Critical path analysis

The Critical Path Method (CPM) and its development to probabilistic environment, the Program Evaluation and Review Technique (PERT) are the most common tools for predicting and managing different short time or long time projects.

Critical Path Analysis (CPA) is a project management tool that:

• Sets out all the individual activities that make up a larger project.
• Shows the order in which activities have to be undertaken.
• Shows which activities can only taken place once other activities have been completed.
• Shows which activities can be undertaken simultaneously, thereby reducing the overall time taken to complete the whole project.
• Shows when certain resources will be needed – for example, a crane to be hired for a building site.

In order to construct a CPA, it is necessary to estimate the elapsed time for each activity – that is the time taken from commencement to completion.
Then the CPA is drawn up a based on dependencies such as:

• The availability of labour and other resources
• Lead times for delivery of materials and other services
• Seasonal factors – such as dry weather required in a building project

Once the CPA is drawn up, it is possible to see the CRITICAL PATH itself – this is a route through the CPA, which has no spare time (called ‘FLOAT’ or ‘slack’) in any of the activities. In other words, if there is any delay to any of the activities on the critical path, the whole project will be delayed unless the firm makes other changes to bring the project back on track.
The total time along this critical path is also the minimum time in which the whole project can be completed.
Some branches on the CPA may have FLOAT, which means that there is some spare time available for these activities.


There is our group's CPA, and it's my work.

Reference:
http://tutor2u.net/business/production/critical-path-analysis.htm
http://www.powerhomebiz.com/vol114/engagement.htm