How to label convergence of simultaneous tasks in PERT chart?

Question

I am trying to create a PERT chart to show the application of Agile to a certain workflow.

There is a node which diverges into 4 parallel edges/nodes, representing 4 tasks which are completed simultaneously.

The results from all 4 simultaneous tasks are then used in the next step, so 4 edges converge from 4 nodes into 1 node, which represents the next task/milestone.

However, since there are 4 edges coverging to 1 node, it's unclear to me as to how to label it. There's only 1 task being done in that next step, but I have 4 edges and each edge is supposed to be labeled.

Should I write the same thing 4 times? or only label 1 of the 4 edges?

Answer 1

Firstly, each edge is supposed to be labeled is not a rule carved in stone. Some use the merging node as the label.

Alternatively, you could label each of the 4 edges as integration or something similar.

Answer 2

With "Activity on Arrow", there should only be one node from which the four arrows are spawned, and then only one further node at which all four arrows terminate.

Please note:

1. Arrows do not need to be a single straight line.
2. Each arrow represents an activity - so if there are four activities, you need only have four arrows.
3. It sounds like you were thinking of having four separate dummy nodes, one at the end of each actual activity, each of which would then have a dummy activity arrow leading to the actual node at the termination of the four parallel activities.

These are unnecessary, as a) they're serving no logical purpose in the PERT network and b) the diagrammatic purpose they serve can be better carried out by having each of the non-dummy arrows made out of three straight lines: four lines that fan out from the first node; then four parallel lines; then four lines that converge on the second node.

You would then label the four parallel sections of the arrows with the four activity descriptions.