Firstly of all it is necessary to explain what a Topographic survey is. Although it can have slightly different meanings in the USA and Europe, it is generally taken to mean the study of the shape of the earth’s surface and the depiction of these shapes on three dimensional maps.
In some parts of Europe the older meaning of the word which was a more general study of a place and included such measures as vegetation, man-made features and local history still pervades. In the United States, however, this meaning is used less and topography is specifically to do with ‘relief’ in other words the difference between changing levels of land. This is the meaning we shall be using for the remainder of this article.
You may sometimes hear topographic surveys referred to as Land Surveys, Level Surveys or Site Surveys and they provide architects, developers, authorities and land owners with vital information about the piece of land in question. This information is presented in the form of a three dimensional map.
The terrestrial position of points and distances and angles between them are determined by the topographic survey. Traditional tools and methods such as dumpy levels and clinometers are used although remote sensing technology has speeded things up and led to greater control over long distances. Surprisingly however, the direct survey still provides the basic framework and control points for all topographic work.
The fieldwork in a topographic survey consists of the establishment of a basic framework of horizontal and vertical controls and also the determination of the horizontal and vertical locations of details in the vicinity of each instrument point. The topographic control consists of two parts – the ‘horizontal control’ which locates the horizontally fixed position of specific control points and the ‘vertical control’ in which the elevations of specified bench marks are established.
Architects, engineers and buyers of land all need to have topographic surveys done. It is vital when the design of the building is being done, and also shows how the building should be constructed. Land buyers should also have a survey done when they are deciding what to do with the land.
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If you want to find out more information about topographic surveys, then visit the Sitechnics website at www.sitechnics.com for more information.
