Project Scheduling: Dynamic Techniques

Dick Billows, PMP
Dick Billows, PMP

Project scheduling is not about developing and printing a schedule and then hanging it on the wall.  Good project schedulers their dynamic schedules daily to model options, assess alternatives and forecast completion dates and costs. Here’s how a good scheduler operates:

A stakeholder stops the project manager at the entrance to the cafeteria and says. “Sorry but I have some bad news for you.”

While listening, the project manager flips open his portable PC and opens the project to which this stakeholder is lending people.

“Oh, what’s happened?” The PM asks, scrolling to a list of the tasks to which this executive’s people are assigned.

I have to pull those three engineers off your project to work on something the marketing VP dumped in my lap.  I need them for 4 weeks.”

The PM scrolls down the list, finds the three engineers, changes their availability for the next 4 weeks to zero and clicks enter.  On the screen Gantt chart a lot bars turn red and shift to the right  (latter finishes). The PM says, as long as you’re talking to the Marketing VP you can tell her that her  tracking  system will be 6 weeks latter than currently scheduled.”

“Oh NO,” the stakeholder moans.

“Yup I’ll tell engineering and accounting about the delays you are causing on their deliverables.  You may hear from them.”

The stakeholder says, “Wait a minute, let me see  if there is another way.”

PM smiles

Dynamic project Scheduling

Successful project managers use dynamic project scheduling because it saves them significant amounts of time and lets them quickly model the impact of changes to resources, work or cost. Dynamic scheduling automatically recalculates the duration and budget for the project every time you make a change in the resources, hourly rates, hours of work and predecessor relationships.

Dynamic Project Scheduling Techniques

Many commercial scheduling software products allow for dynamic scheduling. But you must be aware of the critical elements required for the dynamic schedule to work.

Dynamic Scheduling Element #1 Predecessors

Your schedule must be based on the use of predecessor relationships between tasks, not the use of fixed start and finish dates. There are three primary kinds of predecessor relationships and the entire schedule must be built on these relationships. Predecessor Relationships

  • First is the finish-to-start predecessor relationship between tasks A and B. That tells the software that task B can’t start until task A has finished.
  • Second is the start-to-start predecessor relationship between tasks A and B. That tells the software that tasks A and B can start at the same time.
  • Third is the finish-to-finish predecessor relationship between tasks A and B. That tells the software that tasks A and B must finish on the same date, even though they may not start at the same time.

Dynamic Scheduling Element #2 Work Estimates

Your schedule must be based on work durations that are calculated from resource availability and work estimates. You enter the amount of work and the resource’s availability, that is, how many hours a day each resource can work. As an example, say there is 80 hours of work for a team member who works on the project half-time, or four hours a day. The software calculates the task duration as 25 working days because the half-time team member can only complete four hours of work a day.

Dynamic Scheduling to Track Work & Duration

You use dynamic scheduling with predecessor relationships an work estimates to track progress on the tasks in your project plan. As an example, you may specify a finish-to-finish predecessor relationship. That tells the project management software that you want to schedule two tasks and their resources so both tasks finish at the same time. When you  specify all your predecessor relationships, your project plan becomes a network of tasks, linked by the predecessor relationships. The result is often called a PERT (Program Evaluation and Review Technique) chart. It displays your project plan and its network of tasks.

We link each task bar to the project network.  That allows our dynamic scheduling to control the sequencing of tasks based on the predecessor relationships and the amount of work in the task.  It also give you early warning on problems.  Due dates just hide them until you get to them.