TARLAC AGRICULTURAL UNIVERSITY
Colle ge of Engineering and Technolog y
DEPARTMENT OF GEODETIC ENGINEERING
Leveling
Types and Methods
John Leonard M. Constantino, GE, MSME
January 30, 2024
LEVELING
is the process of directly or indirectly
measuring vertical
distances to determine the elevation of points or their differences
in elevation.
Is an operation in surveying performed to determine the
difference in levels of two points. – Dr. A M Chandra
Leveling
The idea
Compute the elevation of point B if the elevation of
point A is equal to 100
A
B
Leveling
The idea
Compute the elevation of point B if the elevation of
point A is equal to 100
A
Elev. = 100 m
B
Vertical Datum
Elev. = 0 m
Leveling
The idea
Find the elevation of point B?
A
Elev. = 100 m
B
Vertical Datum
Elev. = 0 m
Leveling
The idea
A
Elev. = 100 m
B
Vertical Datum
Leveling
The idea
A
Elev. = 100 m
B
Vertical Datum
Leveling
The idea
1.20 m.
A
Elev. = 100 m
B
Vertical Datum
Leveling
The idea
A
Elev. = 100 m
B
Vertical Datum
Leveling
The idea
A
Elev. = 100 m
B
Vertical Datum
Leveling
The idea
2.10 m.
A
Elev. = 100 m
B
Elev. = ?
Vertical Datum
Leveling
The idea
1.20 m.
2.10 m.
A
Elev. = 100 m.
B
Elev. = ?
Vertical Datum
Leveling
The idea
Elevation B = 100 + 1.20 - 2.10 = 99.10 m.
1.20 m.
2.10 m.
A
Elev. = 100 m.
B
Elev. = ?
Vertical Datum
Common Terminologies
Vertical Datum: A level surface to which elevations are referred, for example: MSL.
A
B
Vertical Datum
Common Terminologies
Vertical Datum: A level surface to which elevations are referred, for example: MSL.
Elevation is the vertical distance from a vertical datum to a point or an object.
A
Elev. = 100 m
B
Vertical Datum
Common Terminologies
Vertical Datum: A level surface to which elevations are referred, for example: MSL.
Elevation is the vertical distance from a vertical datum to a point or an object.
Benchmarks (BM): A relatively permanent artificial or natural object having a point
of known elevation.
A
Elev. = 100 m
B
Vertical Datum
Backsight (BS) is a point which is to be used to determine the elevation and/or
angular orientation of the surveying instrument
BS
A
Elev. = 100 m
B
Vertical Datum
Foresight (FS) is a point to which an instrument sighting is made for measuring or
establishing its elevation and/or its horizontal position
FS
A
Elev. = 100 m
B
Vertical Datum
Turning Point (TP) is a temporary point whose elevation is determined during the
process of leveling; used to establish the Height of Instrument.
A
Elev. = 100 m
TP1
TP2
B
Common Terminologies
Vertical Line = a line that follows the
direction of gravity
Level Surface = A curved surface
perpendicular to the direction of
gravity at every point on it
Level Line = a line that is
perpendicular to the direction of
gravity at every point on it, contained
in a level surface and is a curved
line.
Horizontal Plane = a plane that is
perpendicular to gravity at one point,
a flat surface.
Horizontal Line = a straight line
perpendicular to the direction of
gravity at one point
Level Surface – Is the equipotential surface of
the earth’s gravity field. It is curved surface
and every element of which is normal to the
plumb line.
Datum – is a reference surface of constant
potential, called as a level surface fo the
earth’s gravity field, for measuring the
elevations of the points. One of such surfaces
is the mean sea level surface and is considered
as standard datum. Also an arbitrary surface
may be adopted as a datum.
Level Line – A line lying in a level surface is a
level line. It is thus a curved line.
Station – is the point where the levelling staff is held
Height of Instrument (H.I.) or height of collimation – For any set up of the level, the
elevation of the line of sight is the height of instrument.
Change point (C.P.) or turning point – is the point where both the fore sight and back
sight are made on a staff held at that point. A change point is required before moving the
level from one section to another section.
Intermediate sight (I.S.) – covers all sightings and consequent staff readings made
between back sight and fore sight within each section.
Balancing of sights – When the distances of the stations where back sight and fore sight
are taken from the instrument station, are kept approximately equal, it is known as
balancing of sights. Balancing of sights minimizes the effect of instrumental and other
errors.
