elevations of unknown points. The

most common methods to determine elevation are through the use of a compensator type,

automatic (engineering level) and level rods, and an electronic digital barcode leveling

instrument with barcode rod. A thorough knowledge of leveling principles and proper

application of methods and equipment will prevent costly delays and generate the needed

results and accuracy.

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DEFINITIONS OF KEY TERMS:

Set:

The location of the level. (where it is set-up)

Bench Mark (BM):

A permanent point of known elevation.

Temporary Bench Mark (TBM):

A point of known elevation.

Turning Point (TP):

An intervening point between BMs or TBMs upon which a backsight and a foresight

are taken.

Backsight (BS):

A rod reading taken by "looking back" at a point of known elevation such as a BM or

TP.

Foresight (FS):

A rod reading taken when "looking ahead" at a point where you want to determine

its elevation, such as a TP, TBM or BM.

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FIGURE: Shows an illustration of a typical backsight and foresight.

Height of Instrument (HI):

The elevation of the line of sight in the telescope of the level.

Balancing of Sights:

The rodperson keeps track of the distance of each FS and BS taken and tries to keep

them equal.

Closed Circuit:

A complete trace of the line of sight of the instrument back to the beginning point.

Closure:

The difference between beginning and ending elevations.

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METHODS OF LEVELING:

1. Height of Collimation Method

2. Rise and Fall Method

Collimation Method: It consist of finding the elevation of the plane of collimation ( H.I.) for

every set up of the instrument, and then obtaining the reduced level of point with reference

to the respective plane of collimation.

1. Elevation of plane of collimation for the first set of the level determined by adding back

side to R.L. of B.M.

2. The R.L. of intermediate point and first change point are then obtained by starching the

staff reading taken on respective point (IS & FS) from the elation of the plane collimation.

[H.I.]

3. When the instrument is shifted to the second position a new plane collimation is set up.

The elevation of this plane is obtained by adding B.S. taken on the C.P. From the second

position of the level to the R.L. C.P. The R.L. of successive point and second C.P. are found by

subtract these staff reading from the elevation of second plane of collimation Arithmetical

check

Sum of B.S. – sum of F.S. = last R.L. – First R.L.

This method is simple and easy.

Reduction of levels is easy.

Visualization is not necessary regarding the nature of the ground.

There is no check for intermediate sight readings.

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This method is generally used where more number of readings can be taken with less

number of change points for constructional work and profile leveling.

Rise and Fall Method: It consists of determining the difference of elevation between

consecutive points by comparing each point after the first that immediately preceding it.

The difference between there staff reading indicates a rise fall according to the staff reading

at the point. The R.L is then found adding the rise to, or subtracting the fall from the

reduced level of preceding point.

Arithmetic check

Sum of B.S. – sum of F. S. = sum of rise – sum of fall = last R. L. – first R.L.

This method is complicated and is not easy to carry out.

Reduction of levels takes more time.

Visualization is necessary regarding the nature of the ground.

Complete check is there for all readings.

This method is preferable for check levelling where number of change points are more.

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EQUIPMENT:

AUTOMATIC LEVEL:

An automatic levelling equipment is an optical instrument used to establish or verify points

in the same horizontal plane. It is used in surveying and building with a vertical staff to

measure height differences and to transfer, measure and set heights.

The level instrument is set up on a tripod and, depending on the type, either roughly or

accurately set to a leveled condition using footscrews (levelling screws). The operator looks

through the eyepiece of the telescope while an assistant holds a tape measure or

graduated staff vertical at the point under measurement. The instrument and staff are used

to gather and/or transfer elevations (levels) during site surveys or building construction.

Measurement generally starts from a benchmark with known height determined by a

previous survey, or an arbitrary point with an assumed height.

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LEVEL STAFF:

A level staff, also called levelling rod, is a graduated wooden or aluminium rod, used with

a levelling instrument to determine the difference in height between points or heights of

points above a datum surface. It cannot be used without a leveling instrument. The levelling

rod has two sides, one side with metric unit and the other with imperial unit.

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TRIPOD:

A surveyor's tripod is a device used to support any one of a number of surveying instruments, such as theodolites, total stations, levels or transits. The legs are locked by a lever clamp and adjusted depending on how you set it up.

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TRIBRACH:

A tribrach is an attachment plate used to attach a surveying instrument. A tribrach allows

the survey instrument to be repeatedly placed in the same position with sub-

millimetre precision, by just loosening and re-tightening a locking handle or lever.

The tribrach is attached to the tripod and placed over the monument. Looking through

the optical plummet pick up two of the tripod legs and position the cross hairs over the

monument.

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BULLS EYE LEVEL:

A bull's eye level is a type of spirit level that allows for the leveling of planes in two

dimensions — both the 'pitch' and 'roll' in nautical terms. Standard tubular levels only

consider one dimension. Bull's eye levels are used primarily by carpenters in construction,

but can also be found as features of compasses or other devices that need to be kept from

tipping in certain directions. Small bull's eye levels are also found incorporated into tripods.

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OBJECTIVES:

To learn levelling principles, theory and applications and be able to apply the during fieldwork

To learn to properly assemble and set up automatic level, tripod and other instruments for fieldwork.

To further understand the levelling procedure

To be able to correctly and systematically record data gathered during fieldwork such as (BS) backsight, (IS) intermediate sight and (FS) foresight.

