GEOMATIC - Leveling

7/23/2019 GEOMATIC - Leveling

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With Wisdom, We Explore

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

mailto:[email protected]

http://www.fkass.uthm.edu.my/

http://www.fkass.uthm.edu.my/

mailto:[email protected]



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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




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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




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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$




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! "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




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– 2utomatic Leve!s! /utomatic level is almost universal now$




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– 2utomatic Leve!s




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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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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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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

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GEOMATIC - Leveling