Reduced level (R.L.) – Reduced level of a point is its height or depth above or below the
assumed datum. It is the elevation of the point.
Rise and fall – the difference of level between two consecutive points indicates a rise or
a fall between the two points.
Section – comprises of one back sight, one fore sight and all the intermediate sights
taken from one instrument set up within that section. Thus the number of sections is
equal to the number of setups of the instrument.
Loop closure or misclosure – is the amount by which a level circuit fails to close. It is the
difference of elevation of the measured or computed elevation and known or
established elevation of the same point.
A level is an optical instrument
used to establish or verify points in
the same horizontal plane in a
process known as levelling, and is
used in conjunction with a levelling
staff to establish the relative
heights levels of objects or marks.
Level
A
B
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 vertical datum. It cannot be
used without a leveling instrument.
Leveling Rod/staff
A
B
COMMON TYPES OF LEVELING INSTRUMENT
•Is the most widely used direct leveling
instrument
•It has a long telescope which is rigidly
attached to the level bar. The telescope,
which can be rotated through 360
degrees, fixes the direction of the line
ofsight. Attached to the level bar is a
level vial which always remains in the
same vertical plane as the telescope. A
leveling head supports the telescope and
permits the bubble in the tube to be
centered by means of the leveling
screws. The whole instrument is in turn
supported by means of a tripod.
-----4
Automatic Level
1
4. Horizontal circle
6
7
1. Focusing screw
2. Eyepiece
3. Foot screw
6. Tangent screw
7. Circular bubble
-
l"
5. Base plate
2
8. Collimator (sight)
9. Object lens
3
Self – Leveling features are
incorporated
-It does not use a level vial and its
ability to level itself depends upon
the action of a complex pendulum
and prism device.
WYE LEVEL
- The only distinct difference in
dumpy level is in the telescopes
are attached to the supporting
level bar.
- It has a detachable telescope
which rests in supports called
wyes. It can be removed from the
Y – shaped supports and turned
end for end during adjustment by
releasing the two clamping collars
which fit across the tops of Y’s .
- Curved clips are used to fasten
the telescopein place.
LASER LEVEL
is a control tool consisting
of a laser beam projector
that can be affixed to a
tripod, which is leveled
according to the accuracy
of the device and which
projects a fixed red or
green beam along the
horizontal and/or vertical
axis.
LEVELIN METHODS
G
1. Differential or Spirit Leveling
2. Reciprocal Leveling
3. Profile Leveling
4. Trigonometric Leveling
5. Stadia Leveling
6. Barometric Leveling
7. Cross section
1.Differential
or Spirit Leveling
•Is the commonly employed method
of determining the elevation of points
some distance apart by a seties of
set ups of a leveling instrument along
a selected route.
•Differential leveling, Double – rodded
leveling, and Three wire leveling are
forms of direct leveling.
•It is the most precise method of
leveling, it is used when high degree
of accuracy is requird.
2. BAROMETRIC
Leveling
Involves the determination of
differences in elevation between
points by measuring the variation in
atmosperic pressureat each point by
means of a barometer.
The pressure caused by the weight
of a column of air above the observer
decreases as the observer higher in
altitude
This method is particularly useful for
low precision leveling over rough
terrain where extensive areas need to
be covered and differences in
elevation are large.
It is principally employed on
reconnaissance surveys or other work
requiring onlyapproximate values.
2. Profile
Leveling
Short profiles at right angles to the line of work
are usually plotted at regular intervals for this
purpose
Reciprocal levelling - is employed to determine the correct difference of
level between two points which are quite apart and where it is not possible
to set up the instrument between the two points for balancing the sights. It
eliminates the errors due to the curvature of the earth, atmospheric
refraction and collimation.
Trigonometric Levelling – involves measurement of vertical angle and either
the horizontal or slope distance between the two points between which the
difference of level is to be determined.
SOURCES OF ERROR IN LEVELING
Instrumental Error – due to imperfections in the instruments
1.Instrument out of adjustment – most common instrumental
error is caused by the level being out of adjustment
2.Rod not standard length – it is possible to have inaccurate
graduations or divisions on a rod. This is usually due to
imperfections in their manufacturer.
3.Defective Tripod – the movement of the level due to settling
of the tripod legs can cause possible errors in leveling work.
The tripod usually settles in soft ground or due to vibrations
caused by passing vehicular traffic.
