The measurement of dimensional relationships, as of horizontal distances, elevations, directions, and angles, on the earth's surface especially for use in locating property boundaries, construction layout, and mapmaking.
surveying
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sur·vey·ing (sər-vā'ĭng)  |
n.
| 5min Related Video: surveying |
| Sci-Tech Encyclopedia: Surveying |
The measurement of dimensional relationships among points, lines, and physical features on or near the Earth's surface. Basically, surveying determines horizontal distances, elevation differences, directions, and angles. These basic determinations are applied further to the computation of areas and volumes and to the establishment of locations with respect to some coordinate system.
Surveying is typically used to locate and measure property lines; to lay out buildings, bridges, channels, highways, sewers, and pipelines for construction; to locate stations for launching and tracking satellites; and to obtain topographic information for mapping and charting.
Horizontal distances are usually assumed to be parallel to a common plane. Each measurement has both length and direction. Length is expressed in feet or in meters. Direction is expressed as a bearing of the azimuthal angle relationship to a reference meridian, which is the north-south direction. It can be the true meridian, a grid meridian, or some other assumed meridian. The degree-minute-second system of angular expression is standard in the United States.
Reference, or control, is a concept that applies to the positions of lines as well as to their directions. In its simplest form, the position control is an identifiable or understood point of origin for the lines of a survey. Conveniently, most coordinate systems have the origin placed west and south of the area to be surveyed so that all coordinates are positive and in the northeast quadrant.
Vertical measurement adds the third dimension to an object's position. This dimension is expressed as the distance above some reference surface, usually mean sea level, called a datum. Mean sea level is determined by averaging high and low tides during a lunar month.
Horizontal control
The main framework, or control, of a survey is laid out by traverse, triangulation, or trilateration. Some success has been achieved in locating control points from Doppler measurements of passing satellites, from aerial phototriangulation, from satellites photographed against a star background, and from inertial guidance systems. In traverse, adopted for most ordinary surveying, a line or series of lines is established by directly measuring lengths and angles. In triangulation, used mainly for large areas, angles are again directly measured, but distances are computed trigonometrically. This necessitates triangular patterns of lines connecting intervisible points and starting from a baseline of known length. New baselines are measured at intervals. Trigonometric methods are also used in trilateration, but lengths, rather than angles, are measured. The development of electronic distance measurement (EDM) instruments brought trilateration into significant use.
Distance measurement
Traverse distances are usually measured with a surveyor's tape or by EDM, but also may sometimes be measured by stadia, subtense, or trig-traverse.
Whether on sloping or level ground, it is horizontal distances that must be measured. In taping, horizontal components of hillside distances are measured by raising the downhill end of the tape to the level of the uphill end. On steep ground this technique is used with shorter sections of the tape. The raised end is positioned over the ground point with the aid of a plumb bob. Where slope distances are taped along the ground, the slope angle can be measured with the clinometer. The desired horizontal distance can then be computed.
In EDM the time a signal requires to travel from an emitter to a receiver or reflector and back to the sender is converted to a distance readout. The great advantage of electronic distance measuring is its unprecedented precision, speed, and convenience. Further, if mounted directly onto a theodolite, and especially if incorporated into it and electronically coupled to it, the EDM instrument with an internal computer can in seconds measure distance (even slope distance) and direction, then compute the coordinates of the sighted point with all the accuracy required for high-order surveying.
In the stadia technique, a graduated stadia rod is held upright on a point and sighted through a transit telescope set up over another point. The distance between the two points is determined from the length of rod intercepted between two horizontal wires in the telescope.
In the subtense technique the transit angle subtended by a horizontal bar of fixed length enables computation of the transit-to-bar distance ( Fig. 1). In trig-traverse the subtense bar is replaced by a measured baseline extending at a right angle from the survey line whose distance is desired. The distance calculated in either subtense or trig-traverse is automatically the horizontal distance and needs no correction.
Subtense bar. (Lockwood, Kessler, and Bartlett Inc.)
Angular measurement
The most common instrument for measuring angles is the transit or theodolite. It is essentially a telescope that can be rotated a measurable amount about a vertical axis and a horizontal axis. Carefully graduated metal or glass circles concentric with each axis are used to measure the angles. The transit is centered over a point with the aid of either a plumb bob suspended by a string from the vertical axis or (on some theodolites) an optical plummet, which enables the operator to sight along the instrument's vertical axis to the ground through a right-angle prism.
Elevation differences
Elevations may be measured trigonometrically in conjunction with reduction of slope measurements to horizontal distances, but the resulting elevation differences are of low precision.
