Surveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them, commonly practiced by licensed surveyors, and members of various building professions. These points are usually on the surface of the Earth, and they are often used to establish land maps and boundaries for ownership, locations (building corners, surface location of subsurface features) or other governmentally required or civil law purposes (property sales).
An alternative definition, from 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 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 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 or 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.
Surveyors use various tools to do their work successfully and accurately, such as total stations, robotic total stations, GPS receivers, prisms, 3D scanners, radio communicators, handheld tablets, digital levels, and surveying software.
Surveying has been an essential element in the development of the human environment since the beginning of recorded history (about 6,000 years ago). It is required 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.
History of surveying
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.
A brief history of surveying:
- The Egyptian land register (3000 BC).
- A recent reassessment of Stonehenge (c. 2500 BC) suggests that the monument was set out by prehistoric surveyors using peg and rope geometry.
- The Groma surveying instrument originated in Mesopotamia (early 1st millennium BC).
- 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:[not in citation given]
- Instruments for accurate leveling: A wooden board with a plumb line and two hooks, 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 inhabitants.
- Did not include maps showing exact locations.
In the 18th century in Europe triangulation was used to build a hierarchy of networks to allow point positioning within a country. Highest in the hierarchy were triangulation networks. These were densified into networks of traverses (polygons), into which local mapping surveying measurements, usually with measuring tape, corner prism and the familiar red and white poles, are tied. For example, 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. Large scale surveys are known as geodetic surveys.
- 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.
Historically, distances were measured using a variety of means, such as with chains having links of a known length, for instance a Gunter's chain, or measuring tapes made of steel or invar. To measure horizontal distances, these chains or tapes were 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- use an increment less than the total length of the chain.
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 with 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 (also known as differential leveling), have been developed to do this. With precise leveling, a series of measurements between two points are taken using an instrument and a measuring rod. Differentials in height between the measurements are added and subtracted in a series to derive the net difference in elevation between the two endpoints of the series. With the advent of the Global Positioning System (GPS), elevation can also be derived with sophisticated satellite receivers, but usually with somewhat less accuracy than with traditional precise leveling. However, the accuracies may be similar if the traditional leveling would have to be run over a long distance.
Triangulation is another method of horizontal location made almost obsolete by GPS. With the triangulation method, distances, elevations and directions between objects at great distance from one another can be determined. Since the early days of surveying, this was the primary method of determining accurate positions of objects for topographic maps of large areas. A surveyor first needs to know the horizontal distance between two of the objects. Then the height, distances and angular position of other objects can be derived, as long as they are visible from one of the original objects. High-accuracy transits or theodolites were used for this work, and angles between objects were measured repeatedly for increased accuracy. See also Triangulation in three dimensions.
Turning is a term used when referring to moving the level to take an elevation shot in a different location. When land surveying, there may be trees or other obstructions blocking the view from the level gun to the level rod. In order to "turn" the level gun, one must first take a shot on the rod from the current location and record the elevation. Keeping the level rod in exactly the same location and elevation, one may move the level gun to a different location where the level rod is still visible. Record the new elevation seen from the new location of the level rod and use the difference in elevations to find the new elevation of the level gun. Turning is not only used when there are obstructions in the way, but also when drastically changing elevations. You can turn up or down in elevation but the gun must always be at a higher elevation than the base of the rod. A level rod can usually be raised up to 25 feet high, which enables the gun to be set much higher. However, if the gun is lower than the base of the rod, you will not be able to take a shot because the rod cannot be lowered beyond the ground elevation.
As late as the 1990s, the basic tools used in planar surveying were a tape measure for determining shorter distances, a level to determine height or elevation differences, and a theodolite, set on a tripod, to measure angles (horizontal and vertical), combined with the process of 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). A total station 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.
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. Though Real Time Kinematic GPS systems have increased the speed and precision of surveying, they are still horizontally accurate to only about 20 mm and vertically accurate to about 30–40 mm.