PERSONAL ERROR – due to the limitations of the senses of touch, sight or hearing of
individuals, the skills, training, and teamwork of the members of a leveling party are also
major factors to be considered
1.Bubble not centered – rod readings will be in error when the bubble is not centered in
the level vial. It depends on how sensitive the vial has been designed.
2.Parallax – if a pressure gauge or any
graduated circular meter is viewed from different
angles, one will notice that a numberof slightly divergent values could be read.
Can be
the
elliminated by careful focusing of the telescope until no apparent movement of
be detected.
horizontal hair relative to the rod can
3.Faulty rod readings – misread the number of meters and decimals when taking
a rod
reading.
4.Rod not held plumb – aside from holding the rod on a firm and definite point, it should
be held as nearly vertical as possible.
5.Incorrect setting of target – the rodman at times fails to set properly the target when high rod reading a
is made with it .
NATURAL ERRORS – errors which are due natural sources and could not be totally removed
but their effects can be reduced by applying corrections and using good judgement.
1.Curvature of the earth – the effect of curvature of earth is to increase the rod reading.
Occurs in extra long sights and when backsight and foresight distances are not made
equal.
2.Atmospheric refraction – the presence of heat waves on a hot day is a sign of rapidly
fluctuating refraction in the atmosphere.
3.Temperature variations – changes in temperature causes leveling rods to either expand
or contract and these could introduce errors when taking rod readings.
4.Wind – a strong wind can shake a leveling instrument making it difficult to center the
bubble in the level vial
5.Settlement of the instrument – in soft or thawing ground, mud, and swamps the
instrument may settle in the interval of time between rod readings.
6.Faulty turning points – this condition is similar ro that resulting from settlement of the
instrument.
17-6. ILLUSTRATIVE PROBLEMS.
1. DIFFERENTIAL LEVELING. Complete the differen\al level notes, show below and perform the
customary arithme\c check.
STA
BS
HI
FS
ELEV
BMI
1.256
TPI
1.116
1.886
TP2
1.228
1.527
BM2
1.189
2.246
BM3
1.070
2.017
TP3
1.831
2.656
BM4
127.133
2.765
STA. = STATION
BS = BACK SIGHT
HI = HEIGHT OF
INSTRUMENT FS =
FORESIGHT
ELEV. = ELEVATION
17-6. ILLUSTRATIVE PROBLEMS.
1. DIFFERENTIAL LEVELING. Complete the differen\al level notes, show below and perform the
customary arithme\c ch eck.
STA
BS
HI
FS
ELEV
BMI
1.256 1 28.389
TPI
1.116
1.886
TP2
1.228
1.527
BM2
1.189
2.246
BM3
1.070
2.017
TP3
1.831
2.656
BM4
127.133
2.765
HI = ELEV + BS
HI = 127.133 + 1.256
HI = 128.389
17-6. ILLUSTRATIVE PROBLEMS.
1. DIFFERENTIAL LEVELING. Complete the differen\al level notes, show below and perform the
customary arithme\c check.
STA
BS
HI
FS
ELEV
BMI
1.256 128.389
TPI
1.116
1.886 126.503
TP2
1.228
1.527
BM2
1.189
2.246
BM3
1.070
2.017
TP3
1.831
2.656
BM4
127.133
2.765
HI = ELEV BMI + BS BMI
HI = 127.133 + 1.256
HI = 128.389
ELEV TPI = HI BMI - FS TPI
ELEV TPI = 128.389 - 1.886
ELEV TPI = 126.503
17-6. ILLUSTRATIVE PROBLEMS.
1. DIFFERENTIAL LEVELING. Complete the differen\al level notes, show below and perform the
cu stomary arithme\c c heck.
ST A
B MI
BS
HI
FS
ELEV
1.256 128.389
127.133
T PI
1.116 127.619
1.886 126.503
TP2
1.228
1.527
BM2
1.189
2.246
BM3
1.070
2.017
TP3
1.831
2.656
BM4
2.765
HI = ELEV BMI + BS BMI
HI = 127.133 + 1.256
HI = 128.389
ELEV TPI = HI BMI - FS TPI
ELEV TPI = 128.389 - 1.886
ELEV TPI = 126.503
HI TPI = ELEV TPI + BS TPI
HI TPI = 126.503 +1.116
HI TPI = 127. 619
終わり
끝
la fine
el fin
la fi
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das Ende
το τέλος
The End
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wala na, finish na