3.4 LandSurveying

7/30/2019 3.4 LandSurveying

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Land Surveying


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Definition of Surveying in the State of

Tennessee (T.C.A. 62-18-102)

Any service of work, the adequate performance of which

involves the application of special knowledge of the

principles of mathematics, the related physical and applied

sciences, and the relevant requirements of law for

adequate evidence to the act of measuring and locatinglines, angles, elevations, natural and man-made features

for the purpose of determining areas and volumes, for

the monumenting of property boundaries, and for the

platting and layout of lands and subdivisions thereof,including the topography, drainage, alignment and grades

of streets, and for the preparation and perpetuation of

maps, records, plats, field notes, records and property

descriptions that represent these surveys.


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Famous Land Surveyors

George WashingtonSurveyor General in Virginia, 1749

Thomas JeffersonCounty Surveyor for Albemarle County, VA, 1773

Lewis and ClarkExpedition to explore and survey the west

Daniel BooneResolved Kentucky land disputes

Abraham LincolnSurveyor in Illinois when elected to state

legislature


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Land Surveying

The science of determining the relative

positions of points on the Earths surface.

Geodetic Surveys

Plane Surveys


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Geodetic Survey

Takes into account the true size, shape, andgravity fields of the Earth

The geoid is the equipotential surface of the

Earths gravity field which best fits global mean sea

level Provides significant

precision

Establishes highly

accurate controlnetworks

Images courtesy NOAA

http://celebrating200years.noaa.gov/foundations/gravity_surveys/


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Plane Survey

Assumes the Earths surface to be a plane (flat) More common than geodetic surveys

Precise enough for small-scale surveys in a

limited area, such as a construction site Used to determine legal boundaries,

construction surveys, and small-area

topographic or control surveysiStockphoto.com


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Horizontal Plane

PlumbL

ine

Rod

Geodetic SurveyLine of equal elevation

Plane Survey

Line of equal elevation

Geoid or other Datum

Geodetic vs. Plane Survey

Earths surface

Rod


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Types of Surveys

Control Survey

Topographic Survey

Property Survey Site Survey

Construction Survey


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Control Survey

Establish precisehorizontal and

vertical positions of

points that serve as

a reference for other

surveys

Courtesy Department of Public Works, Seminole County, FL

Photos Courtesy NOAA


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Topographic Survey

Gathers data on the location of natural and man-made features, contours, and ground elevation

to create a topographic map

Courtesy USGS


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Property Survey(or Boundary Survey)

Establishes property

lines for a lot

Used to create a plat


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Site Survey(Plot Survey or Lot Survey)

Combination of a property survey and

topographic survey

May be required to receive a construction permit


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Construction Survey

Locates points and elevations that can beused to establish correct locations and

elevations for engineering and

architectural projects

Courtesy Isle of Palms, SC Recreation Department


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National Spatial Reference

System (NSRS)Common set of reference points for all

surveys

Horizontal Datum = Collection of

points of known latitude and longitude

Vertical Datum = Collection of points

of known elevation

Benchmark (BM) = Permanent mark

that establishes a point of known

elevationWikimedia.org

Courtesy NOAA

http://oceanservice.noaa.gov/education/kits/geod

esy/geo05_horizdatum.html
http://oceanservice.noaa.gov/education/kits/geodesy/media/supp_geo05a.htmlhttp://upload.wikimedia.org/wikipedia/en/5/50/DarienCTUSCoastAndGeodeticSurvey1965Marker11042007.jpg


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Reference System Data

Information on datum points available athttp://www.ngs.noaa.gov/cgi-

bin/datasheet.prl
http://www.ngs.noaa.gov/cgi-bin/datasheets.prlhttp://www.ngs.noaa.gov/cgi-bin/datasheets.prlhttp://www.ngs.noaa.gov/cgi-bin/datasheets.prlhttp://www.ngs.noaa.gov/cgi-bin/datasheets.prlhttp://www.ngs.noaa.gov/cgi-bin/datasheets.prl


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Example Data Sheet


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Optical Equipment

Requires a visual line-of-sight

A theodolite measures

vertical and horizontal

angles

A total station is an

electronic/optical

surveying instrument

iStockphoto.com iStockphoto.co

m


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Optical Equipment

Automatic (Auto) Level

Commonly used on

building sites

Internal compensator

can automatically

level the instrument

Measures difference in elevation between

the line of sight and a point

Kennedy


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Other Equipment

Courtesy USGS

http://gallery.usgs.gov/photos/07_22_20

09_j51Qi76Hgb_07_22_2009_13

TripodLeveling Rod

Professional Tape Measure

iStockphoto.com

Field Book

Kennedy

Kennedy

Kennedy

Kennedy


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GPS Technology

Global Positioning System A global navigation satellite

system

Developed by the U.S.