Most third-order and all second- and first-order measurements are made by differential leveling, wherein a horizontal line of sight of known elevation is sighted on a graduated rod held vertically on the point being checked ( Fig. 2). The transit telescope, leveled, may establish the sight line, but more often a specialized leveling instrument is used. For approximate results a hand level may be used.
Theory of differential leveling.
Other methods of measuring elevation include trigonometric leveling which involves calculating height from measurements of horizontal, distance and vertical angle; barometric leveling, a method of determining approximate elevation difference with aid of a barometer; and airborne profiling, in which a radar altimeter on an aircraft is used to obtain ground elevations.
Astronomical observations
To determine meridian direction and geographic latitude, observations are made by a theodolite or transit on Polaris, the Sun, or other stars. Direction of the meridian (geographic north-south line) is needed for direction control purposes; latitude is needed where maps and other sources are insufficient. The simplest meridian determination is made by sighting Polaris at its elongation, as the star is rounding the easterly or westerly extremity of its apparent orbit. An angular correction is applied to the direction of sighting, which is referenced to a line on the ground. The correction value is found in an ephemeris. See also Ephemeris; Topographic surveying and mapping.
| Dental Dictionary: surveying |
n
The procedure of studying the relative parallelism or lack of parallelism of the teeth and associated structures to select a path of placement for a restoration that will encounter the least tooth or tissue interference and provide adequate and balanced retention; locating guiding plane surfaces to direct placement and removal of the restoration and to achieve the best appearance possible.
| Britannica Concise Encyclopedia: surveying |
For more information on surveying, visit Britannica.com.
| Architecture: surveying |
That branch of engineering concerned with a determination of the earth’s surface features in relation to each other, as the relative position of points, a determination of areas, etc., and their recording on a map.
| US History Encyclopedia: Surveying |
Using little more than a compass and a 66-foot chain, early American surveyors set out early to chart the United States of America. Surveys determine boundaries, chart coastlines and navigable streams and lakes, and provide for mapping of land surfaces. Much of this work done in the early days of the United States used rudimentary, although not necessarily inefficient, equipment.
For instance, surveyors set a 2,000-mile line for the transcontinental railroad in the 1860s without the benefit of maps, aerial views, or precise knowledge of topographical features. A century later, when surveyors set the line for Interstate 80 using everything their predecessors had not, the route followed the railroad's route almost exactly.
The primary tool used by surveyors in North America from the 1600s through the end of the 1800s was a "Gunter's chain," measuring 66 feet long, usually with 100 swiveled links. A retractable steel tape to replace the chain was patented in 1860 by W. H. Paine of Sheboygan, Wisconsin.
Surveyors relied on the compass to set the direction of their chain. Goldsmith Chandlee, a notable clock and instrument maker, built a brass foundry in Winchester, Virginia, in 1783 and made the most advanced surveying compasses of his day.
The biggest breakthrough in surveying technology came in England in 1773, when Jesse Ramsden invented the circular dividing engine, which allowed the manufacture of precise scientific and mathematical instruments. The first American to develop a capability for the mechanical graduation of instruments was William J. Young. Young built the first American transit in Philadelphia in 1831, replacing the heavier, more inconvenient theodolite, which measures horizontal and vertical angles. The transit has a telescope that can be reversed in direction on a horizontal axis. The transit built by Young differs little from the transit used in the early twenty-first century.
The increased demand for accuracy in railroad construction, civil engineering, and city surveys led to the rapid acceptance of the transit. An influx of tradesmen from the Germanic states in the 1830s and 1840s provided a means of manufacturing precision instruments in volume.
To help with mathematical calculations, surveyors began experimenting with a number of nonelectric calculators, including Thacher's Calculating Instrument, patented in 1881, which was the equivalent of a 360-inch-long slide rule precise to 1:10,000. Slide rules replaced calculating instruments, calculators replaced slide rules, and computers have replaced calculators.
America's original thirteen colonies, as well as a few states such as Texas and Kentucky, were originally surveyed by metes and bounds, which is the process of describing boundaries by a measure of their length. On 7 May 1785, Congress adopted the Governmental Land Surveys, which provided for the "rectangular system," which measured distances and bearing from two lines at right angles and established the system of principal meridians, which run north and south, and base lines, running east and west.
Under the Northwest Ordinance of 1787, Ohio served as the experimental site for the new public lands surveying system. The lessons learned culminated in the Land Ordinance of 1796, which determined the surveying and numbering scheme used to survey all remaining U.S. public lands.
The first government-sanctioned survey was the Survey of the Coast, established in 1807 to mark the navigational hazards of the Atlantic Coast. Under Superintendent Ferdinand Hassler, the survey used crude techniques, including large theodolites, astronomical instruments, plane table topography, and lead line soundings to determine hydrography. Despite these techniques, the survey achieved remarkable accuracy.
