---
title: "Total station principle, importance and uses"
subject: "Surveying II"
chapter: 9
key: "semester_4/surveying_ii:total-station-principle-importance-uses"
source: https://www.bctengineer.com/q/semester_4/surveying_ii/total-station-principle-importance-uses
site: BCT Engineering
---

# Total station principle, importance and uses

Surveying II · Chapter 9: Total Station

- Asked in: 2069 Bhadra, 8 marks
- Video: [Total station full tutorial 2020 | Basics | Applications | Advantages and disadvantages | #civilogy](https://www.youtube.com/watch?v=xaQz-VBaHKU) — civilogy
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/surveying_ii/total-station-principle-importance-uses
- Whole chapter: https://www.bctengineer.com/md/semester_4/surveying_ii/chapter-9

## Question

Explain the working principle of total station. Write its importance and uses in surveying and mapping.

## Short answer

A total station merges an electronic theodolite, EDM, and microprocessor to measure angles and slope distance, compute horizontal distance (H=S cos α) and coordinates. Its importance is fast, accurate, single-instrument data capture with reduced booking errors. Uses include topographic survey, setting out, contour/DEM generation, and deformation monitoring.

## Answer

#### Working principle
A total station combines the angle measuring system of an electronic theodolite with an electromagnetic distance meter (EDM) and a microprocessor.

```text
      Prism <---- signal ----> Total station
        (R)      slope dist S      (T)
                 ^ V angle
                 |  H angle from reference
```

- **Angles:** the horizontal and vertical circles are coded glass circles read by an electronic sensor; the angle is displayed digitally.
- **Distance:** the EDM sends a modulated infrared or laser beam to a reflector, which returns it. The phase difference between the transmitted and returned signals gives the double-path distance $2S$, from which the slope distance $S$ is found.
- **Computation:** the microprocessor applies corrections and computes

$$
H = S\cos\alpha,\quad V = S\sin\alpha,\quad \Delta N = H\cos\theta,\quad \Delta E = H\sin\theta
$$

where $\alpha$ is the vertical angle (from horizontal) and $\theta$ is the azimuth of the line (horizontal direction measured from north). From the station coordinates, the coordinates $(N, E, Z)$ of the target are found and stored.

#### Importance
- A single instrument measures angles and distances, so field work is faster and there are fewer observation and booking errors.
- Gives results with high accuracy; computations are automatic.
- Data can be transferred directly to a computer, saving time in plotting and drawing.

#### Uses in surveying and mapping
- Topographic and detail surveys; traversing and control densification.
- Setting out of structures, roads and curves.
- Contour and DEM generation; area and volume computations.
- Deformation monitoring, as-built and cadastral surveys; mapping by direct input to CAD/GIS.

## Check yourself

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

1. How does the EDM find the slope distance?
   A. From the angle subtended at a staff
   B. By counting tape lengths
   C. From the phase difference between the transmitted and returned modulated beam, which gives the double path
   D. From the Doppler shift of satellite signals
   Answer: C. The beam travels to the reflector and back, so the phase difference gives twice the distance. (Key point: EDM distance principle)

2. How are angles read in a total station?
   A. Vernier scales read by microscope
   B. By a magnetic needle
   C. By a plumb bob and graduated arc
   D. Coded glass circles read by an electronic sensor and shown digitally
   Answer: D. The horizontal and vertical circles are coded glass circles read electronically. (Key point: Angle measurement)

3. With vertical angle α from horizontal and slope distance S, what is the horizontal distance?
   A. H = S cos α
   B. H = S sin α
   C. H = S tan α
   D. H = S / cos α
   Answer: A. H = S cos α and V = S sin α when α is measured from the horizontal. (Key point: Reduction formulae)

4. Why does a total station speed up work and reduce errors?
   A. It needs no set-up over the station
   B. One instrument measures angles and distances, computes automatically and transfers data to a computer
   C. It avoids all instrumental errors
   D. It works without a reflector at any distance
   Answer: B. A single instrument with automatic computation and storage reduces booking and plotting errors. (Key point: Importance)

## Related in Surveying II

- [Short note: Total station principle, data recording](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Atotal-station-principle-data-recording) — Surveying II, chapter 9
- [Short note: Total station features and uses](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Atotal-station-features-uses) — Surveying II, chapter 9, asked 18×
- [Tangential tacheometry, total station procedure](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Atangential-tacheometry-total-station-field-procedure) — Surveying II, chapter 2
- [Total station features and data recording steps](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Atotal-station-features-data-recording) — Surveying II, chapter 9
- [Total station, features, data recording points](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Atotal-station-features-recording-points) — Surveying II, chapter 9
- [GPS, components and working principle](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Agps-components-working-principle) — Surveying II, chapter 8, asked 19×

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- [Engineering surveying; two-way principle application](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aengineering-surveying-two-way-angle) — Surveying I, chapter 1
- [Principle of chain surveying; well-conditioned triangle](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Achain-principle-well-conditioned-vs-error) — Surveying I, chapter 3
- [Annual working cost of power station (a, b, c)](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Apower-station-annual-cost-abc) — Utilization of Electrical Energy, chapter 6