Surveying in Civil Engineering

Surveying is one of the first steps before construction starts. In this blog, I’ll explain what surveying is, why it’s important, and how it’s done on site. You’ll also find clear notes on the types of surveys and their classifications by scope, method, and purpose. My goal is to make this topic easy to understand for civil engineering students and anyone who wants to learn how land is measured for design and construction. Through examples and practical insights, this blog will help you see how surveying guides every project from the ground up.

What is Surveying in Civil Engineering

Surveying is the art of measuring distances, angles and positions on or near the Earth’s surface. In other words: The art and science of obtaining quantified and qualified measurement, the interpretation of these measurements and a meaningful presentation of result.

Why is it considered as an art?

Because only a surveyor who understands the importance of surveying can determine the most efficient method to obtain ideal results, e.g.

·       Selecting the appropriate tools for the site conditions, for example “choosing a Total Station over a simple chain on hilly or complicated terrain or knowing how to mitigate field errors."

·       Applying practical knowledge to anticipate and minimize errors caused by environmental factors (like temperature or wind) or obstructions, which requires skill and judgment rather than just formulaic calculation.

Surveying in Civil Engineering

Surveying is mainly classified into two types. In plain surveying the earth is considered as flat where in geodetic or trigonometric surveying the earth is considered as curved.

Surveying is also classified based on instrument such as chain and theodolite surveying whereas it is also classified based on purpose such as topographic, cadastral, engineering and Hydrographic surveying.

Principle of Surveying

There are two basic principles of surveying:

1.       Always work from whole to part.

2.       To locate a new station by at least two measurements (linear or angular) from fixed reference points.

 

Types of Surveying in Civil Engineering

Surveying is mainly divided into two groups.

Plain surveying

If the curvature of the earth is not taken into consideration. Difference of length taken in geodetic and in Plain survey is 0.1 m in 18.2 m and 0.3 m in 54.3 km and 0.5m in 90 km.

Geodetic or trigonometric surveying

If the curvature of the earth is taken into consideration, then the survey is called geodetic survey. The surface of the Earth is a sphere because large distances and areas are covered, the line connecting any two points A and B is Curved or as the Arc of great circle.

  Plain Surveying

Ø  The earth surface is considered as Plain surface

Ø  The curvature of the earth is ignored.

Ø  Line joining any two station is straight.

Ø  The triangle formed by any three points is considered as plain.

Ø  The angles of triangles are considered as plain angles

Ø  Carried out for smaller area < 250km2.

Geodetic Surveying

Ø  The earth surface is considered as curved surface.

Ø  The curvature of the earth is taken into consideration.

Ø  Line joining any two station is considered as spherical.

Ø  The triangle formed by any three points is considered as spherical.

Ø  The angles of triangles are considered as spherical angles.

Ø  The angles of triangles are considered as spherical angles.

 

Classification of surveying According to Area:

Land survey

Land surveying is the science and practice of precisely measuring and mapping the physical features of the earth's surface, including horizontal distances, angles, and elevations.

Marine survey

Marine surveying is the detailed inspection and assessment of a vessel's condition, safety, and value, conducted by a professional marine surveyor.

Hydrographic survey

Hydrographic survey is the science of measuring and mapping the physical features of bodies of water like oceans, seas, and rivers.

Astronomical surveying

A branch of surveying that uses the positions of celestial bodies (like the Sun, Moon, and stars) to find absolute positions and directions on Earth's surface.

According to Purpose:

Engineering survey

An engineering survey is the process of collecting and measuring data to support the conception, planning, design, and construction of civil engineering projects.

Topographical survey

Detailed map of a site's physical features, showing both natural elements like hills and trees, and man-made structures like buildings, roads, and utility lines.

Military survey

The process of using specialized measurement techniques to map terrain, determine strategic locations, and support military operations such as construction, troop movements, and artillery placement.

Mine survey

Mine survey is the practice of determining the relative positions of points on or beneath the surface of earth by direct or indirect measurements of distance, direction and Elevation.

 

 

Geological survey

The systematic investigation and mapping of the Earth's geology, including its rocks, minerals, and subsurface features, to understand the composition, structure, and processes of an area.

Archaeological survey

An Archaeological survey is a systematic, non-excavation process used to locate, identify, and document archaeological sites and cultural resources within a specific area.

 

According to the Instruments Employed

Chain survey

A method of surveying that measures linear distances using a tape or chain to create a framework of connected triangles across a small, relatively flat area.

Compass survey

Compass surveying is an important branch of surveying which is usually adopted in determining the position of an object both by angular and linear measurements. Here angular measurements are taken using a compass and linear measurements are determined using chain or tape.

Plane table survey

Plane Table survey is defined as:

• Plane table is a graphical method of surveying in which the field works, and the plotting is done simultaneously.
• It is particularly adopting in small mapping. 
• Plane table surveying is used for locating the field computation of area of field.
• The principle of plane tabling is parallelism rays of line on paper are parallel to the line on ground.

Tachometric survey

Tachometric surveying is a method of angular surveying using a tachometer-a transit or theodolite-and a stadia rod-to determine horizontal and vertical distances using optical means.

Theodolite survey

Theodolite surveying refers to the technique of measurement of horizontal and vertical angles using a theodolite, an instrument with a swiveling telescope that is mainly used in land surveying, construction, and engineering. 

                             

Aerial or Photographic survey

Photogrammetry, or a photographic survey, is a means for obtaining measurements from photographs and making maps.

                            

Conclusion

Surveying is a very orderly field, which applies well-defined principles in order to control projects of various sizes. The main categorization is into Plain Surveying, in which curvature for smaller areas can be ignored, and Geodetic Surveying, where Earth's curvature must be taken into consideration during a larger project.

Beyond this, we organized the field by what is being measured: from Land and Hydrographic to specialized Geological and Military purposes. We also looked at the instruments employed, distinguishing methods such as traditional Chain and Compass surveys from modern Theodolite and Photographic techniques.

From planning small sites to mapping vast distances, it is the surveyor's expertise in their art of choosing the right method and instrument that forms the bedrock on which all successful civil engineering and construction rest. The precision that you will master in this discipline is the blueprint for all else to follow.

Frequently Asked Questions About Surveying

1. What is the main purpose of surveying?
To measure and map land accurately for planning and construction.

2. Which type of survey is used for large areas?
Geodetic surveying because it considers Earth’s curvature.

3. What instrument is most used today?

Total Station

 

Do you have questions about a specific survey type or the principles we discussed? Don't hesitate to comment below and share your thoughts or field experiences!