Total stations are still used widely, along with other types of surveying instruments, however, because GPS systems do not work well in areas with dense tree cover or constructions. 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 but expensive 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, surveyors place beacons on the ground (about 20 km (12 mi) apart). This method reaches precisions between 5–40 cm (depending on flight height).
Types of surveys and applicability
- ALTA/ACSM Land Title 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 after a construction project for record, completion evaluation and payment purposes. An as-built survey also known as a 'works as executed survey' documents the location of the recently constructed elements that are subject to completion evaluation. As built surveys are typically presented in red or redline and overlayed over existing design plans for direct comparison with design information.
- 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 that establishes 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.
- 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 practice.
- 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.
- Measured survey : a building survey to produce plans of the building. such a survey may be conducted before renovation works, for commercial purpose, or at end of the construction process "as built survey"
- 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.
- Structural survey: a detailed inspection to report upon the physical condition and structural stability of a building or other structure and to highlight any work needed to maintain it in good repair.
- 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 standards that are practiced 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, pipeline transports 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.
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 1/8 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 of the United States, surveying is recognized as a distinct profession apart from engineering. Licensing requirements vary by state, but they generally have components 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. Now, most states insist upon basic qualification of a degree in surveying, plus experience and examination requirements.
The licensing process typically follows two phases. First, upon graduation, the candidate may be eligible to take the Fundamentals of Surveying (FS) exam, to be certified upon passing and meeting all other requirements as a surveying intern (SI),(formerly surveyor in training (SIT)). Upon being certified as an SI, the candidate then needs to gain additional experience to become eligible for the second phase. That typically consists of the Principles and Practice of Land Surveying (PS) exam along with a state-specific examination.
Licensed surveyors usually denote themselves with the letters P.L.S. (professional land surveyor), P.S. (professional surveyor), L.S. (land surveyor), 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 jurisdiction 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.
A licensed land surveyor is typically 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.
||It has been suggested that Construction surveying#Professional status of construction surveyors be merged into this article. (Discuss) Proposed since December 2011.|
Building surveying emerged in the 1970s as a profession in the United Kingdom by a group of technically minded general practice surveyors. Building surveying is a recognised profession in Britain, Ireland, Australia and Hong Kong. In Australia in particular, due to risk mitigation and 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.
Building Surveyors are trained to some extent in all aspects of property but with specific training in Building Pathology, as such they have a wide understanding of the end implications of decisions taken by more specific professions and trades during the realisation process, thus making them suitable for employment as Project and Property Managers on the client side (i.e. managing external contractors).
Services that building surveyors undertake are broad but can include:
- Construction design and building works
- Project management and monitoring
- Property Legislation advice
- Insurance assessment and claims assistance
- Defect investigation and maintenance advice
- Building surveys and measured surveys
- Handling planning applications
- Building inspection to ensure compliance with building regulations
- Pre-acquisition surveys
- Negotiating dilapidations claims
Building surveyors also advise on many aspects of construction including:
- restoration and preservation of buildings and monuments
Clients of a building surveyor can be the government agencies, businesses and individuals. Surveyors work closely with architects, planners, quantity surveyors, engineers, homeowners and tenants groups. A building surveyor may be called to act as an expert witness. It is usual for building surveyors to earn a university degree before undertaking structured training to become a member of a professional organisation.
With the enlargement of the European community, the profession of the building surveyor is becoming more widely known in other European states, particularly France, where many English-speaking people buy second homes.
Lidar Surveying – Three-dimensional laser scanning provides high definition surveying for architectural, as-built, and engineering surveys. Recent technological advances make it the most cost-effective and time-sensitive solution for providing the highest level of detail available for interior and exterior building work.
One of the primary roles of the land surveyor is to determine the boundary of real property on the ground. That boundary has already been established and described in legal documents and official plans and maps prepared by attorneys, engineers, and other land surveyors. The corners of the property will either have been monumented by a prior surveyor, or monumented by the surveyor hired to perform a survey of a new boundary which has been agreed upon by adjoining land owners.
