Q17. The type of surveying which requires the least office work is:
Correct Answer: B. Plane table surveying
📚 Detailed Explanation: Why Plane Table Surveying Requires Least Office Work
The volume of post-field office work in any survey method depends on how much data is collected in the field and how much computation and drafting must be done afterwards. Plane table surveying is unique in that the final map is produced directly on-site, making it the method with the least office work.
Why plane table surveying minimises office work:
In plane table surveying, observations and plotting are done simultaneously in the field. The alidade is used to draw rays directly on the drawing sheet while at the station, distances are scaled onto the rays immediately, and the map takes shape during the survey. When fieldwork is complete, the map is essentially finished — no further drafting or data plotting is required in the office. The only remaining office task may be inking, finishing, and labelling the sheet.
In plane table surveying, observations and plotting are done simultaneously in the field. The alidade is used to draw rays directly on the drawing sheet while at the station, distances are scaled onto the rays immediately, and the map takes shape during the survey. When fieldwork is complete, the map is essentially finished — no further drafting or data plotting is required in the office. The only remaining office task may be inking, finishing, and labelling the sheet.
Comparison of Office Work Required
| Surveying method | Field data collected | Office work needed |
|---|---|---|
| Plane table | Map plotted directly in field | Minimal — inking and finishing only |
| Tacheometry | Tachometric readings (staff intercept, vertical angle) | Calculation of distances and RLs, then plotting |
| Theodolite surveying | Horizontal and vertical angles, distances | Coordinate computation, traverse adjustment, then drafting |
| Trigonometrical levelling | Vertical angles from known stations | Trigonometric computation of heights, drafting contours |
Key Concepts for Students
- Plane table is a “field drawing” method: The distinguishing feature is that drawing and observation happen simultaneously in the field. No separate plotting session is needed because the map is already drawn by the time fieldwork ends. This is the exact reason it requires the least office work.
- Trade-off: weather dependency: The advantage of least office work comes at the cost of being weather-sensitive. Rain, wind, and humidity damage the drawing sheet and make field plotting impossible. All other methods collect numerical data that can be plotted in the shelter of an office regardless of field conditions.
- Tacheometry is sometimes confused with plane table: Tacheometry also allows rapid field data collection, but tachometric data (staff readings, angles) must be computed and plotted in the office. It does not produce an on-site map. Plane table surveying is therefore always preferred over tacheometry when the question is about “least office work.”