--- title: "Field books and reference sketch" subject: "Surveying I" chapter: 3 key: "semester_3/surveying_i:field-book-chain-survey" source: https://www.bctengineer.com/q/semester_3/surveying_i/field-book-chain-survey site: BCT Engineering --- # Field books and reference sketch Surveying I · Chapter 3: Chain Survey - Asked in: 2075 Asoj, 4 marks; 2073 Shrawan, 4 marks (asked 2 times) - Video: [Field book in surveying |Rules of writing field book| single line and double line Field Book](https://www.youtube.com/watch?v=k4J3uw25X_4) — EASY CIVIL - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_3/surveying_i/field-book-chain-survey - Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-3 ## Question With neat sketches explain the types of field books in chain survey. What is the need of a reference sketch of stations? Explain with a sample page of a detailing field book and how offset values are measured and recorded in it. ## Short answer Field books are single-line (central line with offsets on sides) or double-line (two lines with chainage between, offsets outside). Reference sketches enable relocating stations if pegs are lost. Offsets are measured perpendicularly from the chain line; chainage is recorded on the line, offset length on left/right with a note. ## Answer #### Field book The field book is an oblong book (about 20 cm $\times$ 12 cm) in which measurements are recorded in the field. It must be kept neat, and entries must not be erased. The records are made **from the bottom of the page to the top**, so that the page follows the direction in which the line is chained. #### Types of field book 1. **Single-line field book:** A single red line in the middle of the page represents the chain line. The chainages are written on the line, and the offsets are written on both sides (left and right) of it. 2. **Double-line field book:** Two red lines run along the middle of the page, with a space between them. The chainages are written between these lines, and the left and right offsets are written outside them, with the details drawn. ```text Single line type | left offset | chainage | right offset | | 12 (fence)| 60 | | | | 45 | 5 (tree) | | | 0 A | | ``` #### Reference sketch of stations For each station, a small sketch (location sketch) is drawn showing its position, with distances to two or more permanent objects such as corners of buildings, trees or poles. **Need:** - The station can be found again if the peg is lost. - Stations can be re-established for checking or later work. - It records the name and location of the stations and lines. #### Sample page of a detailing book Chain line AB (booked upwards): | Left (m) | Chainage (m) | Right (m) | |---|---|---| | | 100 (B) | | | 8 (fence corner) | 85 | | | | 60 | 12 (tree) | | | 40 | 6 (road edge) | | 5 (well) | 20 | | | | 0 (A) | | #### How offsets are measured and recorded - The tape is stretched from the chain line to the object at right angles to the line (the perpendicular is set by cross-staff or optical square). - The chainage at the foot of the offset is read on the chain. - In the book, the chainage is written on the chain line and the offset length is written on the left or right side, with a short note (fence, tree, building) and a sketch. - For oblique offsets, the two tie lengths are recorded together with the chainages from which they were taken. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. In which direction are entries made in a chain survey field book? A. From the top of the page to the bottom B. From left to right only C. From the bottom of the page to the top D. From the middle outward Answer: C. Booking goes upward like the ground as the surveyor moves forward from the starting station. (Key point: Booking direction) 2. How does the single-line field book differ from the double-line type? A. It has no chain line B. It records only left offsets C. It is used for levelling D. Chainages are written on one red line with offsets on both sides, instead of between two red lines Answer: D. In the double-line book chainages sit between two lines; in the single-line book they sit on the line. (Key point: Single vs double line) 3. Why is a reference (location) sketch of each station made? A. So the station can be found again if the peg is lost B. To compute the area of the plot C. To measure the offsets D. To avoid ranging Answer: A. Distances to permanent objects allow the station to be re-established. (Key point: Need of reference sketch) 4. How are oblique offsets recorded? A. Only the angle is written B. The two tie lengths are written with the chainages they were taken from C. Only the longer length is written D. They are not booked Answer: B. A tie fixes the point from two measured lengths from two points on the line. (Key point: Oblique offsets in the book) ## Related in Surveying I - [Field book and obstacles in chain survey](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Afield-book-and-obstacles) — Surveying I, chapter 3 - [Factors for choosing stations; offset types](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Afactors-stations-and-offset-types) — Surveying I, chapter 3 - [Chain stations and lines; well-conditioned triangle](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Afactors-stations-well-conditioned-triangle) — Surveying I, chapter 3 - [Chain survey principle and operations](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Achain-principle-and-field-procedure) — Surveying I, chapter 3, asked 2× - [Obstacles in chain survey and remedies](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aobstacles-chain-survey) — Surveying I, chapter 3, asked 4× - [Principle of chain survey; types of offsets](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Achain-principle-and-offsets) — Surveying I, chapter 3 ## Related in other subjects - [APA reference page: book and newspaper article](https://www.bctengineer.com/question.md?key=semester_5%2Fcommunication_english%3Areference-page-apa-art-of-writing) — Communication English, chapter 4 - [MLA reference page and APA error correction](https://www.bctengineer.com/question.md?key=semester_5%2Fcommunication_english%3Areference-page-mla-art-of-storytelling) — Communication English, chapter 4 - [Importance of ductile detailing, sketches](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Aimportance-of-ductile-detailing-sketches) — Design of RCC Structure, chapter 12 - [Traverse field procedure between two known stations](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Atraverse-field-procedure-between-known-stations) — Surveying II, chapter 1