Critical Path Analysis Diagrams by Phoebe Barnett

Introduction

phoebe_mb — 2015-10-08 09:23:35 UTC

Critical path analysis shows the relationship between the different parts of the project. A large project is usually made up of many of interrelated smaller ones. CPA can be defined as 'The process of identifying how the tasks within a project fit together so that all tasks occur in a logical order with minimal delay and resourcing issues'. The analysis is based on the assumption that some tasks will be dependent on others and have to be completed prior to moving on.

CPA Theory

phoebe_mb — 2015-10-08 09:27:27 UTC

It is important that enough time is allocated to each project task to enable them to be completed before moving to the next dependent task(s). If enough time has not been allocated to a task or if that task is delayed, and no slack time has been built in, then the delivery of the project may be delayed.

CPA lets the project manager identify the critical path through a project (i.e. the order in which the component tasks have to be completed and, usually, the path that takes the maximum time).

CPA assists the project manager to analyse and plan the order in which tasks in a project should take place and to define by when they should be completed. By doing this, resources can be provisionally allocated. The project manager is, essentially, charting the path that must be taken to ensure that the project is successful.

Any task that is dependent on another being completed is called a dependent or sequential activity. A task that can happen at any time is called a non-dependent or parallel activity.

When developing the CPA the project manager should ensure that tasks are not scheduled before the earliest start date, or, if they are dependent tasks, before the completion of task(s) on which they are dependent. Most of the software-based project planning tools will have an automatic function that will check this.

Slack time, lead and lag, also needs to be built in so that any unforeseen issues do not lead to slippage of the completion date.

Creation

phoebe_mb — 2015-10-08 09:34:21 UTC

List all the tasks that need to be completed. For each task, show the earliest start date/the estimated time it will take to complete the task and if the task is dependent or non-dependent.
Set up a chart, with the total timescale across the top.
Plot the tasks, one per line, on the chart. Start each task at the earliest start and draw a solid horizontal line to show how long the task is expected to last. End each task with a dot labelling the duration line with the name of the task.
Link the dependent tasks.

Example

phoebe_mb — 2015-10-08 09:43:18 UTC