The Critical Path Method (CPM) is a project management technique used to identify the longest sequence of project activities, which dictates the shortest time to complete the project. Developed in the 1950s, CPM involves a series of steps including specifying activities, establishing dependencies, and estimating completion times, ultimately helping project managers to monitor progress and manage timelines effectively. While beneficial for planning and coordination, CPM relies on accurate estimates and may become complex with numerous activities.

1. Critical Path Method
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What is Critical Path??
• The sequence of project
activities which add up to the
longest overall duration.
• The critical path determines
the shortest time possible to
complete the project.

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What is Critical Path Method??
• Critical Path Method (CPM) is basically a step-by-
step Project Management technique that separates
planning and scheduling.
• It also clarifies the inter relationship of time and cost.
• CPM evaluates all the possible
alternative plans for project and
associates each plans with a
schedule.
• It is a mathematical based algorithm
for scheduling a set of project
activities.

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The origins of CPM
• The CPM was developed in the 1950s by Morgan R.
Walker of DuPont (Chemical Company) and James E.
Kelley Jr. of Remington Rand (Machines Manufacturer).
• It was first used in a missile-defense construction
project.
• Since that time, the CPM has been adapted to other
fields including hardware and software product
research and development.

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Where is it used??
And many more…
PROJECTS
Software Development
Construction
Aerospace & Defense
Research Projects
Product Development

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Why CPM is important??
• According to Dr. Larry Bennett (1978), the critical path
method also has three main benefits for project
managers. They are…
Identifies the Most
Important Tasks
Helps to Reduce Timelines
Compares Planned with
Actual

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Key Steps in the Critical Path Method...
• There are six key steps in the critical path method.
They are..
Specify Each Activity
Step 1
Draw the Network Diagram
Step 3
Establish Dependencies (Activity
Sequence)
Step 2
Update the Critical Path Diagram to
Show Progress Step 6
Identify the Critical Path Step 5
Estimate Activity Completion Time Step 4

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Key Steps in the Critical Path Method...
• Step 1 : Specify Each Activity
• The first step is to identify the main deliverables of a
project. Then you can start breaking down the high-
level activities into smaller chunks of work.

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Key Steps in the Critical Path Method...
• Step 2 : Establish Dependencies (Activity Sequence)
• Some activities will depend on the completion of
others. Listing the immediate predecessors of each
activity will help you identify the correct order.

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Key Steps in the Critical Path Method...
• Step 3 : Draw the Network Diagram
• Once you have identified the activities and their
dependencies, you can draw the critical path analysis
chart (CPA), known as the network diagram.

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Key Steps in the Critical Path Method...
• Step 4 : Estimate Activity Completion Time
• Using past experience or the knowledge of an
experienced team member, you must now estimate the
time required to complete each activity. If you are
managing a smaller project, you will most likely
estimate time in days. If you are working with a
complex project, you may have to measure time in
weeks.

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Key Steps in the Critical Path Method...
• Step 5 : Identify the Critical Path
• There are two ways you can now
identify the critical path.
1. You can eyeball your network diagram and
simply identify the longest path
throughout the network (in terms of
longest duration in days).
2. You can also identify critical activities with
the Forward Pass/Backward Pass
technique, identifying the earliest start
and finish times, and the latest start and
finish times for each activity.

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Key Steps in the Critical Path Method...
• Step 6 : Update the Critical Path Diagram to Show
Progress
• As the project progresses, you will learn the actual
activity completion times. The network diagram can
then be updated to include this information (rather
than continuing to use estimations).

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Terms Related to CPM
• Float(slack): It is the amount of time an activity can be
delayed without delaying the project.
• Crashing: Reducing a project’s duration is called
crashing.
• Critical activity: Activity with zero float.
• Resource leveling: It is an iterative process of assigning
crews to activities in order to calculate their duration.

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Terminologies of CPM
• Earliest Start Time (EST)
• Earliest Finish Time (EFT)
• Latest start time (LST)
• Latest Finish Time (LFT)
• The longest path of
planned activities to the
end of the project.
• The earliest and latest that
each activity can start and
finish without making the
project longer.
• We have to determine
“critical” activities.
• Crashing the critical path.
Need to find the following for each activity:

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Advantages of CPM
• Consistent framework for planning, scheduling, monitoring,
and controlling project.
• Helps proper communications between departments and
functions.
• Determines expected project completion date.
• Determines the dates on which tasks may be started or must be
started if the project is to stay in schedule.
• Shows which tasks must be coordinated to avoid resource or
timing conflicts.
• Shows which tasks may run in parallel to meet project
completion date.

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Disadvantages of CPM
• Reliability of CPM largely based on accurate estimates and
assumptions made.
• CPM does not guarantee the success of project.
• Resources may not actually be as flexible as management
hope when they come to address network float.
• Too many activities may the network diagram too
complicated.
• Activities might themselves have to be broken down into
mini projects.

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