Accordions and Iron Bars

No this article is not about the challenges of trying to make a living playing accordion in the subways of New York while avoiding a trip to the local jail for panhandling (although any project manager with more than a few years of experience can spin tales of equal challenge). It’s about a critical attribute associated with the project schedule, which can help you in your planning activities as well as help others better understand one of the most basic yet significant of all project task attributes. That attribute is the ability of a task to flex and compress under the inevitable changes of the project.

Let’s begin with the most ubiquitous of all scheduling tools, the Gantt chart. Imagine the plan in three-dimensional space, magnified to the size of your project war room. There you are, standing in the middle of these long black bars, anchored at both ends—i.e., the task start- and end-dates. What you will notice is that some of these bars are big, heavy iron rods (Figure 1). If you put your shoulder up to one end (the start-date) of these solid bars and begin to push on it, the far end (the end-date) will move a distance equal to the amount that you have pushed. It is one of the basic laws of project physics. Start a week late and you finish a week late. These are the iron bars. They are not immovable objects since they can be moved, but their …