Surveying: Definitions and Types

Surveying Definition

• Surveying determines positions of points on or near Earth by measuring distance, direction, and elevation (Rayner and Schmidt)
• Surveying measures horizontal and vertical distances, angles between lines, and direction of lines (Davis, Foote, Anderson, and Mikhail)
• Surveying makes measurements to draw relative positions of points, exhibiting natural and artificial features in correct relationships (Clarke)
• Surveying is a branch of applied math determining area, boundary lines, contour, and delineation on paper (Webster)
• Surveying measures points above, on, or beneath Earth to determine relative positions or establish points (Breed, Hosmer, and Bone)
• Surveying determines relative positions of points above, on, or beneath Earth, or establishing such points (Brinker and Wolf)

Plane and Geodetic Surveying

• Plane Surveying considers the Earth as a flat surface
• Geodetic Surveying accounts for the Earth's spheroidal shape over wide areas

Types of Surveys

• Cadastral Surveys are closed and fix boundaries in urban/rural areas for municipalities and jurisdictions
• City Surveys plan expansions, locate property lines, and fix monuments in/near cities
• They also aim to delineate physical features, land configuration, and map preparation
• Construction Surveys provide data at construction sites
• Forestry Surveys aid forest management, mensuration, and land conservation
• Hydrographic Surveys map shorelines, chart underwater areas, and measure stream flow
• Industrial Surveys (optical tooling) enable accurate dimensional layouts in industries
• Mine Surveys determine positions of underground excavations
• Photogrammetric Surveys use specialized cameras on airplanes or ground stations
• Route Surveys determine linear project layouts
• Topographic Surveys determine ground shape, location, and elevation of natural/artificial features

Development of Surveying Instruments

• The Astrolabe of Hipparchus, developed in 140 B.C. and improved by Ptolemy, determined the altitude of stars
• The Telescope was invented in 1607 by Lippershey but was only used with surveying instruments after the introduction of cross hairs
• The Transit was invented by Young and Draper in 1830 as the universal surveying instrument
• The Semicircumferentor is an early surveying instrument that measures angles and establishes sight lines
• The Plane Table is one of the oldest surveying instruments used for field mapping which includes a board on a tripod that can be leveled or rotated
• The Dioptra, perfected by Heron of Alexandria, leveled and measured horizontal and vertical angles using a disc and sighting apertures
• The Roman Groma, used by Roman surveyors to align points, consisted of cross arms fixed at right angles on a vertical staff with plumb lines
• The Libella, first used by Assyrians and Egyptians, is believed to have defined the horizontal foundations of the great pyramids of Egypt
• Pierre Vernier invented the Vernier in 1631 which is used in surveying instruments employing direct or retrograde vernier
• The Diopter, an instrument from 130 B.C., used peep sights before the telescope's invention
• The Compass was widely used in the 13th century for determining line direction and in calculating angles and was initially used for navigation
• The Gunter's Chain, invented by Sir Edmund Gunter in 1620, was a forerunner for instruments used for taping distances
• The Chorobates instrument, designed for leveling work, establishes a horizontal line by ensuring water stays level in a groove without spilling
• The Merchet, first used by Chaldeans around 4,000 B.C., measured time and meridian via a plumb bob string

Surveying Measurements

• A measurement gauges a quantity's extent, size, or dimensions against a standard
• Direct Measurements directly compare a measured quantity against a standard unit
• Indirect Measurements determine a value’s relationship to other known values when direct measurement is impossible

The Field Notebook

• The field notebook is comprised of good quality rag paper, with stiff board or leather cover, that can withstand hard usage, and of pocket size

Types of Notes

• Sketches convey impressions approximately to scale without exact precision
• Tabulations present numerical values from the field in a structured table format
• Explanatory Notes describe field activities clarifying numerical data and sketches
• Computations involve calculations in surveying, performed algebraically with arithmetical/trigonometric functions
• The most extensive surveys combine Sketches, Tabulations, Explanatory Notes and Computations to portray data gathered in the field

Information Found in Field Notebooks

• The field notebook must contain the official title/name of the field work or project to be identified; location, nature and purpose must be stated
• Time of Day and Date are necessary to document notes, furnish a timetable, and correlate different surveys and provide possible problems may be referenced
• Weather Conditions affect surveying accuracy and should be noted when reviewing field notes
• Identify Names of Group Members and Their Designations to pinpoint duties and responsibilities
• A proper identification of the List of Equipment aids in isolating errors

The Field Survey Party

• The Chief of Party directs, supervises, and controls the survey party, handling logistics, technical needs, and problems
• The Assistant Chief of Party replaces the chief when absent, conducting ground reconnaissance and site investigations
• The Instrumentman sets up, levels, and operates instruments like transits and ensures proper working order and adjustment
• The Technician operates electronic instruments, ensuring calibration and adjustment
• The Computer performs computations of survey data and performs any necessary checks
• The Recorder records sketches, drawings, measurements, and observations
• The Head Tapeman ensures accurate, swift linear measurements, marking instrument stations and line-of-sight obstructions
• The Rear Tapeman assists the head tapeman during taping
• The Flagman holds the flagpole or range pole, helping tapemen and clearing obstructions
• The Rodman holds the stadia or leveling rod
• The Pacer checks linear measurements made by the tapeman, helping them verify that they are correct
• The Axeman/Lineman clears the line of sight and is responsible for the security of the survey party
• The Aidman provides first aid and may be designed as the assistance instrumentman
• The Utilitymen provide other forms of assistance needed by the survey party and are typically the vehicle driver

