---
title: "Traverse and traverse computation process"
subject: "Surveying II"
chapter: 1
key: "semester_4/surveying_ii:traverse-computation-process"
source: https://www.bctengineer.com/q/semester_4/surveying_ii/traverse-computation-process
site: BCT Engineering
---

# Traverse and traverse computation process

Surveying II · Chapter 1: Traversing

- Asked in: 2065 Kartik (old course), 6 marks
- Video: [Traverse Calculations // Surveying](https://www.youtube.com/watch?v=mMDcODSe_ic) — engiNERDing
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/surveying_ii/traverse-computation-process
- Whole chapter: https://www.bctengineer.com/md/semester_4/surveying_ii/chapter-1

## Question

What is traverse? Explain in brief about traverse computation process.

## Short answer

A traverse is a series of connected lines measured in length and direction. Computation: adjust angles, compute bearings, latitudes and departures, find closing error, balance by Bowditch or transit rule, then compute independent coordinates, normally arranged in Gale's traverse table.

## Answer

A **traverse** is a series of connected survey lines whose lengths and directions (angles or bearings) are measured in the field. The ends of the lines are traverse stations.

#### Computation process
1. **Adjust the angles:** for a closed traverse the sum of interior angles must be $(2n-4)\times90^\circ$; distribute the error equally if it is small.
2. **Find bearings** of all lines from the known bearing of one line and the adjusted angles.
3. **Latitudes and departures:** $L\cos\theta$ and $L\sin\theta$ for each line.
4. **Closing error:** $e=\sqrt{(\Sigma\text{Lat})^2+(\Sigma\text{Dep})^2}$ and relative error $e/\Sigma L=1/N$; compare it with the allowable value.
5. **Balance the traverse** by Bowditch's rule (or transit rule) to get corrected latitudes and departures.
6. **Independent coordinates:** add the corrected latitudes and departures successively to the coordinates of the starting station.
7. **Final lengths and bearings** from the corrected quantities, then plot by coordinates.

All the steps are arranged in a Gale's traverse table.

#### Layout of Gale's traverse table
| Station | Angle (obs., adj.) | Line | Length | Bearing | Lat | Dep | Corrections | Adjusted Lat/Dep | N | E |
|---|---|---|---|---|---|---|---|---|---|---|

One row per station and line, so that angles, bearings, latitudes, departures, corrections and coordinates are tabulated in one place, with the sums checked at the foot of each column.

## Check yourself

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

1. The sum of interior angles of a closed traverse of n sides must be:
   A. (n - 2) x 180° only for open traverses
   B. (2n - 4) x 90°
   C. (2n + 4) x 90°
   D. n x 90°
   Answer: B. (2n - 4) x 90° is equal to (n - 2) x 180°; an error is distributed equally if small. (Key point: Angle check)

2. How is the closing error computed?
   A. e = sum Lat + sum Dep
   B. e = sum L / 2
   C. e = sqrt((sum Lat)^2 + (sum Dep)^2)
   D. e = difference between the longest and shortest line
   Answer: C. The closing error is the resultant of the unclosed latitude and departure sums. (Key point: Closing error)

3. Which is the correct order of steps?
   A. Coordinates, then latitudes, then angle adjustment
   B. Balance the traverse, then find bearings, then angles
   C. Latitudes and departures, then angle adjustment, then bearings
   D. Adjust angles, bearings, lat/dep, closing error, balance, coordinates
   Answer: D. Angles are balanced first, then bearings, lat/dep, closing error, balancing and finally coordinates. (Key point: Order of computation)

## Related in Surveying II

- [Steps of closed traverse computation](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Aclosed-traverse-computation-steps) — Surveying II, chapter 1
- [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
- [Closed loop/link traverse, misclosure balancing](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Aclosed-loop-link-traverse-angular-misclosure) — Surveying II, chapter 1

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