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, but not exclusively, associated with positions 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.
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. It’s
most familiar modern uses are in the fields of transport, building and construction,
communications, mapping, and the definition of legal boundaries for land ownership.
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 upon, through 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 down to a fraction of a degree- such as a turn-of-the-
The simplest method for measuring height is with an altimeter — basically a
barometer — using air pressure as an indication of height. But for surveying more
precision is needed. Toward this end, a variety of means, such as precise levels,
have been developed. 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.
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 benchmark, 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 GPS systems have
increased the speed of surveying, they are still only accurate to about 20 mm. As
well GPS systems do not work in areas with dense tree cover. It is because of this
that total stations have not completely phased out earlier instruments. Robotics
allows surveyors to gather precise measurements without extra workers to look
through and turn the telescope or record data. A faster way to measure (no
obstacles) is with a helicopter with laser echolocation, combined with GPS to
determine the height of the helicopter. To increase precision, beacons are placed on
the ground (about 20 km apart). This method reaches a precision of about 5 mm.
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.
Types of Surveys
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.
ALTA/ACSM surveys, frequently shortened to ALTA surveys, are often required
for real estate transactions.
the actual physical extent of property ownership, typically witnessed by
monuments or markers, such as (typically iron rods, pipes or concrete
monuments in the ground, but also tacks or blazes in trees, piled stone corners
or other types of monuments) are measured, and a map, or plat, is drawn from
A plat or map based on a survey of a parcel of land. Boundary lines are drawn
inside the larger parcel to indicate the creation of new boundary lines and roads.
The subdivision must be permitted by the local authority before a development
permit is issued. At this point monuments are set into the ground to mark the lot
corners, and the plat is recorded with the county Register of Deeds after approval
by the Local Authority. The recording or filing of a subdivision plat is highly
regulated. The final map or plat becomes, in effect, a contract between the
developer and the city or county, determining what can be built on the property
and under what conditions. Further, the transfer of ownership of individual lots is
referenced to the subdivision plat. Upon finally completion of a subdivision an As-
Built Plan, or Record Drawing, is required by the local government, and/or the
utility provider/s to show the location of the installed utilities.
Horizontal Property Regime Survey
An HPR, sometimes called a Sectional, or Fractional ownership development
facilitates the part ownership, or a unit, within a residential, commercial or
industrial building or development. The
This usually entails a survey of the property to show the boundaries, structures,
utilities and roadways and related detail. This survey may be used for mortgage,
or closing purposes, and to satisfy the local authority that a new construction is in
compliance with the approval to build.
Hydrographic Survey: a survey carried out to map the seabed profile.
Construction surveying (otherwise "lay-out" or "setting-out"): the process of
establishing and marking the position and detailed layout of new structures such
as roads, parking lots, utilities or buildings for subsequent construction.
Boundary, Tree and Topographic Survey
This survey will be required for the planning of new construction or development, and
will show the boundaries of the site/s, the trees, with size and species, the topography
by means of contours and elevations, and existing structures, utilities, road access and
other pertinent detail.
Stakeout for Review
Prior to development, the local authority and/or the Property Owner’s Association may
require a review of the proposed activity. Proposed improvements will be flagged and
strung out on the site for the review process. Trees that will be removed will be
indicated with ribbon.
Stakeout for clearing
The clearing limits of the site will be staked, trees slated for removal will be flagged in
preparation for the site preparation.
Stakeout for Dirt Fill
Where required, the limits and grade for building pads will be staked.
Stakeout for Construction
The proposed building envelope will be staked for construction of the foundations, slabs
A plat will be prepared showing the position and extent of the foundation to satisfy the
local building authority that it is correctly sited within the lot. This is done to ensure that
the foundation was constructed in the location authorized in the Plot Plan or Site
Plan, and complies with setbacks, buffers and other restrictions. This survey is
usually required before vertical construction can commence, and is normally
accompanied by and Elevation Certificate.
Two elevation certificates will be required for new construction that lies within a Special
Flood Zone. The first will be provided after the foundation is prepared, and will show
that the structure is set at the required elevation for its particular Base Flood Elevation.
On completion of the project, a second, more comprehensive Elevation Certificate is
required, and is used for Flood insurance evaluation and may be required by the local
authority in order to obtain a Certificate of Occupancy.
As-Built Survey (see above)
Once site is completed and asbuilt survey may be required by the local authority
and the mortgage or lending institution. It will show the position and size, in plan
view, of the improvements on the site.
Geological Survey: generic term for a survey conducted for the purpose of
recording the geologically significant features of the area under investigation. In
the past, in remote areas, there was often no base topographic map available, so
the geologist also needed to be a competent surveyor to produce a map of the
terrain, on which the geological information could then be draped. More recently,
satellite imagery or aerial photography is used as a base, where no published
map exists. Such a survey may also be highly specialist - for instance focusing
primarily on hydrogeological, geochemical or geomagnetic themes. (Do not
confuse this term with Geological Survey, typically a government (national,
regional or local) body, charged with maintaining and improving the record of the
geology of the area in which it operates).
Hydrographic Survey: a survey conducted with the purpose of mapping the
coastline and seabed for navigation, engineering, or resource management
purposes. Products of such surveys are nautical charts. See hydrography.
