CPM: What Do You Prefer?
January 11th, 2004 by HalOver a year ago I published a series of postings on the critical path method that produced all kinds of comments and emails from readers. I collected those postings into a two-page article that I published on this site as CPM: Fool Me Once, Fool Me Twice. Shortly thereafter, Greg Howell caught some article in ENR on CPM. It was the usual stuff about project managers just need to learn how to use the CPM tools. In an unpublished letter to the editor (with a copy to me) he replied this way:
"CPM is the tool for you if you believe what you know is more important than what you can learn, and if you prefer being "In Charge" to getting the project done, and if out-of-date plans are more useful than a team prepared for action."
Without promising the project is full of delay. That is waste. And it leads to more waste.
While I see what he is saying, and I think the phrasing is clever, many people might not get why he says it. Greg is indirectly pointing to the stasis of the use of the CPM tools. People don't have the habits or the inclination to keep the CPM schedules up-to-date. Little variations and missing task status can throw a CPM schedule out of whack. Soon people lose confidence and ignore the schedule.
Another key issue has to do with the authorization of work. The PMBoK® says something like, "Work is authorized by the schedule." Authorization is not the issue. Coordination among the team is the issue. Team members depend on the completion of work (prerequisites) so they can begin their work. But beginning work is the easy part. Other team members want to know when you will finish your work. They, just like you, want a promise. Without promising the project is full of delay. That is waste. And it leads to more waste.
Team members can make promises on the work they will perform informed by a CPM schedule. That would be wonderful. But we don't see that behavior. In fact, we see, as Greg so aptly puts it,
"The usual project meeting is a commitment-free zone." The CPM schedule is just one of the excuses for not doing what needs to be done."
What do you prefer? I don't know anyone who would identify with Greg's characterization. And teams need some guidance of overall sequence of work. Bob Huber, Scheduling Manager, The Boldt Company, suggests The Marriage of CPM and Lean Construction in his paper co-authored with Paul Reiser presented at last year's International Group for Lean Construction's 11th Conference. He urges people to use CPM at a high level rather than a detailed task level. Further detail is left to the people performing the work. The result is a CPM schedule that is easy to keep up-to-date and doesn't have swings in it from week to week. People will use that schedule.
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