To use the correct equation table to enter data into.

To properly calculate and measure levelling

Identifying the reduced level

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Leveling fieldwork Data

Map for fieldwork- (Taylor’s University Carpark)

Height of collimation data

B.S I.S F.S Height of collimation

R.L

1.458 101.458 100.001.390 3.679 99.169 97.7791.619 1.502 99.286 97.6671.243 1.535 98.994 97.7511.553 1.488 99.059 97.5061.276 1.269 99.066 97.7901.274 1.300 99.040 97.7661.627 1.436 99.231 97.6043.571 1.489 101.313 97.7421.348 1.338 101.323 99.975

1.329 99.99416.359

- 16.365 - 0.006

16.365 99.994- 100.000 - 0.006

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Rise and fall data

B.S I.S F.S Rise Fall R.L

1.458 100.001.390 3.679 2.221 97.7791.619 1.502 0.112 97.6671.243 1.535 0.084 97.7511.553 1.488 0.245 97.5061.276 1.269 0.284 97.7901.274 1.300 0.024 97.7661.627 1.436 0.162 97.6043.571 1.489 0.138 97.7421.348 1.338 2.233 99.975

1.329 0.019 99.99416.359

- 16.365 - 0.006

16.365 2.758- 2.764 - 0.006

2.764 99.994- 100.000 - 0.006

Allowable misclosure

Formula= 12 √K mm ; K= No. of instrument set ups

12√10= 37.947mm

Adjusted height of collimation data

B.S I.S F.S Height of collimation

R.L Adjustments Final R.L

1.458 101.458 100.000 100.0001.390 3.679 99.169 97.779 +0.0006 97.77961.619 1.502 99.286 97.667 +0.0012 97.66821.243 1.535 98.994 97.751 +0.0018 97.75281.553 1.488 99.059 97.506 +0.0024 97.50841.276 1.269 99.066 97.790 +0.0030 97.79301.274 1.300 99.040 97.766 +0.0036 97.76961.627 1.436 99.231 97.604 +0.0042 97.60823.571 1.489 101.313 97.742 +0.0048 97.74681.348 1.338 101.323 99.975 +0.0054 97.9804

1.329 99.994 +0.0060 100.000016.359

- 16.365 - 0.006

16.365 99.994- 100.000 - 0.006

100.000- 100.0000 0.00

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Adjusted rise and fall data

B.S I.S F.S Rise Fall R.L Adjustments Final R.L

1.458 100.000 100.0001.390 3.679 2.221 97.779 +0.0006 97.77961.619 1.502 0.112 97.667 +0.0012 97.66821.243 1.535 0.084 97.751 +0.0018 97.75281.553 1.488 0.245 97.506 +0.0024 97.50841.276 1.269 0.284 97.790 +0.0030 97.79301.274 1.300 0.024 97.766 +0.0036 97.76961.627 1.436 0.162 97.604 +0.0042 97.60823.571 1.489 0.138 97.742 +0.0048 97.74681.348 1.338 2.233 99.975 +0.0054 97.9804

1.329 0.019 99.994 +0.0060 100.000016.359

- 16.365 - 0.006

16.365 2.758- 2.764 - 0.006

2.764 99.994- 100.000 - 0.006

100.000- 100.0000 0.00

Correction per set up

Formula= Error of misclosure ÷ No. of instrument set ups

[100.000-99.994] ÷10 = 0.0006m

Two-peg test data

Two sets of readings are taken. For first reading, the instrument is placed on the 15m mark and for the second reading the instrument is placed on the 25m mark. The levering staff will be place at the 0m mark and the 30m mark for the entire time.

First reading

RLa1=1.455RLb1=1.345Δa1-b1=1.455 - 1.345 =0.110Second reading

RLa2=1.415RLb2=1.310Δa2-b2=1.415 – 1.310 =0.105

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∴e= [0.105-0.110] ÷ 30

=-0.005m over 30m

Angle of elevation=tan-1(-0.005/30)

=-00°00 '34 "

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Conclusion

In this assignment, we have learnt how to use the auto level instrument to be used in the procedure for leveling the entire Taylor’s University carpark area and the instrument is also used for the two-peg test procedure. For the first field work which is the leveling test, we used a total of 2 different methods to calculate the reduce level of each of the staff station. The first of which is the height of collimation method and the second is the rise and fall method. We first begin the process by finding out the backsight (BS) of BM1 and the foresight (FS) of turning point 1 (TP1). This process is then repeated by shifting the auto level to acquire the (BS) and (FS) to each consequent staff stations. It was important that we finish our round and reached back at the first point which was (BM1) as we needed to obtain our (FS) from that point in order to calculate the error of misclosure. As for our error of misclosure, we got -0.006mm and as for the allowable range of misclosure is 37.947mm. Thus, our leveling results are acceptable and as such we distributed the error to each set up and the final adjusted reduced level is able to match the benchmark given which is 100.00m.

As for the two-peg test, we first measure a distance of 30m with a measuring tape and marked it on the ground. After that we marked another 2 points which are 15m and 25m on the ground. Then we proceeded to set up our instrument at the 15m mark which is going to be directly in the middle of the 2 levering staff. We first took the reading of point A which is at the 0m mark and then point B which is at the 30m mark. We then shifted the instrument to the 25m mark and repeat the steps again with the 2 levering staff at the same position as before.

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site surveying report-fieldwork

Education