By the time the Coast Survey was assigned to map Alaska's coast, after Alaska was acquired in 1867, technological advancements had provided new kinds of bottom samplers, deep-sea thermometers, and depth lines. A new zenith telescope determined latitude with greater accuracy, and the telegraph provided a means of determining longitudinal differences by flashing time signals between points.
Inland, surveys were more informal. Often under sponsorship from the Army, explorers such as Meriwether Lewis and William Clark, Zebulon Pike, and Stephen H. Long went out on reconnaissance missions, gathering geographic, geologic, and military information.
After the Civil War (1861–1865), westward migration created a need for detailed information about the trans-Mississippi West. Congress authorized four surveys named after their leaders: Clarence King, F. V. Hayden, John Wesley Powell, and George M. Wheeler. In addition to topography and geography, these surveys studied botany, paleontology, and ethnology.
The U.S. Geological Survey was formed in 1879 and began mapping in the 1880s, relying on the chain-and-compass method of surveying. By the early 1900s, surveyors were working with plane tables equipped with telescopic alidades with vertical-angle arcs, allowing lines of survey to be plotted directly from the field. Leveling instruments have been used since 1896 to set permanent elevation benchmarks.
Aerial photography came into use as a survey tool following World War I (1914–1918), and photogrammetry was widely used by the 1930s. Today, satellites enable surveyors to use tools as sophisticated as the global positioning system (GPS), which can eliminate the need for a line-of-sight survey.
Bibliography
Cazier, Lola. Surveys and Surveyors of the Public Domain, 1785–1975. Washington, D.C.: U.S. Department of the Interior, Bureau of Land Management, 1993.
Thompson, Morris M. Maps for America: Cartographic Products of the U.S. Geological Survey and Others. Reston, Va.: U.S. Government Printing Office, 1979.
"Virtual Museum of Surveying." Ingram-Hagen & Co.; updated June 2002. Available at http://www.surveyhistory.org
| Columbia Encyclopedia: surveying |
surveying, method of determining accurately points and lines of direction (bearings) on the earth's surface and preparing from them maps or plans. Boundaries, areas, elevations, construction lines, and geographical or artificial features are determined by the measurement of horizontal and vertical distances and angles and by computations based on geometry and trigonometry.
Types and Branches of Surveying
Hydrographic surveying deals with bodies of water and coast lines, is recorded on charts, and records such features as bottom contours, channels, buoys, and shoals. Land surveying includes both geodetic surveying, used for large areas and taking into account the curvature of the earth's surface (see geodesy), and plane surveying, which deals with areas sufficiently small that the earth's curvature is negligible and can be disregarded. Plane surveying dates from ancient times and was highly developed in Egypt. It played an important role in American history in marking boundaries for settlements; surveying was a profession of distinction-both Washington and Jefferson worked for a time as surveyors. Branches of surveying are named according to their purpose, e.g., topographic surveying, used to determine relief (see contour), route surveying, mine surveying, construction surveying; or according to the method used, e.g., transit surveying, plane-table surveying, and photogrammetic surveying (securing data by photographs).
Instruments and Techniques
In surveying, measurements may be made directly, electronically, by the use of optical instruments, by computations from known lines and angles, or by combination methods. Instruments used for direct linear measurements include the Gunter's chain (known also as the surveyor's chain), which is 66 ft (20 m) long and divided into 100 links; the engineer's chain, 100 ft (30 m) long and also consisting of 100 links; the tape, usually of steel, which has largely superseded chains; and the rod. Tapes and rods made of Invar metal (an alloy of steel and nickel) are used for very precise work because of their low coefficient of thermal expansion. In many situations electronic instruments, such as the geodimeter, which uses light waves, and the tellurometer, which uses microwaves, provide a more convenient and more accurate means of determining distance than do tapes and rods.
The height of points in relation to a datum line (usually mean sea level) is measured with a leveling instrument consisting of a telescope fitted with a spirit level and usually mounted on a tripod. It is used in conjunction with a leveling rod placed at the point to be measured and sighted through the telescope. The transit is used to measure vertical and horizontal angles and may be used also for leveling; its chief elements are a telescope that can be rotated (transited) about a horizontal and about a vertical axis, spirit levels, and graduated circles supplemented by vernier scales. Known also as a transit theodolite, or transit compass, the transit is a modification of the theodolite, an instrument that, in its original form, could not be rotated in a vertical axis. A plane table consists of a drawing board fixed on a tripod and equipped with an alidade (a rule combined with a telescope); it is used for direct plotting of data on a chart and is suitable for rapid work not requiring a high degree of precision.
