Surveying Is A Significant Early Site Appraisal Tool

Survey operations are one of the early work activities to be carried out on a site intended for development. It does not matter if the site is a greenfield or brownfield, survey work has to be done first, in order to plan various aspects of the project.

Surveying 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 such as maps, or to establish the position of points or details. Therefore Surveying activities involves collecting data for mapping the relative positions of points on the surface of the earth.

The main purpose of the survey of a proposed site is to collect field data to prepare a plan of the object to be surveyed or a map showing all the features of the area under consideration. The relative positions of objects and the height of each feature are also measured and analyzed to calculate the field parameters for setting out the operation of actual and further engineering work. Consequently, the goal of surveying works is to prepare maps to show the relative positions of the objects on the surface of the earth.

The basic principles of surveying look “to localize the errors and to reduce and control the accumulation of errors”. This implies that for a Surveyor to achieve this goal, it important the Surveyor work from the “whole to the part” and locate a new station by at least two measurements (linear or angular) from fixed reference points. This means that the whole survey area is first enclosed by main stations and main survey lines and then the area is divided into a number of divisions by forming well-conditioned triangles.

Surveying works have been classified in numerous nomenclatures. When viewed in terms of the desired accuracy, survey works have been classified as Plane Survey, which assumes that the surface of the earth is flat not curved and Geodetic Survey, when the curvature of the earth is taken into consideration to have a higher degree. When the survey activities are classified based on place and location,  we will have Land Survey – which is done on land, Hydrographic Survey – which is done on water bodies, Underground Survey -the survey operations performed beneath the surface of the earth. It is quite different from surveying on the surface and Aerial survey– This survey is about above the ground by taking aerial photographs with a camera fitted to Airplanes or Drones.

Again survey has been classified according to the instruments used to achieve the survey operation, for example, we have Chain Survey, Traverse Survey, Leveling, Tacheometry survey, Plain tabling, Triangulation survey, EDM survey, Total Station survey, etc. When the purpose of the survey operation is used as a means of classification we have a Geological survey, Geographical survey, Engineering survey, Defence survey, Route Survey, etc. All these various names show how diverse and significant Survey Operations are to Site management for infrastructure development.

 In project planning surveying activities provide relevant geospatial data of different kinds in a map. These geospatial data can, therefore, be converted into various types of maps that are useful for planning and records. Some of the known types of maps derived from Survey data are annotated below:

  • Topographical map: captures various geological, natural, cultural and engineering  features like river, villages, towns, mountains, roads, dams, etc
  • Cadastral map: delineates boundaries of countries, states, districts fields, houses, and other properties in an area, etc., avoid disputes.
  • Engineering map: provides details of engineering work like dams, bridges, railways, highways, irrigation canals, tunnels, etc.
  • Military map: assists soldiers to identify strategic points within the defense area.
  • Contour map: is an essential tool for finding the best possible routes or inclinations.
  • Geological map: displays areas that may have mineral resources.
  • Archeological map: designates places of ancient relics and its existence.

 

As we can see, the relevance of Survey works in site development is centered around maps to determine the best possible route and amount of earthwork required, showing engineering details and geological and environmental features. The planning and design of all infrastructure projects are based upon surveying measurements. Moreover, during execution, a project of any magnitude is constructed along the lines and points established by surveying. Thus, surveying is a basic requirement for all infrastructure projects.

Other principal works in which surveying is primarily utilized are: to fix the national and state boundaries; to chart coastlines, navigable streams and lakes; to establish control points, to execute hydrographic and oceanographic charting and mapping; and to prepare a topographic map of the land surface of the earth. When building infrastructure that requires millimeter accuracy, again surveying techniques are very useful. Similarly, when as-built information is not available, a laser 3d scanning survey can provide the information. When planning for a rail or road alignment for hundreds of Kilometres, aerial surveys can help to do the work faster.

In summarizing some of the major uses of surveying are in the preparation of topographical maps, planning and estimating new engineering projects, planning navigation routes, and harbors, military strategic planning, and exploring mineral wealth. In short, surveying is an inseparable part of strategic site planning, civil engineering, and infrastructure development.

 

By Prof. Goodwill Ofunne

Fundamental Integrated Site Appraisal Services(FISAS) Limited, Abuja

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