---
title: "Sources of errors in chaining/taping"
subject: "Surveying I"
chapter: 2
key: "semester_3/surveying_i:errors-in-taping-sources-directions"
source: https://www.bctengineer.com/q/semester_3/surveying_i/errors-in-taping-sources-directions
site: BCT Engineering
---

# Sources of errors in chaining/taping

Surveying I · Chapter 2: Distance Measurements

- Asked in: 2080 Baisakh, 3 marks; 2076 Chaitra, 3 marks; 2076 Asoj, 2 marks; 2073 Shrawan, 4 marks (asked 4 times)
- Video: [10. Errors in chaining l Cumulative l Compensating l Surveying l Civil l GATE 2021 l English lecture](https://www.youtube.com/watch?v=RhlZqW1us9c) — The Civil Girl
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/surveying_i/errors-in-taping-sources-directions
- Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-2

## Question

Tabulate the various sources of errors occurring in chaining/taping with their directions (cumulative or compensating).

## Short answer

Incorrect tape length, temperature, sag, slope, poor alignment cause cumulative errors (measured too long/short). Marking, reading, plumbing variations are compensating (random). Blunders like miscounting are mistakes.

## Answer

Errors are classed as **cumulative (systematic)**, which keep the same sign and add up with the number of tape lengths, and **compensating (accidental)**, which are equally likely to be positive or negative and partly cancel out.

| Source of error | Cause | Effect on measured length | Type |
|---|---|---|---|
| Incorrect length of tape | Tape too long or too short compared with the standard | Too long tape: measured too short ($-$). Too short tape: measured too long ($+$) | Cumulative |
| Temperature variation | Field temperature differs from standard | $+$ or $-$ as temperature is lower or higher | Cumulative (compensating over a day if it varies) |
| Pull (tension) variation | Pull more or less than standard | $\pm$ | Cumulative if pull is always more/less, otherwise compensating |
| Sag | Tape hangs between supports | Measured too long ($+$) | Cumulative |
| Slope (not horizontal) | Tape held along the slope | Measured too long ($+$) | Cumulative |
| Poor alignment | Tape not in line between ends | Measured too long ($+$) | Cumulative |
| Bad straightening | Kinks, curves in tape | Measured too long ($+$) | Cumulative |
| Marking tape ends | Arrow placed slightly ahead or behind | $\pm$ | Compensating |
| Reading and plumbing | Wrong estimate of fractions, plumb bob swinging | $\pm$ | Compensating |
| Variation in pull in a short range | Hand tension changes | $\pm$ | Compensating |
| Wrong booking and miscounting | Mistake, not error | Large $\pm$ | Blunder (mistake) |

Cumulative errors are corrected by calculation; compensating errors are reduced by repeated measurements.

## Check yourself

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

1. What distinguishes a cumulative error?
   A. Equally likely + or - and cancels partly
   B. Same sign every time, so it adds up with the number of tape lengths
   C. Caused by carelessness
   D. Always zero
   Answer: B. Cumulative (systematic) errors keep their sign and accumulate; compensating errors partly cancel. (Key point: Cumulative vs compensating)

2. A tape that is too long gives a measured length that is
   A. Too long
   B. Too short
   C. Correct
   D. Random
   Answer: B. A longer tape covers more ground per reading, so the recorded number is too small. (Key point: Incorrect tape length)

3. A sagging tape makes the measured distance
   A. Too short
   B. Too long, a cumulative error
   C. Random, a compensating error
   D. Unaffected
   Answer: B. The tape hangs in a curve so a full tape length covers less horizontal ground, giving a measured value that is too long. (Key point: Sag effect)

4. Which of these is a compensating error?
   A. Marking tape ends slightly ahead or behind
   B. Sag
   C. Slope
   D. Wrong tape length
   Answer: A. Marking errors are equally likely in both directions and tend to cancel. (Key point: Compensating errors)

## Related in Surveying I

- [Types of errors in surveying](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Atypes-of-errors-surveying) — Surveying I, chapter 2, asked 3×
- [EDM operation principles and errors](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aedm-operation-and-errors) — Surveying I, chapter 2, asked 2×
- [Local attraction: errors and elimination](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Alocal-attraction-sources-elimination) — Surveying I, chapter 4

## Related in other subjects

- [Types and sources of measurement errors](https://www.bctengineer.com/question.md?key=semester_3%2Fmetrology%3Atypes-sources-of-errors) — Metrology, chapter 2