Planning and Scheduling Complex Mega Projects
Critical Path Analysis and PERT are two powerful statistical tools that help a company to schedule and manage complex business projects. They were initially developed by Booz Allen Hamilton and the U.S. Navy in the 1950s to control large defense projects, after that business experts started using them and have been used routinely since then. Like Gantt Charts, Critical Path Method (CPM) or the Critical Path Analysis (CPA) helps a company to plan all tasks that must be completed for the accomplishment of a project.
Critical Path Analysis Definition and Meaning
Critical Path Analysis can be defined as a project management technique that lays out all the activities needed to complete a particular task, the time which each activity will take to complete and the relationships between the activities. It help a company to predict whether a project can be completed on time, and can be also used to reorganize the a project before starting it as well as during progresses, to keep the project’s completion on track and ensure that deliverables are ready on time.
Critical Path Analysis and PERT both act as the basis for preparation of a schedule, and of resource planning for a project. During management of a project, both allow management or project manager to monitor achievement of project goals and objectives. By the help of these tools company or manager can see where remedial action needs to be taken to get a project back on course. Depending on project complexity of a project company may display its final project plan on a Gantt chart, Microsoft Project, other free project software, or an excel spreadsheet.
Advantages of Critical Path Analysis
Within the planning process it helps a company to develop and test project plan to ensure that it is appropriate and up to the mark. As I mentioned above that CPA formally identifies those tasks in a project which must be completed on time to be complete whole project on time. Company may also identify which tasks can be delayed if resource needs to be reallocated to catch up on missed or overrunning tasks. Another advantage of Critical Path Analysis is that it helps project manager or senior management to identify the minimum length of time needed to complete a specific project. If a company need to run an accelerated project, it helps company to identify which project steps or activities should be accelerate to complete the project within the available time.
How to Use the Tool
As it is mentioned in Gantt Charts, the obligatory concept behind Critical Path Analysis is that project team cannot start some activities until others are completed. These activities of a particular company projects need to be completed in a sequence (dependent activities), with each stage being more-or-less completed before the next stage can begin. These are called “sequential” or “linear” activities.
Other activities are not dependent on completion of each other. You can do these at any time before or after a particular stage is reached. These are non-dependent or ‘parallel’ tasks.
How to Drawing a Critical Path Analysis Chart?
A project manager can use the following steps to draw a CPA Chart:
Step 1. List all Key Activities in the Plan
As a project manager show the earliest start date for each activity, estimated time duration it will take, and whether it is sequential or parallel. If tasks are sequential, show which stage they depend on and which activities should complete first.
Step 2. Plot the Activities of Project as a Circle & Arrow Diagram
Critical Path Analyses use circle and arrow diagrams to present the activities of a project.
These circles show events within the particular project, such as the start and finish date of tasks. These circles are sometimes known as nodes. Arrow between two event circles represents the activity needed to complete that task. A description of the task or required time duration is written underneath the arrow. As a principle, all arrows run left to right. Arrows are also sometimes known as arcs.
An critical path analysis diagram is shown as below:
This diagram shows the start event (circle 1), and the completion of the ‘High Level Analysis’ task (circle 5). The arrow between all circles shows the activity of carrying out the High Level Analysis.
If one activity of a project cannot start until another has been completed, you need to start the arrow for the dependent activity at the completion event circle of the previous activity.
Example of Critical Path Analysis
Here the project activities of ‘Select Hardware’ & ‘Core Module Analysis’ cannot be started until ‘High Level Analysis’ has been completed by the project team. This diagram revealed a number of other important points:
- Within CPA, you have to show the activities by the numbers in the circles at each end. For instance, the task ‘Core Module Analysis’ would be called activity 2 to 3 and Select Hardware’ would be activity 2 to 9.
- Activities of project are not drawn to scale. In the above diagram above you can see that, activity high level analysis duration is 1 week long, core module analysis duration is 2 weeks long, and select hardware duration is 1 day long but directive arrows are all the same length.
- In the example above, you can notice a second number in the right hand quadrant of each circle. This number represents the beginning time for the next activity.
A different case is shown below
Here activity no 6 to 7 cannot start until the project team will not complete other four activities (11 to 6, 5 to 6, 4 to 6, and 8 to 6).
In the ‘critical path’ activities of a particular project must be very closely managed by project manager to ensure that activities are completed on time. If activities are de-tracked from critical path, immediate action should be taken by the project manager to get the project back on schedule. Otherwise the whole project will not complete within time.
‘Crash Action’
As a project manager if you find that your company need to complete a project earlier than your Critical Path Analysis says is possible. In this case you should to re-plan your project.
Project managers or top management always have number of options and would need to assess the impact of each alternative option on the project’s cost, quality and time required to complete it.
For example, management may increase resource (HR or financial) available for each project activity to reduce the required time for each activity but keep in mind that the impact of some of this would be insignificant and a more efficient way of doing this would be to look only at activities on the critical path.
For instance a project manager is working on a computer project which requires 8 weeks to complete, now if he hires two analysts for a required activity, this will reduce the time spin almost two week but meanwhile increase the project cost. And also additional time may need to be spent on preparing the other project team members to move with increased speed, coordinating tasks split between them, integrating their contributions, and communicating with them etc.
In some cases, if company or project manger shortening the original critical path of a project this may lead to a different series of activities becoming the critical path. For example if time spin for a particular activity reduced by availing increasing resources, some other activities would come onto the critical path.
If a project manager or management of the company use software tools like Microsoft Project, or Gantt Charts to create CPA Charts these will not only make it easy make to draw, but project manager or company management can also make modification of plans easier and provide facilities for monitoring progress of project against plans.
PERT (Program Evaluation & Review Technique)
The PERT stand for Project Evaluation and Review Technique, is a statistical tool which used in project management. This tool is designed to analyze and represent the tasks involved in completing a particular project. It is first developed in 1950s by the United States, and it is commonly used in combination with the critical path method (CPM).
PERT actually takes a slightly more skeptical view of time estimates made for each project task or activity. To use it, project manager or management needs to estimate the shortest possible time each activity of project will take, the most likely duration of time, and the longest time that might be taken if the particular activity of project takes longer than expected.
Management or manger can use the below formula to calculate the time to use for each project stage:
Shortest time + 4 x likely time + longest time
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This will helps the company or project manager to bias time estimates away from the unrealistically short time-scales normally assumed.