The stadia method of measuring distance, a rapid system useful in surveying inaccessible terrain and in checking more precise measurements, consists in observing through a telescope equipped with two horizontal cross hairs or wires (stadia hairs) the interval delimited by the hairs on a calibrated stadia rod; the interval depends on the distance between the rod and the telescope.
Surveys based on photographs are especially useful in rugged or inaccessible country and for reconnaissance surveys for construction, mapping, or military purposes. In air photographs, errors resulting from tilt of the airplane or arising from distortion of ground relief may be corrected in part by checking against control points fixed by ground surveys and by taking overlapping photographs and matching and assembling the relatively undistorted central portions into a mosaic. These are usually examined stereoscopically.
Bibliography
See W. H. Rayner and M. O. Schmidt, Fundamentals of Surveying (5th ed. 1969); R. F. Spier, Surveying and Mapping (1970); J. Anderson and E. Mikhail, Introduction to Surveying (1989); F. Bell, Surveying and Setting Out Procedures (1991).
| History 1450-1789: Surveying |
Surveying, initially the geometrical and legal description of local lands and county seats, gained importance throughout the early modern period as legal and economic arguments came to rely on accurate descriptions and, increasingly, on measurement and "plotting." By the late seventeenth century, surveying included the mapping of larger political units; by the eighteenth, military leaders and colonial governors, as well as landed individuals, employed surveyors and cartographers. Techniques and instruments developed throughout the period produced a coherent body of theory and practice used for imperial mapping in the late eighteenth and nineteenth centuries.
At the end of the fifteenth century, surveying consisted largely of written descriptions of fields and estates based on visual inspection of an area. Although landmarks and natural division points were more crucial for determining land ownership, these methods were often accompanied by some sort of measurement. In the first half of the sixteenth century, surveying was often restricted to "viewing" or chain-measuring, and the chain often symbolized the surveyors' profession. As the century progressed, and more standardized techniques of measurement were developed and surveying moved from linear and geometrical methods to those based on angular or trigonometric measurement, surveyors began to produce maps or "plots." Although such advanced mathematical methods were developed by the end of the century, chain-measuring continued to be used into the eighteenth century.
The introduction of triangulation methods, the plane table, and the theodolite, as well as rules of acceptable practice, transformed surveying into an exact art. Leonard Digges's Pantometria (1571), for example, introduced these techniques and instruments into England. Throughout the seventeenth century the new surveying instruments were refined, a number of surveying manuals were published, and surveyors were increasingly trained in mathematics and astronomical techniques. Surveying, unlike mapping on a larger scale or the later colonial and country surveys, such as the Ordnance Survey of Ireland (1824–1846), did not require longitude and latitude placement, and therefore did not use astronomical observations in order to achieve accuracy.
Part of the transformation in surveying that took place during the early modern period was related to the changing awareness on the part of landowners of the desirability of surveying and mapping their lands. As surveyors gradually convinced their patrons of the utility of scale maps, this cognitive shift led to a cartographic revolution. Carefully measured and drawn maps (as opposed to earlier sketch maps) began to be used by landowners as evidence in court cases, by generals planning their military strategies, and by governors interested in inventories and tax collecting. All of this was symptomatic of the developing map culture, driven in part by the increasing study of geography at schools and universities.
By the end of the early modern period, Europeans were surveying their own lands and the other parts of the world they were conquering. They believed that, through measurement and cartographic depiction, they could control the land and the people who lived there. Only the impressive developments of surveying instruments and techniques, and the conceptual acceptance of the scale map as an objective and controllable representation of the land, made that idea plausible.
Bibliography
Bennett, James A. The Divided Circle: A History of Instruments for Astronomy, Navigation and Surveying. Oxford, 1987.
Kain, Robert J. P., and Elizabeth Baigent. The Cadastral Map in the Service of the State: A History of Property Mapping. Chicago, 1992.
Richeson, Allie Wilson. English Land Measuring to 1800: Instruments and Practices. Cambridge, Mass., 1966.
—LESLEY B. CORMACK
| Wikipedia: Surveying |
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For other uses, see Survey.
Surveying or land surveying is the technique and science of accurately determining the terrestrial or three-dimensional space position of points and the distances and angles between them. These points are usually on the surface of the Earth, and are often used to establish land maps and boundaries for ownership or governmental purposes. In order to accomplish their objective, surveyors use elements of geometry, engineering, trigonometry, mathematics, physics, and law.
An alternative definition, per the American Congress on Surveying and Mapping (ACSM), is the science and art of making all essential measurements to determine the relative position of points and/or physical and cultural details above, on, or beneath the surface of the Earth, and to depict them in a usable form, or to establish the position of points and/or details.
