geomatic - leveling
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LEVELING SURVEY
Mohd Efendi Daud (Dr. Sc)B.Surv (UTM, Malaysia) Msc (UTM, Malaysia), Dr.Sc, (a!oya U"iv.,
#apa")
(Geomatic Division)
acu!t" o# $ivi! % Environmenta! En&ineerin&'Universiti un ussein *nn Ma!a"sia' +,- /atu 0ahat'
1ohor' M2L2YSI2.0hone 3 4,5-6757,78 4,9:5+675-8 a; 3
4,5-675,E<mai! 3 efendi=uthm.edu.m"
>e?3 htt@3AABBB.#Cass.uthm.edu.m"A
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Leve!in& Surve"
Learnin& *utcomes
– Explain the basic principle of leveling process,
– Set up and carry out adjustment of a levelinstrument, book leveling data, adjust forerrors,
– Carry out reductions of eld observations and
apply checks to leveling work, and– Explain the concept of crosssections and
proles
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Introduction
! "eveling is the most fre#uently usedsurvey skill$
! %eomatic or Civil engineers candetermine the elevation of a speciedlocation relative to another CnoBne!evation$
! &t is a simple concept that measuresvertical distance relative to a hori'ontalline of sight$
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Introduction
! "eveling re#uires a &raduated staf for the vertical measurements and
an instrument called !eve! that willprovide a hori'ontal line of sight$
! "eveling is perhaps the most basic of
geomatic surveying operation andform an important fundamental partof almost every geomatic project$
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r nc @ es an2@@!ication o#
Leve!in&! "eveling is a measurement process
whereby the di(erence in heightbetween two or more points can bedetermined$
! )he engineer will rst take a backsight
reading *+S to a point of knownelevation *datum to determine theelevation of the instrument$
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! )he engineer will then took aforesight reading *-S to a point of
unknown elevation$! -inally the elevation of that points
*-S can be determined using the
elevation of the instrument minus thevalue on the level sta( read throughthe level.s telescope *+S – -S$
r nc @ es an2@@!ication o#
Leve!in&
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0rinci@!es o#Leve!in&
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+ac ks ig h t
/0 knownelevation
-or esight
+S 1od1eading
-S 1od1eading
+0 unknownelevation
0rinci@!es o#Leve!in&
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elev/ 2
345$678m
9atum0 elev 24$444m
:& 2346$68;m
+S *<
3$45=m
-S *
4$>87m
elev+ 2
345$;43m
Elev+ 2 Elev/ < +S
-S
Elev/ < +S 2 :&:& – -S 2 Elev+
/0 knownelevation
+0 unknownelevation
0rinci@!es o#Leve!in&
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! ?nce the elevation of a point isdetermined, that point can be usedfor determining the elevations ofother points$
! )herefore, the concept of levelinginvolves the measurement of verticaldistance relative to a hori'ontal lineof sight$
0rinci@!es o#Leve!in&
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0rinci@!es o#Leve!in&
! "eveling re#uires a graduated sta(*level sta( for the vertical
measurements and an instrument*level that will provide a hori'ontalline of sight$
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2@@!ications o#Leve!in&
! )ypical examples of leveling applicationsincludes@
– Establishing new vertical control *+A or )+A– 9etermining the heights of discrete points,
– Broviding spot heights or contours on a plan,
– Broviding data for road crosssections or
volumes of earthworks, and– Broviding a level or inclined plane in the
setting out of construction works$
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Leve!in& erms
! )here are various terms in levelingprocedure that should be
familiari'ed$– Datum
! / datum is any reference surface to whichelevations of points are referred to$ &n mostcase the most common datum which is usedthat of Mean Sea Leve! (MSL)$
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Leve!in& erms
– /ench MarC (/M)!-or a datum to be accessible to users, a series
of permanent marks must be established$ )hese
marks are known as /ench MarCs$ )heelevations of these /ench MarCs can beestablished by di(erential leveling over a periodof years$
– Reduced Leve! (RL)! )he reduced level *1" of a @oint is its
e!evation a?ove or ?e!oB a re#erencedatum o# /M$
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Leve!in& erms
– em@orar" /ench MarC (/M)
! / point placed or selected *e$g$ peg, nail,
spike, center of manhole to provide atem@orar" re#erence @oint durin& aconstruction or surve"in& BorC $
– /acCsi&ht (/S)
! /lways the rst readin& for a newinstrument station$
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Leve!in& erms
– oresi&ht (S)
!/lways the !ast reading from the currentinstrument station$
– Intermediate Si&ht (IS)
!/ny sighting that is not a backsight or aforesight$
–$han&e 0oint ($0)!"ocation of the sta( when the level is moved$
Changed point should be– Stable,
– ell dened
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Leve!in& erms
– Leve!in& Staf ! )his is the instrument where the vertical
distance above or below the hori'ontalsurface is read o($ &t may be telescopic orfolding, extending to a
length usually of 6m or7m and graduated to be
easily read in the eld ofview of the leveltelescope$
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E;ercise 7.9
! hat are the applications of levelingin civil engineeringD
! hat is the relation between
9atum +ench AarkD
! hat are the sta( reading
of /, +, and CD
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$!assication o#Leve!
