Surveying is the art of determining the relative positions of different object on the surface of the earth by measuring the horizontal distance between them and by preparing a map to any suitable scale. Thus, in this process, the measurements are taken only in the horizontal plane.
The traditional role of a surveyor has been to determine the position of features in both the natural and built environment on or below the surface of the Earth and to represent these on a map.
As stated in the definition, object of surveying is to show relative positions of various objects of an area on paper and produce plan or map of that area.
Various uses of surveying are listed below:
- Plans prepared to record property lines of private, public and government lands help in avoiding unnecessary controversies
- Maps prepared for marking boundaries of countries, states, districts etc., avoid disputes.
- Locality plans help in identifying location of houses and offices in the area.
- Road maps help travellers and tourist.
- Topographic maps showing natural features like rivers, streams, hills, forests help in planning irrigation projects and flood control measures.
- For planning and estimating project works like roads, bridges, railways, airports, water supply and waste water disposal surveying is required.
- Marine and hydrographic survey helps in planning navigation routes and harbours.
- Military survey is required for strategic planning.
- Mine surveys are required for exploring minearl wealth.
- Geological surveys are necessary for determining different strata in the earth crust so that proper location is found for reservoirs.
- Archeological surveys are useful for unearthing relics of antiquity.
- Astronomical survey helps in the study of movements of planets and for calculating local and standard times.
Leveling
Leveling is the art of determining the relative vertical distance of different points on the surface of earth. Hence, in leveling, the measurements are taken only in the vertical plane.
Types of Surveying [Classification]
Primary Classification or Primary Division :
- Plane surveying
- Geodetic surveying
Plane Surveying
The shape of the earth is spherical. Thus the surface is obviously curved. But in plane surveying the curvature of earth is not taken into account. This is because plane surveying is carried out over a small area, so the surface of the earth is considered as a plane. The degree of accuracy required in this type of surveying is completely low. Plane surveying is done on an area of less than 250km^2.
Geodetic surveying
In geodetic surveying the curvature of the earth is taken into consideration. It is extended over a large area greater than 250km2. The line joining any two points considered as a curved line. Very refined methods and instruments are used in this type of surveying. IN this method very high precision or accuracy is required.
Secondary classification:
Survey can be classified on different bases.
1. Based on instrument:
- Chain Survey
- Compass survey
- Plane Table survey
- Theodolite survey
- Tacheometric Survey
- Photographic survey
2. Based on methods:
- Triangulation Survey
- Traverse Survey
3. Based on Objects:
- Geological survey
- Mine survey
- Archeological Survey
- Military survey
4. Based on nature of field
- Land Survey
- Marine survey
- Astronomical survey
Again Land Survey is classified into following Classes:
- Topographical Survey : To determine natural features of a country such as valleys, rivers and artificial features such as road, railways, etc.
- Cadastral Survey: To determine boundaries of field, estate
- City survey: To locate premises, streets, water supply and drainage systems
- Engineering survey: To collect detailed data for the design for of projects involving roads, railways, etc Engineering surveys are sub divided into: Reconnaissance Survey, Preliminary Survey, and Location Survey
Brief History of Surveying
- Surveying had it’s beginning in Egypt about 1400 BC
- Land along the Nile River was divided for taxation. Divisions were washed away by annual floods.
- “ROPE-STRETCHERS” Egyptian surveyors were created to relocate the land divisions (measurements were made with ropes having knots at unit distances).
- Extensive use of surveying in building of Egyptian monuments
- Greeks: expanded Egyptian work and developed Geometry.
- Developed one of the earliest surveying instruments – Diopter (a form of level).
- Romans: developed surveying into a science to create the Roman roads, aqueducts, and land division systems.
- Surveyors held great power, had schools and a professional organization
- Developed several instruments:
- Groma – cross instrument used to determine lines and right angles
- Libella – “A” frame with a plumb bob used for leveling
- Chorobates – 20’ straight edge with oil in notch for leveling
- Middle Ages: land division of Romans continued in Europe.
- Quadrans – square brass frame capable of turning angles up to 90° and has a graduated scale developed by an Italian named Von Piso.
- 18th & 19th Century in the New World: the need for mapping and marking land claims caused extensive surveying, especially by the English.
- 1785: United Stated began extensive surveys of public lands into one mile square sections
- 30 states surveyed under the U.S. Public Land System (also called the Rectangular System)
- 1807: United States Geological Survey founded to establish an accurate control network and mapping
- Famous American Surveyors: George Washington, Thomas Jefferson, George Rogers Clark, Abe Lincoln and many more.
- 1785: United Stated began extensive surveys of public lands into one mile square sections
- 20th Century and Beyond: As technology advanced, population increased, and land value caused development of licensure for surveyors in all states.
- Educational requirements for licensure began in the early 1990’s
- Capable of electronic distance measurement, positioning using global positioning systems, construction machine control, and lidar (scanning) mapping
- Involvement in rebuilding of the infrastructure and geographic information systems (GIS)
- Shortage of licensed professionals is projected well into the 21st century
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