Furthermore, as alluded to above, a particular type of surveying known as "land surveying" (also per ACSM) is the detailed study or inspection, as by gathering information through observations, measurements in the field, questionnaires, or research of legal instruments, and data analysis in the support of planning, designing, and establishing of property boundaries. It involves the re-establishment of cadastral surveys and land boundaries based on documents of record and historical evidence, as well as certifying surveys (as required by statute or local ordinance) of subdivision plats/maps, registered land surveys, judicial surveys, and space delineation. Land surveying can include associated services such as mapping and related data accumulation, construction layout surveys, precision measurements of length, angle, elevation, area, and volume, as well as horizontal and vertical control surveys, and the analysis and utilization of land survey data.
Surveying has been an essential element in the development of the human environment since the beginning of recorded history (ca. 5000 years ago) and it is a requirement in the planning and execution of nearly every form of construction. Its most familiar modern uses are in the fields of transport, building and construction, communications, mapping, and the definition of legal boundaries for land ownership.
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Origins
Surveying techniques have existed throughout much of recorded history. In ancient Egypt, when the Nile River overflowed its banks and washed out farm boundaries, boundaries were re-established by a rope stretcher, or surveyor, through the application of simple geometry. The nearly perfect squareness and north-south orientation of the Great Pyramid of Giza, built c. 2700 BC, affirm the Egyptians' command of surveying.
- The Egyptian land register (3000 BC).
- A recent reassessment of Stonehenge (c.2500 BC) indicates that the monument was set out by prehistoric surveyors using peg and rope geometry[1].
- Under the Romans, land surveyors were established as a profession, and they established the basic measurements under which the Roman Empire was divided, such as a tax register of conquered lands (300 AD).
- The rise of the Caliphate led to extensive surveying throughout the Arab Empire. Arabic surveyors invented a variety of specialized instruments for surveying, including:[2]
- Instruments for accurate leveling: A wooden board with a plumb line and two hook [disambiguation needed]s, an equilateral triangle with a plumb line and two hooks, and a reed level.
- A rotating alhidade, used for accurate alignment.
- A surveying astrolabe, used for alignment, measuring angles, triangulation, finding the width of a river, and the distance between two points separated by an impassable obstruction.
- In England, The Domesday Book by William the Conqueror (1086)
- covered all England
- contained names of the land owners, area, land quality, and specific information of the area's content and habitants.
- did not include maps showing exact locations
- Continental Europe's Cadastre was created in 1808
- founded by Napoleon I (Bonaparte)
- contained numbers of the parcels of land (or just land), land usage, names etc., and value of the land
- 100 million parcels of land, triangle survey, measurable survey, map scale: 1:2500 and 1:1250
- spread fast around Europe, but faced problems especially in Mediterranean countries, Balkan, and Eastern Europe due to cadastre upkeep costs and troubles.
A cadastre loses its value if register and maps are not constantly updated. Because of the fundamental value of land and real estate to the local and global economy, land surveying was one of the first professions to require Professional Licensure. In many jurisdictions, the land surveyors license was the first Professional Licensure issued by the state, province, or federal government.
Large-scale surveys are a necessary pre-requisite to map-making. In the late 1780s, a team from the Ordnance Survey of Great Britain, originally under General William Roy began the Principal Triangulation of Britain using the specially built Ramsden theodolite.
Surveying techniques
Historically, distances were measured using a variety of means, such as chains with links of a known length, for instance a Gunter's chain or measuring tapes made of steel or invar. In order to measure horizontal distances, these chains or tapes would be pulled taut according to temperature, to reduce sagging and slack. Additionally, attempts to hold the measuring instrument level would be made. In instances of measuring up a slope, the surveyor might have to "break" (break chain) the measurement- that is, raise the rear part of the tape upward, plumb from where the last measurement ended.
Historically, horizontal angles were measured using a compass, which would provide a magnetic bearing, from which deflections could be measured. This type of instrument was later improved, with more carefully scribed discs providing better angular resolution, as well as through mounting telescopes with reticles for more precise sighting atop the disc (see theodolite). Additionally, levels and calibrated circles allowing measurement of vertical angles were added, along with verniers for measurement to a fraction of a degree- such as a turn-of-the-century transit.
The simplest method for measuring height is with an altimeter — basically a barometer — using air pressure as an indication of height, but surveying requires greater precision. A variety of means, such as precise levels, have been developed to do this. Levels are calibrated to provide a precise plane from which differentials in height between the instrument and the point in question can be measured, typically through the use of a vertical measuring rod.
