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TABLE 5.2 Finding a critical path

Task Start Date End Date Predecessor Duration in Days

A 10/6 10/8 None 3

B 10/9 10/10 A 2
C 10/9 10/18 A 10

D 10/11 10/25 B 15

E 10/19 10/21 C 3

Again refer to Figure 5.2 and Table 5.2. What happens to the critical path if you
eliminate Task E? Nothing changes, because the longest path (or the activities with the
longest durations that are in the same path or have the same predecessors) is still A-B-
D with 20 days. Path A-C-E has a duration of 16 days. If you eliminated Task B, the
critical path changes to 18 days, which is along the new path A-D.

For the exam, make certain you understand that the critical path is the
longest full path on the project. The simplest calculation you can use for the exam
is to add up the duration of each activity for each path on the project and
determine which one is the longest. It might be helpful to draw a network diagram
on your scrap paper so that you can more easily see which tasks are dependent on
each other and add up the durations of each path.

In addition to calculating the overall time to complete the project and identifying tasks

on the critical path, CPM provides other useful information. You will be able to
determine which tasks can start late or can take more time than planned without
impacting the project end date. During project execution, the project manager can use
this information to focus attention on the tasks that have the most impact on the
overall project completion date.

There are times when you complete the schedule, calculate the critical path, and find
that the duration of the project is unacceptable to the project stakeholders. If you find

yourself in that situation, you can use duration compression techniques to help shorten
the schedule. You’ll learn about those techniques next.

Duration Compression

What happens if your calculation of the total project duration is longer than your target
project completion date?

This is where duration compression scheduling techniques come into play. These
techniques can be used during planning to shorten the planned duration of the project

or during project execution to help resolve schedule slippage. The two duration
compression techniques are crashing and fast tracking. You’ll learn about both next.

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