Errors, Mistakes, Accuracy and Precision

• An Error is the difference between the true and measured value, inherent to measurements
• Mistakes are inaccuracies from surveyor carelessness, inattention, or misunderstanding, with large ones deemed "blunders"
• Systematic Errors maintain consistent sign and magnitude under constant field conditions
• Accidental Errors are random, with a chance of being positive or negative and are addressed via probability
• Instrumental Errors are from instrument imperfections or improper adjustments
• Natural Errors stem from environmental variations (magnetic declination, temp, humidity, wind, refraction, gravity, curvature)
• Personal Errors arise from human limitations in sight, touch, and hearing
• Accuracy is the closeness of measurements to the true value
• Precision signifies measurement refinement and repeatability

Theory of Probability

• Probability is defined as the number of times something will probably occur over the range of possible occurrences

Measurement of Distance

• Distance by pacing entails counting steps to approximate distance, measured from heel to heel or toe to toe
• Distance determination via Taping is stretching calibrated tape, common in construction
• Distance by Tachymetry (tacheometry) indirectly measures horizontal distances using optical geometry
• The Stadia Method, was introduced in 1771 by James Watt of Scotland and was referred to as a micrometer for measuring distances that rapidly calculate horizontal distances
• The Subtense Bar Method conveniently measures horizontal distances quickly and accurately
• Distance acquired by graphical/mathematical methods determines distances geometrically in plane table surveys/triangulation
• Distance found using mechanical devices utilizes the following methods
• Odometer entails attaching a device to a wheel for roughly measuring surface distances
• Measuring Wheel entails using a portable, self-contained device
• Optical Rangefinder entails using the sam principle as a rangefinder on single-lens reflex camera
• Distance by photogrammetry entails measuring images on a photograph. These photographs are taken from an aircraft that is pointed vertically towards the terrain
• Electronic distance measurement (EDM) enhances surveying through modern instrumentation/techniques
• Basic Principle: Linear measurements determined by EDM instruments are based on measuring the time required for a wave to travel between two points
• Classification: Advancements in science lead to electronic distance tools
• Electro-Optical Instruments transmit wavelengths within or slightly beyond the visible spectrum
• Microwave Instruments transmit microwaves (1.0 to 8.6 mm wavelengths), enabling long-distance operation in drizzle or fog
• Although there are advantages, initial EDM instruments were bulky, heavy, and expensive
• EDM instruments determine linear measurements for traversing, construction, optical tooling, triangulation, trilateration, and layouts
• Operating Ranges vary by instrument type (short, medium, long), mostly electro-optical with some using infrared
• The Geodimeter (geodetic distance meter) electro-optically measures light velocity (Erik Bergstrand, 1948)
• The Tellurometer measures distances up to 80 km using microwave transmission (Dr. T,L. Wadley, 1957)

Measuring Tapes

• The Steel Tape (surveyor's/engineer's tape) is common in loops of 2 meters as a figure 8 and is designed for standard surveying/engineering, weighing .8 to 1.5 kg per 30 meters
• The Metallic Tape is moisture-proof linen fabric woven with brass, copper, or bronze wires
• The Non-Metallic Tape contains a plastic material to diminish moisture, humidity, and abrasion
• The Invar Tape is an alloy of nickel (35%) and steel (65%) making it a special tape with very low thermal expansion; its name was derived from the word "invariable"
• The Lovar Tape is a newer type of measuring tape which costs somewhere between typical steel tapes and the invar tape
• A Fiber glass Tape is made by weaving fiberglass which makes them strong and flexible
• Wires were used before steel tapes (still practical for hydrographic work)
• The Builder's Tape has smaller cross sections and lighter weight and are graduated for building dimensions
• The Phosphor-Bronze Tape is a rust-proof tape design for use in the vicinity of salt water
• The Nylon-coated Steel Tape is a flexible crack-resistant steel core tape that does not rust or corrode

Taping Accessories

• The Range Pole (flags/lining rods) marks points and alignment
• The Tape Clamping Handle applies tension to steel tapes without causing damage or discomfort
• The Chaining Pins (surveyor's arrows/taping pins) mark tape ends, replacing stakes
• The Tension Handle applies correct pull to a tape (spring scale)
• The Tape Thermometer measures air/tape temperature
• The Plumb Bob projects tape ends vertically
• The Wooden Stake/Hub marks points (5cm x 5cm x 30cm)
• Leather Thongs is attached to a ring located near the zero-meter mark of the tape to provide a comfortable grip on the tape when measuring
• The Hand Level/Clinometer is a 15-cm metal sighting tube with a level bubble
• The Tape Repair Kit allows for repairs in remote areas
• Crayons (lumber crayons) mark measurements (blue, yellow, red, and hexagonal ) with a 10 cm in length

Composition of Taping Party:

• Head Tapeman ensures accurate, swift linear measurements
• Recorder keeps records, sketches, and observations checking by pacing
• Flagman holds range pole, assisting in clearing obstructions with the line of sight
• Rear Tapeman assists the head tapeman

Procedure of Taping

• Begin by aligning tape and marking line ends with establishing intermediate points and points for a straight line
• Stretch tape aligned by tapemen - all right" or "OK
• Plum the area - if its covered by vegetation, brush and weeds
• The tape is marked depending on the previous measurement for a full tape length
• Tallying is all measurements depends on how far the rear tapeman is holding one pin and the head tapeman begins with ten pins

Breaking Tape

• During sloping tape measure horizontally with on both ends and on either or uneven terrain

Slope Taping

• The Ground provides unitform Inclination, fairly smooth and break tape every few meter rather than break tape very few meters

Correction in Taping

• 1st Rule: with a tape is too long", the corrections are applied to the observed length by adding
• 2nd Rule: laying out a line. if the tape is long Corrections are subtracted (add the opposite)
• 3rd Rule: laying out a line lengths and applying the corrections from the first two rules