---
title: "Short note: Swimlanes"
subject: "Object Oriented Analysis and Design"
chapter: 2
key: "semester_6/object_oriented_analysis_and_design:short-note-swimlanes"
source: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/short-note-swimlanes
site: BCT Engineering
---

# Short note: Swimlanes

Object Oriented Analysis and Design · Chapter 2: Object Oriented Analysis

- Asked in: 2069 Bhadra, 5 marks
- Video: [What is the use of swim lanes in activity diagram in uml in English.? Class=10:](https://www.youtube.com/watch?v=3kdIx7qvmOg) — DesignBox /Sabir Khan
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/short-note-swimlanes
- Whole chapter: https://www.bctengineer.com/md/semester_6/object_oriented_analysis_and_design/chapter-2

## Question

Write a short note on Swimlanes.

## Short answer

Swimlanes are partitions in UML activity diagrams that divide the workflow into lanes representing actors, departments, or roles. They show who performs each activity and the handover of work between parties. Lanes are separated by lines with names at top; activities placed in responsible lane, arrows cross lanes when work moves. They clarify responsibility, reveal bottlenecks, and aid business process modeling.

## Answer

**Swimlanes** (partitions) are a feature of the UML **activity diagram**. They divide the diagram into parallel vertical (or horizontal) lanes, each lane representing a person, department, role, class or system that is responsible for the activities placed in it.

#### Purpose
- Show **who does what** in a workflow.
- Show the hand-over of work between actors or organisational units.
- Combine the flow of control with responsibility, so a business process becomes easy to read.

#### Notation
Lanes are separated by vertical lines; the lane name is at the top. Activities (rounded boxes) are placed in the lane of the responsible party, and arrows cross lanes when the work moves from one party to another.

```text
 |  Customer  |   Clerk    |  Warehouse |
 |------------|------------|------------|
 |  (start)   |            |            |
 |    v       |            |            |
 | [Place     |            |            |
 |  order] ---|-> [Verify  |            |
 |            |   order] --|-> [Ship    |
 |            |            |   goods]   |
 | [Receive <-|------------|--- /       |
 |  goods]    |            |            |
 |  (end)     |            |            |
```

#### Advantages
Responsibility is clear, bottlenecks and unnecessary hand-offs show up, and the diagram is useful for business process modelling and for assigning activities to classes or departments.

## Check yourself

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

1. Swimlanes belong to which UML diagram?
   A. Class diagram
   B. Activity diagram
   C. Sequence diagram
   D. Deployment diagram
   Answer: B. They partition an activity diagram into lanes. (Key point: What swimlanes are)

2. What does each lane represent?
   A. A time interval
   B. A person, department, role, class or system responsible for the activities in it
   C. A data store
   D. A class attribute
   Answer: B. They show who does what in a workflow. (Key point: Purpose)

3. What does an arrow crossing lanes show?
   A. A decision
   B. Hand-over of work from one party to another
   C. End of the process
   D. An error
   Answer: B. This reveals hand-offs and bottlenecks. (Key point: Notation and benefit)