---
title: "Plane table principles; advantages, disadvantages"
subject: "Surveying I"
chapter: 6
key: "semester_3/surveying_i:principles-adv-disadv-plane-table"
source: https://www.bctengineer.com/q/semester_3/surveying_i/principles-adv-disadv-plane-table
site: BCT Engineering
---

# Plane table principles; advantages, disadvantages

Surveying I · Chapter 6: Plane Table Survey

- Asked in: 2080 Baisakh, 4 marks; 2076 Asoj, 4 marks (asked 2 times)
- Video: [Plane Table Surveying | Part 1 | Engineering Surveying | Principle Of Plane Tabling | Nilesh Jha](https://www.youtube.com/watch?v=PvN9pZNKrHE) — Nilesh Jha Life
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/surveying_i/principles-adv-disadv-plane-table
- Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-6

## Question

What are the principles of plane table surveying? List out the advantages and disadvantages of plane table surveying.

## Short answer

Plane table surveying's principle is that rays drawn from station points on the sheet must be parallel to the ground lines, achieved by levelling, centring, and orientation. Advantages include simultaneous fieldwork and plotting, no angular booking, quick for small maps, and not affected by local attraction when back-sighted. Disadvantages include unsuitability in bad weather, heavy instruments, lower accuracy, and dependence on the single plan without field notes.

## Answer

#### Principles of plane table surveying
Plane tabling is a graphical surveying method in which fieldwork and plotting are done together on the spot, using a drawing sheet fixed on a board (plane table), an alidade for sighting and a tripod.

**Principle:** the table is set up so that the rays drawn on the sheet from a station point towards the objects are *parallel* to the corresponding lines on the ground. The plotted figure is then similar to the ground figure. This needs three things at every station:

1. **Levelling** - the board is kept horizontal (spirit level on the board).
2. **Centring** - the point on the sheet is kept vertically above the ground station (plumbing fork and plumb bob).
3. **Orientation** - the board is turned so that all lines on the sheet stay parallel to their ground lines (by magnetic needle or by back-sighting a previously plotted line).

#### Advantages and disadvantages
**Advantages**
- Fieldwork and plotting are done together, so omissions and mistakes are detected on the spot.
- Contours and details can be drawn directly by looking at the ground.
- Less field book work; no angular booking is needed.
- Not affected by local attraction when oriented by back-sighting.
- Quick and economical for small and medium-scale maps.
- Inaccessible points can be plotted by intersection and resection.
- Needs less skill than theodolite surveying and the instruments are simple.

**Disadvantages**
- Not suitable in rainy, windy, foggy weather or in thick forest and built-up areas where intervisibility is poor.
- Instruments are heavy and many accessories must be carried; difficult to transport.
- Less accurate than a theodolite survey for large areas; accuracy depends on drawing quality.
- The whole work depends on the plan only; a plan cannot be re-drawn to a different scale from field data as there are no field notes.
- Paper may shrink or expand with weather.
- Plotting is done in the field, so work stops in bad weather, and an unskilled person may make a poor drawing.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the basic principle of plane table surveying?
   A. Rays drawn on the sheet are parallel to the corresponding ground lines, so the plan is similar to the ground figure
   B. Rays on the sheet are perpendicular to the ground lines
   C. Angles are booked in a field book and plotted later in the office
   D. Distances are measured with a chain and plotted at a larger scale than the ground
   Answer: A. The table is set so that sheet rays are parallel to the ground lines, which makes the plotted figure similar to the ground figure. (Key point: Core principle)

2. Which three operations are needed at every station of plane tabling?
   A. Levelling, focusing and parallax removal
   B. Levelling, centring and orientation
   C. Centring, booking and reduction
   D. Orientation, traversing and closing
   Answer: B. Levelling keeps the board horizontal, centring puts the sheet point over the ground station, and orientation keeps all lines parallel to the ground. (Key point: Three requirements)

3. How is centring done in plane tabling?
   A. The spirit level is used to keep the board horizontal
   B. The board is turned until the needle floats at zero
   C. The plumbing fork and plumb bob keep the sheet point vertically above the ground station
   D. The alidade is placed along the plotted line
   Answer: C. Centring is achieved with the plumbing fork and plumb bob; the spirit level does levelling. (Key point: Centring)

4. Which is an advantage of plane table surveying?
   A. It gives very high accuracy for large areas
   B. It works well in rain and fog
   C. Field notes allow re-plotting to another scale
   D. Omissions and mistakes are detected on the spot because plotting is done in the field
   Answer: D. Plotting in the field lets the surveyor compare the plan with the ground immediately. (Key point: Advantage)

## Related in Surveying I

- [Plane and geodetic surveying; principles](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aplane-geodetic-and-principles) — Surveying I, chapter 1, asked 7×
- [Plane table principles; orientation by back sighting](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aorientation-back-sighting) — Surveying I, chapter 6, asked 4×
- [Principles of surveying with examples](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aprinciples-of-surveying) — Surveying I, chapter 1, asked 9×
- [Principles of surveying; scales used](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aprinciples-and-scales-used) — Surveying I, chapter 1
- [Plane versus geodetic surveying](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aplane-vs-geodetic-surveying) — Surveying I, chapter 1, asked 5×
- [Objectives of surveying; plane vs geodetic](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aobjectives-plane-geodetic) — Surveying I, chapter 1

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- [In-plane, out-of-plane failure and remedial measures](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ain-plane-out-of-plane-remedial) — Concrete Technology and Masonry Structure, chapter 9
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