Plane Table Surveying: A Fundamental Method in Civil Engineering

Introduction:

Surveying plays a role, in engineering as it involves measuring and mapping the Earth’s surface to gather vital data for design and construction projects. Among the surveying techniques, Plane Table Surveying holds significant importance due to its simplicity and effectiveness. In this blog post, we will delve into the concept of Plane Table Surveying exploring its methods, types, advantages and disadvantages.

What is Plane Table Surveying?

Plane Table Surveying is a method where a flat surface called a plane table is used as a reference point for plotting field observations on a sheet of paper. This technique empowers surveyors to create maps and plans while working in the field without needing calculations after the survey.

Methods of Plane Table Surveying

There are two primary methods of Plane Table Surveying:

1. Radiation Method: In this method, the surveyor chooses a point of interest known as the station and measures both distances and directions from that station to points known as objects. Using either a theodolite or compass the surveyor determines angles between their line of sight and a reference meridian. These observations are then plotted directly on the paper fixed onto the plane table.
2. Intersection Method: The intersection method involves securing the plane table at a station and sighting objects of interest using either a theodolite or alidade. The angles, between these lines of sight are. Their intersections are marked on the paper. This technique proves to be quite beneficial when it comes to mapping areas that have shapes.

Types of Plane Surveying

Plane Table Surveying can be categorized into three types based on the position of the plane table:

1. Simple Plane Table Surveying: In this approach, the plane table stays fixed at a location and observations are made from that point. It is most suitable, for areas that have limited details.
2. Traverse Plane Table Surveying: The plane table is moved from one location to another. A series of interconnected spots are observed and marked. This approach is utilized for mapping intricate areas.
3. Resection Plane Table Surveying: Resection involves determining the position of the plane table by sighting known objects from a spot. It is commonly used in situations where there are no reference points.

Advantages of Plane Table Surveying

1. Simplicity: Plane Table Surveying is relatively straightforward. Requires equipment making it an excellent choice for small-scale surveying projects.
2. Real-time Mapping: It allows for map creation in the field reducing the need for post-processing and data manipulation.
3. Suitable for Hilly or Irregular Terrain: Plane Table Surveying can adapt to terrains, including uneven landscapes, where other surveying methods may be less effective.
4. Visual Representation: The nature of Plane Table Surveying aids in interpreting data and conveying information to non-technical stakeholders.

Disadvantages of Plane Table Surveying

1. Limited Accuracy: Plane Table Surveying may not achieve the level of accuracy as advanced surveying techniques like Total Station or GPS surveying.
2. Time-Consuming: Compared to modern surveying methods it can be time-consuming due, to the plotting of data manually.
3. Dependent on Weather: The accuracy of observations can be hindered by weather conditions, like rain or fog which also affect visibility.
4. Limited Coverage: When it comes to larger-scale surveys Plane Table Surveying may not be as efficient as it is more suitable for, sized areas.

Conclusion

Plane Table Surveying continues to be a tool, for engineers and surveyors. Its simplicity and ability to create real-time maps make it a practical option for surveying tasks in challenging terrains where accuracy needs are moderate. However, aspiring engineers must recognize its limitations and select the suitable surveying method for each project guaranteeing precise and dependable outcomes, in the field.