! )he level instruments may be
classied on the following basis0
– Classication of level based onaccuracy, and
– Classication of level based on design$
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Leve! /ased on2ccurac"
! )he levels can be divided into threetypes based on their accuracy@
– 0recise Leve!! Brecise level is a very accurate instrument
for geodetic or any other very preciseleveling work$
– Medium 2ccurac" Leve!! )here are used for engineering surveys$ )hey
may be tilting or automatic instruments$
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– /ui!ders Leve!! +uilders. level is a low accuracy instrument
which is used for short range leveling suchas setting out on building sites$
Leve! /ased on2ccurac"
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Leve! /ased onDesi&n
! )here are three types of levels
– Dum@" Leve!s
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– i!tin& Leve!s
Leve! /ased onDesi&n
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– 2utomatic Leve!s! /utomatic level is almost universal now$
Leve! /ased onDesi&n
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– 2utomatic Leve!s
Leve! /ased onDesi&n
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em@orar"2dFustment
! )emporary adjustments are theadjustments which are carried out at
each setting of the level instrument$! )hese are of three types@
– Setting Fp,
– "eveling, and– -ocusing
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o hen pond bubble is center in theinstrument.s standing axis approximatelyvertical$
0ond /u??!e(Leve!in&)
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o hen focusing any optical instrument it isvitally important that we eliminate Barallax$
E!imination o# 0ara!!a;
-ocus the crosshairs *using the Eyepiece
-ocus the object *using the -ocusing screw
Aove eye up and down over the eyepiece
&mages appears to move
Barallax exists and must be removed by betterfocusing
Barallax has been removed$ )herefore focusing isgood
0ara!!a;(ocusin&)
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E;ercise 7.
! 9ene the following terms0
– 1educed "evel,
– +ench Aark,– Change Boint, and
– Barallax$
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Ru!es o# Leve!in&
! )he rules of leveling are0
– /lways commence and nish a level run on
a +enchmark *+A or )+A of known height,– Geep foresight and backsight distances as
e#ual as possible,
– Geep lines of sight short *normally H54 m,
– Iever read below 4$7 m on a sta(*refraction, and
– Fse stable, well dened change points$
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ie!d 0rocedure
! ?bservation Brocedures
– Consider a series of measurements of
level loop as shown$
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BM A (elev.134.685m)
B
1.055m
TP1
1.451m0.927m
TP2
1.295m
0.713m 1.835m
*?servation0rocedures
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! +ooking Brocedures
– )wo methods of leveling eld book and
computation$! 1ise -all, and
! :eight of Collimation
ie!d 0rocedures
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BS IS FS RISE FALL REDUCE
LEVEL
ADJUSTMENT REDUCE
LEVEL (T)
DIST. REMARK
2.390 31.517 0 31.517 0 TBM=31.517
1.985 0.405 31.922 0 31.922 A
1.318 0.667 32.589 0 32.589 B
0.988 1.612 0.294 32.295 -0.002 32.293 60 C (TP)
1.502 0.514 31.781 -0.002 31.779 D
1.415 0.087 31.868 -0.002 31.866 E2.420 0.316 1.099 32.967 -0.003 32.964 120 F (TP)
0.532 1.888 34.855 -0.005 34.850 160 TBM2=34.850
CHEKS
∑BS=
5.798
∑FS=
2.460
∑RISE=
4.146
∑FALL=
0.808
R.L(B)=34.855
∑FS=
2.460
∑FALL=
0.808
R.L (T)=
31.517
3.338 3.338 3.338
/ooCin&0rocedures
Rise % a!! Metho
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/S IS S RISE 2LL REDU$E
LEVEL
2D1USMEN
REDU$ELEVEL(2)
DIS. REM2RH
J$584
3$8>7
3$53>
3$;3J4$8>>
3$74J
3$637
4$53;J$6J4
4$75J
4$647
4$;;=
4$J86
4$736
4$4>=
3$488
3$>>>
C:ECGS
∑+S 2 7$=8> ∑-S 2 J$6;4∑1 2 6$36;∑- 2 4$>4>
53$73=
53$8JJ
5J$7>8
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o Bage checks
o Compute closure
obased on endpoint
odene allowable closure
ocompared eld closure toallowable closure
oapply correction
$!osure
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BS IS FS RISE FALL REDUCE
LEVEL
2.390 31.517
1.985 0.405 31.922
1.318 0.667 32.589
