3.3.4 Critical Path Analysis

Critical path analysis

🔗 A tool that uses network analysis to help project managers handle complex and time-sensitive operations.

Function of the model

🔗 The model can be used to identify the most efficient way to complete risky and complex projects. The model must contain the following:

• A list of all activities required to complete the project.
• The time (duration) that each activity will take to complete.
• The dependencies between the activities. The process determines which activities are 'critical' (on the longest path) and which activities are 'total float' (can be delayed without making the project longer).

The 3 components of network analysis

How to construct the network diagram

Calculating EST

EST of Task A is 0 months, as there are no tasks before it.

EST of Task B is 2 months (EST of 1 + duration of A)

EST of Task C is 6 months (EST of 2 + duration of B)

EST of Task D is 8 months (EST of 3 + duration of C)

EST of Task E is 11 months (EST of 4 + duration of D). The duration of D is chosen rather than the duration of C. This is because when calculating the EST with a branch, the largest number out of the two is taken.

Calculating LFT

LFT is calculated by looking right to left on the network diagram.

LFT of Task G is 15, as there are no tasks after it.

LFT of Task F is 14 (LFT of 7 – duration of G)

LFT of Task D is 10 (LFT of 5 – duration of E). The duration of E is chosen rather than F. This is because when calculating LFT with a branch, the smallest value out of the two is taken.

LFT of Task C is 10 (LFT of 14 – duration of F)

Float

🔗 The duration of the activity can be extended or postponed but still allows the project to finish within the minimum time.

$$Formula: LFT – EST – Duration$$

Pros and Cons of CPA

Pros:

• Reduces risks and costs of a project.
• Helps identify which activities have 'float', therefore allows better resource allocation.
• Both are a decision-making and planning tool, which saves time and costs in making both.

Cons:

• Largely based on estimates and assumptions, which decreases reliability.
• Resources may not be as flexible as suggested by the diagram, making them harder to allocate from 'float activities.'
• Too many activities make the diagram too complicated. Takes time to make