Plane Table Surveying in Surveying – Complete Guide for JKSSB Aspirants

📖 Introduction

Plane Table Surveying is a traditional but effective method used in civil engineering for plotting and recording features of an area. It is unique because both observation and plotting are carried out simultaneously in the field.

This method is commonly included in competitive exams like JKSSB Draftsman, JKSSB JE (Civil), and survey-related posts under departments like RDD, PWD, and PMGSY.

🎓 What is Plane Table Surveying?

Plane table surveying is a graphical surveying method in which the survey data is plotted directly in the field using a plane table and drawing instruments. It eliminates the need for detailed field notes and later plotting, making it time-efficient and more visual.

🧰 Instruments Used in Plane Table Surveying

🧭 Key Terms You Must Know

• Centering: Placing the plane table exactly over a survey point.
• Leveling: Making the table horizontal using the spirit level.
• Orientation: Aligning the table so the plotted lines match actual ground directions.
• Backsighting: Aligning the alidade on a previously known station to maintain orientation.

📌 Methods of Plane Table Surveying (JKSSB Important Topic)

There are four primary methods, each suitable for specific situations:

1. Radiation Method

• Used when the location of the plane table is known.
• Objects are sighted using the alidade.
• Lines (rays) are drawn from the instrument station to the object.
• Distances are measured using chain/tape and plotted to scale.

✅ Best suited for locating features from a single point like trees, poles, buildings.

2. Intersection Method

• Uses two known points and intersects sightlines (rays) to locate the position of an unknown point.
• No need to measure distances.

✅ Useful when obstacles like rivers or valleys prevent measurement.

3. Traversing Method

• Similar to theodolite or compass traversing.
• Used to determine the relative positions of successive stations by measuring angles and distances.
• Each new station becomes the origin for the next.

✅ Ideal for road, railway, canal alignment surveys.

4. Resection Method

• Used when the plane table is set up at an unknown location.
• Rays are drawn to at least two or three known points.
• The intersection of these rays fixes the position of the table.

✅ Commonly used in large-scale mapping and triangulation.

🧪 Step-by-Step Procedure for Plane Table Surveying

Here’s the standard workflow used in field practice and asked in JKSSB viva and theory exams:

1. Setting Up: Mount the plane table on the tripod.
2. Fixing Drawing Sheet: Place and clip the drawing sheet securely.
3. Leveling: Use the spirit level to make the table horizontal.
4. Centering: Center the table over the station point using the plumbing fork and plumb bob.
5. Orientation: Align the table using a compass or backsighting to match previous plotted direction.
6. Sighting: Use the alidade to sight objects and draw rays.
7. Plotting: Measure distances and mark points to scale.
8. Repeat: Shift to new stations and repeat the above steps.

✅ Advantages of Plane Table Surveying

❌ Disadvantages of Plane Table Surveying

🧠 Tips for JKSSB Aspirants

• Remember all four methods with use-cases and key advantages.
• Practice labeled diagrams of instrument setup and survey lines.
• Learn to identify instruments like alidade, plumb bob, and spirit level in diagrams.
• Focus on simple definitions and step-by-step processes for short answer questions.

📚 Conclusion

Plane Table Surveying is a fundamental and exam-friendly topic in the JKSSB syllabus for civil engineering and draftsman posts. Its practical application, visual representation, and simplicity make it essential for both written and practical exams.

🛠 Master this topic to secure 2–3 easy marks in your next JKSSB exam!

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Sahil Digra

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