Before many projects have even begun, in the planning stages they are given an estimated completion time. This can help accurately determine how far along the project is as well as if it is ahead or behind schedule. Having an estimated completion time can help teams but they can also be a hinderance. “You can debate scope and cost overruns and make actual numbers appear closer to estimates, but once a project schedule is set, people remember the projected completion date, and anyone can quickly estimate schedule performance by subtracting the original time estimate from how long it really took to complete the project.” (Schwalbe, 2018, p. 242) Projects can see any number of unforeseen complications or issues that might not have been taken into account when estimating completion time during the planning stages. This creates an even larger dependency on project schedule management than might would normally be considered. There are several main processes involved in effective project schedule management:
1. Planning schedule management
2. Defining activities
3. Sequencing activities
4. Estimating activity durations
5. Developing the schedule
6. Controlling the schedule
We have discussed the first few in some of our other posts so today we’re going to be discussing the actual development of the schedule itself.
Development Methods
Developing a schedule relies on the effectiveness and accuracy of the steps before it. Obviously, the purpose of the developing the schedule is for it to be as accurate and reliable as possible as to give an accurate and reliable of a project timeframe as possible. This means that the schedule also needs to be as realistic as possible. Since all projects are unique, there is not a best approach that that is effective for every single type of project. There are, however, several popular approaches to developing schedules each with their pros and cons.
Gantt Charts
Gantt charts are a common way to help visualize a project’s schedule information because it utilizes a calendar structure to list project activities and their start and end dates. “The activities on the Gantt chart are driven by the deliverables on the WBS, and should coincide in turn with the activity list and milestone list.” (Schwalbe, p. 255) Below is a simple Gantt chart with several tasks and their corresponding timeframes. The bars represent the actual estimated length of the task while the arrows and lines show which task immediately follows and is dependent on the first tasks completion.
Obviously for most real-world corporate projects, these charts can become far more complex as there is more information to include in the chart. A special form of Gantt chart creates the ability to compare planned and actual project schedule information. This can serve as a visual reminder of any tasks that were completed before or after their expected completion date. In the chart below, the bars once again represent the length of the task but now they are broken up into planned and actual completion times. The percentages represent how much of the task is completed. The diamonds represent milestones for the project, white are milestones that were late.
Gantt charts are great for simpler projects or just to have as a visual aid for a project’s schedule. The main issue with Gantt charts is that they tend to not show relationships or dependencies between tasks. If these relationships are needed in the chart, then a network diagram might be more effective.
Critical Path Method
One common network diagram technique is the critical path method. “A critical path for a project is the series of activities that determine the earliest time by which the project can be completed. It is the longest path through the network diagram.” (Schwalbe, p. 259) Finding the critical path depends on creating a network diagram of all activities, their estimated completion times and their relationships to other activities. The longest path through the network is the critical path. Below is an example of a network diagram finding the critical path.
Why is it important to find the critical path in the first place? Since the critical path is the longest path through the project, it is the quickest timeframe that the project can be completed in since the project is not complete until all activities are finished. It’s important that teams and managers on the project know and understand the critical path to know when to change scheduling if needed. “A technique that can help project managers make schedule trade-offs is determining the free slack and total slack for each project activity. Free slack or free float is the amount of time an activity can be delayed without delaying the early start date of any immediately following activities. The early start date is the earliest possible time an activity can start based on the project network logic. Total slack or total float is the amount of time an activity can be delayed from its early start without delaying the planned project finish date.”(Schwalbe, p. 261) Being aware of all of this information regarding the project is important for management to effective guide and manipulate the schedule when needed to ensure the earliest completion time for the project.
While both of these techniques are useful most corporate projects are complex enough to utilize network diagrams and the critical path method. While this method is effective in determining and keeping up with the earliest completion time for the project, Gantt charts tend to be easier to visually summarize the project. All projects are unique though so feel free to experiment with either of these methods on with your next project.
Bibliography
Schwalbe, K. (2018). Information Technology Project Management. Boston: Cengage.