PERT: a lead time optimization project management tool



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Control project lead times by identifying task sequences. The PERT method was invented by the US Navy in the 1950s and uses a diagram to visualize task scheduling and planning. PERT stands for “Program Evaluation and Review Technique”. The diagram helps to optimize project management by providing greater visibility on different task sequences and interdependencies, resulting in better lead time control. The completed diagram highlights the critical path, i.e. all the tasks with no float or slack. This process helps teams plan for various scenarios and prioritize critical tasks as levers to shorten deadlines and deliver on time.

As a team, work out the most realistic lead time for each task required to implement the whole project.

The PERT method will guarantee optimal lead times and deadline compliance.

Use the PERT template to ask the following questions at the beginning of the project and answer them as a team. What tasks can be carried out simultaneously to save time? What stages of the project cannot begin until other stages have been completed? What tasks can be carried out in advance without affecting the rest of the project?

This is the ideal project management template. Before you start, get all the stakeholders together to design the diagram. Creating the diagram together will increase your overall visibility on task sequencing and planning. It will enable you to compare the ideal project end date with actual progress by monitoring task sequencing and completion. This graphic method is suitable for any project and can be adjusted as you go along. Anticipate possible obstacles and visualize progress in real-time. If you can’t meet a deadline, find solutions as a team to ensure project success.

Who invented the PERT method?

PERT, the “Program Evaluation and Review Technique”, was developed by the US Navy in 1958 to run the POLARIS project, which was designed to catch up with the USSR’s ballistic missile program. The project required rigorous planning and coordination because it entailed simultaneously delivering a submarine and the missile it was designed to launch. This huge project involved a massive number of people and tasks to be completed, which gave birth to the PERT method. Thanks to this method, the project was completed two years ahead of schedule, by optimizing the performance of coordinated tasks in a logical sequence, thus increasing the Navy’s engineering efficiency.

Why use the PERT project management method?

The PERT method is a project management tool used to optimize lead time control. It allows you to monitor project progress in real time and gives you a better overview of all the interrelated tasks and parallel implementation paths.

In project management, meeting deadlines is crucial as any overshoot may have financial consequences or harm your relationship with the project owners. Accurate planning is therefore paramount and you must be able to respond immediately to any problems that may arise.

The PERT diagram gives you an overarching view of all the tasks that can be carried out simultaneously. A project consists of a series of tasks that have to be carried out in a pre-determined sequence because they are all interrelated. They make up a task network. The nature of a project means that some tasks cannot start before others are completed.

The PERT diagram highlights a number of critical tasks. These are tasks that cannot be delayed without postponing the delivery date for the whole project because they have no “float”. This means that they represent a “critical path”. Project players may redirect certain financial, human or material resources to compensate for delays and meet the initial deadline.

How is the Klaxoon template used to create the PERT diagram?

Start building the diagram with the interdependent task table.  This involves listing all the project tasks and briefly describing each task. Each one represents one stage in the implementation of the project.

Then, as a team, identify the duration of each task in days and highlight the predecessor tasks, i.e. those that necessarily come before another task.   

Then build up your diagram by calculating all the earliest start dates for each task, and once this stage has been completed, calculate the latest start dates for the same tasks. Connect the different items easily with the connectors included in the Board. Both these calculations will reveal the “float” available for each task, i.e. how long task completion may be delayed without affecting the whole project.  There are two types of “float”:

 Total float: the delay allowed for each task without it affecting the project end date. If total float = 0, the task is critical and any delay will necessarily affect project delivery.
It is calculated as follows: latest start date for the following stage minus duration of the task minus earliest start date for the previous stage.

Free float: this means the delay allowed for a task without affecting the earliest start date for the following task.
It is calculated as follows: Earliest start date for the following stage minus duration of the task minus earliest start date for the previous stage.

Klaxoon’s PERT template means time savings and easier communication

The PERT method focuses on organizing, planning and coordinating task sequences to achieve better visibility on lead times and overall project progress. Klaxoon’s Board, the unlimited digital whiteboard, enables you to imagine an infinite number of scenarios. As the project progresses, team members can easily make changes and interact with other team members via the Questions tool, for instance.  If a problem arises, you can alert the team at any time by posting an idea or a question on the Board. The team will immediately receive a warning notice.

With the diagram on the Board, you can monitor, anticipate and respond more easily to delays or unexpected events. Reducing the unexpected is a major advantage in any project.

How to deal with overshoot  

Some tasks may take longer than expected without necessarily affecting the project end date, while other will definitely have an effect on lead times. The PERT method can be linked to the Critical Path method, which highlights all the tasks where delays will affect the whole project, therefore requiring particular attention.

When delays are unavoidable, you can use two methods to reorganize the task schedule.

The first is “fast-tracking” which means breaking the link between certain activities so they can be implemented in parallel.  

If this method doesn’t save enough time, “crashing” is another possible technique. This implies bringing in additional resources in order to increase productivity. This means calculating cost/time saving ratios.

Optimize you project management methods with other Klaxoon templates.  

Other templates in the Klaxoon library can help you optimize your project management methods.  The OKR method, for instance, can be used to clearly define objectives, while the RACI method facilitates task, role and responsibility allocation and Greenstorm allows you to monitor your project’s carbon footprint. Using these templates with the PERT template will make project management so much easier.

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