With the triangulation method, one first needs to know the horizontal distance to the object. If this is not known or cannot be measured directly, it is determined as explained in the triangulation article. Then the height of an object can be determined by measuring the angle between the horizontal plane and the line through that point at a known distance and the top of the object. In order to determine the height of a mountain, one should do this from sea level (the plane of reference), but here the distances can be too great and the mountain may not be visible. So it is done in steps, first determining the position of one point, then moving to that point and doing a relative measurement, and so on until the mountaintop is reached.
Surveying equipment
As late as the 1990s the basic tools used in planar surveying were a tape measure for determining shorter distances, a level for determine height or elevation differences, and a theodolite, set on a tripod, with which one can measure angles (horizontal and vertical), combined with triangulation. Starting from a position with known location and elevation, the distance and angles to the unknown point are measured. A more modern instrument is a total station, which is a theodolite with an electronic distance measurement device (EDM) and can also be used for leveling when set to the horizontal plane. Since their introduction, total stations have made the technological shift from being optical-mechanical devices to being fully electronic with an onboard computer and software. Modern top-of-the-line total stations no longer require a reflector or prism (used to return the light pulses used for distancing) to return distance measurements, are fully robotic, and can even e-mail point data to the office computer and connect to satellite positioning systems, such as a Global Positioning System (GPS). Though real-time kinematic GPS systems have increased the speed of surveying, they are still only horizontally accurate to about 20 mm and vertically accurate to about 30–40 mm.[3] However, GPS systems do not work well in areas with dense tree cover or constructions. Total stations are still used widely, along with other types of surveying instruments. One-person robotic-guided total stations allow surveyors to gather precise measurements without extra workers to look through and turn the telescope or record data. A faster way to measure large areas (not details, and no obstacles) is with a helicopter, equipped with a laser scanner, combined with a GPS to determine the position and elevation of the helicopter. To increase precision, beacons are placed on the ground (about 20 km apart). This method reaches precisions between 5–40 cm (depending on flight height).[4]
Types of surveys and applicability
- ALTA/ACSM Survey: a surveying standard jointly proposed by the American Land Title Association and the American Congress on Surveying and Mapping that incorporates elements of the boundary survey, mortgage survey, and topographic survey.
- Archaeological survey: used to accurately assess the relationship of archaeological sites in a landscape or to accurately record finds on an archaeological site.
- As-Built Survey: a survey carried out during or immediately following a construction project for record, completion evaluation and payment purposes.
- Bathymetric Survey: a survey carried out to map the topography and features of the bed of an ocean, lake, river or other body of water.
- Boundary Survey: a survey to establish the boundaries of a parcel using its legal description which typically involves the setting or restoration of monuments or markers at the corners or along the lines of the parcel, often in the form of iron rods, pipes, or concrete monuments in the ground, or nails set in concrete or asphalt. Surveying is regarded as a sub-discipline of civil engineering all over the world. All Degree and Diploma level Engineering institutions, world wide, have detailed items of Surveying in the curriculum for undergraduate courses in the discipline of Civil Engineering.
- Deformation Survey: a survey to determine if a structure or object is changing shape or moving. The three-dimensional positions of specific points on an object are determined, a period of time is allowed to pass, these positions are then re-measured and calculated, and a comparison between the two sets of positions is made.
- Engineering Surveys: those surveys associated with the engineering design (topographic, layout and as-built) often requiring geodetic computations beyond normal civil engineering practise.
- Foundation Survey: a survey done to collect the positional data on a foundation that has been poured and is cured. This is done to ensure that the foundation was constructed in the location, and at the elevation, authorized in the Plot Plan, Site Plan, or Subdivision Plan.
- Geological Survey: generic term for a survey conducted for the purpose of recording the geologically significant features of the area under investigation. .
- Hydrographic Survey: a survey conducted with the purpose of mapping the coastline and seabed for navigation, engineering, or resource management purposes.
- Mortgage Survey or Physical Survey: a simple survey that delineates land boundaries and building locations. In many places a mortgage survey is required by lending institutions as a precondition for a mortgage loan.
- Soil survey, or soil mapping, is the process of determining the soil types or other properties of the soil cover over a landscape, and mapping them for others to understand and use.
- Tape Survey: this type of survey is the most basic and inexpensive type of land survey. Popular in the middle part of the 20th century, tape surveys while being accurate for distance lack substantially in their accuracy of measuring angle and bearing. ards that are practised by professional land surveyors.
- Topographic Survey: a survey that measures the elevation of points on a particular piece of land, and presents them as contour lines on a plot.
Surveying as a career
The basic principles of surveying have changed little over the ages, but the tools used by surveyors have evolved tremendously. Engineering, especially civil engineering, depends heavily on surveyors.
