Swimlane Diagram – Definitions, Uses, Examples

What Is a Swimlane Diagram?

A swimlane diagram is a type of flowchart that outlines who does what in a given process. Based on the analogy of lanes in a pool, a swimlane diagram places process steps within the horizontal or vertical “swimlanes” of a particular department, work group or employee, thus ensuring clarity and accountability. Highlighting connections and communications between these lanes, it can serve as an indicator of waste, redundancy and inefficiency in a process.

This kind of flowchart is also known as a cross-functional diagram (with swimlanes being called “functional bands”) or a Rummler-Brache diagram, after the authors who developed the first model. In 1990, Geary Rummler and Alan Brache documented the concept of swimlane diagrams in their work “Improved Processes”. The two built on the already existing multi-column process charts (a variation of the early flow process charts that appeared in the 1940s) to spell out processes which involve more than one unit or department.

Swimlanes (also written as “swim lanes”) represent a valuable element in process flow diagrams (PFDs), as well as in what’s called the Business Process Model and Notation (BPMN) and its software design counterpart – Unified Modeling Language (UML). They introduce parallel (vertical or horizontal) lines to group process steps by actor (which can be a department, work group, employee or even an information system). A swimlane diagram not only spells out processes designated to a specific actor, it also shows how different actors interact to keep a process rolling efficiently.

What Is the Purpose of a Swimlane Diagram?

Providing an easy-to-read representation of responsibilities within a process, a swimlane diagram can serve the following purposes:

• To communicate and highlight which process steps or sub-processes are assigned to a particular actor within an organization, thus helping everyone involved know who is doing what.

• To identify bottlenecks and other inefficiencies, which in turn helps detect redundancies between various lanes, duplicative steps, process delays or capacity constraints that can be later addressed and resolved. All this leads to increased performance and quality.

• To better structure a given process and account for evolving circumstances, such as staffing or technology changes.

• To provide a formal model of integrating processes between teams and departments, which results in clearer, more organized workflows on an ongoing basis.

Examples of Swimlane Diagrams

Given the various purposes that they can serve, swimlane diagrams have evolved to include several specific sub-types, such as:

Swimlane Activity Diagrams

– describing how activities are coordinated to create a workflow.

Swimlane Process Maps

– documenting a particular process based on scenario testing and what-if assessment.

Cross-functional Flow Charts

– showing how micro-processes are sequentially linked together in an operation, they describe the attributes of more complex processes; there are several types of cross-functional flow charts: the matrix, deployment and opportunity flow charts.