Shipulski On Design

When planning a project, we usually start with a traditional left-to-right schedule. On the left is the project’s start date, where tasks are added sequentially rightward toward completion. When all the tasks are added and the precedence relationships shift tasks rightward, the completion date becomes known. No one likes the completion date, but it is what it is until we’re asked to pull it in.

I propose a different approach – a reverse schedule.  Instead of left to right, the reverse schedule moves right to left.  It starts with the completion date on the right and stacks tasks backward in time toward today. The start date emerges when all the tasks are added and precedence relationships work their magic.  Where the traditional schedule tells us when the project will finish, the reverse schedule tells us when we should start.  And, usually, the reverse schedule says we should have started several months ago and the project is already late.

There are some subtle benefits of the reverse schedule.  It’s difficult to game the schedule and reduce task duration to achieve a desired start date because the tasks are stacked backward in time. (Don’t believe me?  Give it a try and you’ll see.)  And because the task duration is respectful of the actual work content, the reverse schedule is more realistic.  And when there’s too much work in a reverse schedule, the tasks push their way into the past and no one can suggest we should go back in time and start the project three months ago.  And since the end date is fixed, we are forced to acknowledge there’s not enough time to do all the work.  The beauty of the reverse schedule is it can tell us the project is late BEFORE we start the project.

Here’s a rule: You want to know you’re late before it’s too late.

The real power of the reverse schedule is that it creates a sense of urgency around starting the project.  In the project planning phase, a delay of a week here and there is no big deal. But, when the start date slips a day, the completion date slips a day.  The reverse schedule clarifies the day-for-day slip and helps the resources move the project sooner so the project can start sooner.  And those of us who run projects for a living know this is a big deal.  What would you pay for an extra two weeks at the end of a project that’s two weeks behind schedule?  Well, if you started two weeks sooner, you wouldn’t need the extra time.

The project doesn’t start when the project schedule says it starts.  The project starts when the resources start working on the project in a full-time way.  The reverse schedule can create the sense of urgency needed to get the critical resources moved to the project so they can start the work on time.

Image credit — Steve Higgins

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