Surveying

 Surveying

     Surveying  is the art and science of measuring the surface of the earth and its feature in order to be able to determine the “spatial location” of point or establish pre-determined points on or  near the surface of the earth.These measured points are draw to scale so that they can be shown in their correct two or three- dimensional  relationships.

    The rapid growth in modern technology has created the awareness for the society to think of building beautiful and well-planned environment. We want our vehicles to move freely along our roads without “hold up”, We want structures to be in exactly where we want  them to be. For all these to be possible we need to carry out surveying.

     Surveying plays important role in the development of our physical environment because accurate surveying and maps are needed to aid the design process, to direct the construction engineers where to place building or structure foundation, to locate structures under construction, and to track the progress of construction, and to track the progress of construction. Sitting and location of roads, houses, school, refinary and location of our natural resources and our local and international boundaries are all parts of surveyor duty.

          On many occasions, surveyors in the construction industries may be involved in any or the entire following task;

•       Layout survey.
•       Preparation of boundary survey plan
•       Establishment of horizontal and vertical control
•       Re-establishment of lost bacons
•       Setting out of road and buildings
•       Determination of areas and volumes of the earth work
•       As-built surveying
•       Data collection, analysis and presentation for Geographic information system

          Construction is one of the largest industries in the world , and surveying plays an extremely important role in many construction project.

CLASSIFICATION OF SURVEYING

There are different types of surveys but one thing we must first known is that surveys will either take into account the true shape of the earth.

LAND SURVEYING CAN BE DIVIDED INTO TWO PARTS

·       Plane Surveying

·        Geodetics Surveying

 Plane Surveying:  are the most commonly practiced method of surveying and treat the earth as a flat or plane surface. The curvature of the earth has no effect on the results. Thus the computation and the result can be referenced to a plane or flat surface.

Plane surveys are used for the determination of legal boundaries, for engineering surveys.

PLANE SURVEYING IS CLASSFIED AS FOLLOWS

§  Topographic Surveys

§  Cadastral Surveys

§  Control Surveys

§  Aerial surveys

§  Hydrographic Surveys

§  Route surveys

§  Construction surveys

 Topographic surveys: preliminary surveys used to locate and map the natural and manmade surface features of an area. The features are located relative to one another by tying them all into the same control lines or control grid

Cadastral surveys: preliminary, layout, and control surveys that are involved in determining boundary locations or in laying out new property boundaries (also known as Property surveys

Control surveys: are used to reference both preliminary and layout surveys. Horizontal control can be arbitrarily placed, but it is usually tied directly to property lines, roadway centerlines, or coordinated control stations. Vertical control is often a series of benchmarks, permanent points whose elevations above a datum (e.g., MSL) have been carefully determined.

Aerial surveys: preliminary and final surveys using both traditional aerial photography and aerial imagery. Aerial imagery includes the use of digital cameras, multispectral scanners, LiDAR, and radar.

Hydrographic surveys: preliminary surveys that are used to tie in underwater features to surface control points. Usually shorelines, marine features, and water depths are shown on the hydrographic map or electronic chart

Route surveys: preliminary, layout, and control surveys that range over a narrow but long strip of land. Typical projects that require route surveys are highways, railroads, electricity transmission lines, and channels.

Construction surveys: layout surveys for engineering works.

Geodetics Surveying: is the true shape of the earth, is carried out with great precision, often over long distances, and are used not only to determine the size, shape and gravity field of the earth (the science of Geodesy) but also to establish highly accurate control networks.

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.

v  The Egyptian land register (3000 BC).

v  A recent reassessment of Stonehenge (c. 2500 BC) indicates that the monument

was set out by prehistoric surveyors using peg and rope geometry.

v  The Groma surveying instrument originated in Mesopotamia (early 1st

millennium BC).

v  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).

v  The rise of the Caliphate led to extensive surveying throughout the Arab Empire.

Arabic surveyors invented a variety of specialized instruments for surveying,

including:

·         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.

v  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

v  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.