Land Surveying Definition of Surveying in the State

Land Surveying

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 locating lines, 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.

Famous Land Surveyors • George Washington Surveyor General in Virginia, 1749 • Thomas Jefferson County Surveyor for Albemarle County, VA, 1773 • Lewis and Clark Expedition to explore and survey the west • Daniel Boone Resolved Kentucky land disputes • Abraham Lincoln Surveyor in Illinois when elected to state legislature

Land Surveying The science of determining the relative positions of points on the Earth’s surface. – Geodetic Surveys – Plane Surveys

Geodetic Survey • Takes into account the true size, shape, and gravity fields of the Earth – The geoid is the equipotential surface of the Earth’s gravity field which best fits global mean sea level • Provides significant precision • Establishes highly accurate control networks Images courtesy NOAA http: //celebrating 200 years. noaa. gov/foundations/gravity_surveys/

Plane Survey • Assumes the Earth’s 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 surveys ©i. Stockphoto. com

Geodetic Survey Line of equal elevation Plumb Line Geodetic vs. Plane Survey Rod Plane Survey Line of equal elevation Rod Horizontal Plane Earth’s surface Geoid or other Datum

Types of Surveys • • • Control Survey Topographic Survey Property Survey Site Survey Construction Survey

Control Survey Establish precise horizontal and vertical positions of points that serve as a reference for other surveys Photos Courtesy NOAA Courtesy Department of Public Works, Seminole County, FL

Topographic Survey Gathers data on the location of natural and manmade features, contours, and ground elevation to create a topographic map Courtesy USGS

Property Survey (or Boundary Survey) • Establishes property lines for a lot • Used to create a plat

Site Survey (Plot Survey or Lot Survey) • Combination of a property survey and topographic survey • May be required to receive a construction permit

Construction Survey Locates points and elevations that can be used to establish correct locations and elevations for engineering and architectural projects Courtesy Isle of Palms, SC Recreation Department

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 Courtesy NOAA http: //oceanservice. noaa. gov/education/kits/geod esy/geo 05_horizdatum. html Benchmark (BM) = Permanent mark that establishes a point of known elevation Wikimedia. org

Reference System Data Information on datum points available at http: //www. ngs. noaa. gov/cgibin/datasheet. prl

Example Data Sheet

Optical Equipment Requires a visual line-of-sight ©i. Stockphoto. com A theodolite measures vertical and horizontal angles ©i. Stockphoto. co m A total station is an electronic/optical surveying instrument

Optical Equipment Automatic (Auto) Level • Commonly used on building sites • Internal compensator can automatically level the instrument Kennedy • Measures difference in elevation between the line of sight and a point

Kennedy Other Equipment ©i. Stockphoto. com Professional Tape Measure Kennedy Leveling Rod Courtesy USGS http: //gallery. usgs. gov/photos/07_22_200 9_j 51 Qi 76 Hgb_07_22_2009_13 Tripod Kennedy Field Book

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 several satellite signals in order to determine precise location Courtesy NASA Widimedia. com

GPS Kennedy ©i. Stockphoto. com

Telescope Auto Level Sight Mirror Diopter Adjustment Ring Bulls Eye Level Horizontal Tangent Knob Horizontal Angle Rotation Ring Eyepiece Leveling Screws Kennedy

Reading the Rod Vertical crosshair Stadia hairs Horizontal crosshair View through the telescope Beveled hatch marks

Reading the Rod Upper Stadia Reading = 5. 30 ft Rod Reading = 5. 25 ft Lower Stadia Reading = 5. 20 ft

Stadia Readings • Estimate distance between rod and instrument • Rod intercept is the difference between stadia readings • Estimated distance • Stadia multiplier typically = 100 – Indicated on inside of instrument case or in Instructional Manual

Stadia Readings Upper Stadia Reading = 5. 30 ft Lower Stadia Reading = 5. 20 ft Rod Intercept = 0. 10 ft

Stadia Reading Upper Stadia = 5. 13 ft Rod Reading = 5. 06 ft Lower Stadia = 4. 99 ft

Read the Rod

Differential Leveling The establishment of differences in elevation between two or more points with respect to a datum Instrument Rod BM Point of Unknown Elevation

Differential Leveling Elev. 350. 00 ft

Differential Leveling • Start with point of known elevation • Sight to rod on BM Backsight (BS) • Height of Instrument (HI) HI = BM elev + BS HI = 350. 00 + 7. 59 = 357. 59 ft (HI) 7. 59 ft Benchmark (BM) Point of Reference (POR) Rod reading 7. 59 ft (BS)

Field Notes AUTO LEVEL READINGS STADIA PT BM (+) BS HI 7. 59 357. 59 (-) FS ELEV TOP/BOT STADIA DIST /Angle 350. 00 7. 85 / 7. 33 52 ft �

Without moving the tripod, • Sight to rod on point of unknown elevation Foresight (FS) Rod reading 2. 36 ft (FS) • Identify elevation of point Elev = HI - FS Elev = 357. 59 – 2. 36 = 355. 23 ft 2. 36 ft Differential Leveling Elev. 355. 23 ft Point of Interest

Field Notes AUTO LEVEL READINGS STADIA PT BM PTA (+) BS 7. 59 HI (-) FS ELEV TOP/BOT STADIA DIST /Angle 357. 59 x 350. 00 7. 85 / 7. 33 52 ft 2. 36 355. 23 2. 54 / 2. 19 35 ft �

Differential Leveling 2. 36 ft (FS) 7. 59 ft (BS)

Field Notes AUTO LEVEL READINGS STADIA PT BM (+) BS 7. 59 HI (-) FS 357. 59 x ELEV TOP/BOT STADIA DIST /Angle 350. 00 7. 85 / 7. 33 52 ft 35 ft PT-A 2. 36 355. 23 2. 54 / 2. 19 PT- B 4. 17 353. 42 4. 40 / 3. 93 � ft 47 PT-C 12. 91 344. 68 13. 21 / 12. 61 60 ft

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/marks 1. html Istockphoto. com