CPM- Critical Path Method in Project Management.CPM is a Project Schedule Modeling technique. It manages both the time and cost of the project. CPM is commonly used in conjunction with the Program Evaluation and Review Technique (PERT).CPM aids in project planning, scheduling, and controlling.For bigger projects, CPM networks can be too complicated
2. Overview of lecture
O Introduction to CPM - Critical Path
Method
O Steps to use Critical Path Method
O CPM - Advantages
O CPM - Disadvantages
3. Introduction
O CPM stands for Critical Path Method.
O CPM is a project schedule modeling technique
developed by Mr. Morgan R. Walker and James E.
Kelly in the late 1950s.
O CPM is based on the estimation of the standard time
needed for execution of a activity.
O CPM manages the both time and cost of the project.
4. Introduction
O In this method, the critical path of the project is
established by identifying the critical activities of the
project.
O Critical activities are the activities whose total float value
is ‘0’.
O The Critical Path is the longest sequence of activities in a
project plan which must be completed on time for the
project to complete on due date.
O CPM is commonly used in conjunction with the Program
Evaluation and Review Technique (PERT).
6. Step 1
Identify activities based on WBS
O The WBS (Work Breakdown Structure), describes
deliverables, not activities. This is why all its components
are described using nouns or adjectives, not verbs.
O The CPM, however, focuses on activities described using
verbs.
O The first step of the CPM process, therefore, is to list all
the activities required to create deliverables at each level
of the WBS.
7. Step 1
Identify activities based on WBS
Figure- a
O This list of
activities as in
figure-a , will
form the
foundation of the
CPM
8. Step 2
Identify all dependencies
O Any project has two types of tasks.
O Tasks that depend on other tasks for their completion, i.e.
dependent tasks
O Tasks that are independent of others and can be done in
parallel to others, i.e. concurrent tasks
O The next step in the CPM process is to establish which of the
tasks are dependent and which are concurrent
9. Step 2
Identify all dependencies
O Go through the list of activities and identify which tasks each
depends on, and in what order, as follow:
O A list of dependent tasks is called an activity sequence.
These are used to figure out the critical path
10. Step 3
Create a network diagram
O Once you’ve identified all tasks and their dependencies, it’s
time to create a network diagram, also known as a critical
path analysis chart.
O This chart visualizes separate activity sequences and enables
you to map dependencies easily.
O To create it, make a list of all activity sequences.
O Create separate boxes for each task in the sequence.
11. Step 3
Create a network diagram
O Next, use arrows to identify dependencies between tasks
in each sequence, as follow:
12. Step 4
Estimate duration of each activity
O We first need to estimate the duration of each activity. The
activity sequence that takes the longest time would then be our
critical path.
O List the duration (t) of each activity next to its name in the
network diagram.
14. Step 5
Calculate the Critical Path
O In the network diagram, write down the start and end time of
each activity next to its box.
O The first activity in the sequence would have a start time
of ‘0’. Mark the Start Time to the left and End time to the right
of the first activity. (Usually, this would be 0). Its end-time would
be its duration.
O The second activity’s start time would be the end-time of the
first activity. Its end-time would be the start time + the duration.
15. Step 5
Calculate the Critical Path
O In this way now mark the Earliest Start (ES) time of each
activity. This is given by the largest number to the right of the
activity's immediate predecessor (i.e. its Earliest Finish time, or
EF).
O If the activity has two predecessors, the one with the later
EF time would give you the ES of the activity.
17. Finally
O The activity sequence with the longest duration would be your
critical path as shown below:
18. CPM - Advantages
O CPM shows a graphical view of the project.
O CPM helps the project manager in identifying the most
critical elements of the project.
O CPM provides demonstration of dependencies which helps
in the scheduling of individual activities
O CPM aids in project planning, scheduling, and controlling.
19. CPM - Disadvantages
O For bigger projects, CPM networks can be too
complicated.
O CPM also does not handle the scheduling of the resource
allocation.
O CPM does not consider resource dependencies.
O There is a chance of misusing float or slack in CPM
method.