Mortgage Survey or Physical Survey: a simple survey that generally determines
land boundaries and building locations. Mortgage surveys are required by title
companies and lending institutions when they provide financing to show that
there are no structures encroaching on the property and that the position of
structures is generally within zoning and building code requirements. Some
jurisdictions allow mortgage surveys to be done to a lesser standard, however
most modern U.S. state minimum standards require the same standard of care
for mortgage surveys as any other survey. The resulting higher price for
mortgage surveys has led some lending institutions to accept "Mortgage
Inspections" not signed or sealed by a surveyor.
Plot Plan or Site Plan: a proposal plan for a construction site that include all
existing and proposed conditions on a given site. The existing and proposed
conditions always include structures, utilities, roadways, topography, and
wetlands delineation and location if necessary. The plan might also, but not
always, include hydrology, drainage flows, endangered species habitat, FEMA
Federal Flood Insurance Reference Maps and traffic patterns.
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.
Subdivision Plan: a plot or map based on a survey of a parcel of land. Boundary
lines are drawn inside the larger parcel to indicate the creation of new boundary
lines and roads . The number and location of plats, or the newly created parcels,
are usually discussed back and forth between the developer and the surveyor
until they are agreed upon. At this point monuments, usually in the form of
square concrete blocks or iron rods or pins, are driven into the ground to mark
the lot corners and curve ends, and the plat is recorded in the cadastre (USA,
elsewhere) or land registry (UK). In some jurisdictions, the recording or filing of a
subdivision plat is highly regulated. The final map or plat becomes, in effect, a
contract between the developer and the city or county, determining what can be
built on the property and under what conditions. Always upon finally completion
of a subdivision an As-Built Plan is required by the local government. This is
done so that the roadway constructed therein will pass ownership from the
developer to said local government by way of a contract called a Covenant.
When this stage is completed the roadways will now be maintained, repaved,
swept, and plowed (if necessary for your geographic region) by the local
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. Considering that a survey is the documentation of one-half (1/2)
distances and one-half (1/2) bearings this type of survey is no longer accepted
amongst local, state, or federal regulatory committees for any substantial
construction work. However for determining the extent of your property
boundaries and for your peace-of-mind this type of survey is the least expensive,
least time consuming and least invasive, while being nowhere close to accurate
for the 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 contours on a plot.
Wetlands Delineation & Location Survey: a survey that is completed when
construction work is to be done on or near a site containing defined wetlands.
Depending on your local, state, or federal regulations wetlands are usually
classified as areas that are completely inundated with water more than two (2)
weeks during the growing season. (For USA only) Contact your local or state
Conservation Commission or Wetlands Regulatory Commission to
determine the particular definition for wetlands in your given geographical
region. The boundary of the wetlands is determined by observing the soil colors,
vegetation, erosion patterns or scour marks, hydrology, and morphology.
Typically blue or pink colored flags are then placed in key locations to denote the
boundary of the wetlands. A survey is done to collect the data on the locations of
the placed flags and a plan is drawn to reference the boundary of the wetlands
against the boundary of the surrounding plots or parcels of land and the
construction work proposed within.
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, dams,
retaining walls, bridges or residential areas to be built, surveyors are involved. They
determine the boundaries of private property 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
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 metric 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-hundreth 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 this 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, many
states require a Bachelor of Science in Surveying, or a Bachelor of Science in Civil
Engineering with additional coursework 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.
Typically a licensed land surveyor is required to seal all plans, the format of which is
dictated by their state jurisdiction, which shows their name and registration number.
In many states, land surveyors are also required to place caps bearing their
registration number on property corners that they have set.
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 recognized profession within Britain but not widely recognized overseas
although there is growth of the profession within Australia. The Services that
Building Surveyors undertake are broad but include:
Construction design and building works
Project Management and monitoring
Planning Supervisor under CDM Regulations
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
Building Surveyors also advise on many aspects of construction including:
Clients of a building surveyor can be the public sector, Local Authorities,
Government Departments as well as private sector organizations and work closely
with architects, planners, homeowners and tenants groups. Building Surveyors may
also be called to act as an expert witness. Building surveyors must undertake an
accredited degree qualification and undertake professional training for a period of at
least two years, at the end of which sit an assessment of professional competence.
Professional organizations for building surveyors include CIOB and RICS.
Quantity Surveyors play a key role in the organization and financial management of
construction projects. In essence they manage projects to ensure that they are built
on time and to budget. Their job is to manage costs effectively and to ensure that
they get the best value from contractors and suppliers. This involves obtaining
tenders, arranging contracts and managing costs for the client while the works are
undertaken. It is also their job to negotiate with the client's representative on
payments and the final settlement. Quantity Surveyors deal with other professionals
within their company as well as clients out-with the organization.
It is an extremely diverse area and can include project management, facility
management, construction management and management consultancy.
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 neighbors, 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.
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. The boundary pegs will most likely be replaced by fences of varying
durability which then become evidence of land boundary location which can be used
for future re-instatement of boundary location. Typical monuments are steel posts
with brass caps containing descriptive markings, aluminum rods, stones with
inscriptions, rebar with aluminum caps, etc. These monuments must meet the
standards described in the BLM's Manual of Survey Instructions 1973.
The surveyor then examines the site and gathers survey measurements and
observations. A total station is used to measure bearings and distances and provide
measurements from survey control points. A data collector is used to electronically
record data which is downloaded to a computer later. GPS equipment can be used
to provide absolute coordinates of positions using Global Positioning Satellites.
Detail of occupation and boundary fencing is recorded to provide evidence upon
which boundary locations can be assessed.
The 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.
The data is analyzed 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 cloth 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.
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
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
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
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.