Introduction to project planning

1 – Tasks decomposition

The classic technique for project planning is to decompose the project works in tasks, define the estimated duration of each task, and define the precedence links between tasks (a task must be completed before other tasks).

From these data, the start date of project and project calendar information(days worked and not worked), we can calculate the start and end at the earliest for each task and the associated margins, and represent them in tables or charts (Gantt chart in general).

2 - Free margin and total margin, critical path

Classically two margins are calculated for each task:

• the free margin, it is the possible shift of a task without causing the shift of another task,
• the total margin, it is the possible shift of a task without causing shift of the end of the project.
• A task whose total margin is zero is called critical. The set of critical tasks is the critical path.

3 – Task characteristics

The task is the basic unit for planning and project management.

For project management a task is a set of project work for which we can define:

• a beginning and an end,
• a clear content,
• a unique responsible,
• inputs and outputs.

To make planning it will be estimated the expected duration for each task.

If we want information on workloads for the project and their distribution in time, it will also be assessed the workload of each task. If we want information on the resources (personnel and equipment) used by the project, it will also be assessed the resources required for each task.

4 - Monitoring the project

The realization of a project almost never meets the at the earliest schedule calculated initially. It is therefore desirable to update the schedule during the project to improve the estimation of tasks remaining to do and the at the earlier end date of the project. For this we can take in account the actual begin dates of started tasks, the actual dates of completion of tasks completed, improving the time estimates for tasks not completed in view of the experience, and thus establish a more realistic schedule for the future.