Monuments are categorized into two groups which are known as natural and artificial. Natural monuments are things such as trees, large stones and other substantial, naturally occurring objects that were in place before the survey was made. An artificial monument is anything within the regulations that are usually placed at corner points by landowners, surveyors, engineers and others. They may be referred to as iron pins or pipes, stakes, trees, concrete monuments or whatever the surveyor decides to use at the time, within the regulations for the area. The courts have held that natural monuments control over artificial monuments because they are more certain in identification and less likely to be disturbed.
Over time, construction and maintenance of roads and many other acts of man, along with acts of nature such as earthquakes, movement of water, and tectonic shift can obliterate or damage the monumented locations of land boundaries. The land surveyor is often compelled to consider other evidence such as fence locations, wood lines, monuments on neighboring properties and recollections of people. This other evidence is known as Extrinsic Evidence and is a fairly common principle. Extrinsic evidence is defined as evidence outside the writings, in this case the deed. Extrinsic evidence is held to be synonymous with evidence from another source.
Today's land surveyor sets monumentation at actual physical points on the ground that define angle points of boundary lines that divide neighboring parcels. These monuments are most often 1/2" or 5/8" iron rebar rods or pipes placed at 18" minimum depth, but varies state by state. The more recent rods or pipes may have an affixed plastic cap over the top bearing the responsible surveyors' name and license number. Older monuments may exist such as old pipes, gun barrels, axles, mounds of stone, whiskey bottles, or even wooden stakes. In addition to rods and pipes, surveyors might use 4x4" concrete posts at corners of large parcels or anywhere that would require more stability (e.g. beach sand). They place them three feet deep. In places where there is asphalt or concrete, it is common to place nails or aluminum alloy caps to re-establish boundary corners. Marks are meant to be durable, stable, and as "permanent" as possible. The aim is to provide sufficient marks so some marks will remain for future re-establishment of boundaries. The material and marking used on monuments placed to mark boundary corners are often subject to state laws. Many states have laws that protect existing monuments and can have civil penalties if disturbed or destroyed.
Cadastral land surveyors are licensed by 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). They consult with USFS, Park Service, Corps of Engineers, BIA, Fish and Wildlife Service, Bureau of Reclamation, etc. In states that have been organized per the Public Land Survey System (PLSS), surveyors carry out BLM Cadastral Surveys in accordance with that system.
A common use of a survey is to determine a legal property boundary. The first stage in such a survey, known as a resurvey, is to obtain copies of the deed description and all other available documents from the owner. The deed description is that of the deed and not a tax statement or other incomplete document. The surveyor should then obtain copies of deed descriptions and maps of the adjoining properties, any records from the municipality or county, utility maps and any records of surveys. Depending on which region the survey is located in some or most of this information may not be available or even exist. Whether the information exists or not a thorough search should be conducted so that no records are neglected. Copies of deeds usually can be located in the county recorder's office and maps or plats can usually be found at the county recorder or surveyor's office. These arrangements will vary state to state and survey system to survey system so some familiarity maybe needed. When all the records are assembled, the surveyor examines the documents for errors, such as closure errors. When a metes and bounds description is involved, the seniority of the deeds must be determined. The title abstract usually gives the order of seniority for the deeds related to the tract being surveyed and should be used if available. After this data is gathered and analyzed the field survey may commence. The initial survey operations should be concentrated on locating monuments. In urban regions or a city, monuments should be sought initially but in the absence of monuments property corners marked by iron pins, metal survey markers, iron pipes and other features that may establish a line of possession should be located. When the approximate positions for the boundaries of the property have been located a traverse is run around the property. While the control traverse is being run, ties should be measured and all details relevant to the boundaries should be acquired. This includes but is not limited to locating the property corners, monuments, fences, hedge rows, walls, walks and all buildings on the lot. The Surveyor then takes this data collected and compares it to the records that were received. When a solution is reached the property corners that are chosen as those that best fit all the data are coordinated and ties by direction and distance are computed from the nearest traverse point. Once this has been established the features on the lot can be drawn, dimensions can be shown from these features to the boundary line and a map or plat is prepared for 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. Many times a surveyor must solve a puzzle using pieces that do not exactly fit together. In these cases, the solution is based upon the surveyor's research and interpretation, along with established procedures for resolving discrepancies. This essentially is a process of continual error correction and update, where official recordation documents countermand the previous and sometime erroneous survey documents recorded by older monuments and older survey methods.