Department of Defense

A constellation of satellites that

broadcast radio signals

Receivers intercept severalsatellite signals in order to

determine precise location

Courtesy NASA

Widimedia.com
http://upload.wikimedia.org/wikipedia/commons/8/8d/GPS_Satellite_NASA_art-iif.jpg


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GPS

iStockphoto.com

Kennedy


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Auto Level

Bulls Eye

Level

Telescope

Leveling

Screws

Horizontal

Angle

Rotation Ring

EyepieceHorizontal

Tangent

Knob

Sight

Diopter

Adjustment

Ring

Mirror

Kennedy


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Reading the Rod

View through the telescope

Horizontal

crosshair

Verticalcrosshair

Stadia hairs

Beveled

hatch

marks


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Reading the Rod

Upper Stadia Reading = 5.30 ft

Rod Reading = 5.25 ft

Lower Stadia Reading = 5.20 ft


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Stadia Readings

Estimate distance between rodand instrument

Rod intercept is the difference

between stadia readings

Estimateddistance

Stadia multiplier typically = 100 Indicated on inside of instrument

case or in Instructional Manual


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Stadia Readings

Upper Stadia Reading = 5.30 ft

Lower Stadia Reading = 5.20 ft

Rod Intercept = 0.10 ft


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Stadia Reading

Rod Reading = 5.06 ft

Lower Stadia = 4.99 ft

Upper Stadia = 5.13 ft


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Read the Rod


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Instrument

Point ofUnknown

Elevation

Differential Leveling

The establishment of differences in

elevation between two or more points with

respect to a datum

BM

RodRod


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Elev. 350.00 ft


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Start with point of

known elevationBenchmark (BM)

Point of Reference(POR)

Rod reading

7.59 ft (BS)

7.5

9ft

Sight to rod on BM

Backsight (BS)

Height of Instrument (HI)HI = BM elev + BS

HI = 350.00 + 7.59 = 357.59 ft

357.59 ft (HI)

357.5

9ft


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Field Notes

AUTO LEVEL READINGSSTADIA

PT

(+)

BS HI

(-)

FS ELEV

TOP/BOT

STADIA

DIST

/Angle

BM 350.007.59 357.59 7.85 / 7.33 52 ft


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Without moving thetripod,

Sight to rod on point

of unknownelevation

Foresight (FS)

Identify elevation ofpoint

Elev.

355.23 ft

Rod reading

2.36 ft (FS) 2.3

6

ft

Point of Interest

Elev = HI - FS

Elev = 357.59 2.36 = 355.23 ft


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Field Notes


PT

(+)

BS HI

(-)

FS ELEV

TOP/BOT

STADIA

DIST

/Angle

BM 7.59 357.59 350.00 7.85 / 7.33 52 ftxPT- A 2.36 355.23 2.54 / 2.19 35 ft


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2.36 ft (FS)

7.59 ft (BS)


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Field Notes


PT

(+)

BS HI

(-)

FS ELEV

TOP/BOT

STADIA

DIST

/Angle

BM 7.59 357.59 350.00 7.85 / 7.33 52 ft

PT-A 2.36 355.23 2.54 / 2.19 35 ft

x

PT- B 4.17 353.42

PT-C 12.91 344.68

4.40 / 3.93 47 ft

13.21 / 12.61 60 ft


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Image Sources

Sanford, F. (2006). Seminole County geodetic control

points. Seminole County, Florida: Department of Public

Works.

United States Geological Survey (USGS)

National Oceanographic and Atmospheric Administration

Photo Library

http://www.photolib.noaa.gov/cgs/marks1.html

Istockphoto.com
http://www.photolib.noaa.gov/cgs/marks1.htmlhttp://www.photolib.noaa.gov/cgs/marks1.html

3.4 LandSurveying

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