0.988 1.612 0.294 32.295
1.502 0.514 31.781
1.415 0.087 31.868
2.420 0.316 1.099 32.9670.532 1.888 34.855
CHEKS
∑BS=
5.798
∑FS=
2.460
∑RISE=
4.146
∑FALL =
0.808
R.L(B)=34.855
∑FS=
2.460
∑FALL =
0.808
R.L (T)=
31.517
3.338 3.338 3.338
∀Σ+S – Σ-S 2 7$=8>m – J$6;4m 2 5$55>m
∀Σ1&SE – Σ-/"" 2 6$36;m 4$>4>m 2 5$55>m
!1$"
+ottom 1$"
)op 2 56$>77m 53$73=m 2
5$55>m
0a&e $hecCs
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BS IS FS RISE FALL REDUCE
LEVEL
ADJUSTMENT REDUCE
LEVEL (T)
DIST. REMARK
2.390 31.517 0 31.517 0 TBM=31.517
1.985 0.405 31.922 0 31.922 A
1.318 0.667 32.589 0 32.589 B
0.988 1.612 0.294 32.295 -0.002 32.293 60 C (TP)
1.502 0.514 31.781 -0.002 31.779 D1.415 0.087 31.868 -0.002 31.866 E
2.420 0.316 1.099 32.967 -0.003 32.964 120 F (TP)
0.532 1.888 34.855 -0.005 34.850 160 TBM2=34.850
!End closure 2 56$>77m 56$>74m 2 4$447m K7mm
!/llowable closure0
mm
mm
2 >mm
D
distance
16.0
acceptale
$!osure
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/djustment 2 EndclosureLΣ )B, or
/djustment 2 "oopclosureLΣ )B 2 4$447L5 2 4$443=m per -SBS IS FS RISE FALL REDUCE
LEVEL
ADJUSTMENT REDUCE
LEVEL (T)
DIST. REMARK
2.390 31.517 0 31.517 0 TBM=31.517
1.985 0.405 31.922 0 31.922 A1.318 0.667 32.589 0 32.589 B
0.988 1.612 0.294 32.295 -0.002 32.293 60 C (TP)
1.502 0.514 31.781 -0.002 31.779 D
1.415 0.087 31.868 -0.002 31.866 E
2.420 0.316 1.099 32.967 -0.003 32.964 120 F (TP)
0.532 1.888 34.855 -0.005 34.850 160 TBM2=34.850
2dFustment
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BS IS FS H!C REDUCE
LEVEL
C!RRECTI!N REDUCE
LEVEL (T)
DIST. REMARK
2.390 33.90" 31.517 0 31.517 0 TBM=31.517
1.985 31.922 0 31.922 A
1.318 32.589 0 32.589 B
0.988 1.612 33.283 32.295 -0.002 32.293 60 C (TP)
1.502 31.781 -0.002 31.779 D
1.415 31.868 -0.002 31.866 E2.420 0.316 35.38" 32.967 -0.003 32.964 120 F (TP)
0.532 34.855 34.855 -0.005 34.850 160 TBM2=34.850
CHEKS
∑BS=
5.798
∑FS=
2.460
R.L(B)=34.855
∑FS=
2.460
R.L (T)=
31.517
3.338 3.338
ie!d 0rocedures
ei&ht o#$o!!imation
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Summar"
! 1ise -all Aethod
o +S – -S 2 <ve *1&SE
o +S – -S 2 ve *-/""! :eight of Collimation Aethod
o :?C 2 1" < +S
o 1"*I, 2 :?C – -SL&S
! /rithmetic Check
ο ∑+S ∑-S 2 ∑1&SE ∑-/"" 2 1"*E,1"*+,
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Errors in Leve!in&
! )he following are the sources oferrors in levelling0
– %ross Errors *Aost Common! rong sta( reading,
! rong crosshair used to read sta(,
! rong booking,
! ?mission or wrong entry on booking sheet,and
! Spirit level not centered
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Errors in Leve!in&
– Constant Errors
! IonMertically of sta(,
! Collimation error of instrument, and
! Sta( graduation errors$
– 1andom ErrorL/ccidental
! eatherstrong windLground shimmer,
! Aovement of the change point, and! :uman erroreyesight peculiarities
E % h
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o 1efraction varies with line of sight, andtime
!"#i$"ntal
%ine "& si'(t
+S 2 -SSight top the same sta( rst
9on.t take reading lower than
Errors % hoB toe!iminate
E % h t
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o Sighting errors
o Ainimi'e line of sight
o Compare readings on left and right handside of the sta(
o &nstrument errors
o /djust of the circular bubble
o Sta( errorso %raduation errors
o Sta( not verticality
Errors % hoB toe!iminate
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E;ercise 7.7
! hat are the sources of errors inlevelingD
! hat precautions you will take toavoid them$
ermanen
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ermanen2dFustment o#
Leve!s! )he permanent adjustment is carried
out to establish the xed relationship
between the fundamental lines of alevel$
! )he fundamental lines of level are
+ubble axis, line of collimation,vertical axis, and the axis of thetelescope
ermanen
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! )he only permanent adjustment that willbe discussed here is the collimation errori$e$ to determine the line of collimationparallel to the bubble axis$
! Collimation error is much moresignicant than the other errors$ &t
should be kept as small as possible sothat one need not be too precise inensuring that ND
ermanen2dFustment o#
Leve!s