Chain Surveying MCQ with answer and solution

Concept

A compensating error can be plus or minus, so it tends to cancel out over many chain lengths.

Formula

Compensating error ∝ √n; Cumulative error ∝ n (n = number of chain lengths)

Step-by-step solution

1. Compensating error: it can be + or −, so errors partly cancel. 2. Cumulative error: it always has the same sign, so it adds up. 3. Careless holding and marking can make the length too long or too short, so it is compensating. 4. Sag, bad ranging and temperature change always act in one direction, so they are cumulative. 5. Answer is (A).

Explanation

Careless holding and marking of arrows is a random error. Sometimes the measured length is more and sometimes less, so the errors cancel each other over a long line. That is why it is a compensating error.

Why the other options are wrong

B: Sag always makes the measured length too long (positive cumulative error). C: Bad ranging always makes the measured length too long (positive cumulative error). D: A temperature change acts in one direction for the whole survey (cumulative error).

Shortcut

If the error can be both + and − (random human error), it is compensating. If it has a fixed sign, it is cumulative.

Common mistake

Students often think temperature error is compensating because temperature changes, but on a given day it acts in one direction.