1.17.1. Advantages and disadvantages of plane table surveying

Advantages

(a) The map is prepared in the field; therefore, the office work is minimal. (b) The observations and plotting are done simultaneously, and the surveyor can see the terrain before him/her, so chances of losing the details are rare. (c) Errors in plotting the details on the plane table can be checked by drawing the check lines using several methods. (d) The angles and distance measurements can be obtained graphically, and hence there is no need to carry out measurements in the field. (e) Many far-off objects/details can be plotted accurately using the intersection method to prepare the map in the shortest time. (f) It is advantageous in magnetic areas where compass survey is not reliable.

This chunk highlights the benefits of plane table surveying, which is a method used in mapping. The advantages include:

1. Field Preparation: Maps can be created directly in the field, which reduces the amount of work that needs to be done in the office later.
2. Simultaneous Observations and Plotting: The surveyor can see the terrain and create representations of it at the same time, minimizing the risk of missing important details.
3. Error Checking: Mistakes made during the plotting can be identified easily through the use of check lines, ensuring greater accuracy.
4. Graphical Measurements: There is no need for physical tools like measuring tapes since angles and distances can be graphically assessed.
5. Efficient Plotting of Distant Objects: The intersection method allows quick and accurate plotting of objects that are far away from the surveyor’s location.
6. Utility in Certain Areas: In regions with unreliable compass usage, such as those affected by magnetic fields, plane table surveying is particularly useful.

Imagine a painter who prefers to paint a landscape directly from the spot rather than sketching in a studio based on memory. This painter's experience allows them to capture details vibrant and full of life that a memory might lose. Similarly, plane table surveying allows surveyors to create detailed and accurate maps directly in the field, ensuring they capture the true essence of the terrain.

Disadvantages

(a) Plane tabling work is dependent on weather conditions (e.g., rains, high winds). (b) The plane table is not very much suitable in a dense forest area or urban area. (c) If survey map is to be replotted at some different scale, entire work has to be re-done. (d) Its accessories are heavy to carry in the field from one location to another. (e) The paper maps are subject to shrinkage or expansion while working in the field for a long time. (f) It is laborious and time-consuming to prepare a map of a large area. (g) It requires large manpower for doing various activities from observations to plotting.

In this chunk, we look at the limitations of plane table surveying. These include:

1. Weather Dependency: Bad weather, such as rain or strong winds, can halt surveying work, making it unreliable.
2. Environmental Limitations: Dense forests or urban areas with tall buildings create obstacles that make it impractical to set up a plane table effectively.
3. Replotting Issues: If a survey map needs to be modified to a different scale, the entire process of mapping must be started anew, causing inefficiency.
4. Heavy Equipment: The plane table and its accessories can be cumbersome to transport, making fieldwork challenging.
5. Paper Limitations: Maps made on paper can shrink or expand due to temperature or humidity changes, leading to inaccuracies.
6. Time-Consuming: Mapping large areas takes significant time and effort due to the labor-intensive nature of the process.
7. Manpower Intensive: The need for multiple personnel to handle various tasks increases logistical requirements.

Think of setting up a picnic. If it rains or the wind blows hard, everything becomes challenging. You may need to cancel or delay your plans. Similarly, plane table surveying can be disrupted by weather, and setting it up in a crowded city or thick forest may be impossible, which highlights the practicality issues faced in certain environments.

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