basics of surveying

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SURE 110 - Fundamentals of Surveying Basics of Surveying 1 BASICS OF SURVEYING Robert Burtch Surveying Engineering Department Ferris State University DEFINITION The art and science of making such measurements as are necessary to determine the relative position of points above, on, or beneath the surface of the earth, or to establish such points in a specified position Surveyor needs understanding of rigorous mathematical to analyze and adjust scientific principles underlying and affecting measurements

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Page 1: Basics of surveying

SURE 110 - Fundamentals of Surveying

Basics of Surveying 1

BASICS OF SURVEYING

Robert BurtchSurveying Engineering DepartmentFerris State University

DEFINITIONThe art and science of making such measurements as are necessary to determine the relative position of points above, on, or beneath the surface of the earth, or to establish such points in a specified positionSurveyor needs understanding of

rigorous mathematical to analyze and adjustscientific principles underlying and affecting measurements

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BRANCHES OF SURVEYING

Geodetic SurveyingBranch of surveying in which account is taken of figure and size of earth

Plane SurveyingBranch of surveying in which the surface of the earth is considered a plane surface

PHASES OF SURVEYING

Field WorkData procurement phase

Office Work – data areAnalyzedReduced to useful form by mathematical calculationsAdjustedFrequently converted to graphical mode of expression

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KINDS OF SURVEYSProperty surveys

Determine boundary lines, location of property corners, acquisition of data to prepare land subdivisions

Route surveysDesigning and constructing engineering projects associated with transportation and communications

Industrial surveysSurveys in aircraft and other industries where accurate dimensional layouts necessary

KINDS OF SURVEYSTopographic surveys

Collect field data to prepare topographic maps

Hydrographic surveysMap shorelines of water bodies, chart bottom areas of streams, lakes, harbors, etc., measure flow of rivers, assess other issues related to navigation and water resources

Aerial surveys (photogrammetry)Use photographs mounted in specially designed planes

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KINDS OF SURVEYSMine surveys

Determine position of underground works and surface mines, fix position and direction of tunnels and shafts, define surface boundaries

Construction surveysPerformed during building of structure or project to fix elevations, horizontal position, and dimensions

Control surveysProvide basic horizontal and vertical position data for engineering mission

KINDS OF SURVEYSFinal (“As Built”) survey

Tie in features that have just been constructed to provide final record of construction and to check that construction has proceeded according to design plan

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BASIC SURVEY MEASUREMENTS: DEFINITIONS

Direction of gravity used as reference direction

Vertical – means direction of gravityHorizontal – means direction perpendicular to gravity

SURVEY GEOGRAPHIC REFERENCE Latitude (φ)

Lines run east-west parallel to equatorMax angle 90°South latitudes negative

Longitude (λ)Lines run north south, converge at poles0° - GreenwichMeasured east and west - 180° max angleWest longitude negative

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DEFINITIONSOblate Spheroid

Ellipsoid of RevolutionSolid obtained by rotating an ellipse on its shorter axisIdealized figure of earth

DEFINITIONSLevel surface (geoid)

Continuous surface that is at all points perpendicular to the direction of gravityCan be thought of as the surface of large body of water at complete rest (unaffected by tides, etc.)

ElevationVertical distance above or below a given reference level surface

Difference in elevationVertical distance between two level surfaces containing the two points

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DEFINITIONSVertical line

Line following direction of gravityVertical line passing through several different points on surface of earth do not intersect at a common pointVertical lines not necessarily normal to surface of the earth

Deflection of verticalAngle between perpendicular to geoidand ellipsoid

DEFINITIONSHorizontal line

Line perpendicular to vertical line at a pointHorizontal plane

Plane perpendicular to vertical line at pointOnly 1 horizontal plane through a given point

Vertical planePlane containing vertical line at the pointInfinite number of vertical planes as a given point

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DIRECTIONAzimuth- clockwise angle from north to line

Bearing – angle measured from north or south to east or west

ACCURACY & PRECISION

Accuracy –closeness between measurement and “true” valuePrecision –closeness to one another of a set of repeated observations

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ERRORS

No measurement free of error (except counting)

Mistakes or blundersNot really errors because they are usually so gross in magnitudeMost common reason – carelessnessMust be discovered and eliminated

ERRORSSystematic error

Occur according to a system which can be expressed mathematicallyMagnitude and sign can be determinedFollow definite patternCan be caused by observer, instrument, environment

Random errorError left after systematic error removedMay tend to cancel themselves

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UNITS OF LENGTH

Imperial units (feet)

Usually subdivided into decimal units in surveyingUse of inches

SI units (meters)Le SystemeInternationale d’Unites(International System of UnitsNormally subdivided into decimeter, centimeter, millimeter

NORMAL PREFIXES FOR METER

exa (E) 1018

peta (p) 1015

tera (t) 1012

giga (g) 109

mega (m) 106

kilo (k) 103

hecto (h) 102

deka (da) 101

Ex: kilometer = 1,000m

deci (d) 10-1

centi (c) 10-2

milli (m) 10-3

micro (µ)10-6

nana (n) 10-9

pico (p) 10-12

femto (f) 10-15

atto (a) 10-18

Ex: millimeter = 0.001m

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METRIC SYSTEM

1791 French Academy of Sciences recommended metre to be 1/10,000,000th part of polar quadrant passing through Paris1799 Academy of Sciences developed new standard – Metre of the Archives –made of platinum 1 meter in length1999 General Conference of Weights and Measures adopts “International Prototype Metre” – platinum & iridium bar

METRIC SYSTEM

1960 National Prototype Meter –1,650,763.73 wavelengths of Krypton 86 atom in a vacuum1983 Conference Generale des Poids et Mesures redefined meter as length of the path traveled by light in a vacuum during a time interval of 1/299792458 of a second

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FEET-METER CONVERSION

FEET-METER CONVERSIONFerdinand Hassler brought iron meter bar to U.S. in 1805 for work with Coast Survey1866 Congress legalized use of metric system1893 – Mendenhall Order

Superintendent of Weight & Measures1 meter = 39.37 inches (exact)1 U.S. Yard = (3600/3927) meter (exact)

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FEET-METER CONVERSION1959 U.S. & U.K. agreed that Imperial units used in both countries should be the same

Defined 1 Yard = 0.9144 metre (exact)1 ft = 0.3048 m (exact)1 inch = 25.4 mm (exact)Did not change relationship established by Congress – kept for surveying and called U.S. Survey foot