surveying lecture 1 - copy

8/3/2019 Surveying Lecture 1 - Copy

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SURVEYING

( LECTURE 1 )


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SURVEYING

SURVEYING IS THE ART OF DETERMINING THEPOSITIONS OF POINTS ON OR NEAR THE EARTHS

SURFACE BY MEANS OF MEASUREMENTS IN THE 3ELEMENTS OF SPACE ; NAMELY, DISTANCE ,DIRECTION , AND ELEVATION.RAYNER AND SCHMIDT

SURVEYING IS THE ART OF MEASURING HORIZONTALAND VERTICAL DISTANCES BETWEEN OBJECTS , OFMEASURING ANGLES BETWEEN LINES , OFDETERMINING THE DIRECTION OF LINES , AND OF

ESTABLISHING POINTS BY PREDETERMINED ANGULARAND LINEAR MEASUREMENTS.

DAVIS , FOOTE , ANDERSON , AND MIKHAIL


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SURVEYING

SURVEYING IS THE ART OF MAKING SUCHMEASUREMENTS OF THE RELATIVE POSITIONS OFPOINTS ON THE SURFACE OF THE EARTH THAT , ONDRAWING THEM TO SCALE , NATURAL AND ARTIFICIALFEATURES MAY BE EXHIBITED IN THEIR CORRECTHORIZONTAL OR VERTICAL RELATIONSHIPS.CLARKE

SURVEYING IS THAT BRANCH OF APPLIEDMATHEMATICS WHICH TEACHES THE ART OFDETERMINING THE AREA OF ANY PORTION OF THEEARTHS SURFACE , THE LENGTH AND DIRECTIONS OF

THE BOUNDARY LINES , THE CONTOUR OF THESURFACE , AND OF ACCURATELY DELINEATING THEWHOLE IN PAPER.

WEBSTER


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SURVEYING

SURVEYING IS THE SCIENCE OR ART OF MAKING SUCHMEASUREMENTS AS ARE NECESSARY TO DETERMINETHE RELATIVE POSITION OF POINTS ABOVE , ON , ORBENEATH THE SURFACE OF THE EARTH , OR TOESTABLISH SUCH POINTS.BREED , HOSMER AND BONE

SURVEYING IS THE SCIENCE AND ART OFDETERMINING RELATIVE POSITIONS OF POINTSABOVE , ON OR BENEATH THE SURFACE OF THE EARTH, OR ESTABLISHING SUCH POINTS.

BRINKER AND WOLF


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SURVEYING

SURVEYING IS THE ART AND SCIENCE OFDETERMINING ANGULAR AND LINEARMEASUREMENTS TO ESTABLISH THE FORM , EXTENT ,AND RELATIVE POSITION OF POINTS , LINES ANDAREAS ON OR NEAR THE SURFACE OF THE EARTH ORON OTHER EXTRATERRESTIAL BODIES THROUGHAPPLIED MATHEMATICS AND THE USE OF SPECIALIZEDEQUIPMENT AND TECHNIQUES.JUNY PILAPIL LA PUTT


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Two Main Categories

Equatorial plane

Polar axis

Ellipsoid

Geoid

b

a

Geodetic line /

Plumb line

Geocentric line

Geodetic Surveying Considers curvature of the earth

Provide an accurate framework for a largesurvey

Plane Surveying Surface of the earth: as an infinite horizontal

plane

Direction of gravity:

Constant over the entire site.

Defines vertical lines( plumb lines),

Plane normal to a plumb line horizontalplane.

Hence, rectangular coordinate system:most suitable for plane surveying


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Types of Surveying

Cadastral surveys Determine lawful boundaries & areas of properties rather

than detail features of the landscape Used in legal disputes, taxation, etc.

Also calledpropertysurveys / boundary surveys

City surveys Surveys of areas in and near city

For planning expansions or improvements , locatingproperty lines , fixing reference monuments , determiningphysical features and configuration of the land , andpreparing maps.


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Types of Surveying

Construction surveys Surveys undertaken at construction site For providing data regarding grades , reference lines ,

dimensions , ground configuration , and location and

elevation of structures which are of concern toengineers, architects, and builders.

Forestry surveys Surveys executed in connection with forest management

and mensuration, and the production and conservation offorest lands.


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Types of Surveying

Hydrographic surveys Surveying streams , lakes , reservoirs , harbors, oceans , and

other bodies of water. Made to map shore lines , chart the shape of areas

underlying water surfaces, and measure the flow of streams. Of general importance in connection with navigation,

development of water supply and resources , flood control ,irrigation , production of hydro electric power, subaqueousconstructions, and recreation.


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Types of Surveying

Industrial surveys Sometimes known as optical tooling. Refers to use of surveying techniques in shipbuilding ,

construction and assembly of aircraft , layout and installation

of heavy and complex machinery, and in other industries wherevery accurate dimensional lay outs are required.

Mine surveys Performed to determine the position of all underground

excavations and surface mine structure , to fix surfaceboundaries of mining claims, determine geological formations,to calculate excavated volumes, and establish lines and gradesfor other related mining work.


