The Pros and Cons of Soft Dependencies

Andy Jordan is President of Roffensian Consulting S.A., a Roatan, Honduras-based management consulting firm with a comprehensive project management practice. Andy always appreciates feedback and discussion on the issues raised in his articles and can be reached at [email protected]. Andy's new book Risk Management for Project Driven Organizations is now available.

  New Practitioners   Scheduling  

Every project manager understands dependencies. There are three types:

• finish-to-start (FS)
• finish-to-finish (FF)
• start-to-start (SS)

Some would argue that there are also start-to finish dependencies, but I’ve never seen a “real” one; they are invariably misstated FS dependencies.

Most new PM training stops with that basic explanation of dependencies and then focuses on examples. Lead and lag are added to the mix to reflect when a task can start before (lead) or has to start after (lag) the FS, FF or SS event. And that’s pretty much it, at least in basic PM training.

But I don’t like leaving it there. I want to add in the idea of hard and soft dependencies. A hard FS dependency can be expressed as:

• Task B cannot begin until task A has finished.

But a soft version of the same dependency would be:

• Task B should not begin until task A has finished.

It’s not a definite, it’s a recommendation—and as such is open to interpretation. The ability to interpret those dependencies appropriately can make or break a project, so that’s what I want to explore.

Exploring soft dependencies
For me, soft dependencies represent an opportunity to recover from problems, or potentially to prevent problems from occurring. This particularly applies to the schedule of course, because dependencies are …

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