Whenever there are roads, railways, reservoir, dams, retaining walls, bridges or residential areas to be built, surveyors are involved. They establish the boundaries of legal descriptions and the boundaries of various lines of political divisions. They also provide advice and data for geographical information systems (GIS), computer databases that contain data on land features and boundaries.
Surveyors must have a thorough knowledge of algebra, basic calculus, geometry, and trigonometry. They must also know the laws that deal with surveys, property, and contracts. In addition, they must be able to use delicate instruments with accuracy and precision. In the United States, surveyors and civil engineers use units of feet wherein a survey foot is broken down into 10ths and 100ths. Many deed descriptions requiring distance calls are often expressed using these units (125.25 ft). On the subject of accuracy, surveyors are often held to a standard of one one-hundredth of a foot; about 1/8th inch. Calculation and mapping tolerances are much smaller wherein achieving near perfect closures are desired. Though tolerances such as this will vary from project to project, in the field and day to day usage beyond a 100th of a foot is often impractical.
In most states of the U.S., surveying is recognized as a distinct profession apart from engineering. Licensing requirements vary by state, however these requirements generally all have a component of education, experience and examinations. In the past, experience gained through an apprenticeship, together with passing a series of state-administered examinations, was required to attain licensure. Nowadays, most states insist upon basic qualification of a Degree in Surveying in addition to experience and examination requirements. Typically the process for registration follows two phases. First, upon graduation, the candidate may be eligible to sit for the Fundamentals of Land Surveying exam, to be certified upon passing and meeting all other requirements as a Surveyor In Training (SIT). Upon being certified as an SIT, the candidate then needs to gain additional experience until he or she becomes eligible for the second phase, which typically consists of the Principles and Practice of Land Surveying exam along with a state-specific examination. Registered surveyors usually denote themselves with the letters P.S. (professional surveyor), L.S. (land surveyor), or P.L.S. (professional land surveyor), or R.L.S. (registered land surveyor), R.P.L.S. (Registered Professional Land Surveyor), or P.S.M. (professional surveyor and mapper) following their names, depending upon the dictates of their particular state of registration.
In Canada Land Surveyors are registered to work in their respective province. The designation for a Land Surveyor breaks down by province but follows the rule whereby the first letter indicates the province followed by L.S. There is also a designation as a C.L.S. or Canada Lands Surveyor who has the authority to work on Canada Lands which include Indian Reserves, National Parks, the three territories and offshore lands.
In many Commonwealth countries, the term Chartered Land Surveyor is used for someone holding a professional license to conduct surveys.
Typically a licensed land surveyor is required to sign and seal all plans, the format of which is dictated by their state jurisdiction, which shows their name and registration number. In many states, when setting boundary corners land surveyors are also required to place survey monuments bearing their registration numbers, typically in the form of capped iron rods, concrete monuments, or nails with washers.
Building surveying
Building Surveying emerged in the 1970s as a profession in the United Kingdom by a group of technically minded General Practice Surveyors.[1] Building Surveying is a recognized profession within Britain and Australia. In Australia in particular, due to risk mitigation/limitation factors the employment of surveyors at all levels of the construction industry is widespread. There are still many countries where it is not widely recognized as a profession. The Services that Building Surveyors undertake are broad but include:
- Construction design and building works
- Project Management and monitoring
- CDM Co-ordinator under the Construction (Design & Management) Regulations 2007
- Property Legislation adviser
- Insurance assessment and claims assistance
- Defect investigation and maintenance adviser
- Building Surveys and measured surveys
- Handling Planning applications
- Building Inspection to ensure compliance with building regulations
- Undertaking pre-acquisition surveys
- Negotiating dilapidations claims [2]
Building Surveyors also advise on many aspects of construction including:
- design
- maintenance
- repair
- refurbishment
- restoration[3]
Clients of a building surveyor can be the public sector, Local Authorities, Government Departments as well as private sector organisations and work closely with architects, planners, homeowners and tenants groups. Building Surveyors may also be called to act as an expert witness. It is usual for building surveyors to undertake an accredited degree qualification before undertaking structured training to become a member of a professional organisation. For Chartered Building Surveyors, these courses are accredited by the Royal institution of Chartered Surveyors. Other Professional organisations that have building surveyor members include CIOB, ABE, HKIS and RICS.
With the enlargement of the European community, the profession of the Chartered Building Surveyor is becoming more widely known in other European states,particularly France http://www.surveyorsinfrance.com. Chartered Building Surveyors, where many English speaking people buy second homes.