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Types of Surveying

Topographic surveys Made for determining the shape of the ground, and the

location and elevation of natural and artificial features upon it.

The features shown include such natural objects as hills ,mountains , rivers , lakes , relief of the ground surface, andworks of man , such as roads , buildings , ports , towns ,municipalities, and bridges.


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Compass

For measuring angles anddirections

Observe bearings

Used in reconnaissance and hastywork

Compass

CommonSurveying Instruments


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For measuring lengths:

Measuring tape

Direct linearmeasurements

Cheap & robust

For small details

Fiberglass

measuringtape

Steeltape

Tapes


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Alidade and Plane Table Survey

The alidade is an instrument

designed mainly for

moderately accurate surveys

and geological mapping


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Leveling Instrument

AutomaticLevel

For measuringheight differences:

Level: has a telescope thatcan be rotated about thevertical axis whilemaintaining a horizontal lineof sight

Staff: long rod, when heldvertically over the point ofinterest, provides height

readings to be read by thelevel

A pair of readingsdetermines the change in

height

StaffReadings

on

a staff


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EngineersTransit

For measuring angles,directions & distance

A telescopic sight pivoted

both horizontally & vertically

Built-in graduated circles for

measuring horizontal & vertical

angles


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Theodolite

Optical TheodoliteElectronic theodolite withEDM mounted on top

For measuring angles, directions &distance

A telescopic sight pivoted both

horizontally & vertically

Built-in graduated circles for

measuring horizontal & vertical

angles

Theodolites used on construction

sites: 20, 6, 5 or 3 of arc

Geodetic theodolites: 1 or even 0.1


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Electronic Distance Measurement

ED

M

EDM & rechargeable

battery

Laser equipment for very accurate

distance measurement

Can typically measure thousands of

meters with only a few mms error

Used in all serious control work, &

often in detail surveys as well


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Total Station

More advanced instrument:

Theodolite, EDM, dataprocessor & display unitcombined into one; providesinstant data conversion intothree-dimensionalcoordinates & interface withcomputers

Total station withmemory cards


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Global Positioning System (GPS)

Satellites-based systemsgiving accurate three-dimensional coordinates ofany point on earth occupied bya GPS receiver. Also used fornavigation purposes


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ERRORS

Defined as the difference between the true valueand the measured value of a quantity and is oftenbeyond the control of the one performing theoperation.

MISTAKES

Are inaccuracies in measurements which occurbecause some aspect of a surveying operation is

performed by the surveyor with carelessness,inattention, poor judgment , and improperexecution. Also caused by a misunderstanding ofa problem , inexperience, or indifference of thesurveyor.


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TYPES OF ERRORS

SYSTEMATIC ERRORSThis type of error is one which will always have the same signand magnitude as long as field conditions remains constantand unchanged.

Will repeat itself in other measurements still maintaining thesame sign, and thus will accumulate.

Can be computed and their effects be eliminated by applyingcorrections , employing proper techniques in the use ofinstruments or by adopting a field procedure which will

automatically eliminate it.


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TYPES OF ERRORS

ACCIDENTAL ERRORSThis type of error is purely accidental in character.

Caused by factors beyond the control of the surveyor and arepresent in all surveying measurements.

Usually of minor importance in surveying operations sincethey are variable in sign and are of a compensating nature.


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SOURCES OF ERRORS

INSTRUMENTAL ERRORSDue to imperfections of the instrument used , either fromfaults in their construction or from improper adjustmentsbetween the different parts prior to use.

a. Measuring with a tape of incorrect lengthb. Using a leveling rod with painted graduations not perfectlyspaced

NATURAL ERRORS

Caused by variations in the phenomena of nature such aschanges in magnetic declination , temperature , humidity ,wind , refraction , gravity and curvature of the earth.


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SOURCES OF ERRORS

PERSONAL ERRORSArise principally from limitations of the senses of sight , touchand hearing of the human observer which are likely to beinaccurate.

ex. error in determining a reading on a rod which is out ofplumb


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ACCURACY AND PRECISION

ACCURACYIndicates how close a given a given measurement is to theabsolute or true value of the quantity measured.

PRECISION

The degree of refinement and consistency with which anyphysical measurement is made.

Portrayed by the closeness of one another of a set of repeatedmeasurements of quantities.


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MOST PROBABLE VALUE ( MPV or X )

ARITHMETIC MEAN OR THE AVERAGE.

REFERS TO A QUANTITY WHICH, BASED ON AVAILABLEDATA , HAS MORE CHANCES OF BEING CORRECT THANHAS ANY OTHER.


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SAMPLE PROBLEMS

1. A SURVEYING INSTRUCTOR SENT OUT SIX GROUP OF

STUDENTS TO MEASURE A DISTANCE BETWEEN TWO

POINTS MARKED ON THE GROUND. THE STUDENTS CAME

UP WITH THE FOLLOWING SIX DIFFERENT VALUES :

250.25, 250.15, 249.90, 251.04, 250.50, AND 251.22 METERS.

