Schedule

In this article we will discuss project scheduling. Project schedule is such a big knowledge area, that makes it difficult to write a short article and cover the main facets of scheduling.

First and and most important area to discuss is why we need a schedule? What is its purpose? A project schedule provides visibility of the activities to be executed, overall visibility and prediction of project completion. In our experience, the main purpose of the schedule is to serve as a communication tool to be used by the stakeholders. It should contain all relevant information to enable the multiple departments to execute their scope according to the requirements.

There are two main scheduling software available in the market today: Primavera and MS-Project. Additionally there are ERP systems with scheduling capabilities integrated. All options have their unique benefits and shortfalls. All of them are able to help the project team to achieve the project goals and objectives. 

The selection of the scheduling software is just the first hurdle. After the software has been selected, more difficult definitions should take place, like what level of detail will be input in the schedule? If One decides to include everything, the schedule could end up having thousands of activities and consequently unmanageable. On the other hand, if the schedule is only a couple of dozen lines, it might not provide enough details for the stakeholders. The burning question is what is the best criteria to decide if a task should be added to the schedule or not? Would this criteria vary as the project matures? At the beginning of the project there are not many details available, as the project progresses more details are known and at the very end of the project, normally the project team needs to track very small and critical items that might prevent the project conclusion. Other hurdles are: decision if resources will be added; decision if project expenses will be tracked; are the activities going to use the same priority or not? If not, what is the criteria? and many more.

The schedule is intimately related to the work breakdown structure of the project. If you have not read our article where we discuss work breakdown structure, Click here. 

Now let's move on to predecessors and successors. Those are the intelligence of the schedule. They define the sequence of the activities. The project team should constantly review the predecessors and successors for every activity and make sure it is as accurate as possible. There is no harm in inserting multiple predecessors and successors for each task as nowadays the computational effort to calculate the schedule is not an issue anymore as the computers are very powerful. What is extremely important is that these connections are correct.

One important result of the schedule is the definition of the current critical path of the project. Critical path is the shortest duration possible of the project. Consequently any delay in one of the critical path activities will cause project delays. Conversely, it doesn't mean that an activity that is not in the critical path can not cause delays in the project. This specific activity that is getting late could use all float available for it and even more, impacting the project completion. Now you're asking yourself what is float? Float is the amount of time (normally expressed in days) between the activity completion date and the latest completion date that does not impact the project completion. It's important to highlight that the critical path is not fixed. It will vary as the project progresses.

The most common project monitoring tool is the "S-curve". The S-curve is a cumulative curve of project progress. Normally we plot a chart with the planned and actual S-curves to be able to visualize and monitor the project. Of course there are other methods to monitor progress.

The current scheduling software allows the user to track resources for the tasks, expenses, derive metrics like earned value, schedule performance index and many more.

The secret sauce of a good scheduler is the ability to implement the correct level of details and not over-complicate the schedule and controls. The project scheduling plan should be compatible with the project size, complexity, number of sites and other criterias. There are extensive literature and standards for scheduling. We strongly recommend you to get familiar with the main standards and read a few scheduling books.