Which of the following statements is INCORRECT about a total station?

Question

Question

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RRB JE CBT 2 (Civil Engineering) ReExam Official Paper (Held On: 04 Jun, 2025)

Height of collimation error exists when the optical axis of the theodolite is not exactly perpendicular to the telescope axis.
Circle graduation error can be eliminated by photo-etching the graduations onto a glass circle.
Horizontal collimation error and height of standards error can magnify each other
Horizontal collimation error is eliminated after checking the height of standards.

Answer 1

Explanation:

Total Station

A total station is an advanced surveying instrument that combines the functions of an electronic theodolite, electronic distance measurement (EDM), and microprocessor with a data collector.
It is used for measuring horizontal and vertical angles, distances, and elevations, and for automated data processing.
Accurate use requires attention to instrument errors, setup procedures, and calibration.

Horizontal Collimation Error

This occurs when the optical line of sight is not exactly perpendicular to the vertical axis of the instrument.
It causes errors in horizontal angle measurement.
The error cannot be corrected by adjusting the height of the standards (tripod/platform).
Correction is done through face left/face right observations or instrument calibration.

Height of Collimation Error

Also known as vertical collimation error, it is caused when the line of sight is not perpendicular to the horizontal axis (trunnion axis).
It affects vertical angle readings, especially in steep sighting situations.

Additional Information Circle Graduation Error

Refers to inaccuracies in the angular graduation markings on the horizontal and vertical circles.
In modern instruments, photo-etching on glass discs ensures precise, error-free graduations.
This method eliminates manual marking errors and improves long-term accuracy.

Combined Error Effects

Horizontal collimation error and height of standards error can interact, leading to magnified total angular error if not individually corrected.
These errors are independent, but if both are present, their combined effect can cause significant deviations in observations.