What is surveying in civil engineering?
Surveying is the technique of determining relative positions of different objects on, above, and below the surface of the earth. In the surveying method, all the measurements are taken in the horizontal plane. There are different methods of surveying according to various factors. But all of these methods commonly follow two principles of surveying.
What is surveying and basic principles of surveying in civil engineering?
There are two basic principles of surveying in civil engineering. Those principles of surveying are as follows:
(i) To work from whole to part.
(ii) To locate a new station by taking at least two reference measurements ( linear or angular) from the fixed reference points.
What is the principle of whole-to-part surveying?
Work from whole to part
To work from whole to the part is the main principle of surveying. This principle is followed in order to prevent the accumulation of errors. As the total work is divided into parts, the error of one part will not influence the other parts. As a result, an error will not affect the whole surveying work. This is how the effect of the error is minimized by following the principles of surveying.
But if the opposite process(i.e., from the part to the whole ) is followed, then the minor errors in the measurement will be magnified. Hence ultimately a situation will come when the effects of those errors will be absolutely out of control.
Explanation :1 (Principles of surveying)
Let us assume that we are measuring a straight line of 30 on fairly level ground. We can measure the distance with a 30 m tape in a single measurement. But due to the long-distance, the self-weight of the tape will affect the measurement. Because of this, there will be a sag in the measurement. Due to this sag, the measured distance will be higher than the original distance.
Now if we divide the distance into a number of spans, the error can be eliminated. Suppose we are measuring the same 30 m distance but in a 3 span of 10 m. Now as the span is small the effect of the self-weight will be eliminated, so the error due to sagging.
Explanation :2 (Principles of surveying)
Let’s assume the area of survey work is ABCD as shown in the figure below. During the measurement of the main survey lines (i.e. AB, BC, CD, DA) suppose there was an error in measuring one of the lines, say line CD is incorrect. So now if we calculate the area at a whole, the error in line CD will affect the total area.
But if we divide the total area into a framework of triangles, the error in line CD will no affect the total area. Hence the error will be minimized.
What is the second principle of surveying in civil engineering
(ii) To locate a new station by taking at least two reference measurements
Any new survey stations should always be established by at least two measurements (linear or angular) from fixed reference points. Horizontal distances measured by chain and tape are the linear measurements. Angular measurements are the magnetic bearing or horizontal angle taken by a theodolite or a prismatic compass.
Explanation :(Principles of surveying-2)
Let’s say, two reference points A and B are selected and the length AB is accurately measured. Hence AB line can be plotted to a suitable scale on the paper.Â
Now the position of any point X can be fixed with reference points A and B by a number of geometrical construction as shown in Fig. 1.1 to Fig. 1.5. The numbers 1 and 2 indicate the two measurements to be taken.Â
Fig 1.1 – Here the lengths AX and BX are measured and by swinging arc, the position of point X can be established. This method is largely used in chain surveying.
Fig 1.2- Here the angular measurements XAB and XBA are measured and plotting these angles protractor, the position of X can be determined. This method is largely used in triangulation surveying.
Fig 1.3- Here a line XC perpendicular to ACÂ is measured then, the position of X can be determined with the help of a set square.
Fig 1.4- Here the angle XAB and distance AX are measured. Then plotting angle XAB by protractor and extending the length up to AX, the position of point X can be determined. This method is generally used in traversing.
Fig 1.5- Here the angle XAB and distance AX are measured. Then plotting angle XAB by protractor and swinging the arc length of BX, the position of point X can be determined.
These two principles of surveying are very important for controlling and minimizing the accumulation of error. These two principles of surveying also establish a good connection between the field data and the plotting.
FAQs
What is the primary purpose of surveying?
Surveying is primarily used to measure and map the Earth’s surface, providing essential data for various applications.
How do surveyors ensure accuracy in their measurements?
Surveyors follow strict principles of accuracy, including error minimization and precise calibration of instruments.
What are some common surveying errors?
Common errors include instrumental errors, observational errors, and environmental factors affecting measurements.
How has technology transformed surveying?
Technology advancements have introduced tools like GPS, laser scanning, and GIS, enhancing the precision and efficiency of surveying.
What role does surveying play in environmental assessment?
Surveying is crucial in assessing and mitigating the environmental impact of construction, infrastructure, and development projects.
Can surveying be used in urban planning?
Absolutely! Surveying provides essential data for urban planners to design and manage cities efficiently.
Are there any ethical considerations in surveying?
Yes, surveyors must adhere to ethical standards, including respecting property rights and ensuring data privacy.
What is the future of surveying technology?
The future of surveying lies in automation, AI, and real-time data processing, enabling faster and more accurate measurements.
Is surveying a sustainable profession?
Surveying plays a vital role in sustainable development by guiding responsible land use and resource management.
How can I pursue a career in surveying?
To become a surveyor, you’ll need formal education in surveying or related fields, followed by certification and practical experience.
What is the main principle of surveying?
The main principle of surveying is to work from whole to part.
What is the principle of Chain surveying?
The principle of chain surveying is triangulation. The total surveying area in chain surveying is divided into a network of well-conditioned triangles. In chain surveying, only linear measurements are taken. No angular measurements are taken in chain surveying.
What is the principle of Compass surveying?
The principle of compass surveying is traversing. In compass traversing the linear measurements are taken with chains and angular measurements are taken with a compass. There are two types of compass that are used in compass surveying. The prismatic compass measures the angle in the whole circle bearing system. Surveyor’s compass measures the angle in the reduced bearing system.
What is the principle of plane table surveying?
The principle of plane table surveying is parallelism. In the plane table surveying the rays drawn from instrument stations on the sheet is always parallel to the actual line connecting the station and the object on the ground. The plane table stations are also parallel to the position they occupied at the previous station.
In the plane table surveying, fieldwork and plotting are done simultaneously on the field.
What is the principle of Tacheometric surveying?
The principle of tacheometric surveying is based on the theorem of similar isosceles triangles. According to this principle, among the similar triangles, the ratio of the distance of the base from the apex and the base length is always constant.
What is the principle of theodolite?
The principle of theodolite operation revolves around accurately measuring horizontal and vertical angles using precise rotations, sighting, and leveling. Theodolites are valuable tools in various applications, including land surveying, construction, geodetic measurements, and geospatial sciences, where precise angle measurements are essential for determining positions, distances, and elevation differences.
Conclusion
Surveying, with its principles deeply rooted in precision and accuracy, remains an indispensable discipline in today’s world. By understanding and applying these principles, surveyors contribute to the success of projects, the resolution of disputes, and the advancement of industries. So, whether you’re a seasoned surveyor or someone considering a career in this field, remember that precision and success go hand in hand in the world of surveying.