Land surveyor
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Cadastral land surveyors are licensed by State governments. In the United States, cadastral surveys are typically conducted by the Federal government, specifically through the Cadastral Surveys branch of the Bureau of Land Management (BLM), formerly the General Land Office (GLO). In the states that have been subdivided as per the Public Land Survey System (PLSS), the BLM Cadastral Surveys are carried out in accordance with said system. This information is required to define ownership and rights in real property (land, water, mineral, easements, rights-of-way, etc.), to resolve boundary disputes between neighbours, and for any subdivision of land, building development, road boundary realignment, etc.
The aim of cadastral surveys is normally to re-establish and mark the corners of original land boundaries. The first stage is to research relevant records such as land titles (deeds), easements, survey monumentation (marks on the ground) and any public or private records that provide relevant data. The job of a boundary surveyor retracing a deed or prior survey is to locate such monuments and verify their correct position. Over time, development, vandalism and acts of nature often wreak havoc on monuments, so the boundary surveyor is often forced to consider other evidence such as fence locations, woodlines, monuments on neighboring property, parole evidence and other evidence.
Monuments are marks on the ground that define location. Pegs are commonly used to mark boundary corners, and nails in bitumen, small pegs in the ground (dumpys) and steel rods are used as instrument locations and reference marks, commonly called survey control. Marks should be durable and long lasting, stable so the marks do not move over time, safe from disturbance and safe to work at. The aim is to provide sufficient marks so some marks will remain for future re-establishment of boundaries. Examples of typical man-made monuments are steel rods, pipes or bars with plastic, aluminum or brass caps containing descriptive markings and often bearing the license number of the surveyor responsible for the establishment of such. The material and marking used on monuments placed to mark boundary corners are often subject to state laws/statutes.
The job of a boundary surveyor retracing a deed or prior survey is to locate such monuments and verify their correct position. Over time, development, vandalism and acts of nature often wreak havoc on monuments, so the boundary surveyor is often forced to consider other evidence such as fence locations, woodlines, monuments on neighboring property, parole evidence and other evidence.
A total station or GPS is set-up over survey marks which were placed as part of a previous survey, or newly placed marks. The bearing datum is established by measuring between points on a previous survey and a rotation is applied to orientate the new survey to correspond with the previous survey or a standard map grid. The data is analysed and comparisons made with existing records to determine evidence which can be used to establish boundary positions. The bearing and distance of lines between the boundary corners and total station positions are calculated and used to set out and mark the corners in the field. Checks are made by measuring directly between pegs places using a flexible tape. Subdivision of land generally requires that the external boundary is re-established and marked using pegs, and the new internal boundaries are then marked. A plat (survey plan) and description (depending on local and state requirements) are compiled, the final report is lodged with the appropriate government office (often required by law), and copies are provided to the client.
The Art of Surveying
Many properties have considerable problems with regards to improper bounding, miscalculations in past surveys, titles, easements, and wildlife crossings. Also many properties are created from multiple divisions of a larger piece over the course of years, and with every additional division the risk of miscalculation increases. The result can be abutting properties not coinciding with adjacent parcels, resulting in hiatuses (gaps) and overlaps. The art comes in when a surveyor must solve a puzzle using pieces that do not exactly fit together. In these cases the solution is based upon the research and interpretation of the surveyor, and following established procedures for resolving discrepancies.
References
- ^ Johnson, Anthony, Solving Stonehenge: The New Key to an Ancient Enigma. (Thames & Hudson, 2008) ISBN 978-0-500-05155-9
- ^ Donald Routledge Hill (1996), "Engineering", pp. 766-9, in Rashed, Roshdi & Régis Morelon (1996), Encyclopedia of the History of Arabic Science, Routledge, 751-795, ISBN 0415124107
- ^ National Cooperative Highway Research Program: Collecting, Processing and Integrating GPS data into GIS, p. 40. Published by Transportation Research Board, 2002 ISBN 0309069165, 9780309069168
- ^ Toni Schenk1, Suyoung Seo, Beata Csatho: Accuracy Study of Airborne Laser Scanning Data with Photogrammetry, p. 118
- Notes
- Keay J (2000), The Great Arc: the dramatic tale of how India was mapped and Everest was named, Harper Collins, 182pp, ISBN 0-00-653123-7.
- Pugh J C (1975), Surveying for Field Scientists, Methuen, 230pp, ISBN 0-416-07530-4
- Genovese I (2005), Definitions of Surveying and Associated Terms, ACSM, 314pp, ISBN 0-9765991-0-4.
External links
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Look up surveying in Wiktionary, the free dictionary. |
- As-builts – Problems & Proposed Solutions — Discussion on Building Surveys within Construction industry by Stephen R. Pettee, CCM
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