- Johnson, Anthony, Solving Stonehenge: The New Key to an Ancient Enigma. (Thames & Hudson, 2008) ISBN 978-0-500-05155-9
- Hong-Sen Yan & Marco Ceccarelli (2009), International Symposium on History of Machines and Mechanisms: Proceedings of HMM 2008, Springer, p. 107, ISBN 1-4020-9484-1
- Lewis, M. J. T. (2001-04-23). Surveying Instruments of Greece and Rome. Cambridge University Press. ISBN 9780521792974. Retrieved 30 August 2012.
- Donald Routledge Hill (1996), "Engineering", pp. 766–9, in Rashed, Roshdi; Morelon, Régis (1996), Encyclopedia of the History of Arabic Science, Routledge, pp. 751–795, ISBN 0-415-12410-7
- National Cooperative Highway Research Program: Collecting, Processing and Integrating GPS data into GIS, p. 40. Published by Transportation Research Board, 2002 ISBN 0-309-06916-5, ISBN 978-0-309-06916-8
- Toni Schenk1, Suyoung Seo, Beata Csatho: Accuracy Study of Airborne Laser Scanning Data with Photogrammetry, p. 118
- Thomas Kibblewhilte and Sara J Wilkinson, Building Surveying: A UK Phenomenon or a Profession with Genuine Global Appeal?, International Federation of Surveyors 2004. Retrieved 13 December 2011.
- Brown, C., Wilson, D., & Robillard, W. (2003). Brown's boundary control and legal principles. (5th ed., p. 30). Hoboken, NJ: John Wiley & Sons, Inc.
- Richards, D., & Hermansen, K. (1995). Use of extrinsic evidence to aid interpretation of deeds. Journal of Surveying Engineering, (121), 178.
- A History of the Rectangular Survey System by C. Albert White, 1983, Pub: Washington, D.C. : U.S. Dept. of the Interior, Bureau of Land Management : For sale by Supt. of Docs., U.S. G.P.O.,
- Anderson, J., & Mikhail, E. (1998). Surveying: Theory and practice. (7th ed., p. 1011). McGraw-Hill.
- 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.
|Look up surveying in Wiktionary, the free dictionary.|
- Géomètres sans Frontières : Association de géometres pour aide au développement. NGO Surveyors without borders (French)
- The National Museum of Surveying The Home of the National Museum of Surveying in Springfield, Illinois
- Land Surveyors United Support Network Global social support network featuring surveyor forums, instructional videos, industry news and support groups based on geolocation.
- Natural Resources Canada – Surveying Good overview of surveying with references to construction surveys, cadastral surveys, photogrammetry surveys, mining surveys, hydrographic surveys, route surveys, control surveys and topographic surveys
- As-builts -– Problems & Proposed Solutions — Discussion on Building Surveys within Construction industry by Stephen R. Pettee, CCM
- Table of Surveying, 1728 Cyclopaedia
- Google Map with overlays for principal meridians, coordinate zones, NGS Control, USGS topographic maps and more
- Surveying & Triangulation The History Of Surveying And Survey Equipment
-  BASIC programs for surveying and mapping
- NCEES National Council of Examiners for Engineering and Surveying (NCEES)
- International Federation of Surveyors International Federation of Surveyors (FIG)