Skip to content
Thinking in Diagrams

Swimlane diagram

Processes & experienceField guide · Processes & experience · 2 of 6

Who does each step, and where does work change hands?

On a swimlane diagram, the steps of a piece of work run left to right through horizontal bands, one for each party, each step in the band of whoever does it, so a line with an arrowhead that crosses into another band is the work changing hands.

Marks

Section titled “Marks”
MarkDrawn asStands forSource
lanea horizontal band between two ruled lines, its party’s name at the leftone function, department or roleRummler and Brache; Cymru
A lane on a swimlane diagram: a band between two ruled lines One lane, a band between two ruled lines, named at its left: teacher. In it, an oval: trip planned. teacher tripplanned
step, decision, start or enda box, a diamond with a question, or an oval, inside the lane of whoever does ita task; a question with one path out for each answer; where the process starts or endsCymru, step 3
An oval, a box and a diamond, each in its party's lane on a swimlane diagram Two lanes, one above the other, each named at its left. In the teacher's lane, an oval: trip planned, and a box: write the letter and form. In the school office's lane, a diamond: all forms back by the deadline? teacher schooloffice tripplanned write theletter andform all formsback by thedeadline?
the next stepa line with an arrowhead, crossing lanes where the work changes handsthe order of the work; across lanes, one party supplying its work to anotherRummler and Brache
The next step on a swimlane diagram: a line with an arrowhead, crossing lanes Two lanes, one above the other, each named at its left: teacher, school office. In the teacher's lane, a box: write the letter and form; its line with an arrowhead runs down into the school office's lane to a box: copy and send forms home. teacher schooloffice write theletter andform copy andsend formshome
a lane’s coloreach step colored by its laneoptional in the source; not in the figure, which is drawn in one colorCymru

A line with an arrowhead

Section titled “A line with an arrowhead”

A line with an arrowhead means then: the step at its head comes next, and where it crosses from one lane to another, the work changes hands. Rummler and Brache treat each crossing as a point where one function supplies another, and read the whole map for disconnects: steps that are missing, illogical or extra. Whereas an effect produces a change in the variable at its head, this line only orders two steps, so a path back to an earlier step is rework, the step done again, not a loop.

Section titled “Consent forms for a school trip”
Consent forms for a school trip, as a swimlane diagram Three lanes, one above another, each named at its left: teacher, school office, parent. Time runs left to right, and each step sits in the lane of whoever does it, joined to the next by a line with an arrowhead. In the teacher's lane, an oval: trip planned; its line runs right to a box: write the letter and form, whose line runs down into the school office's lane to a box: copy and send forms home, whose line runs down into the parent's lane to a box: read the letter. Its line runs right to a box: return the signed form, whose line runs right and up into the school office's lane to a diamond: all forms back by the deadline? Its line marked no runs left to a box: send a reminder, whose line runs down into the parent's lane and back into the box: return the signed form. The diamond's line marked yes runs right to a box: record consents, whose line runs up into the teacher's lane to an oval: trip list fixed. teacher schooloffice parent tripplanned write theletter andform copy andsend formshome read theletter return thesignedform all formsback by thedeadline? no send areminder yes recordconsents trip listfixed

The teacher’s letter and form go down to the school office to be copied and sent home, then to the parent to be read, signed and returned. Until every form is back by the deadline, the office sends reminders and the work goes round again. Five of the nine lines cross a lane, each a change of hands where a form can be lost or late.

When to draw one

Section titled “When to draw one”

Draw one where the work crosses departments or roles, as Rummler and Brache found most processes do, “spanning the ‘white space’ between the boxes on the organization chart”. A team draws the process as it is done now, its “is” map, then as it should be done, and agrees the second.

When not to draw one

Section titled “When not to draw one”

Work done wholly within one party, such as Rummler and Brache’s example of programming, crosses no lanes, and a process map orders its steps. Who answers for what, with no order of steps, is a table of roles against tasks, which Rummler and Brache call a role/responsibility matrix.

Reasoning and polish

Section titled “Reasoning and polish”
  • Reasoning4 of 5
  • Polish4 of 5‘is’ map → agreed ‘should’ map
  1. One path across two or three lanes
  2. Decisions, queues, systems, and return paths
  3. Times at each change of lane, disconnects marked, and the ‘should’ map beside the ‘is’ map
Section titled “Related types”
  • A swimlane diagram is a process map with a lane for each party that does part of the work.
  • BPMN’s swimlanes are of two kinds, a band for each participant and lanes within it, where a swimlane diagram has a lane for each party.

Sources

Section titled “Sources”
  • Geary A. Rummler and Alan P. Brache, The Process Level of Performance (Rummler-Brache Group), on the horizontal band for each function, the points where one function supplies another, disconnects, the “is” and “should” maps, processes within one function or across several, and the role/responsibility matrix.
  • Patricia A. Galagan, “Managing the White Space: The Work of Geary Rummler”, Training & Development, August 1992, pp. 26–30, on Rummler’s cross-functional process map.
  • Improvement Cymru Academy, Toolkit Guide: Swimlane Diagrams (NHS Wales, 2024), on a lane for each role, steps drawn as a flowchart’s shapes, and steps colored by lane or not.