Surveying is the first and most essential step in starting any civil engineering project. It is a fundamental branch of civil engineering that deals with the measurement and representation of the Earth’s surface. To properly understand surveying techniques, a student must first have a clear idea of the basic principles. Therefore, the study of surveying should begin with its definition and importance.
What is Surveying?
Surveying is the technique of determining the relative positions of different points or features on, above, or beneath the surface of the earth by means of direct or indirect measurements. These measured details are finally represented on a sheet of paper in the form of a plan or map.
According to the American Congress on Surveying and Mapping (ACSM),
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, or to establish the position of points or details.
Surveying also includes the process of establishing points using predetermined angular and linear measurements. From the plans, sections, and maps prepared through surveying, the area and volume of a plot of land can be accurately calculated. A map represents the horizontal projection of the surveyed area and not the actual surface area. However, vertical distances and height differences are more clearly represented by drawing sections.
During a survey, surveyors use various modern and traditional instruments to perform their work accurately. These include total stations, GPS receivers, prisms, digital levels, 3D scanners, radio communicators, surveying software, and instruments such as the dumpy level. The selection of instruments depends on the nature, accuracy, and scale of the survey work.
To better understand the practical scope of surveying, you can watch the following video.
History of Surveying
The practice of surveying dates back to ancient civilizations. Early surveying was used for land measurement, boundary fixing, and the construction of monuments. The Egyptians used surveying techniques for re-establishing land boundaries after annual flooding of the Nile. The Romans further developed surveying for roads, aqueducts, and military planning. With the advancement of science and technology, modern surveying now uses electronic instruments, satellite systems, and digital data processing.
Principles of Surveying
Surveying is based on a few fundamental principles that ensure the accuracy and reliability of measurements. The main principles of surveying are as follows:
- Working from whole to part: First, a framework of control points is established with high accuracy. Then, smaller details are filled in within this framework to minimize the accumulation of errors.
- Fixing positions by at least two measurements: The position of any point should be determined by at least two independent measurements to provide a check against errors.
Importance of Surveying
Knowledge of surveying is highly advantageous in almost all phases of engineering works. Surveying plays a vital role in the planning, design, and execution of engineering projects. No civil engineering project can be properly started, executed, or completed without accurate surveying. The major importance of surveying is discussed below.
- The primary purpose of surveying is to prepare plans and sections of the project area. Based on these drawings, the best possible alignment, quantity of earthwork, and other essential design details can be determined.
- The planning and design of all civil engineering projects, such as railways, highways, tunnels, irrigation works, dams, reservoirs, water supply systems, sewerage works, airfields, ports, and large buildings, are based on surveying measurements.
- During the execution stage, projects of any size are constructed strictly along the lines, levels, and reference points established by surveying.
- Measurement of land and accurate fixation of property boundaries cannot be carried out without proper surveying.
- The technical and economic feasibility of an engineering project cannot be properly assessed without conducting detailed survey work.
- Surveying is essential for hydrographic and oceanographic charting and mapping of rivers, lakes, seas, and coastal areas.
- Surveying is also used to prepare a topographic map showing natural and man-made features of the earth’s surface.
Conclusion
Surveying is a fundamental and indispensable branch of civil engineering. It provides the basic data required for planning, design, execution, and maintenance of engineering projects. Accurate surveying ensures safety, economy, and efficiency in construction works. With continuous technological advancements, surveying continues to play a vital role in modern infrastructure development.