ASSUMING THESE VALUES ARE EQUALLY RELIABLE AND

THAT VARIATIONS RESULT FROM ACCIDENTAL ERRORS,

DETERMINE THE MOST PROBABLE VALUE OF THE

DISTANCE MEASURED.


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SAMPLE PROBLEMS

2. THE ANGLES ABOUT A POINT Q HAVE THE FOLLOWING

OBSERVED VALUES, 1301520 , 1423730 , AND 870740.

DETERMINE THE MOST PROBABLE VALUE OF EACH

ANGLE.

Q3 1

2

SAMPLE PROBLEMS


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SAMPLE PROBLEMS3. THE OBSERVED INTERIOR ANGLES OF A TRIANGLE ARE

A = 351437, B = 963009, AND C = 481505. DETERMINE

THE DISCRIPANCY FOR THE GIVEN OBSERVATION ANDTHE MOST PROBABLE VALUE OF EACH ANGLE

P

4. MEASUREMENT OF THREE HORIZONTAL ANGLES ( SEE

ACCOMPANYING FIGURE ) ABOUT A POINT P ARE:

APB= 123150, BPC= 372920,AND CPD= 473630. IF

THE MEASUREMENT OF THE SINGLE ANGLE APD=

973700,DETERMINE THE MOST PROBABLE VALUES OF

THE ANGLES.

A

B

CD


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RESIDUAL ( V )

SOMETIMES REFERRED TO AS DEVIATION.

DEFINED AS THE DIFFERENCE BETWEEN ANY MEASUREDVALUE OF A QUANTITY AND ITS MOST PROBABLE VALUE.


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PROBABLE ERROR ( PES )

A QUANTITY WHICH , WHEN ADDED TO AND SUBTRACTED

FROM THE MOST PROBABLE VALUE , DEFINES A RANGEWITHIN WHICH THERE IS A 50 PERCENT CHANCE THAT THETRUE VALUE OF THE MEASURED QUANTITY LIES INSIDE (OR OUTSIDE ) THE LIMITS THUS SET.


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RELATIVE ( ERROR ) PRECISION

EXPRESSED BY A FRACTION HAVING THE MAGNITUDE OF

THE ERROR IN THE NUMERATOR AND THE MAGNITUDE OFA MEASURED QUANTITY IN THE DENOMINATOR.


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SAMPLE PROBLEMS

1. PROBABLE ERROR. THE FOLLOWING VALUES WEREDETERMINED IN A SERIES OF TAPE MEASUREMENTS OF A

LINE : 1000.58, 1000.40, 1000.38, 1000.48, 1000.40, AND 1000.46

METERS. DETERMINE THE FOLLOWING:

A. MOST PROBABLE VALUE OF THE MEASURED LENGTHB. PROBABLE ERROR OF A SINGLE MEASUREMENT AND

PROBABLE ERROR OF THE MEAN.

C. FINAL EXPRESSION OF THE MOST PROBABLE LENGTH

D. RELATIVE PRECISION OF THE MEASUREMENT


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SAMPLE PROBLEMS

1. WEIGHTED MEASUREMENTS. FOUR MEASUREMENTS

OF A DISTANCE WERE RECORDED AS 284.18 , 284.19 , 284.22, AND 284.20 METERS AND GIVEN WEIGHTS OF 1 , 3 , 2 ,

AND 4 , RESPECTIVELY. DETERMINE THE WEIGHTED

MEAN.

2. WEIGHTED MEASUREMENTS. IT IS DESIRED TO

DETERMINE THE MOST PROBABLE VALUE OF AN ANGLE

WHICH HAS BEEN MEASURED AT DIFFERENT TIMES BY

DIFFERENT OBSERVERS WITH EQUAL CARE. THE VALUES

OBSERVED WERE AS FOLLOWS : 743945 ( IN 2MEASUREMENTS ) , 743927(IN 4 MEASUREMENTS) , AND

743935(IN 6 MEASUREMENTS)


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SAMPLE PROBLEMS

3. WEIGHTED MEASUREMENTS. LINES OF LEVELS TO

ESTABLISH THE ELEVATION OF A POINT ARE RUN OVER 4DIFFERENT ROUTES. THE OBSERVED ELEVATIONS OF THE

POINT WITH PROBABLE ERRORS ARE GIVEN BELOW

DETERMINE THE MOST PROBABLE VALUE OF THE

ELEVATION OF THE POINT.

LINE

OBSERVED

ELEVATION

(ELEV)

PROBABLE

ERROR

( E )

E2 W= 1 / E2 RELATIVE

WEIGHT

( RW )

P=ELEV(RW)

1 219.832 0.006 0.000036 27778

2 219.930 0.012 0.000144 6944

3 219.701 0.018 0.000324 3086

4 220.021 0.024 0.000576 1736 1

1.78

416 3517.312

879.720

391.608

220.021

22.78SUM 5008.121


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surveying lecture 1 - copy

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